Who Cds Csr Eph 2002.12 Fre (Guia Da Such)- Ingles

WHO/CDS/CSR/EPH/2002.12

Prevention of hospital-acquired infectionsA practical guide2nd edition

World Health OrganizationDepartment of Communicable Disease,Surveillance and Response

This document has been downloaded from the WHO/CSR Web site. The original coverpages and lists of participants are not included. See http://www.who.int/emc for moreinformation.

World Health OrganizationThis document is not a formal publication of the World Health Organization (WHO), andall rights are reserved by the Organization. The document may, however, be freelyreviewed, abstracted, reproduced and translated, in part or in whole, but not for sale norfor use in conjunction with commercial purposes.

The views expressed in documents by named authors are solely the responsibility ofthose authors. The mention of specific companies or specific manufacturers' productsdoes no imply that they are endorsed or recommended by the World Health Organizationin preference to others of a similar nature that are not mentioned.

Prevention ofhospital-acquired

infectionsA PRACTICAL GUIDE

2nd edition

Editors

G. Ducel, Fondation Hygie, Geneva, Switzerland

J. Fabry, Universit Claude-Bernard, Lyon, France

L. Nicolle, University of Manitoba, Winnipeg, Canada

Contributors

R. Girard, Centre Hospitalier Lyon-Sud, Lyon, France

M. Perraud, Hpital Edouard Herriot, Lyon, France

A. Prss, World Health Organization, Geneva, Switzerland

A. Savey, Centre Hospitalier Lyon-Sud, Lyon, France

E. Tikhomirov, World Health Organization, Geneva, Switzerland

M. Thuriaux, World Health Organization, Geneva, Switzerland

P. Vanhems, Universit Claude Bernard, Lyon, France

WHO/CDS/CSR/EPH/2002.12DISTR: GENERAL

ORIGINAL: ENGLISH

WORLD HEALTH ORGANIZATION

Acknowledgements

The World Health Organization (WHO) wishes to acknowledge the significant support for this work from theUnited States Agency for International Development (USAID).

This document was developed following informal meetings of the editorial working group in Lyon and Ge-neva from 1997 to 2001.

The editors wish to acknowledge colleagues whose suggestions and remarks have been greatly appreciated:Professor Franz Daschner (Institute of Environmental Medicine and Hospital Epidemiology, Freiburg, Ger-many), Dr Scott Fridkin (Centers for Disease Control and Prevention, Atlanta, USA), Dr Bernardus Ganter(WHO Regional Office for Europe, Copenhagen, Denmark), Dr Yvan Hutin (Blood Safety and Clinical Technol-ogy, WHO, Geneva, Switzerland), Dr Sudarshan Kumari (WHO Regional Office for South-East Asia, New Delhi,India), Dr Lionel Pineau (Laboratoire Biotech-Germande, Marseille, France).

The editors would like to thank Brenda Desrosiers, Georges-Pierre Ducel and Penny Ward for their help inmanuscript preparation.

World Health Organization 2002

This document is not a formal publication of the World Health Organization (WHO), and all rights are reserved by theOrganization. The document may, however, be freely reviewed, abstracted, reproduced and translated, in part or in whole,but not for sale or for use in conjunction with commercial purposes.

The views expressed in documents by named authors are solely the responsibility of those authors.

The designations employed and the presentation of the material in this document, including tables and maps, do not implythe expression of any opinion whatsoever on the part of the secretariat of the World Health Organization concerning thelegal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers orboundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement.

The mention of specific companies or of certain manufacturers products does not imply that they are endorsed or recom-mended by WHO in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, thenames of proprietary products are distinguished by initial capital letters.

Designed by minimum graphicsPrinted in Malta

Contents

iii

Introduction 1

Chapter I. Epidemiology of nosocomial infections 4

1.1 Definitions of nosocomial infections 41.2 Nosocomial infection sites 5

1.2.1 Urinary infections 5

1.2.2 Surgical site infections 5

1.2.3 Nosocomial pneumonia 5

1.2.4 Nosocomial bacteraemia 6

1.2.5 Other nosocomial infections 6

1.3 Microorganisms 6

1.3.1 Bacteria 6

1.3.2 Viruses 6

1.3.3 Parasites and fungi 7

1.4 Reservoirs and transmission 7

Chapter II. Infection control programmes 9

2.1 National or regional programmes 9

2.2 Hospital programmes 9

2.2.1 Infection Control Committee 9

2.2.2 Infection control professionals (infection control team) 10

2.2.3 Infection control manual 10

2.3 Infection control responsibility 10

2.3.1 Role of hospital management 10

2.3.2 Role of the physician 10

2.3.3 Role of the microbiologist 11

2.3.4 Role of the hospital pharmacist 11

2.3.5 Role of the nursing staff 12

2.3.6 Role of the central sterilization service 12

2.3.7 Role of the food service 13

2.3.8 Role of the laundry service 13

2.3.9 Role of the housekeeping service 13

2.3.10 Role of maintenance 14

2.3.11 Role of the infection control team (hospital hygiene service) 14

Chapter III. Nosocomial infection surveillance 16

3.1 Objectives 16

3.2 Strategy 16

3.2.1 Implementation at the hospital level 17

3.2.2 Implementation at the network (regional or national) level 17

3.3 Methods 17

3.3.1 Prevalence study 18

3.3.2 Incidence study 18

3.3.3 Calculating rates 19

3.4 Organization for efficient surveillance 19

3.4.1 Data collection and analysis 20

3.4.2 Feedback/dissemination 23

3.4.3 Prevention and evaluation 23

3.5 Evaluation of the surveillance system 23

3.5.1 Evaluation of the surveillance strategy 23

3.5.2 Feedback evaluation 24

3.5.3 Validity/data quality 24

Chapter IV. Dealing with outbreaks 26

4.1 Identifying an outbreak 26

4.2 Investigating an outbreak 26

4.2.1 Planning the investigation 26

4.2.2 Case definition 26

4.2.3 Describing the outbreak 27

4.2.4 Suggesting and testing a hypothesis 27

4.2.5 Control measures and follow-up 28

4.2.6 Communication 28

Chapter V. Prevention of nosocomial infection 30

5.1 Risk stratification 30

5.2 Reducing person-to-person transmission 30

5.2.1 Hand decontamination 30

5.2.2 Personal hygiene 32

5.2.3 Clothing 32

5.2.4 Masks 33

5.2.5 Gloves 33

5.2.6 Safe injection practices 33

5.3 Preventing transmission from the environment 33

5.3.1 Cleaning of the hospital environment 33

5.3.2 Use of hot/superheated water 34

5.3.3 Disinfection of patient equipment 34

5.3.4 Sterilization 34

Chapter VI. Prevention of common endemic nosocomial infections 38

6.1 Urinary tract infections (UTI) 38

6.2 Surgical wound infections (surgical site infections) 39

iv

PREVENTION OF HOSPITAL-ACQUIRED INFECTIONS: A PRACTICAL GUIDE WHO/CDS/CSR/EPH/2002.12

6.2.1 Operating room environment 40

6.2.2 Operating room staff 40

6.2.3 Pre-intervention preparation of the patient 40

6.2.4 Antimicrobial prophylaxis 41

6.2.5 Surgical wound surveillance 41

6.3 Nosocomial respiratory infections 41

6.3.1 Ventilator-associated pneumonia in the intensive care unit 41

6.3.2 Medical units 41

6.3.3 Surgical units 41

6.3.4 Neurological patients with tracheostomy 41

6.4 Infections associated with intravascular lines 41

6.4.1 Peripheral vascular catheters 42

6.4.2 Central vascular catheters 42

6.4.3 Central vascular totally implanted catheters 42

Chapter VII. Infection control precautions in patient care 44

7.1 Practical aspects 44

7.1.1 Standard (routine) precautions 44

7.1.2 Additional precautions for specific modes of transmission 44

7.2 Antimicrobial-resistant microorganisms 45

Chapter VIII. Environment 47

8.1 Buildings 47

8.1.1 Planning for construction or renovation 47

8.1.2 Architectural segregation 47

8.1.3 Traffic flow 47

8.1.4 Materials 48

8.2 Air 48

8.2.1 Airborne contamination and transmission 48

8.2.2 Ventilation 48

8.2.3 Operating theatres 49

8.2.4 Ultra-clean air 49

8.3 Water 50

8.3.1 Drinking-water 50

8.3.2 Baths 50

8.3.3 Pharmaceutical (medical) water 51

8.3.4 Microbiological monitoring 51

8.4 Food 51

8.4.1 Agents of food poisoning and foodborne infections 52

8.4.2 Factors contributing to food poisoning 52

8.4.3 Prevention of food poisoning 52

8.5 Waste 53

8.5.1 Definition and classification 53

8.5.2 Handling, storage and transportation of health care waste 54

v

CONTENTS

Chapter lX. Antimicrobial use and antimicrobial resistance 56

9.1 Appropriate antimicrobial use 57

9.1.1 Therapy 57

9.1.2 Chemoprophylaxis 57

9.2 Antimicrobial resistance 57

9.2.1 MRSA (methicillin-resistant Staphylococcus aureus) 58

9.2.2 Enterococci 59

9.3 Antibiotic control policy 59

9.3.1 Antimicrobial Use Committee 59

9.3.2 Role of the microbiology laboratory 59

9.3.3 Monitoring antimicrobial use 60

Chapter X. Preventing infections of staff 61

10.1 Exposure to human immunodeficiency virus (HIV) 61

10.2 Exposure to hepatitis B virus 62

10.3 Exposure to hepatitis C virus 62

10.4 Neisseria meningitidis infection 62

10.5 Mycobacterium tuberculosis 62

10.6 Other infections 62

Annex 1. Suggested further reading 63

Annex 2. Internet resources 64

vi


1Anosocomial infection also called hospital-acquired infection can be defined as:An infection acquired in hospital by a patient who wasadmitted for a reason other than that infection (1). An in-fection occurring in a patient in a hospital or other healthcare facility in whom the infection was not present or incu-bating at the time of admission. This includes infectionsacquired in the hospital but appearing after discharge, andalso occupational infections among staff of the facility (2).

Patient care is provided in facilities which range fromhighly equipped clinics and technologically ad-vanced university hospitals to front-line units withonly basic facilities. Despite progress in public healthand hospital care, infections continue to develop inhospitalized patients, and may also affect hospitalstaff. Many factors promote infection among hospi-talized patients: decreased immunity among patients;the increasing variety of medical procedures andinvasive techniques creating potential routes ofinfection; and the transmission of drug-resistantbacteria among crowded hospital populations, wherepoor infection control practices may facilitate trans-mission.

Frequency of infection

Nosocomial infections occur worldwide and affectboth developed and resource-poor countries. Infec-tions acquired in health care settings are among themajor causes of death and increased morbidityamong hospitalized patients. They are a significantburden both for the patient and for public health. Aprevalence survey conducted under the auspices ofWHO in 55 hospitals of 14 countries representing4 WHO Regions (Europe, Eastern Mediterranean,South-East Asia and Western Pacific) showed anaverage of 8.7% of hospital patients had nosocomialinfections. At any time, over 1.4 million people world-wide suffer from infectious complications acquiredin hospital (3). The highest frequencies of nosoco-mial infections were reported from hospitals in the

Eastern Mediterranean and South-East Asia Regions(11.8 and 10.0% respectively), with a prevalence of7.7 and 9.0% respectively in the European and West-ern Pacific Regions (4).

The most frequent nosocomial infections are infec-tions of surgical wounds, urinary tract infections andlower respiratory tract infections. The WHO study,and others, have also shown that the highest preva-lence of nosocomial infections occurs in intensivecare units and in acute surgical and orthopaedicwards. Infection rates are higher among patients withincreased susceptibility because of old age, under-lying disease, or chemotherapy.

Impact of nosocomial infections

Hospital-acquired infections add to functional dis-ability and emotional stress of the patient and may,in some cases, lead to disabling conditions that re-duce the quality of life. Nosocomial infections arealso one of the leading causes of death (5). The eco-nomic costs are considerable (6,7). The increasedlength of stay for infected patients is the greatestcontributor to cost (8,9,10). One study (11) showedthat the overall increase in the duration of hospi-talization for patients with surgical wound infectionswas 8.2 days, ranging from 3 days for gynaecologyto 9.9 for general surgery and 19.8 for orthopaedicsurgery. Prolonged stay not only increases direct coststo patients or payers but also indirect costs due tolost work. The increased use of drugs, the need forisolation, and the use of additional laboratory andother diagnostic studies also contribute to costs.Hospital-acquired infections add to the imbalancebetween resource allocation for primary and sec-ondary health care by diverting scarce funds to themanagement of potentially preventable conditions.

The advancing age of patients admitted to healthcare settings, the greater prevalence of chronic dis-eases among admitted patients, and the increaseduse of diagnostic and therapeutic procedures which

Introduction


2

affect the host defences will provide continuingpressure on nosocomial infections in the future.Organisms causing nosocomial infections can betransmitted to the community through dischargedpatients, staff, and visitors. If organisms are multire-sistant, they may cause significant disease in thecommunity.

Factors influencing the development ofnosocomial infections

The microbial agent

The patient is exposed to a variety of microorgan-isms during hospitalization. Contact between thepatient and a microorganism does not by itself nec-essarily result in the development of clinical disease other factors influence the nature and frequencyof nosocomial infections. The likelihood of expo-sure leading to infection depends partly on the char-acteristics of the microorganisms, including resistanceto antimicrobial agents, intrinsic virulence, andamount (inoculum) of infective material.

Many different bacteria, viruses, fungi and parasitesmay cause nosocomial infections. Infections may becaused by a microorganism acquired from anotherperson in the hospital (cross-infection) or may becaused by the patients own flora (endogenous in-fection). Some organisms may be acquired from aninanimate object or substances recently contami-nated from another human source (environmentalinfection).

Before the introduction of basic hygienic practicesand antibiotics into medical practice, most hospitalinfections were due to pathogens of external origin(foodborne and airborne diseases, gas gangrene, teta-nus, etc.) or were caused by microorganisms notpresent in the normal flora of the patients (e.g. diph-theria, tuberculosis). Progress in the antibiotic treat-ment of bacterial infections has considerably reducedmortality from many infectious diseases. Most in-fections acquired in hospital today are caused bymicroorganisms which are common in the generalpopulation, in whom they cause no or milder dis-ease than among hospital patients (Staphylococcusaureus, coagulase-negative staphylococci, enterococci,Enterobacteriaceae).

Patient susceptibility

Important patient factors influencing acquisition ofinfection include age, immune status, underlying

disease, and diagnostic and therapeutic interventions.The extremes of life infancy and old age are as-sociated with a decreased resistance to infection.Patients with chronic disease such as malignant tu-mours, leukaemia, diabetes mellitus, renal failure,or the acquired immunodeficiency syndrome (AIDS)have an increased susceptibility to infections withopportunistic pathogens. The latter are infectionswith organism(s) that are normally innocuous, e.g.part of the normal bacterial flora in the human, butmay become pathogenic when the bodys immuno-logical defences are compromised. Immunosuppres-sive drugs or irradiation may lower resistance toinfection. Injuries to skin or mucous membranesbypass natural defence mechanisms. Malnutrition isalso a risk. Many modern diagnostic and therapeu-tic procedures, such as biopsies, endoscopic exami-nations, catheterization, intubation/ventilation andsuction and surgical procedures increase the risk ofinfection. Contaminated objects or substances maybe introduced directly into tissues or normally ster-ile sites such as the urinary tract and the lower res-piratory tract.

Environmental factors

Health care settings are an environment where bothinfected persons and persons at increased risk ofinfection congregate. Patients with infections or car-riers of pathogenic microorganisms admitted tohospital are potential sources of infection for pa-tients and staff. Patients who become infected in thehospital are a further source of infection. Crowdedconditions within the hospital, frequent transfers ofpatients from one unit to another, and concentra-tion of patients highly susceptible to infection in onearea (e.g. newborn infants, burn patients, intensivecare ) all contribute to the development of nosoco-mial infections. Microbial flora may contaminateobjects, devices, and materials which subsequentlycontact susceptible body sites of patients. In addi-tion, new infections associated with bacteria such aswaterborne bacteria (atypical mycobacteria) and/orviruses and parasites continue to be identified.

Bacterial resistance

Many patients receive antimicrobial drugs. Throughselection and exchange of genetic resistance elements,antibiotics promote the emergence of multidrug-resistant strains of bacteria; microorganisms in thenormal human flora sensitive to the given drug are

3suppressed, while resistant strains persist and maybecome endemic in the hospital. The widespread useof antimicrobials for therapy or prophylaxis (includ-ing topical) is the major determinant of resistance.Antimicrobial agents are, in some cases, becomingless effective because of resistance. As an antimicro-bial agent becomes widely used, bacteria resistantto this drug eventually emerge and may spread inthe health care setting. Many strains of pneumo-cocci, staphylococci, enterococci, and tuberculosis arecurrently resistant to most or all antimicrobials whichwere once effective. Multiresistant Klebsiella and Pseu-domonas aeruginosa are prevalent in many hospitals.This problem is particularly critical in developingcountries where more expensive second-line anti-biotics may not be available or affordable (12).

Nosocomial infections are widespread. They are im-portant contributors to morbidity and mortality. Theywill become even more important as a public healthproblem with increasing economic and human impactbecause of:

Increasing numbers and crowding of people.

More frequent impaired immunity (age, illness,treatments).

New microorganisms.

Increasing bacterial resistance to antibiotics (13).

Purpose of this manual

This manual has been developed to be a practical,basic, resource which may be used by individualswith an interest in nosocomial infections and theircontrol, as well as those who work in nosocomialinfection control in health care facilities. It is appli-cable to all facilities, but attempts to provide rationaland attainable recommendations for facilities withrelatively limited resources. The information shouldassist administrators, infection control personnel, andpatient care workers in such facilities in the initialdevelopment of a nosocomial infection control pro-gramme, including specific components of such pro-grammes. Additional reading in specific areas isprovided in the list of WHO relevant documents andinfection control texts at the end of the manual (An-nex 1), as well as relevant references in each chapter.

References

1. Ducel G et al. Guide pratique pour la lutte contrelinfection hospitalire. WHO/BAC/79.1.

2. Benenson AS. Control of communicable diseasesmanual, 16th edition. Washington, American Pub-lic Health Association, 1995.

3. Tikhomirov E. WHO Programme for the Controlof Hospital Infections. Chemiotherapia, 1987, 3:148151.

4. Mayon-White RT et al. An international surveyof the prevalence of hospital-acquired infection.J Hosp Infect, 1988, 11 (Supplement A):4348.

5. Ponce-de-Leon S. The needs of developing coun-tries and the resources required. J Hosp Infect, 1991,18 (Supplement):376381.

6. Plowman R et al. The socio-economic burden of hospi-tal-acquired infection. London, Public Health Labo-ratory Service and the London School of Hygieneand Tropical Medicine, 1999.

7. Wenzel RP. The economics of nosocomial infec-tions. J Hosp Infect 1995, 31:7987.

8. Pittet D, Taraara D, Wenzel RP. Nosocomial blood-stream infections in critically ill patients. Excesslength of stay, extra costs, and attributable mor-tality. JAMA, 1994, 271:15981601.

9. Kirkland KB et al. The impact of surgical-site in-fections in the 1990s: attributable mortality, ex-cess length of hospitalization and extra costs. InfectContr Hosp Epidemiol, 1999, 20:725730.

10. Wakefield DS et al. Cost of nosocomial infection:relative contributions of laboratory, antibiotic,and per diem cost in serious Staphylococcus aureusinfections. Amer J Infect Control, 1988, 16:185192.

11. Coella R et al. The cost of infection in surgicalpatients: a case study. J Hosp Infect, 1993, 25:239250.

12. Resources. In: Proceedings of the 3rd Decennial Inter-national Conference on Nosocomial Infections, PreventingNosocomial Infections. Progress in the 80s. Plans for the90s, Atlanta, Georgia, July 31August 3, 1990:30(abstract 63).

13. Ducel G. Les nouveaux risques infectieux.Futuribles, 1995, 203:532.

INTRODUCTION


4

CHAPTER I

Epidemiology ofnosocomial infections

Changes in health care delivery have resulted inshorter hospital stays and increased outpatient care.It has been suggested the term nosocomial infec-tions should encompass infections occurring inpatients receiving treatment in any health care set-ting. Infections acquired by staff or visitors to thehospital or other health care setting may also beconsidered nosocomial infections.

Simplified definitions may be helpful for somefacilities without access to full diagnostic techniques(17). The following table (Table 1) provides defini-tions for common infections that could be used forsurveys in facilities with limited access to sophisti-cated diagnostic techniques.

TABLE 1. Simplified criteria for surveillance ofnosocomial infections

Type of nosocomial Simplified criteriainfection

Surgical site infection Any purulent discharge, abscess, orspreading cellulitis at the surgicalsite during the month after theoperation

Urinary infection Positive urine culture(1 or 2 species) with at least105 bacteria/ml, with or withoutclinical symptoms

Respiratory infection Respiratory symptoms with atleast two of the following signsappearing during hospitalization: cough purulent sputum new infiltrate on chest

radiograph consistent withinfection

Vascular catheter Inflammation, lymphangitis orinfection purulent discharge at the insertion

site of the catheter

Septicaemia Fever or rigours and at least onepositive blood culture

Studies throughout the world document thatnosocomial infections are a major cause ofmorbidity and mortality (113). A high frequency ofnosocomial infections is evidence of a poor qualityof health service delivery, and leads to avoidablecosts. Many factors contribute to the frequency ofnosocomial infections: hospitalized patients areoften immunocompromised, they undergo invasiveexaminations and treatments, and patient care prac-tices and the hospital environment may facilitate thetransmission of microorganisms among patients. Theselective pressure of intense antibiotic use promotesantibiotic resistance. While progress in the preven-tion of nosocomial infections has been made, changesin medical practice continually present new oppor-tunities for development of infection. This chaptersummarizes the main characteristics of nosocomialinfections, based on our current understanding.

1.1 Definitions of nosocomial infections

Nosocomial infections, also called hospital-acquiredinfections, are infections acquired during hospitalcare which are not present or incubating at admis-sion. Infections occurring more than 48 hours afteradmission are usually considered nosocomial. Defi-nitions to identify nosocomial infections have beendeveloped for specific infection sites (e.g. urinary,pulmonary). These are derived from those publishedby the Centers for Diseases Control and Prevention(CDC) in the United States of America (14,15) or dur-ing international conferences (16) and are used forsurveillance of nosocomial infections. They are basedon clinical and biological criteria, and include ap-proximately 50 potential infection sites.

Nosocomial infections may also be considered eitherendemic or epidemic. Endemic infections are mostcommon. Epidemic infections occur during out-breaks, defined as an unusual increase above thebaseline of a specific infection or infecting organ-ism.

51.2 Nosocomial infection sites

An example of the distribution of sites of nosoco-mial infections is shown in Figure 1.

FIGURE 1. Sites of the most comon nosocomialinfections: distribution according to theFrench national prevalence survey (1996)*

organ spaces are identified separately. The infectionis usually acquired during the operation itself;either exogenously (e.g. from the air, medical equip-ment, surgeons and other staff), endogenously fromthe flora on the skin or in the operative site or, rarely,from blood used in surgery. The infecting microor-ganisms are variable, depending on the type andlocation of surgery, and antimicrobials received bythe patient. The main risk factor is the extent ofcontamination during the procedure (clean, clean-contaminated, contaminated, dirty), which is to alarge part dependent on the length of the operation,and the patients general condition (25). Other fac-tors include the quality of surgical technique, thepresence of foreign bodies including drains, the viru-lence of the microorganisms, concomitant infectionat other sites, the use of preoperative shaving, andthe experience of the surgical team.

1.2.3 Nosocomial pneumonia

Nosocomial pneumonia occurs in several differentpatient groups. The most important are patients onventilators in intensive care units, where the rateof pneumonia is 3% per day. There is a high case-fatality rate associated with ventilator-associatedpneumonia, although the attributable risk is diffi-cult to determine because patient comorbidity is sohigh. Microorganisms colonize the stomach, upperairway and bronchi, and cause infection in the lungs(pneumonia): they are often endogenous (digestivesystem or nose and throat), but may be exogenous,often from contaminated respiratory equipment.

The definition of pneumonia may be based on clini-cal and radiological criteria which are readily avail-able but non-specific: recent and progressiveradiological opacities of the pulmonary parenchyma,purulent sputum, and recent onset of fever. Diagno-sis is more specific when quantitative microbiologi-cal samples are obtained using specialized protectedbronchoscopy methods. Known risk factors forinfection include the type and duration of ventila-tion, the quality of respiratory care, severity of thepatients condition (organ failure), and previous useof antibiotics.

Apart from ventilator-associated pneumonia,patients with seizures or decreased level of con-sciousness are at risk for nosocomial infection, evenif not intubated. Viral bronchiolitis (respiratory syn-cytial virus, RSV) is common in childrens units, andinfluenza and secondary bacterial pneumonia mayoccur in institutions for the elderly. With highly

CHAPTER I. EPIDEMIOLOGY OF NOSOCOMIAL INFECTIONS

* Adapted fom Enqute nationale de prvalence des infections nosocomiales,1996. BEH, 1997, 36:161163.

1.2.1 Urinary infections

This is the most common nosocomial infection; 80%of infections are associated with the use of an ind-welling bladder catheter (1,2,3). Urinary infectionsare associated with less morbidity than other noso-comial infections, but can occasionally lead to bacter-aemia and death. Infections are usually defined bymicrobiological criteria: positive quantitative urineculture (105 microorganisms/ml, with a maximumof 2 isolated microbial species). The bacteria respon-sible arise from the gut flora, either normal (Escherichiacoli) or acquired in hospital (multiresistant Klebsiella).

1.2.2 Surgical site infections

Surgical site infections are also frequent: the inci-dence varies from 0.5 to 15% depending on the typeof operation and underlying patient status (18,19,20).These are a significant problem which limit the po-tential benefits of surgical interventions. The impacton hospital costs and postoperative length of stay(between 3 and 20 additional days) (21,22,23,24) isconsiderable.

The definition is mainly clinical: purulent dischargearound the wound or the insertion site of the drain,or spreading cellulitis from the wound. Infections ofthe surgical wound (whether above or below theaponeurosis), and deep infections of organs or

Urinary tract U

Lower respiratorytract R1Surgical

site S

Skin andsoft tissue SST

Respiratory tract(other) R2

Bacteraemia B

ENT/Eye E/E

Catheter site C

Othersites O

U

RIS

SST

R2

B

E/E

OC


6

immunocompromised patients, Legionella spp. andAspergillus pneumonia may occur. In countries witha high prevalence of tuberculosis, particularlymultiresistant strains, transmission in health caresettings may be an important problem.

1.2.4 Nosocomial bacteraemia

These infections represent a small proportion ofnosocomial infections (approximately 5%) but case-fatality rates are high more than 50% for somemicroorganisms. The incidence is increasing, particu-larly for certain organisms such as multiresistantcoagulase-negative Staphylococcus and Candida spp.Infection may occur at the skin entry site of theintravascular device, or in the subcutaneous path ofthe catheter (tunnel infection). Organisms coloniz-ing the catheter within the vessel may producebacteraemia without visible external infection. Theresident or transient cutaneous flora is the source ofinfection. The main risk factors are the length ofcatheterization, level of asepsis at insertion, andcontinuing catheter care.

1.2.5 Other nosocomial infections

These are the four most frequent and importantnosocomial infections, but there are many otherpotential sites of infection. For example:

Skin and soft tissue infections: open sores (ulcers,burns and bedsores) encourage bacterial coloni-zation and may lead to systemic infection.

Gastroenteritis is the most common nosocomialinfection in children, where rotavirus is a chiefpathogen: Clostridium difficile is the major cause ofnosocomial gastroenteritis in adults in developedcountries.

Sinusitis and other enteric infections, infectionsof the eye and conjunctiva.

Endometritis and other infections of the repro-ductive organs following childbirth.

1.3 Microorganisms

Many different pathogens may cause nosocomialinfections. The infecting organisms vary among dif-ferent patient populations, different health care set-tings, different facilities, and different countries.

1.3.1 Bacteria

These are the most common nosocomial pathogens.A distinction may be made between:

Commensal bacteria found in normal flora ofhealthy humans. These have a significant protec-tive role by preventing colonization by patho-genic microorganisms. Some commensal bacteriamay cause infection if the natural host is com-promised. For example, cutaneous coagulase-negative staphylococci cause intravascular lineinfection and intestinal Escherichia coli are the mostcommon cause of urinary infection.

Pathogenic bacteria have greater virulence, andcause infections (sporadic or epidemic) regardlessof host status. For example:

Anaerobic Gram-positive rods (e.g. Clostridium)cause gangrene.

Gram-positive bacteria: Staphylococcus aureus(cutaneous bacteria that colonize the skin andnose of both hospital staff and patients) causea wide variety of lung, bone, heart and blood-stream infections and are frequently resistantto antibiotics; beta-haemolytic streptococci arealso important.

Gram-negative bacteria: Enterobacteriacae (e.g.Escherichia coli, Proteus, Klebsiella, Enterobacter,Serratia marcescens), may colonize sites when thehost defences are compromised (catheter in-sertion, bladder catheter, cannula insertion)and cause serious infections (surgical site, lung,bacteraemia, peritoneum infection). They mayalso be highly resistant.

Gram-negative organisms such as Pseudomonasspp. are often isolated in water and dampareas. They may colonize the digestive tract ofhospitalized patients.

Selected other bacteria are a unique risk inhospitals. For instance, Legionella species maycause pneumonia (sporadic or endemic)through inhalation of aerosols containing con-taminated water (air conditioning, showers,therapeutic aerosols).

1.3.2 Viruses

There is the possibility of nosocomial transmissionof many viruses, including the hepatitis B and Cviruses (transfusions, dialysis, injections, endoscopy),respiratory syncytial virus (RSV), rotavirus, and

7enteroviruses (transmitted by hand-to-mouth con-tact and via the faecal-oral route). Other viruses suchas cytomegalovirus, HIV, Ebola, influenza viruses,herpes simplex virus, and varicella-zoster virus, mayalso be transmitted.

1.3.3 Parasites and fungi

Some parasites (e.g. Giardia lamblia) are transmittedeasily among adults or children. Many fungi andother parasites are opportunistic organisms andcause infections during extended antibiotic treatmentand severe immunosuppression (Candida albicans,Aspergillus spp., Cryptococcus neoformans, Cryptosporidium).These are a major cause of systemic infections amongimmunocompromised patients. Environmental con-tamination by airborne organisms such as Aspergil-lus spp. which originate in dust and soil is also aconcern, especially during hospital construction.

Sarcoptes scabies (scabies) is an ectoparasite which hasrepeatedly caused outbreaks in health care facilities.

1.4 Reservoirs and transmission

Bacteria that cause nosocomial infections can beacquired in several ways:

1. The permanent or transient flora of the patient(endogenous infection). Bacteria present in the nor-mal flora cause infection because of transmissionto sites outside the natural habitat (urinary tract),damage to tissue (wound) or inappropriate anti-biotic therapy that allows overgrowth (C. difficile,yeast spp.). For example, Gram-negative bacteriain the digestive tract frequently cause surgical siteinfections after abdominal surgery or urinary tractinfection in catheterized patients.

2. Flora from another patient or member of staff(exogenous cross-infection). Bacteria are transmittedbetween patients: (a) through direct contact be-tween patients (hands, saliva droplets or otherbody fluids), (b) in the air (droplets or dust con-taminated by a patients bacteria), (c) via staffcontaminated through patient care (hands, clothes,nose and throat) who become transient or per-manent carriers, subsequently transmitting bac-teria to other patients by direct contact duringcare, (d) via objects contaminated by the patient(including equipment), the staffs hands, visitorsor other environmental sources (e.g. water, otherfluids, food).

3. Flora from the health care environment (endemicor epidemic exogenous environmental infections). Severaltypes of microorganisms survive well in the hos-pital environment:

in water, damp areas, and occasionally in sterileproducts or disinfectants (Pseudomonas ,Acinetobacter, Mycobacterium)

in items such as linen, equipment and sup-plies used in care; appropriate housekeepingnormally limits the risk of bacteria survivingas most microorganisms require humid or hotconditions and nutrients to survive

in food

in fine dust and droplet nuclei generated bycoughing or speaking (bacteria smaller than10 m in diameter remain in the air for sev-eral hours and can be inhaled in the same wayas fine dust).

People are at the centre of the phenomenon:

as main reservoir and source of microorganisms

as main transmitter, notably during treatment

as receptor for microorganisms, thus becoming anew reservoir.

References

1. Mayon-White R et al. An international survey ofthe prevalence of hospital-acquired infection.J Hosp Infect, 1988, 11 (suppl A):4348.

2. Emmerson AM et al. The second national preva-lence survey of infection in hospitals overviewof the results. J Hosp Infect, 1996, 32:175190.

3. Enqute nationale de prvalence des infectionsnosocomiales. MaiJuin 1996. Comit techniquenational des infections nosocomiales. Bulletinpidmiologique Hebdomadaire, 1997, No 36.

4. Gastmeier P et al. Prevalence of nosocomial in-fections in representative German hospitals. J HospInfect, 1998, 38:3749.

5. Vasque J, Rossello J, Arribas JL. Prevalence ofnosocomial infections in Spain: EPINE study19901997. EPINE Working Group. J Hosp Infect,1999, 43 Suppl:S105S111.

CHAPTER I. EPIDEMIOLOGY OF NOSOCOMIAL INFECTIONS


8

6. Danchaivijitr S, Tangtrakool T, Chokloikaew S. Thesecond Thai national prevalence study on noso-comial infections 1992. J Med Assoc Thai, 1995, 78Suppl 2:S67S72.

7. Kim JM et al. Multicentre surveillance study fornosocomial infections in major hospitals inKorea. Am J Infect Control, 2000, 28:454458.

8. Raymond J, Aujard Y, European Study Group.Nosocomial Infections in Pediatric Patients: AEuropean, Multicenter Prospective Study. InfectControl Hosp Epidemiol, 2000, 21:260263.

9. Pittet D et al. Prevalence and risk factors for no-socomial infections in four university hospitalsin Switzerland. Infect Control Hosp Epidemiol, 1999,20:3742.

10. Gikas A et al. Repeated multi-centre prevalencesurveys of hospital-acquired infection in Greekhospitals. J Hosp Infect, 1999, 41:1118.

11. Scheel O, Stormark M. National prevalence sur-vey in hospital infections in Norway. J Hosp Infect,1999, 41:331335.

12. Valinteliene R, Jurkuvenas V, Jepsen OB. Preva-lence of hospital-acquired infection in a Lithua-nian hospital. J Hosp Infect, 1996, 34:321329.

13. Orrett FA, Brooks PJ, Richardson EG. Nosocomialinfections in a rural regional hospital in a devel-oping country: infection rates by site, service, cost,and infection control practices. Infect Control HospEpidemiol, 1998, 19:136140.

14. Garner JS et al. CDC definitions for nosocomialinfections, 1988. Am J Infect Control, 1988, 16:128140.

15. Horan TC et al. CDC definitions of nosocomialsurgical site infections, 1992: a modification ofCDC definition of surgical wound infections. AmJ Infect Control, 1992, 13:606608.

16. McGeer A et al. Definitions of infection for sur-veillance in long-term care facilities. Am J InfectControl, 1991, 19:17.

17. Girard R. Guide technique dhygine hospitalire. Alger,Institut de la Sant publique et Lyon, FondationMarace Mrieux, 1990.

18. Cruse PJE, Ford R. The epidemiology of woundinfection. A 10 year prospective study of 62,939wounds. Surg Clin North Am, 1980, 60:2740.

19. Horan TC et al. Nosocomial infections in surgicalpatients in the United States, 19861992 (NNIS).Infect Control Hosp Epidemiol, 1993, 14:7380.

20. Hajjar J et al. Rseau ISO Sud-Est: un an de sur-veillance des infections du site opratoire. Bulle-tin pidmiologique Hebdomadaire, 1996, No 42.

21. Brachman PS et al. Nosocomial surgical infec-tions: incidence and cost. Surg Clin North Am, 1980,60:1525.

22. Fabry J et al. Cost of nosocomial infections: analy-sis of 512 digestive surgery patients. World J Surg,1982, 6:362365.

23. Prabhakar P et al. Nosocomial surgical infections:incidence and cost in a developing country. Am JInfect Control, 1983, 11:5156.

24. Kirkland KB et al. The impact of surgical-site in-fections in the 1990s: attributable mortality, ex-cess length of hospitalization and extra costs. InfectControl Hosp Epidemiol, 1999, 20:725730.

25. Nosocomial infections rates for interhospital com-parison: limitations and possible solutions Areport from NNIS System. Infect Control HospEpidemiol, 1991, 12:609621.

9CHAPTER II

Infection control programmes

Professional and academic organizations must alsobe involved in this programme.

2.2 Hospital programmes

The major preventive effort should be focused inhospitals and other health care facilities (2). Risk pre-vention for patients and staff is a concern of every-one in the facility, and must be supported at thelevel of senior administration. A yearly work plan toassess and promote good health care, appropriateisolation, sterilization, and other practices, staff train-ing, and epidemiological surveillance should be de-veloped. Hospitals must provide sufficient resourcesto support this programme.

2.2.1 Infection Control Committee

An Infection Control Committee provides a forumfor multidisciplinary input and cooperation, andinformation sharing. This committee should includewide representation from relevant programmes: e.g.management, physicians, other health care workers,clinical microbiology, pharmacy, central supply,maintenance, housekeeping, training services. Thecommittee must have a reporting relationshipdirectly to either administration or the medical staffto promote programme visibility and effectiveness.In an emergency (such as an outbreak), this com-mittee must be able to meet promptly. It has thefollowing tasks:

to review and approve a yearly programme ofactivity for surveillance and prevention

to review epidemiological surveillance data andidentify areas for intervention

to assess and promote improved practice at alllevels of the health facility

to ensure appropriate staff training in infectioncontrol and safety

Prevention of nosocomial infections is the respon-sibility of all individuals and services providinghealth care. Everyone must work cooperatively toreduce the risk of infection for patients and staff.This includes personnel providing direct patient care,management, physical plant, provision of materialsand products, and training of health workers. Infec-tion control programmes (1) are effective providedthey are comprehensive and include surveillance andprevention activities, as well as staff training. Theremust also be effective support at the national andregional levels.

2.1 National or regional programmes

The responsible health authority should develop anational (or regional) programme to support hospi-tals in reducing the risk of nosocomial infections.Such programmes must:

set relevant national objectives consistent withother national health care objectives

develop and continually update guidelines forrecommended health care surveillance, preven-tion, and practice

develop a national system to monitor selectedinfections and assess the effectiveness of inter-ventions

harmonize initial and continuing training pro-grammes for health care professionals

facilitate access to materials and products essen-tial for hygiene and safety

encourage health care establishments to monitornosocomial infections, with feedback to the pro-fessionals concerned.

The health authority should designate an agency tooversee the programme (a ministerial department,institution or other body), and plan national activi-ties with the help of a national expert committee.


10

to review risks associated with new technologies,and monitor infectious risks of new devices andproducts, prior to their approval for use

to review and provide input into investigation ofepidemics

to communicate and cooperate with other com-mittees of the hospital with common interests suchas Pharmacy and Therapeutics or AntimicrobialUse Committee, Biosafety or Health and SafetyCommittees, and Blood Transfusion Committee.

2.2.2 Infection control professionals (infectioncontrol team)

Health care establishments must have access to spe-cialists in infection control, epidemiology, andinfectious disease including infection control physi-cians and infection control practitioners (usuallynurses) (2). In some countries, these professionals arespecialized teams working for a hospital or a groupof health care establishments; they may be admin-istratively part of another unit, (e.g. microbiologylaboratory, medical or nursing administration, pub-lic health services). The optimal structure will varywith the type, needs, and resources of the facility.The reporting structure must, however, ensure theinfection control team has appropriate authority tomanage an effective infection control programme.In large facilities, this will usually mean a direct re-porting relationship with senior administration.

The infection control team or individual is respon-sible for the day-to-day functions of infection con-trol, as well as preparing the yearly work plan forreview by the infection control committee and ad-ministration. These individuals have a scientific andtechnical support role: e.g. surveillance and research,developing and assessing policies and practicalsupervision, evaluation of material and products,control of sterilization and disinfection, implemen-tation of training programmes. They should alsosupport and participate in research and assessmentprogrammes at the national and internationallevels.

2.2.3 Infection control manual

A nosocomial infection prevention manual (3), com-piling recommended instructions and practices forpatient care, is an important tool. The manual shouldbe developed and updated by the infection controlteam, with review and approval by the committee.

It must be made readily available for patient carestaff, and updated in a timely fashion.

2.3 Infection control responsibility

2.3.1 Role of hospital management

The administration and/or medical management ofthe hospital must provide leadership by supportingthe hospital infection programme. They are respon-sible for:

establishing a multidisciplinary Infection ControlCommittee

identifying appropriate resources for a programmeto monitor infections and apply the most appro-priate methods for preventing infection

ensuring education and training of all staffthrough support of programmes on the preven-tion of infection in disinfection and sterilizationtechniques

delegating technical aspects of hospital hygieneto appropriate staff, such as:

nursing

housekeeping

maintenance

clinical microbiology laboratory

periodically reviewing the status of nosocomialinfections and effectiveness of interventions tocontain them

reviewing, approving, and implementing policiesapproved by the Infection Control Committee

ensuring the infection control team has authorityto facilitate appropriate programme function

participating in outbreak investigation.

2.3.2 Role of the physician

Physicians have unique responsibilities for the pre-vention and control of hospital infections:

by providing direct patient care using practiceswhich minimize infection

by following appropriate practice of hygiene(e.g. handwashing, isolation)

serving on the Infection Control Committee

supporting the infection control team.

11

Specifically, physicians are responsible for:

protecting their own patients from other infectedpatients and from hospital staff who may be in-fected

complying with the practices approved by theInfection Control Committee

obtaining appropriate microbiological specimenswhen an infection is present or suspected

notifying cases of hospital-acquired infection tothe team, as well as the admission of infected pa-tients

complying with the recommendations of the An-timicrobial Use Committee regarding the use ofantibiotics

advising patients, visitors and staff on techniquesto prevent the transmission of infection

instituting appropriate treatment for any infec-tions they themselves have, and taking steps toprevent such infections being transmitted to otherindividuals, especially patients.

2.3.3 Role of the microbiologist (4)

The microbiologist is responsible for:

handling patient and staff specimens to maximizethe likelihood of a microbiological diagnosis

developing guidelines for appropriate collection,transport, and handling of specimens

ensuring laboratory practices meet appropriatestandards

ensuring safe laboratory practice to prevent in-fections in staff

performing antimicrobial susceptibility testingfollowing internationally recognized methods, andproviding summary reports of prevalence of re-sistance

monitoring sterilization, disinfection and theenvironment where necessary

timely communication of results to the InfectionControl Committee or the hygiene officer

epidemiological typing of hospital microorgan-isms where necessary.

2.3.4 Role of the hospital pharmacist (5)

The hospital pharmacist is responsible for:

obtaining, storing and distributing pharmaceuti-cal preparations using practices which limitpotential transmission of infectious agents topatients

dispensing anti-infectious drugs and maintain-ing relevant records (potency, incompatibility,conditions of storage and deterioration)

obtaining and storing vaccines or sera, and mak-ing them available as appropriate

maintaining records of antibiotics distributed tothe medical departments

providing the Antimicrobial Use Committee andInfection Control Committee with summary re-ports and trends of antimicrobial use

having available the following information ondisinfectants, antiseptics and other anti-infectiousagents:

active properties in relation to concentration,temperature, length of action, antibiotic spec-trum

toxic properties including sensitization orirritation of the skin and mucosa

substances that are incompatible with anti-biotics or reduce their potency

physical conditions which unfavourably affectpotency during storage: temperature, light,humidity

harmful effects on materials.

The hospital pharmacist may also participate in thehospital sterilization and disinfection practicesthrough:

participation in development of guidelines forantiseptics, disinfectants, and products used forwashing and disinfecting the hands

participation in guideline development for reuseof equipment and patient materials

participation in quality control of techniques usedto sterilize equipment in the hospital includingselection of sterilization equipment (type ofappliances) and monitoring.

CHAPTER II. INFECTION CONTROL PROGRAMMES


12

2.3.5 Role of the nursing staff

Implementation of patient care practices for infec-tion control is the role of the nursing staff. Nursesshould be familiar with practices to prevent theoccurrence and spread of infection, and maintainappropriate practices for all patients throughout theduration of their hospital stay.

The senior nursing administrator is responsible for:

participating in the Infection Control Committee

promoting the development and improvement ofnursing techniques, and ongoing review of asep-tic nursing policies, with approval by the Infec-tion Control Committee

developing training programmes for members ofthe nursing staff

supervising the implementation of techniques forthe prevention of infections in specialized areassuch as the operating suite, the intensive care unit,the maternity unit and newborns

monitoring of nursing adherence to policies.

The nurse in charge of a ward is responsible for:

maintaining hygiene, consistent with hospitalpolicies and good nursing practice on the ward

monitoring aseptic techniques, including hand-washing and use of isolation

reporting promptly to the attending physician anyevidence of infection in patients under the nursescare

initiating patient isolation and ordering culturespecimens from any patient showing signs of acommunicable disease, when the physician is notimmediately available

limiting patient exposure to infections from visi-tors, hospital staff, other patients, or equipmentused for diagnosis or treatment

maintaining a safe and adequate supply of wardequipment, drugs and patient care supplies.

The nurse in charge of infection control is a member of theinfection control team and responsible for :

identifying nosocomial infections

investigation of the type of infection and infect-ing organism

participating in training of personnel

surveillance of hospital infections

participating in outbreak investigation

development of infection control policy andreview and approval of patient care policiesrelevant to infection control

ensuring compliance with local and national regu-lations

liaison with public health and with other facili-ties where appropriate

providing expert consultative advice to staff healthand other appropriate hospital programmes inmatters relating to transmission of infections.

2.3.6 Role of the central sterilization service

A central sterilization department serves all hospitalareas, including the operating suite. An appropri-ately qualified individual must be responsible formanagement of the programme. Responsibility forday-to-day management may be delegated to a nurseor other individual with appropriate qualifications,experience, and knowledge of medical devices.

The responsibilities of the central sterilization service areto clean, decontaminate, test, prepare for use, steri-lize, and store aseptically all sterile hospital equip-ment. It works in collaboration with the InfectionControl Committee and other hospital programmesto develop and monitor policies on cleaning anddecontamination of:

reusable equipment

contaminated equipment

including

wrapping procedures, according to the typeof sterilization

sterilization methods, according to the type ofequipment

sterilization conditions (e.g. temperature, du-ration, pressure, humidity) (see Chapter V).

The director of this service must:

oversee the use of different methods physical,chemical, and bacteriological to monitor thesterilization process

ensure technical maintenance of the equipmentaccording to national standards and manufactur-ers recommendations

report any defect to administration, maintenance,infection control and other appropriate personnel

13

maintain complete records of each autoclave run,and ensure long-term availability of records

collect or have collected, at regular intervals, alloutdated sterile units

communicate, as needed, with the InfectionControl Committee, the nursing service, the op-erating suite, the hospital transport service,pharmacy service, maintenance, and other appro-priate services.

2.3.7 Role of the food service (see Chapter VIII)

The director of food services must be knowledgeable infood safety, staff training, storage and preparationof foodstuffs, job analysis, and use of equipment.

The head of catering services is responsible for:

defining the criteria for the purchase of foodstuffs,equipment use, and cleaning procedures to main-tain a high level of food safety

ensuring that the equipment used and all work-ing and storage areas are kept clean

issuing written policies and instructions forhandwashing, clothing, staff responsibilities anddaily disinfection duties

ensuring that the methods used for storing, pre-paring and distributing food will avoid contami-nation by microorganisms

issuing written instructions for the cleaning ofdishes after use, including special considerationsfor infected or isolated patients where appropri-ate

ensuring appropriate handling and disposal ofwastes

establishing programmes for training staff in foodpreparation, cleanliness, and food safety

establishing a Hazard Analysis of Critical ControlPoints (HACCP) programme, if required.

2.3.8 Role of the laundry service (see Chapter VIII)

The laundry is responsible for:

selecting fabrics for use in different hospitalareas, developing policies for working clothes ineach area and group of staff, and maintainingappropriate supplies

distribution of working clothes and, if necessary,managing changing rooms

developing policies for the collection and trans-port of dirty linen

defining, where necessary, the method for disin-fecting infected linen, either before it is taken tothe laundry or in the laundry itself

developing policies for the protection of cleanlinen from contamination during transport fromthe laundry to the area of use

developing criteria for selection of site of laundryservices:

ensuring appropriate flow of linen, separationof clean and dirty areas

recommending washing conditions (e.g. tem-perature, duration)

ensuring safety of laundry staff throughprevention of exposure to sharps or laundrycontaminated with potential pathogens.

2.3.9 Role of the housekeeping service (see 5.3)

The housekeeping service is responsible for the regu-lar and routine cleaning of all surfaces and main-taining a high level of hygiene in the facility. Incollaboration with the Infection Control Committeeit is responsible for :

classifying the different hospital areas by varyingneed for cleaning

developing policies for appropriate cleaning tech-niques

procedure, frequency, agents used, etc., for eachtype of room, from highly contaminated tothe most clean, and ensuring that these prac-tices are followed

developing policies for collection, transport anddisposal of different types of waste (e.g. contain-ers, frequency)

ensuring that liquid soap and paper towel dis-pensers are replenished regularly

informing the maintenance service of any build-ing problems requiring repair: cracks, defects inthe sanitary or electrical equipment, etc.

caring for flowers and plants in public areas

pest control (insects, rodents)



14

providing appropriate training for all new staffmembers and, periodically, for other employees,and specific training when a new technique isintroduced

establishing methods for the cleaning and disin-fection of bedding (e.g. mattresses, pillows)

determining the frequency for the washing ofcurtains, screening curtains between beds, etc.

reviewing plans for renovations or new furniture,including special patient beds, to determine fea-sibility of cleaning.

There should be a continuing programme for stafftraining.This programme should stress personalhygiene, the importance of frequent and carefulwashing of hands, and cleaning methods (e.g.sequence of rooms, correct use of equipment, dilu-tion of cleaning agents, etc.). Staff must also under-stand causes of contamination of premises, and howto limit this, including the method of action of dis-infectants. Cleaning staff must know to contact staffhealth if they have a personal infection, especiallyinfections of the skin, digestive tract and respiratorytract.

2.3.10 Role of maintenance

Maintenance is responsible for:

collaborating with housekeeping, nursing staff orother appropriate groups in selecting equipmentand ensuring early identification and prompt cor-rection of any defect

inspections and regular maintenance of theplumbing, heating, and refrigeration equipment,and electrical fittings and air conditioning; recordsshould be kept of this activity

developing procedures for emergency repairs inessential departments

ensuring environmental safety outside the hos-pital, e.g. waste disposal, water sources.

Additional special duties include:

participation in the choice of equipment ifmaintenance of the equipment requires tech-nical assistance

inspection, cleaning and regular replacementof the filters of all appliances for ventilationand humidifiers

testing autoclaves (temperature, pressure,vacuum, recording mechanism) and regularmaintenance (cleaning the inner chamber,emptying the tubes)

monitoring the recording thermometers ofrefrigerators in pharmacy stores, laboratories,the blood bank and kitchens

regularly inspecting all surfaces walls, floors,ceilings to ensure they are kept smooth andwashable

repairing any opening or crack in partitionwalls or window frames

maintaining hydrotherapy appliances

notifying infection control of any anticipatedinterruption of services such as plumbing orair conditioning.

2.3.11 Role of the infection control team(hospital hygiene service)

The infection control programme is responsible foroversight and coordination of all infection controlactivities to ensure an effective programme.

The hospital hygiene service is responsible for:

organizing an epidemiological surveillance pro-gramme for nosocomial infections

participating with pharmacy in developing a pro-gramme for supervising the use of anti-infectivedrugs

ensuring patient care practices are appropriate tothe level of patient risk

checking the efficacy of the methods of disinfec-tion and sterilization and the efficacy of systemsdeveloped to improve hospital cleanliness

participating in development and provision ofteaching programmes for the medical, nursing,and allied health personnel, as well as all othercategories of staff

providing expert advice, analysis, and leadershipin outbreak investigation and control

participating in the development and operationof regional and national infection control initia-tives

the hospital hygiene service may also provideassistance for smaller institutions, and undertakeresearch in hospital hygiene and infection con-

15

trol at the facility, local, national, or internationallevel.

References

1. Haley RW et al. The efficacy of infection surveil-lance and control programs in preventing noso-comial infections in US hospitals. Am J. Epidem,1985, 121:182205.

2. Schechler WE et al. Requirements for infrastruc-ture and essential activities of infection controland epidemiology in hospitals: a consensus panelreport. Society of Healthcare Epidemiology ofAmerica. Infect Control Hosp Epidemiol, 1998, 19:114124.

3. Savey A, Troadec M. Le Manuel du CLIN, un outilpour une demande de qualit CoordinationC.CLIN Sud-Est. Hygines, 2001, IX:73162.

4. Emory TG, Gaynes RP. An overview of nosoco-mial infections including the role of the micro-biology laboratory. Clin Microbiol Rev, 1993,6:428442.

5. American Society of Health System Pharmacists.ASHP statement on the pharmacists role ininfection control. Am J Hosp Pharm, 1986, 43:20062008.



16

CHAPTER III

Nosocomial infection surveillance

to identify the need for new or intensified pre-vention programmes, and evaluate the impact ofprevention measures

to identify possible areas for improvement inpatient care, and for further epidemiological stud-ies (i.e. risk factor analysis).

3.2 Strategy

A surveillance system must meet the followingcriteria (Table 1):

simplicity, to minimize costs and workload, andpromote unit participation by timely feedback

flexibility, to allow changes when appropriate

acceptability (e.g. evaluated by the level of par-ticipation, data quality)

consistency (use standardized definitions, meth-odology)

sensitivity, although a case-finding method withlow sensitivity can be valid in following trends,as long as sensitivity remains consistent over timeand cases identified are representative

specificity, requiring precise definitions andtrained investigators.

The nosocomial infection rate in patients in afacility is an indicator of quality and safety ofcare. The development of a surveillance process tomonitor this rate is an essential first step to identifylocal problems and priorities, and evaluate the ef-fectiveness of infection control activity. Surveillance,by itself, is an effective process to decrease the fre-quency of hospital-acquired infections (1,2,3).

improvements in health care with increasedquality and safety

but

changes in care with new techniques, newpathogens or changes in resistance, increasedpatient acuity, ageing population, etc.

= need for active surveillance to monitor changing

infectious risks

and

identify needs for changes in control measures.

3.1 Objectives

The ultimate aim is the reduction of nosoco-mial infections, and their costs.

The specific objectives of a surveillance programmeinclude:

to improve awareness of clinical staff and otherhospital workers (including administrators) aboutnosocomial infections and antimicrobial resist-ance, so they appreciate the need for preventiveaction

to monitor trends: incidence and distribution ofnosocomial infections, prevalence and, wherepossible, risk-adjusted incidence for intra- andinter-hospital comparisons

TABLE 1. Desired characteristics of a nosocomialinfection surveillance system*

Characteristics of the system:

timeliness, simplicity, flexibility acceptability, reasonable cost representativeness (or exhaustiveness)

Quality of the data provided:

sensitivity, specificity predictive value (positive and negative) usefulness, in relation to the goals of the surveillance

(quality indicators)

* Adapted from Thacker SB, 1988 (4).

17

CHAPTER III. NOSOCOMIAL INFECTION SURVEILLANCE

The extent to which these characteristics are met willvary among different institutions.

3.2.1 Implementation at the hospital level

Ensuring a valid surveillance system is an impor-tant hospital function. There must be specific objec-tives (for units, services, patients, specific care areas)and defined time periods of surveillance for allpartners: e.g. clinical units and laboratory staff,infection control practitioner (ICP)/nurse, and direc-tor, administration.

Initially, discussion should identify the informationneeds, and the potential for the chosen indicators tosupport implementation of corrective measures (whator who is going to be influenced by the data). Thisdiscussion will include:

the patients and units to be monitored (definedpopulation)

the type of infections and relevant informationto be collected for each case (with precise defini-tions)

the frequency and duration of monitoring

methods for data collection

methods for data analysis, feedback, and dissemi-nation

confidentiality and anonymity.

The surveillance programme must report to hospi-tal administration, usually through the InfectionControl Committee (ICC), and must have a dedicatedbudget to support its operation.

3.2.2 Implementation at the network (regionalor national) level

Hospitals should share nosocomial infection data,on a confidential basis, with a network of similarfacilities to support standards development for in-ter-facility comparisons (5), and to detect trends.Local, regional, national or international networksmay be developed. The advantages include:

technical and methodological assistance

reinforcing compliance to existing guidelines andclinical practices

evaluating the importance of surveillance (morelegitimacy) to encourage participation

facilitating the exchange of experiences andsolutions

promoting epidemiological research, includinganalysis of the impact of interventions

assisting nation/states in scope and magnitudeestimates to help with resource allocation nation-ally and internationally

the key advantage: possibility of developing validinter-hospital comparisons using standardizedmethods and adjusted rates.

3.3 Methods

Simply counting infected patients (numerator) pro-vides only limited information which may be diffi-cult to interpret. Further data are necessary to fullydescribe the problem on a population basis, to quan-tify its importance, to interpret variations, and topermit comparisons. Risk factor analysis requiresinformation for both infected and non-infectedpatients. Infection rates, as well as risk-adjusted rates,can then be calculated.

Passive surveillance with reporting by individualsoutside the infection control team (laboratory-basedsurveillance, extraction from medical records post-discharge, infection notification by physicians ornurses) is of low sensitivity. Therefore some form ofactive surveillance for infections (prevalence orincidence studies) is recommended (Table 2).

FIGURE 1. Surveillance is a circular process

3.Prevention: decisions and

corrective actions

2.Feedback and

dissemination: dataanalysis,

interpretation,comparisons,

discussion

4.Evaluation of the

impact onnosocomialinfections by

surveillance (trends)or other studies

1.Implementation of surveillance:

goals definition, surveillanceprotocol data collection

The optimal method (Figure 1) is dependent on hos-pital characteristics, the desired objectives, resourcesavailable (computers, investigators) and the level ofsupport of the hospital staff (both administrative andclinical).


18

3.3.1 Prevalence study (cross-sectional/transverse)

Infections in all patients hospitalized at a given pointin time are identified (point prevalence) in the en-tire hospital, or on selected units. Typically, a teamof trained investigators visits every patient of thehospital on a single day, reviewing medical and nurs-ing charts, interviewing the clinical staff to identifyinfected patients, and collecting risk factor data. Theoutcome measure is a prevalence rate.

Prevalence rates are influenced by duration of thepatients stay (infected patients stay longer, leadingto an overestimation of patients risk of acquiringan infection) and duration of infections.

Another problem is determining whether an infec-tion is still active on the day of the study.

In small hospitals, or small units, the number ofpatients may be too few to develop reliable rates, orto allow comparisons with statistical significance.

A prevalence study is simple, fast, and relatively in-expensive. The hospital-wide activity increasesawareness of nosocomial infection problems amongclinical staff, and increases the visibility of the in-fection control team. It is useful when initiating asurveillance programme to assess current issues forall units, for all kinds of infections, and in all pa-tients, before proceeding to a more focused continu-ing active surveillance programme. Repeatedprevalence surveys can be useful to monitor trendsby comparing rates in a unit, or in a hospital, overtime.

3.3.2 Incidence study (continuous/longitudinal)

Prospective identification of new infections (incidencesurveillance) requires monitoring of all patientswithin a defined population for a specified time pe-riod. Patients are followed throughout their stay, andsometimes after discharge (e.g. post-discharge sur-veillance for surgical site infections). This type of

surveillance provides attack rates, infection ratio andincidence rates (Table 3). It is more effective indetecting differences in infection rates, to followtrends, to link infections to risk factors, and forinter-hospital and inter-unit comparisons (6).

This surveillance is more labour-intensive than aprevalence survey, more time-consuming, and costly.Therefore, it is usually undertaken only for selectedhigh-risk units on an ongoing basis (i.e. in intensivecare units), or for a limited period, focusing onselected infections and specialties (i.e. 3 months insurgery) (7,8,9,10).

Recent trends in targeted surveillance include:

Site-oriented surveillance: priorities will be tomonitor frequent infections with significant im-pact in mortality, morbidity, costs (e.g. extra-hospital days, treatment costs), and which maybe avoidable.

Common priority areas are:

ventilator-associated pneumonia (a high mor-tality rate)

surgical site infections (first for extra-hospitaldays and cost)

primary (intravascular line) bloodstream in-fections (high mortality)

multiple-drug resistant bacteria (e.g. methicil-lin-resistant Staphylococcus aureus, Klebsiella spp.with extended-spectrum beta-lactamase).

This surveillance is primarily laboratory-based.The laboratory also provides units with regularreports on distribution of microorganisms isolated,and antibiotic susceptibility profiles for the mostfrequent pathogens.

Unit-oriented surveillance: efforts can focus onhigh-risk units such as intensive care units, sur-gical units, oncology/haematology, burn units,neonatalogy, etc.

Priority-oriented surveillance: surveillance un-dertaken for a specific issue of concern to thefacility (i.e. urinary tract infections in patients withurinary catheters in long-term care facilities).

While surveillance is focused in high-risk sectors,some surveillance activity should occur for therest of the hospital. This may be most efficientlyperformed on a rotating basis (laboratory-basedor repeated prevalence studies).

TABLE 2. Key points in the process of surveillancefor nosocomial infection rates

Active surveillance (prevalence and incidence studies)

Targeted surveillance (site-, unit-, priority-oriented)

Appropriately trained investigators

Standardized methodology

Risk-adjusted rates for comparisons

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TABLE 3. Prevalence and incidence rates (11,12)

Prevalence rate Examples

Number of infected patients* at the time of study / Prevalence (%) of nosocomial infections (NI)Number of patients observed at the same time for 100 hospitalized patients

X100 Prevalence (%) of urinary tract infections (UTI)(*or number of infections) for 100 hospitalized patients

Number of infected patients at the time of the study / Prevalence (%) of UTI for 100 patients withNumber of patients exposed at the same time a urinary catheter

X100

Attack rate (cumulative incidence rate)

Number of new infections acquired in a period / Attack rate (%) of UTI for 100 hospitalized patientsNumber of patients observed in the same period

X100

Number of new infections acquired in a period / Attack rate (%) of surgical site infections (SSI)Number of patients exposed in the same period for 100 operated patients

X100

Incidence rate

Number of new nosocomial infections acquired Incidence of bloodstream infection (BSI)in a period / for 1000 patient-days

Total of patient-days for the same periodX1000

Number of new device-associated nosocomial Incidence of ventilator-associated pneumoniainfections in a period / for 1000 ventilation-days

Total device-days for the same periodX1000

3.3.3 Calculating rates

Rates are obtained by dividing a numerator (numberof infections or infected patients observed) by adenominator (population at risk, or number ofpatient-days of risk). The frequency of infection canbe estimated by prevalence and incidence indica-tors (Table 3).

For multiple-drug resistant bacteria surveillance, thethree main indicators used are :

percentage of antimicrobial resistant strains withinisolates of a species, e.g. percentage of Staphylococ-cus aureus resistant to methicillin (MRSA)

attack rate (i.e. number of MRSA/100 admissions)

incidence rate (MRSA/1000 patient-days).

For both prevalence and incidence rates, either theglobal population under surveillance, or onlypatients with a specific risk exposure, may be thedenominator.

Attack rates can be estimated by the calculation of asimplified infection ratio using an estimate of thedenominator for the same period of time (i.e. numberof admissions or discharges, number of surgical pro-cedures).

Incidence rates are encouraged as they take into ac-count the length of exposure, or the length of stay(and/or follow-up) of the patient; this gives a betterreflection of risk and facilitates comparisons. Eitherpatient-day rates or device-associated rates can beused.

3.4 Organization for efficient surveillance

Nosocomial infection surveillance includes data col-lection, analysis and interpretation, feedback lead-ing to interventions for preventive action, andevaluation of the impact of these interventions (seeFigure 1 earlier in this chapter). The director (physi-cian and/or nurse from the infection control team,


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the unit under surveillance, or from the InfectionControl Committee) must be a trained professionalspecifically responsible for surveillance, includingtraining of personnel for data collection. A writtenprotocol must describe the methods to be used, thedata to be collected (e.g. patient inclusion criteria,definitions), the analysis that can be expected, andpreparation and timing of reports (13).

3.4.1 Data collection and analysis

3.4.1.1 Sources

Data collection requires multiple sources of infor-mation as no method, by itself, is sensitive enoughto ensure data quality. Trained data extractors (train-ing should be organized by the infection control teamor the supervisor) performing active surveillance willincrease the sensitivity for identifying infections.Techniques for case-finding include:

Ward activity: looking for clues such as:

the presence of devices or procedures knownto be a risk for infection (indwelling urinaryand intravascular catheters, mechanical ven-tilation, surgical procedures)

record of fever or other clinical signs consist-ent with infection

antimicrobial therapy

laboratory tests

medical and nursing chart review.

Laboratory reports: isolation of microorgan-isms potentially associated with infection, anti-microbial resistance patterns, serological tests.Microbiology laboratory reports have low sensi-tivity because cultures are not obtained for allinfections, specimens may not be appropriate,some infectious pathogens may not be isolated(e.g. virus), and the isolation of a potential patho-gen may represent colonization rather thaninfection (e.g. for surgical site infections, pneu-monia). Laboratory reports are, however, reliablefor urinary tract infection, bloodstream infections,and multiple-drug resistant bacteria surveillance,because the definitions for these are essentiallymicrobiological.

Other diagnostic tests: e.g. white blood counts,diagnostic imaging, autopsy data.

Discussion of cases with the clinical staff dur-ing periodic ward visits.

Continuing collaboration among infection controlstaff, the laboratory, and clinical units will facilitatean exchange of information and improve data qual-ity (14). The patient is monitored throughout thehospital stay, and in some cases (e.g. for surgical siteinfections), surveillance includes the post-dischargeperiod (15). The progressive reduction of the aver-age length of stay with recent changes in health caredelivery increases the importance of identifying post-discharge infections.

3.4.1.2 Data elements

Some examples of data collection forms for a preva-lence study and for surgical site infection surveil-lance are given in Figures 2 and 3. One form iscompleted for each patient. Simple, validated, andstandardized definitions (16,17) are essential for cred-ibility of the surveillance system and to ensure dataquality. A complete guide for data collection shouldinclude:

patient inclusion criteria

precise definitions for each variable to be collected(not only definitions for infections)

lists of codes for each variable, including specificcodes for missing data.

This data collection guide is also useful in trainingdata extractors.

The information to be collected should include:

administrative data (e.g. hospital number, admis-sion date)

additional information describing demographicrisk factors (e.g. age, gender, severity of underly-ing illness, primary diagnosis, immunologicalstatus) and interventions (e.g. device exposure,surgical procedure, treatments) for infected andfor non-infected patients

presence or absence of infection: date of onset,site of infection, microorganisms isolated, andantimicrobial susceptibility.

Data validation is essential to ensure correct inter-pretation and meaningful comparisons. Validationis a continuous process which may incorporate vari-ous methods:

before data input, information validated by asecond extractor

if computerized data collection is used, the soft-ware should include input checks (each variable

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FIGURE 2. Example of a minimum data collection form for prevalence study

Date (dd/mm/yy) __ __ __ __ __ __

Hospital __ __

Unit __ __

Unit specialty __ __

Patient

Patient identification __ __ __ __ __

Age (years) __ __ __

Gender male female __Date of admission in the hospital (dd/mm/yy) __ __ __ __ __ __

Patient exposure

Surgical procedure (during the last month) Yes No __Urinary catheter Yes No __Mechanical ventilation Yes No __Intravascular catheter Yes No __Antibiotic Yes No __

If yes, prescription for

Prophylaxis Therapy Other/unknown __

Nosocomial infection

Yes No __If yes, fill the following items

Surgical site infection Yes No __Urinary tract infection Yes No __Bloodstream infection Yes No __Pneumonia Yes No __Other respiratory infection Yes No __Line-related infection Yes No __Other nosocomial infection Yes No __


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FIGURE 3. Example of a data collection form for surgical site infection surveillance

Hospital __ __

Unit __ __

Patient

Patient identification __ __ __

Age (years) __ __ __

Gender male female __Date of admission (in the hospital) (dd/mm/yy) __ __ __ __ __ __

Date of discharge (from the unit) (dd/mm/yy) __ __ __ __ __ __

Operation

Date of operation (dd/mm/yy) __ __ __ __ __ __

Main procedure (code)

Wound class Clean Contaminated Clean-contaminated Dirty/infected __

ASA score 1 2 3 4 5 __Duration of operation (minutes) __ __ __

Urgent Yes No __Prosthesis/implant Yes No __Multiple procedures Yes No __Coeliosurgery Yes No __

Antibiotics

Antimicrobial prophylaxis Yes No __Starting date (dd/mm/yy) __ __ __ __ __ __

Duration (days) __ __

Surgical site infection

Surgical site infection Yes No __Date of infection (dd/mm/yy) __ __ __ __ __ __

Infection site superficial deep organ/space __Microorganism 1 __ __ __

Microorganism 2 __ __ __

Date of last contact (dd/mm/yy) __ __ __ __ __ __

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collected must be coded according to the proto-col)

before analysis, a retrospective data validationperformed to identify missing values, inconsist-encies, outliers/possible errors, unexpected val-ues or codes.

3.4.1.3 Analysis

Information should be collected only if it will beused in the analysis.

Analysis includes the description of the population,frequency of risk exposure and infections, calcula-tion of rates, comparisons of patient groups (withsignificance testing), comparisons of rates over time,etc.

For adequate sample size, and monitoring long-termtrends, continuous surveillance or surveillanceundertaken at periodic intervals of sufficient lengthis recommended.

Inclusion of risk factors allows stratification of pa-tients by risk, and risk-adjusted rates for accuratecomparisons. A single overall nosocomial infectionrate is not useful for inter-hospital comparisons.Adjusted rates will enable the unit or the hospital tocompare its performance over time with its ownprevious results, and with other similar units/hos-pitals, or with populations of patients with similarrisk levels.

Computerization of data collection and analysisshould be considered, if possible, as it will ensurerapid feedback and better data quality. Low-costcomputers and different types of software are nowwidely available to facilitate analysis for the epide-miologist. Information already collected and acces-sible through the hospital computer system shouldbe used, wherever possible. Integration of nosoco-mial infection surveillance into routine data han-dling should be encouraged by defining specificrequirements for hospital information systems.

3.4.2 Feedback/dissemination

To be effective, feedback must be prompt, relevantto the target group, i.e. the people directly involvedin patient care, and with the potential for maximalinfluence on infection prevention (i.e. surgeons forsurgical site infection, physicians and nurses in in-tensive care units). Reporting may include meetingsfor sharing of information and discussion, micro-

biological review, and summary or graphic presen-tations on a notice board in the unit. Disseminationof information is also organized through the Infec-tion Control Committee to other units, management,and laboratories.

Reports should not identify individual patients.Codes must also be assigned to hospitals, units andresponsible physicians, to ensure anonymity. Reportsmust be returned or disposed of confidentially fol-lowing established procedures.

3.4.3 Prevention and evaluation

An effective surveillance system must identify pri-orities for preventive interventions and improvementin quality of care (18).

By providing quality indicators, surveillance enablesthe infection control programme, in collaborationwith patient care units, to improve practice, and todefine and monitor new prevention policies. Thefinal aim of surveillance is to decrease nosocomialinfections and reduce costs.

Surveillance is a continuous process which needs toevaluate the impact of interventions to validate theprevention strategy, and determine if initial objec-tives are attained.

3.5 Evaluation of the surveillance system

A surveillance system must be continuing if it is t

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