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Modes of Transmission, Personal Protective

Equipment, and Isolation Precautions

L E A R N I N G O B J E C T I V E S

Upon completion of this chapter, the reader will be able to:

1. List and define the three main modes of infectious disease transmission.2. Identify various forms of personal protective equipment (PPE).3. Explain the two-tiered approach to preventing the transmission of infectious agents,

as recommended by HICPAC and the CDC.4. Define and provide examples of pathogens that require standard, contact, droplet,

and airborne precautions.5. Compare and contrast the concepts of isolation and quarantine as infection

prevention strategies.6. Discuss recommendations targeting administration and education in healthcare

facilities to increase compliance with use of PPE, standard precautions, andtransmission-based precautions.

7. Understand the challenges involved with identification and isolation of patients withdiagnosed or suspected Mycobacterium tuberculosis disease.

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3CHAPTER

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Introduction

The rise of healthcare-associated infections (HAIs) underscores the need for prevention and control of the transmission of infectious agents within the healthcare setting. Once the modes of transmission are understood, the types of personal protective equipment (PPE) can be pre-sented, and the corresponding precautions can be explained. This chapter will also cover the concepts of isolation and quarantine. The Practical Scenario portion of the chapter will focus on identification of patients with active Mycobacterium tuberculosis disease and prevention of transmission of that pathogen in high-risk and healthcare settings.

Modes of Transmission

In order to understand how to prevent transmission of diseases, it is essential to define the modes in which transmission may occur. There are three principal routes of infection: contact, droplet, and airborne.1(p15) These are shown in Table 3.1.

Contact TransmissionContact transmission is the most common mode of transmission and can be either direct or indirect. Direct transmission involves person-to-person transmission without an intermediary object. Examples of direct contact transmission include contact of blood or other body fluids from a patient with the mucous membranes or nonintact skin of a healthcare worker (HCW),2,3 transference of mites from a scabies-infected patient to the skin of an HCW while the HCW is having ungloved contact with the patient’s skin,4,5 or development of a herpetic whitlow on an HCW’s finger after providing oral care to a patient with oral herpes without using gloves.6

Indirect contact transmission occurs when the infectious agent, or pathogen, is transferred from one infected person to another through an intermediate object or person.1(p16) As discussed earlier in this text, the hands of healthcare personnel (HCP) are a common source of indirect contact transmission of pathogens.1(p16) Indirect transmission tends to go unidentified, but can

Table 3.1 Modes of Transmission

Data from Siegel JD, Rhinehart E, Jackson M, et al. 2007 guideline for isolation precautions: preventing transmission of infectious agents in healthcare settings. http://www.cdc.gov/hicpac/pdf/isolation/isolation2007.pdf. 2007. Accessed October 13, 2014.

Contact Transmission Most Common Mode of Transmission

Direct contact Transmission from person to person without an intermediary person or object

Indirect contact Transmission through contact with a contaminated object or personDroplet transmission Person-to-person transmission that occurs when respiratory droplets

carrying pathogens travel directly from the infectious individual to the mucous membranes of the susceptible host

Airborne transmission Transmission that occurs when airborne droplet nuclei or small particles containing pathogens are disseminated (potentially over large distances) and are inhaled by a susceptible host

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involve objects such as the hands of HCWs, burn dressings and bed linens,7 ventilator equip-ment,8 endoscopes,9 environmental surfaces in patient rooms,10 and stethoscopes.11

Droplet TransmissionRespiratory droplets from an infectious individual (patient) enter the air when the patient coughs, sneezes, or talks, or when certain medical procedures are performed. These droplets con-tain pathogens, which can transmit the disease when they come into contact with the mucous membranes of a susceptible host.1(p17) Technically, droplet transmission can be considered a form of contact transmission, although it is typically discussed as a category unto itself.1(p17)

There is some dispute as to the distance infectious droplets can travel. Historically, it was thought that these droplets could not reach anyone outside a 3-foot radius from the patient.12,13,14 However, more recent experiments relating to smallpox and the virus implicated in sudden acute respiratory syndrome (SARS) suggest that infectious droplets may travel up to 6 feet.1(p17) There are several factors that impact how far the infectious droplets can travel, including but not limited to the velocity and mechanism by which the droplets are propelled into the air, the den-sity of the respiratory secretions, temperature and humidity, air circulation, and the pathogen’s inherent ability to remain infectious while the droplet is traveling to the infectious host.1(p17)

The respiratory droplets involved in droplet transmission are larger than the droplet nuclei involved in airborne transmission, > 5 μm and ≤ 5 μm, respectively. Because of the larger size of infectious droplets, diseases transmitted via this route do not require special air handling and ventilation.1(p17)

Airborne TransmissionDroplet nuclei or small particles containing infectious material may become airborne, disseminated, and then inhaled by a susceptible host.1(p18) Pathogens involved in this type of transmission are typi-cally able to remain infectious over time and distance, and the droplet nuclei or small particles may travel large distances.1(p18) Therefore, the susceptible host may become infected without ever having face-to-face contact with the initially infectious individual, or source patient. Examples of diseases transmitted via droplet and airborne route are shown in Box 3.1.

Other Types of TransmissionWhile contact, droplet, and airborne transmission are the most common and the focus of this chap-ter, transmission may also occur from common environmental sources, such as contaminated food, water, and medications.1(p20) Vector-borne diseases are those that are transmitted indirectly through an animal or insect vector, such as the transmission of malaria via the bite of a mosquito.1(p20)

Personal Protect ive Equipment

Personal protective equipment (PPE) protects HCP by providing a barrier between the infec-tious agent and the mucous membranes, airways, skin, and clothing of the HCP.1(p49) PPE for a specific task are chosen based on what kind of interaction is going to take place between the

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Box 3.1 Selected Diseases Transmitted via Droplet and Airborne Route

Pathogens Transmitted via Infectious Droplets●● Bordetella pertussis●● Influenza virus●● Rhinovirus●● SARS-associated coronavirus (SARS-CoV)●● Group A streptococci●● Neisseria meningitidis

Pathogens Transmitted via Airborne Route●● M. tuberculosis●● Rubeola virus●● Varicella-zoster virus

Data from Siegel JD, Rhinehart E, Jackson M, et al. 2007 guideline for isolation precautions: preventing transmission of infectious agents in healthcare settings. http://www.cdc.gov/hicpac/pdf/isolation/isolation2007.pdf. 2007. Accessed October 13, 2014.

HCP and patient, the pathogen involved, and the likely mode of transmission.1(p50) The Health-care Infection Control Practices Advisory Committee (HICPAC) associated with the Centers for Disease Control and Prevention (CDC) issued recommendations for the prevention of trans-mission of infectious agents in the healthcare setting.1 A significant portion of these recommen-dations relate to the use of PPE. The recommendation ranking system is shown in Table 3.2. The information presented in this chapter is based on category IA and IB recommendations.

HICPAC recommends that PPE be worn when there is a potential for blood or body fluid exposure [IB/IC].1(p79) This PPE should be removed and discarded before leaving the patient’s room [IB/IC].1(p79) Figure 3.1 shows the proper way to don, or put on, PPE. Not all components are needed for every type of patient care task.

Table 3.2 CDC Recommendation Ranking System

Data from Siegel JD, Rhinehart E, Jackson M, et al. 2007 Guideline for isolation precautions: preventing transmission of infectious agents in healthcare settings. http://www.cdc.gov/hicpac/pdf/isolation/isolation2007.pdf. 2007. Accessed October 13, 2014.

Ranking Recommendation Evidence

Category IA Strongly recommended for implementation

Strongly supported by well-designed experimental, clinical, or epidemiologic studies

Category IB Strongly recommended for implementation

Supported by some experimental, clinical, or epidemiologic studies and by a strong theoretical rationale

Category IC Required by state or federal regulations

N/A

Category II Suggested for implementation

Supported by suggestive clinical or epidemiologic studies or by a theoretical rationale

No recommendation Unresolved issue May include practices for which insufficient evidence or no consensus exists


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Figure 3.1 Donning Personal Protective Equipment (PPE)

Reproduced from Siegel JD, Rhinehart E, Jackson M, Chiarello L, Healthcare Infection Control Practices Advisory Committee. 2007 Guideline for isolation precautions: preventing transmission of infectious agents in healthcare settings. http://www.cdc.gov/hicpac/pdf/isolation/isolation2007.pdf. 2007. Accessed October 13, 2014.


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GlovesNitrile or latex gloves are used to protect against contamination of the HCW’s hands or from transmission of a pathogen from the HCW’s hands to the patient.1(p50) Vinyl gloves are available but are not recommended for use in the healthcare setting due to high failure rates.1(p50) Gloves should be used when there is possibility of direct contact with blood or body fluids, mucous membranes, nonintact skin, or other potentially infectious materials [IB/IC].1(p79) HCP should wear gloves that properly fit and are durable enough for the task at hand [IB].1(p79)

Additional IB recommendations regarding the use of gloves include removing gloves using proper technique to avoid hand contamination; not using the same pair of gloves for care of more than one patient; and not washing and reusing gloves (Figure 3.2).1(p79)

Isolation GownsIsolation gowns are worn to protect the arms and clothing of the HCW during patient care activities. Isolation gowns are not the same as clinical or laboratory coats or jackets worn by HCP as part of their daily uniform.1(p51) Isolation gowns are always used in combination with gloves, as well as any other PPE needed for the patient care task.1(p51) The ideal isolation gown provides full coverage of the arms and front of the body, from neck to at least mid-thigh.1(p51)

Figure 3.2 Donning and Doffing Gloves

Reproduced from World Health Organization. Glove use information leaflet. http://www.who.int/gpsc/5may/Glove_Use_Information_Leaflet.pdf. 2009.


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When performing procedures or patient care activities that may result in contact with blood or other body fluids, secretions, or excretions, HCP should wear a gown that is appropriate to the task to protect skin and prevent soiling and contamination of clothing [IB/IC].1(p79) Addi-tionally, a gown should be worn for direct patient contact if the patient has uncontained secre-tions or excretions, such as patients who are incontinent of urine and stool [IB/IC].1(p79)

Certain units of the hospital, such as the intensive care unit, are deemed high risk for trans-mission of infectious agents. However, routine donning of gowns upon entering these high risk units is not recommended [IB].1(p79) Before exiting the patient’s room, the gown should be removed and hand hygiene performed [IB/IC].1(p79) It can be challenging to remove an isolation gown without unintentionally contaminating oneself. Figure 3.3 shows the appropriate way to remove, or doff a gown.

Mouth, Nose, and Eye ProtectionLike gloves and gowns, HCWs should select masks, goggles, face shields, and combinations of each according to the task and risk at hand [IB/IC].1(p80) PPE should be used to “protect the mucous membranes of the eyes, nose and mouth during procedures and patient care activities that are likely to generate splashes or sprays of blood, body fluids, secretions, and excretions.”1(p80)

Some patient care procedures are referred to as “aerosol generating.” These procedures include bronchoscopy (where a scope is inserted into the respiratory tract to visualize the bronchi), suc-tioning secretions from the respiratory tract, and endotracheal intubation (where a tube is inserted into the airway to assist the patient with breathing). Unless the patient is suspected of being infected with an agent, such as M. tuberculosis, SARS, or one of the hemorrhagic fever viruses, for which respiratory protection is otherwise recommended, HCP should wear one of the following: a face shield that fully covers the front and sides of the face, a mask with attached shield, or a mask and goggles [IB].1(p80) During these procedures, gloves and a gown should also be worn.

Eye ProtectionEye protection may be provided by goggles or face shields. Personal eye glasses or contact lenses are not considered adequate eye protection.1(p53) The National Institutes for Occupational Health and Safety (NIOSH) publishes detailed specifications for eye protection that are beyond the scope of this text. Eye protection should be comfortable, not impede peripheral vision, and adjustable to ensure a secure fit.1(p53),14 Goggles can be effective in protecting the eyes from splashes or sprays, but do not provide protection to the rest of the face.

One significant benefit of face shields is that they cover other areas of the face.1(p53) Face shields that extend from the top of the head to the chin are the best option to protect the face from sprays and splashes of blood and body fluids.1(p53)

MasksTwo types of masks are available for use in the healthcare setting: surgical masks and proce-dure/isolation masks. Each make or design of a surgical mask from a manufacturer must be cleared by the US Food and Drug Administration (FDA) and must meet specifications for fluid- resistant properties.1(p52) Isolation/procedure masks do not have approval from the FDA. There


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Figure 3.3 Doffing Personal Protective Equipment (PPE)

Reproduced from Siegel JD, Rhinehart E, Jackson M, Chiarello L, Healthcare Infection Control Practices Advisory Committee. 2007 Guideline for isolation precautions: preventing transmission of infectious agents in healthcare settings. http://www.cdc.gov/hicpac/pdf/isolation/isolation2007 .pdf. 2007. Accessed October 13, 2014.


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are various designs and features for masks, sizes, filtration efficiencies, and method of attach-ment. One type of mask may work well in one healthcare setting or type of patient care activity, but not in another. Therefore, one facility may need several different masks.

Particulate respirators are sometimes referred to as TB masks. These masks are used to protect against inhalation of the droplet nuclei or small infectious particles transmitted via the airborne route.1(p52) Particulate respirators will be discussed separately and are not considered masks when describing PPE.

After use, the front of a mask, goggles, and face shield are considered contaminated. The ties, ear pieces, or headband are considered clean and can be removed with ungloved hands after hand hygiene has been performed.1(p53)

Precautions

HICPAC and the CDC recommend a two-tiered approach to preventing the transmission of infectious agents: standard precautions and transmission-based precautions.1(p66) Stan-dard precautions are used with every patient, whether they are known to be infected or not. Transmission-based precautions are built around a suspicion or identification of a specific infec-tions agent.1(p66)

Standard PrecautionsThe HICPAC/CDC recommendations (Box 3.2) stress the importance of standard precautions in containing the spread of HAIs and state, in bold print, “Implementation of Standard precau-tions constitutes the primary strategy for the prevention of healthcare-associated transmission of

Box 3.2 Additional HICPAC/CDC Recommendations for Standard Precautions

●● During the delivery of health care, avoid unnecessary touching of surfaces in close proximity to the patient to prevent both contamination of clean hands from environmental surfaces and transmis-sion of pathogens from contaminated surfaces to hands [IB/IC].

●● When hands are visibly dirty, contaminated with proteinaceous material (organic matter), or vis-ibly soiled with blood or body fluids, wash hands with soap (either nonantimicrobial or antimi-crobial) and water [IA].

●● If hands are not visibly soiled, or after removing visible material with soap and water, decontami-nate hands. The preferred method of hand decontamination is alcohol-based hand rub. Alterna-tively, hands may be washed with an antimicrobial soap and water [IB].

●● Perform hand hygiene:●❍ Before having direct contact with patients [IB];●❍ After contact with blood, body fluids or excretions, mucous membranes, nonintact skin, or

wound dressings [IA]; and●❍ After contact with a patient’s intact skin (e.g., when taking a pulse or lifting a patient) [IB].

●● Do not wear artificial fingernails or extenders if duties include direct contact with patients at high risk for infection and associated adverse outcomes (e.g., patients in the intensive care unit or oper-ating room) [IA].


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infectious agents among patients and healthcare personnel.”1(p66) In years past, techniques such as universal precautions or body substance isolation have been used.1(p66) Standard precautions is the current technique, which is based on the assumption that all blood, body fluids, secretions, excretions except sweat, nonintact skin, and mucous membranes may be infectious.1(p66)

Standard precautions are used with all patients, but are tailored to the nature of the patient care task and extent of anticipated exposure to blood or other body fluid, or pathogen exposure.1(p66) Standard precautions include hand hygiene; use of gloves, gown, mask, eye protection or face shield; and safe injection practices. Hand hygiene and safe injection practices are discussed elsewhere in this text. HCP must be educated on the principles of standard precautions so that they can accurately identify the risk associated with a certain patient interaction and then use the PPE to address that risk.1(p66)

Transmission-Based PrecautionsTransmission-based precautions are used for patients where infection with a specific pathogen is suspected or confirmed.1(p69) Typically, these types of precaution are used when standard pre-cautions are not sufficient to interrupt transmission of the involved pathogen. Contact precau-tions, droplet precautions, and airborne precautions may be used alone or overlap each other, depending on the circumstances and the infectious agent involved.1(p69) However, all three of the transmission-based precautions are used along with standard precautions.1(p70)

HICPAC/CDC recommend that transmission-based precautions be used for “patients with documented or suspected infection or colonization with highly transmissible or epidemiologically-important pathogens for which additional precautions are needed to prevent transmission.”1(p83)

Contact PrecautionsLike its name implies, contact precautions are used for patients with known or suspected infec-tions or evidence of syndromes that have an increased likelihood of being spread by direct con-tact with the patient or the patient’s environment.1(p70) Other circumstances that require contact precautions include is excessive wound drainage, fecal incontinence, or other discharges from the body that increase the potential for “extensive environmental contamination” and increase the risk of transmission.1(p70) It’s preferred that patients who require contact precautions are placed in single-patient (or private) rooms.1(p70) When a private room is not available, the infec-tion control personnel at the facility must be consulted, and there are very detailed guidelines about what precautions should be taken.1(p70)

HCP entering the room of a patient under contact precautions should don a gown and gloves for all interactions that involve contact with the patient or potentially contaminated areas of the patient’s environment.1(p70) Potentially contaminated areas are not always obvious (e.g., bedpans, toilets) and include areas that the patient touches, such as the bed rails, telephone, and doorknob to the bathroom. The main concept of contact precautions is to contain the infectious material within the patient’s room, so PPE are put on before entering the room but discarded before exiting the room.1(p70) The HICPAC/CDC recommendations for contact precautions are summarized in Box 3.3.


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Droplet PrecautionsInfectious agents spread through droplets require close respiratory or mucous membrane contact with respiratory secretions.1(p70) These secretions do not remain infectious over long distances in the air and do not require special air handling precautions.1(p70) Examples of pathogens that require droplet precautions include Bordetella pertussis (whooping cough), influenza virus, Neisseria meningitidis (the pathogen that causes meningitis), and group A streptococci.1(p70)

Like contact precautions, a private room is preferred and infection control personnel should be consulted if a single-patient room is not available.1(p70) HCP entering the room of a patient under droplet precautions should don a mask.1(p71) A particulate respirator (TB mask or N95 mask) is not necessary.1(p71) If the patient has to leave the room, the patient should wear a mask and follow respiratory hygiene/cough etiquette.1(p71) The HICPAC/CDC recommendations for droplet precautions are summarized in Box 3.4.

Box 3.3 HICPAC/CDC Recommendations for Contact Precautions

●● Wear gloves whenever touching the patient’s intact skin or surfaces and articles in close proximity to the patient. Don gloves upon entry into the room or cubicle [IB].

●● Wear a gown whenever anticipating that clothing will have direct contact with the patient or potentially contaminated environmental surfaces or equipment in close proximity to the patient. Don gown upon entry into the room or cubicle. Remove gown and observe hand hygiene before leaving the patient care environment [IB].

●● Handle patient care equipment and instruments/devices according to standard precautions [IB/IC].●● In acute care hospitals and long-term care and other residential settings, use disposable noncritical

patient care equipment (e.g., blood pressure cuffs) or implement patient-dedicated use of such equipment. If common use of equipment for multiple patients is unavoidable, clean and disinfect such equipment before use with another patient [IB].

●● Ensure the rooms of patients on contact precautions are prioritized for frequent cleaning and disinfection (e.g., at least daily) with a focus on frequently touched surfaces and equipment in the immediate vicinity of the patient [IB].

●● Discontinue contact precautions after signs and symptoms of the infection have resolved and according to pathogen-specific recommendations [IB].


Box 3.4 HICPAC/CDC Recommendations for Droplet Precautions

●● Use droplet precautions for patients known or suspected to be infected with pathogens transmitted by respiratory droplets that are generated by a patient who is coughing, sneezing, or talking [IB].

●● HCP should don a mask upon entry into the patient room or cubicle [IB].●● If transport or movement in any healthcare setting is necessary, instruct the patient to wear a mask

and follow respiratory hygiene/cough etiquette [IB].●● Discontinue droplet precautions after signs and symptoms have resolved or according to

pathogen-specific recommendations [IB].


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Airborne PrecautionsCertain infectious agents, such as the rubeola virus (measles), varicella virus (chickenpox), and M. tuberculosis (TB), remain airborne and infectious over long distances.1(p71) An airborne infec-tion isolation room, or AIIR, is a single-patient room that meets some very specific guide-lines established by the American Institute of Architects/Facility Guidelines Institutes (AIA/FGI).1(p71) These specifications are intended to decrease the number of infectious particles in the air inside the room, but also keep what infectious particles that exist inside the room. For example, the room should have monitored negative pressure relative to the surrounding area.15,16 This prevents the air (and suspended infectious particles) from rushing into the hallway when the door is opened. Another example of an AIIR engineering specification is that the air from inside the room must be exhausted directly outside or through high-efficiency particulate air (HEPA) filters before being recirculated.15,16

Whether a mask or particulate respirator is needed for HCP caring for a specific patient depends on the pathogen in question.1(p71) HCP should don the mask or respirator prior to entering the room.1(p71) For certain diseases that are vaccine preventable, such as varicella and rubeola, nonimmune HCP should not care for the patients unless it is unavoidable.1(p71) The HICPAC/CDC recommendations for airborne precautions are summarized in Box 3.5.

Box 3.5 HICPAC/CDC Recommendations for Airborne Precautions

●● Use airborne precautions as recommended for patients known or suspected to be infected with agents transmitted person to person by the airborne route [IA/IC].

●● In acute care hospitals and long-term care settings, place patients who require airborne precau-tions in an AIIR that has been constructed in accordance with current guidelines [IA/IC].

●● In ambulatory settings, develop systems (e.g., triage) to identify patients with known or suspected infections that require airborne precautions upon entry in to the ambulatory setting [IA].

●● Place the patient in an AIIR as soon as possible. If an AIIR is not available, place a surgical mask on the patient and place him/her in an examination room. Once the patient leaves, the examination room should remain vacant for the appropriate time, generally 1 hour, to allow for a full exchange of air [IB/IC].

●● Instruct patients with a known or suspected airborne infection to wear a surgical mask and observe respiratory hygiene/cough etiquette. Once in an AIIR, the mask may be removed. The mask should remain on if the patient is not in an AIIR [IB/IC].

●● Restrict susceptible HCP from entering the rooms of patients known or suspected to have measles (rubeola), chickenpox (varicella), shingles (disseminated zoster), or smallpox if other immune HCP are available [IB].

●● Wear a fit-tested NIOSH-approved N95 or higher level respirator for respiratory protection when entering the room or home of a patient when infectious pulmonary or laryngeal tuberculosis (TB) is suspected or confirmed or when infectious TB skin lesions are present and procedures that would aerosolize viable organisms (e.g., incision and drainage) are performed [IB].

●● For patients with skin lesions associated with varicella or smallpox or draining lesions caused by M. tuberculosis, cover the affected areas to prevent aerosolization or contact with the infectious agent in the skin lesions [IB].

●● Discontinue airborne precautions according to pathogen-specific recommendations [IB].



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Protective EnvironmentThe protective environment is intended for patients who have had hematopoietic stem cell transplants (HSCT). Due to the nature of their treatment, these patients have extremely sup-pressed immune systems are susceptible to fungal infections. Protective environment guidelines are intended to reduce the fungal spore counts in the air.1(p73) HSCT patients are a special focus, and the specifications are highly technical. Guidelines for the protective environment will not be covered in this text.

Isolat ion

Transmission-based precautions are sometimes referred to as isolation precautions or contact isolation. Isolation is a long-standing public health practice to limit the spread of disease by limiting the contact of ill and infectious persons have with susceptible hosts.17 In many cases, isolation occurs in the hospital setting while the patient is receiving treatment. However, public health officials do have the authority to isolate a sick person in order to protect the public.17

The length of a person’s isolation depends on the type of disease involved and the effectiveness of available treatments. Typically, isolation lasts for as long as the patient is infectious.

QuarantineQuarantine is another public health practice to limit the spread of infectious diseases that is frequently confused with isolation.17 Isolation applies to individuals who are already ill or diag-nosed with a disease, while quarantine applies to individuals who have been exposed to a conta-gious disease and may (or may not) become ill.17 Historically, quarantine equated to detention and forced segregation of persons suspected of carrying a contagious disease (e.g., immigrants entering the United States).18 Quarantine is currently used when exposure is well defined and when the disease involved is dangerous and highly contagious.17 When a high level of risk exists, persons who have been exposed have limited or controlled contact with other susceptible indi-viduals or potential new hosts until it can be determined whether they have acquired the infec-tious disease.

The decision to quarantine an individual or group of individuals must consider the resources available to provide care for the quarantined individual, as well as the resources required to implement and maintain the quarantine and deliver essential services.17 Modern-day quarantine strategies include short-term, voluntary home curfew; restrictions on the assembly of groups of people (e.g., school events); cancellation of public events; suspension of public gatherings and closing of public places (e.g., theaters); restrictions on travel (air, rail, water, motor vehicle, or pedestrian); closure of mass transit systems; or restrictions on passage into and out of a specified geographic area.17

Quarantine does not have to be absolute in order to provide some benefit. Partial quarantine can be effective in slowing the spread of disease because any decrease in the number of contacts with an infectious person decreases the number of people who may potentially develop the

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disease.17 Quarantine is likely to involve small groups, or rings, of people in small areas than large numbers of people (e.g., whole neighborhood or cities).17 Examples of this “ring” strategy of quarantine include17:

●● Travelers on an airplane or cruise ship that traveled at the same time as a passenger ill with a suspected contagious disease;

●● People in a setting such as a theater or stadium where an intentional release of a contagious disease has occurred; and

●● People who had contact with an infected person who source of disease exposure is unknown and, therefore, may be due to an intentional release of a contagious pathogen (e.g., bioterrorism).

The period of quarantine is determined by the specific situation, but should only last as long as necessary to protect the public.17 If there is a suspicion of infection with or exposure to an infectious agent, passengers on airplanes, trains, or boats may be delayed for a few hours while public officials assess the situation and risk. In some cases, officials might collect individual’s names and contact information and release them, while ill individuals might require transporta-tion to a hospital for treatment.17 Alternately, if it is determined that one or more passengers on a plane, train, or boat are ill with a contagious disease, public health officials may quarantine the remaining passengers in a designated facility to receive preventative care and monitoring.17

The successful implementation of quarantine requires cooperation from the public and may raise legal hurdles and public perception issues.17 In most instances, the legal authority to impose a quarantine lies with the state.18 However, if interstate commerce was involved or affected, then the federal government may become involved as the superior authority.18 A discussion about the legal authority to impose quarantine inevitably includes a discussion of individual autonomy and free will, as opposed to the health and well-being of the public.17,18

Multidrug-Resistant Organisms

Multidrug-resistant organisms (MDROs) lead to increased morbidity and mortality from health-care associated infections (HAIs). Therefore, HICPAC/CDC has issued a guideline addressing ways in which to monitor and prevent HAIs caused by MDROs.19 This guideline presents rec-ommendations for various aspects of monitoring and preventing MDROs, including adminis-trative measures, education and training of personnel, use of antimicrobial agents, surveillance, and precautions.19 The administrative and HCP education and training recommendations are similar to those presented from the 2007 Guideline for Isolation Precautions.1,19 The guideline contains separate recommendations for settings outside the hospital (e.g., long-term care facili-ties). Unless otherwise noted, the recommendations presented here relate to the hospital setting.

HCP should follow standard precautions with all patients (IB).19(p38) Compliance with the recommendation prevents transmission of several types of infectious agents, including MDROs. If the HCP will be performing patient care tasks with the potential for splashing, such as wound irrigation, oral suctioning, or intubation, then a mask should be worn.19(p38) When providing care to patients with tracheostomies or with certain types of wounds that have a high likelihood


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of colonization with MDROs (e.g., burn wounds), a mask should be worn.19(p38) However, masks are not recommended for routine patient care for the sole purpose of preventing MDRO transmission.19(p38)

In acute-care hospitals, contact precautions should be routinely implemented for patients infected with target MDROs and for patients who have been previously identified as being colonized with target MDROs [IB].19(p38) “Target MDROs” are those that are of particular epi-demiologic importance or have been identified by the facility for monitoring.19(p5) Examples of target MDROs are methicillin-resistant Staphylococcus aureus, vancomycin-resistant Entero-coccus, gram-negative bacteria, and S. aureus that is either has intermediate susceptibility to vancomycin or is vancomycin resistant.19(p5) Patients who have recently been discharged or are transferred from another facility may already be known to be colonized with an MDRO and should be treated under contact precautions.19(p38)

There are category II recommendations regarding implementation of contact precautions for patients infected or colonized with a target MDRO, including long-term care facilities, ambula-tory care facilities, and home care settings.

In both acute care hospitals and long-term care facilities, patients with known or suspected MDRO colonization or infection should have high priority for placement in single-patient rooms [IB].19(p40) Patients with conditions that increase the likelihood of transmission, such as those that result in uncontained secretions or excretions, should be given highest priority for placement in a single-patient room [IB].19(p40) If a single-patient room is not available, patients should be placed in the same patient room or patient care area as other patients with the same MDRO.19(p40) The practice of placing patients with like infections, including MDROs, together is referred to as cohorting.

Certain situations may call for an increased intensity in prevention and control efforts for MDROs. Indications for intensified MDRO control efforts include: 1) “when incidence or prevalence of MDROs are not decreasing despite implementation of and correct adherence to the routine control measures”19(p42) described in the guideline or 2) “when the first case or outbreak of an epidemiologically important MDRO is identified within a healthcare facility or unit” [IB].19(p42)

With these increased infection control efforts comes enhanced infection control precautions.19(p45) Contact precautions should be routinely implemented for all patients colo-nized or infected with a target MDRO [IA].19(p45) HCP should don gloves and gowns before or upon entry to the patient’s room or cubicle.19(p45) In long-term care facilities, contact precautions should be modified for patients whose site of colonization or infections can be appropriately contained and who can observe good hand hygiene practices so that these patients can enter common areas and participate in group activities [IB].19(p45)

Policies for patient admission and placement will need to be implemented in order to pre-vent transmission of the target MDRO(s) [IB].19(p45) These policies should include placement of MDRO patients in single patient rooms and cohorting patients with the same MDRO in des-ignated areas [IB].19(p46) If transmission of the target MDRO(s) continues despite single-patient room placement and cohorting, then dedicated nursing and support staff should be assigned to care for MDRO patients only [IB].19(p46) This recommendation requires the identification

Multidrug-Resistant Organisms 47

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of a group of nurses and other healthcare staff who will only care for the infected or colonized patients under the premise that if these dedicated HCP are not treating noninfected or noncolo-nized patients, then the MDROs cannot be transmitted by the HCP. Use of a dedicated pool of staff also provides an opportunity for more intense training and education about adherence to contact precautions. If transmission of the target MDRO(s) continues despite the efforts described herein, then the facility should stop any new admissions [IB].19(p46)

Administrat ion and Education

Support from the administration of a facility and ongoing staff education can significantly impact HCW compliance with use of PPE, standard precautions, and transmission-based pre-cautions. As a result, HICPAC/CDC set forth guidelines addressing these pieces of a successful program to prevent transmission of infectious agents in healthcare settings. Selected recommen-dations from those guidelines are presented here.

Administrators should incorporate the prevention of transmission of infectious agents into the organization’s patient and occupational safety program objectives [IB/IC]; prioritize preven-tion of transmission of infectious agents (e.g., provide fiscal and human resources support) and maintenance of infection control programs [IB/IC]; assure that individuals with training in infection control are employed by or available by contract to all healthcare facilities so that the infection control program is managed by one or more qualified individuals [IB/IC]; and deter-mine the specific infection control staffing needs (full-time equivalents, or FTEs) according to the scope of the infection control program, the complexity of the healthcare facility or system, the characteristics of the patient population, the unique or urgent needs of the facility and com-munity, and the proposed staffing levels.1(p74)

Administrators should also include prevention of HAIs as one determinant of nurse staffing levels and composition, especially in high-risk units such as the intensive care unit [IB].1(p75) Infection control personnel should be involved in decisions on facility construction and design, including determination of how many AIIR are needed [IB/IC].1(p75) Human and fiscal resources need to be available for a wide variety of clinical microbiology laboratory support, including a sufficient number of medical technologists trained in microbiology for monitoring transmis-sion of microorganisms, planning and conducting epidemiologic investigations, and detecting emerging pathogens [IB].1(p75) Plans must be in place to meet the human and fiscal needs of an occupational health program, as it relates to infection control, including HCP immunization and postexposure follow-up [IB/IC].1(p75)

The supplies and equipment necessary for consistent adherence to standard precautions, including hand hygiene supplies and PPE, should be available in all areas where healthcare is delivered [IB/IC].1(p75) Policies and procedures should be developed and implemented to insure that reusable patient care equipment is cleaned and reprocessed appropriately before use on another patient [IA/IC].1(p75)

Education and training for HCP regarding PPE and precautions must be presented in a man-ner that is both efficient and effective. It should be job specific or task specific on preventing transmission of infectious agents in the healthcare setting, presented during initial orientation


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to the healthcare facility, and updated periodically during ongoing education programs [IB].1(p76) All HCP should be targeted for this type of education and training, including but not limited to medical, nursing, and laboratory staff, clinical technicians, students, contract staff, and vol-unteers; as well as housekeeping, laundry workers, maintenance and dietary workers, [IB].1(p76) The education and training should be based on the principles of adult learning and use a reading level and language appropriate for the targeted audience, including online materials [IB].1(p75)

Main Messages

Contact transmission is the most common mode of transmission. Droplet transmission involves infectious disease transmission through respiratory droplets (> 5 μm), which are large enough that they do not require special air handling and ventilation. Airborne transmission occurs when droplet nuclei (≤ 5 μm) become airborne, disseminated, and inhaled by a new host. Pathogens that are spread via airborne transmission are able to remain infectious over time and distance.

PPE protects HCP by providing a barrier between the infectious material and the mucous membranes, airways, skin, and clothing of the HCP. PPE should be worn whenever there is a potential for blood or body fluid exposure and should be specific to the intended patient care task.

HICPAC and the CDC recommend a two-tiered approach to preventing the transmission of infectious agents: standard precautions and transmission-based precautions. Isolation is an infection prevention strategy used with individuals who are symptomatic or ill. Quarantine is used with individuals who have been exposed or who are likely to have been exposed but are not ill yet. Each can be used as an intervention to stop the spread of disease, but they are not the same technique.

Administrative measures and staff education are essential components to promoting PPE use and compliance.

Practical Scenario: Tuberculosis

Tuberculosis Background

Tuberculosis presents a public and occupational health concern, particularly in the healthcare set-ting. Tuberculosis disease is caused by M. tuberculosis and primarily affects the airway and lungs. The disease is spread when a patient whose upper airway (larynx) or lungs are infected introduces infec-tious airborne particles into the air by coughing, sneezing, shouting, or singing.20(p4) These infectious particles are approximately 1–5 m in size and referred to as droplet nuclei.20(p4) Prevention of trans-mission of tuberculosis in the healthcare setting is challenging because of the ability of the droplet nuclei to remain suspended and infectious for prolonged periods of time.20(p4) Once airborne, the droplet nuclei can spread through a room or building, including through the circulation system. When a susceptible host inhales the infectious airborne particles and the particles travel through the respiratory system to the alveoli in the lungs, the new host becomes infected.20(p4)

There are several known risk factors for exposure to M. tuberculosis, including foreign-born per-sons, especially those who have arrived in the United States within the past 5 years after moving from an area with a high concentration of TB disease or who frequently travel to countries with a high prevalence of TB disease; residents and employees of congregate settings that are high risk, such as correctional facilities, long-term care facilities, and homeless shelters; HCWs who serve

(Continues)

Main Messages 49

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Practical Scenario: Tuberculosis (Continued)

patients who are at high risk; HCWs with unprotected exposure to a patient with TB disease; and infants, children, and adolescents exposed to adults in high-risk categories.20(p5) The details of some high-risk groups can vary from area to area and must be defined locally, such as “certain popu-lations who are medically underserved and low income” and “populations at high risk who are defined locally as having an increased incidence of TB disease.”20(p5)

Once infected, a person can be categorized in two ways: 1) latent tuberculosis infection (LTBI) and 2) active disease.20(p4) Someone with LTBI is asymptomatic and not infectious.20(p4)

In addition to the high-risk groups described previously for exposure to M. tuberculosis, there are also known risk factors that increase the likelihood that someone with LTBI will progress to an active infection. Individuals with high risk for progression to active disease include persons infected with HIV; persons infected with M. tuberculosis within the past 2 years; infants and children less than 4 years of age; persons with certain preexisting clinical conditions or immunocompromising conditions, such as sili-cosis, diabetes mellitus, chronic renal failure, certain blood disorders, body weight ≥ 10% below ideal body weight, prolonged corticosteroid use, organ transplant; and persons with a history of untreated or inadequately treated TB disease. Someone with LTBI is asymptomatic and not infectious.20(p5)

In order to be infectious, an individual most have active pulmonary or laryngeal (airway) TB disease. However, some patients with active TB disease present a higher risk for transmission than others. Risk factors for increased likelihood of infectiousness include presence of a cough; cavita-tion on chest X-ray; positive acid-fast bacilli sputum smear result; respiratory tract disease with involvement of the larynx; respiratory tract disease with involvement of the lung or pleura; failure to cover the mouth and nose when coughing; incorrect, lack of, or short duration of antituberculosis treatment; and undergoing cough-inducing or aerosol-generating procedures.20(pp5,6)

Environmental factors can also increase the probability of transmission of M. tuberculosis. These risk factors include exposure to TB in small, enclosed spaces; inadequate ventilation that results in insuf-ficient dilution or removal of infectious droplet nuclei; recirculation of air containing infectious droplet nuclei; inadequate cleaning and disinfection of medical equipment; and improper procedures for han-dling specimens.20(p6) Because of these various groups of risk factors, the degree of risk of transmission within healthcare settings varies based on the specific setting, occupational group, prevalence of TB in the community, patient population, and effective TB infection-control measures within the facility.20(p6)

Basics of TB Infection ControlInfection control and prevention of TB disease is a complex practice with a significant knowledge base that exceeds the bounds of this text. However, there are fundamentals of TB infection control that should be emphasized. Healthcare-associated transmission of M. tuberculosis most often occurs with patients who have unrecognized TB disease and are not promptly handled with appropriate airborne precautions or who are moved from an AIIR too soon.20(p6) These basic guidelines focus on early identification and isolation of patients with suspected or confirmed TB disease.

There are three hierarchies of TB control: 1) administrative controls; 2) environmental controls; and 3) respiratory-protective controls.20(p7)

Administrative Controls Administrative controls are measures that reduce the likelihood that suscep-tible individuals (or potential new hosts) have access to someone who might have TB disease.20(p7) These measures, as recommended by the CDC, consist of20(p7):

●● Assigning responsibility for TB infection control in the setting;●● Conducting a TB risk assessment of the setting;●● Developing and instituting a written TB infection-control plan to ensure prompt detection,

airborne precautions, and treatment of persons who have suspected or confirmed TB disease;●● Ensuring the timely availability of recommended laboratory processing, testing, and reporting

of results to the ordering physician and infection-control team;●● Implementing effective work practices for the management of patients with suspected or con-

firmed TB disease;●● Ensuring proper cleaning and sterilization or disinfection of potentially contaminated equip-

ment (usually endoscopes);


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●● Training and educating HCWs regarding TB, with specific focus on prevention, transmission, and symptoms;

●● Screening and evaluating HCWs who are at risk for TB disease or who might be exposed to M. tuberculosis;

●● Applying epidemiologic-based prevention principles; and●● Promoting respiratory hygiene and cough etiquette with signage.

Environmental Controls Environmental controls aim to prevent the spread and reduce the concen-tration of infectious droplet nuclei in ambient air.20(p7) Primarily, environmental controls include controlling the source of infection with local exhaust ventilation (e.g., hoods, tents, or booths) and diluting and removing contaminated air by using general ventilation.20(p7) A second level of environ-mental controls consists of controlling the airflow to prevent contamination of air in areas next to the source (e.g., areas next to the AIIR) and cleaning the air by using HEPA filtration or ultraviolet gamma irradiation.20(p7)

Respiratory-Protection Controls The third level in the hierarchy of TB control entails the use of respiratory-protection equipment for persons entering an area where they might be exposed to M. tuberculosis.20(p7) This level of controls consists of implementing a respiratory-protection plan, training HCWs on respiratory protection, and training patients on respiratory hygiene and cough etiquette procedures.20(p7)

Managing Patients Who Have Suspected or Confirmed TBThe greatest TB risk to HCWs is from patients who have active disease but are not suspected or diagnosed.20(p16) Airborne precautions are only implemented once the patient is identified as a potential risk. For this reason, all patients should be promptly triaged to determine TB risk. All patients should be routinely asked, when a medical history is taken, about 1) a history of TB exposure, infection, or disease; 2) symptoms or signs of TB disease; and 3) medical conditions that increase their risk for TB disease.20(p16) Symptoms or signs of infection in the lungs, pleura, or airways, including coughing for at least 3 weeks, loss of appetite, unexplained weight loss, night sweats, bloody sputum, hoarseness, fever, fatigue, or chest pain should prompt consideration of a diagnosis of respiratory TB disease.20(p16)

In the healthcare setting, TB airborne precautions should be used for any patient who has signs or symptoms of TB disease, or who has documented infectious TB disease and has not completed antituberculotic treatment.20(p16) The patient may be removed from the AIIR and airborne precau-tions when infectious TB is considered unlikely and either 1) an alternate diagnosis is made that explains the clinical syndrome or 2) the patient has three consecutive, negative acid-fast bacilli sputum smear results.20(p16)

Tuberculosis Outbreak ExamplesReviewing prior outbreaks allows for identification of risk factors or missed opportunities for preven-tion. In 2006, eight TB cases from a small community in Connecticut and a ninth incarcerated-related case were identified.21 The source patient involved in this cluster of TB cases had been diagnosed with TB 10 years earlier while a resident in New Jersey.21 This source patient was lost to follow-up after an initial 2 weeks of treatment. She subsequently moved to Connecticut, where she was incarcerated from May 2005 through January 2006.21 During this incarceration period in Connecticut, the source patient exhibited signs and symptoms of TB disease and had abnormal chest X-rays.21 She was not diagnosed and was still symptomatic when released.21 In May of 2006, the source patient was diag-nosed with M. tuberculosis infection while a patient at a local community hospital.21

Her clinical isolates were susceptible to standard anti-TB treatment (they were not resistant) and she began a four-drug regimen as part of directly observed therapy.21 Directly observed therapy is a public health intervention to control the spread of TB disease and development of multidrug-resistant TB by ensuring that patients take their medication as prescribed.21 Public health officials, home health workers, or nursing staff observe the patient taking the medication at the appropriate times each day.21

In May 2006, an initial contact investigation for the source patient identified four secondary pulmonary TB cases (one adult and three children).21 Three additional adults had pulmonary TB diagnosed in October 2006.21 The source patient had multiple living arrangements before and after incarceration. The first eight cases had all shared living accommodations with the source patient at

(Continues)

Main Messages 51

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Practical Scenario: Tuberculosis (Continued)

some point prior to her second diagnosis in 2006.21 Of the 22 identified household contacts, three adults and three children had TB diagnosed and six adults and six children were diagnosed with LTBI.21 In other words, 82% of the known contacts from this one source patient were diagnosed with either TB disease or LTBI. A ninth, incarceration-related case was also linked to this source patient.21

The largest lesson from this outbreak investigation relates to the missed opportunities for treat-ment and identification. For example, this outbreak would not have occurred if the patient had been adequately treated at the time of the initial diagnosis in 1996.21 During intake screening at the jail or prison (high-risk congregate living situations), the patient could have been identified as exhibiting symptoms of TB disease or self-reported the previous diagnosis and been sent for further diagnosis and treatment.

This outbreak also highlights some of the social factors that influence the spread of infectious diseases, including TB. The patient lived in three different households and prison while she was infectious.21 The households had crowded living conditions and female household members and the children often shared bedrooms, further increasing risk.21 All of the women and children who shared a bedroom with the source patient were diagnosed with TB disease.21 While no further cases were identified related to this source patient, patient No. 7 identified in this outbreak disappeared after 6 weeks of treatment.21 Failure to complete treatment means that she may still be infectious and is also at risk to develop multidrug-resistant TB. Public health officials, law enforcement, and social service agencies in two states were unsuccessful in locating this patient.21 Therefore, patient No. 7 from this outbreak has the potential to become a source patient in a new outbreak of TB.21

The second outbreak for review will also illustrate a missed opportunity for prevention and con-trol.22 Suspicions about a possible TB outbreak were raised at a private hospital in early 2010 when 38 employees had positive tuberculin skin test (TST) conversions.22 All of the involved employees had negative TST results within the preceding 6 months and all worked on the same medical- surgical floor.22 The “red flag” was emphasized by the fact that no employee in the hospital had a TST conver-sion in the past 2 years.22 Clearly, there was a significant deviation from the normal trend.

The hospital was located in a geographic area that experienced higher TB rates than the overall state and national rates.22 Hospital policy required HCWs with direct contact with patients to receive a TB screening at hire and then every 6 months thereafter.22 All patients were screened at admission using a respiratory risk assessment tool that included questions about history of TB dis-ease or infection, treatment, symptoms, and medical history.22 Any patients identified as potentially infectious were placed in one of eight AIIRs.22

The initial step in this investigation was to confirm the validity of the positive TST results. Pos-sible alternate explanations such as changes in staff administering the TST or changes in location of administration, storage of TB antigen, or changes in procedures for reading results were all considered and discarded as factors.22 The screening tests were repeated using an alternate method (interferon-γ release assay blood test).22 Remaining protein derivative tuberculin (the liquid used in the TST) was sent to the local public health laboratory so that bacterial contamination could be ruled out.22 In addition, another local hospital using the same lot numbers for their employee screenings was consulted to determine if it had seen similar increases (it had not).22

Based on the time frame between the involved employee’s last negative TST and the new conver-sion to positive TST, the time frame for exposure to an infectious patient was narrowed down to September–December 2009 on the specific floor “X.”22 Medical records for patients treated on floor X during this time period were reviewed for risk factors and cross-referenced with known TB patients from the local public health department.22

Ultimately, it was determined that in July 2009, “patient A was arrested on the same day and time as another inmate (patient B), who was hospitalized and under … care on floor X in October–November 2009.”22(p535) These two patients arrived at the jail within 10 minutes of each other and were transferred to general population in the same time frame.22 In October 2009, patient B, a Spanish-speaking, HIV-infected male in his mid-20s, was admitted to floor X from the county jail.22 At that time, he had textbook TB symptoms, including cough, fever, chills, and weight loss.22 His initial chest X-ray showed abnormal findings. The admitting diagnosis was community-acquired pneumonia and he was discharged back to the jail after hospitalization for 7 days.22(p535)


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Two days after discharge, patient B was readmitted with cough and fever. He was initially placed on airborne precautions with a portable air filtration system, but that was discontinued after 1 day because it was felt that his pneumonia was not infectious.22 Patient B died 36 days after the second admission day.22 A record review showed that during his hospitalization, patient B had bloody spu-tum and worsening chest X-rays.22 This patient also had risk factors for TB disease, such as a history of drug use and homelessness.22 In 2007, patient B had been treated under a different name at the same hospital for drug-susceptible TB and HIV/AIDS.22 The strain involved in patient B’s 2007 TB infection was different than that of patient A or the index HCW.22

Infection preventionists and public health workers involved in the investigation hypothesized that there was an initial transmission of TB from patient A to patient B in the county jail in July 2009.22 It’s likely that patient B was then the source of a second wave of transmission from days 2–37 during his second admission in 2009.22

It was also discovered that large numbers of HCWs, correctional staff, and other patients and visitors on floor X were potentially exposed due to patient B’s habit of taking frequent walks around floor X while accompanied by jail staff.22 Among identified hospital-based contacts with patient B, 77% (23 of 30) of floor X staff and 87% (13 of 15) of correctional staff had a positive TST or interferon-γ release assay blood test following a previously negative TST.22 Additionally, from March 2010 to March 2012, 9 persons who spent time on floor X were diagnosed with TB disease: 3 hospi-tal employees, 3 correctional officers, 2 visitors, and 1 patient.22 Two of these patients had culture-negative, clinically diagnosed pleural TB; the remaining 7 patients had culture-positive pulmonary TB with genotyping results that match patient A’s genotype and had isoniazid-monoresistant TB.22

This outbreak demonstrates how one missed TB diagnosis can be linked to infections in dozens of contacts and at least nine new cases of TB disease. 22 There were multiple missed opportunities for identification, isolation, and treatment of patients A and B. Fortunately, the involved facility’s infection control program included routine TB screening of employees and baseline TST results were available for the correctional staff.22 This routine screening raised suspicion and started the investigation that identified patient A and B.22 In the course of this investigation, staff from the hos-pital, local and state public health departments, a university, and the correctional facility collabo-rated to identify the source patient(s), locate potential exposures, and provide necessary screening and treatment.

References

1. Siegel JD, Rhinehart E, Jackson M, et al. 2007 guideline for isolation precautions: preventing transmis-sion of infectious agents in healthcare settings. http://www.cdc.gov/hicpac/pdf/isolation/isolation2007.pdf. Accessed October 13, 2014.

2. Rosen HR. Acquisition of hepatitis C by a conjunctival splash. Am J Infect Control. 1997;25(3):242–247.3. Beltrami EM, Kozak A, Williams IT, et al. Transmission of HIV and hepatitis C from a nursing home

patient to a health care worker. Am J Infect Control. 2003;31(3):168–175.4. Obasanjo OO, Wu P, Conlon M, et al. An outbreak of scabies in a teaching hospital: lessons learned.

Infect Control Hosp Epidemiol. 2001;22(1):13–18.5. Andersen BM, Haugen H, Rasch M, et al. Outbreak of scabies in Norwegian nursing homes and home

care patients: control and prevention. J Hosp Infect. 2000;45(2):160–164.6. Avitzur Y, Amir J. Herpetic whitlow infection in a general pediatrician—an occupational hazard. Infec-

tion. 2002;30(4):234–236.7. Bache SE, Maclean M, Gettinby G, et al. Quantifying bacterial transfer from patients to staff during

burns dressing and bed changes: implications for infection control. Burns. 2013;39(2):220–228.8. Zabel LT, Heeg P, Goelz R. Surveillance of Pseudomonas aeruginosa-isolates in a neonatal intensive care

unit over a one year-period. Eviron Health. 2004;207(3):259–266.9. Langenberg W, Rauws EA, Oudbier JH, et al. Patient-to-patient transmission of Campylobacter pylori

infection by fiberoptic gastroduodenoscopy and biopsy. J Infect Dis. 1990;161(3):507–511.

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10. Sexton T, Clarke P, O’Neill E, et al. Environmental reservoirs of methicillin-resistant Staphylococcus aureus in isolation rooms: correlation with patient isolates and implications for hospital hygiene. J Hosp Infect. 2006;62(2):187–194.

11. Leontsini F, Papapetropoulos A, Vantarakis A. Stethoscopes as vectors of multi-resistant coagulase nega-tive staphylococci in a tertiary hospital. Int J Med Sci Public Health. 2013;2(2):324–330.

12. Feigin RD, Baker CJ, Herwaldt LA, et al. Epidemic meningococcal disease in an elementary-school classroom. N Engl J Med. 1982;307(20):1255–1257.

13. Dick EC, Jennings LC, Mink KA, et al. Aerosol transmission of rhinovirus colds. J Infect Dis. 1987;156(3):442–448.

14. National Institute for Occupational Health and Safety. Eye protection for infection control. http://www.cdc.gov/niosh/topics/eye/eye-infectious.html. Reviewed July 29, 2013. Accessed November 7, 2014.

15. Centers for Disease Control and Prevention (CDC). Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005. MMWR Recomm Rep. 2005;54(17):1–141.

16. American Institute of Architects (AIA). Guidelines for design and construction of hospital and healthcare facilities. American Institute of Architects. Washington, DC: American Institute of Architects Press; 2006.

17. Centers for Disease Control and Prevention (CDC). Understand quarantine and isolation. http:// emergency.cdc.gov/preparedness/quarantine/. Updated February 20, 2014. Accessed November 3, 2014.

18. Barbera J, Macintyre A, Gostin L, et al. Large-scale quarantine following biological terrorism in the United States: scientific examination, logistic and legal limits, and possible consequences. JAMA. 2001;286(21):2711–2717.

19. Siegel JD, Rhinehart E, Jackson M, et al. Management of multidrug-resistant organisms in health-care settings. http://www.cdc.gov/hicpac/pdf/guidelines/MDROGuideline2006.pdf. 2006. Accessed November 1, 2014.

20. Centers for Disease Control and Prevention (CDC). Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings. MMWR Recomm Rep. 2005;54(RR-17):1–119.

21. Medrano BA, Salinas G, Sanchez C, et al. A missed tuberculosis diagnosis resulting in hospital trans-mission. Infect Control Hosp Epidemiol. 2014;35(5):534–537.

22. Buff AM, Sosa LE, Hoopes AJ, et al. Two tuberculosis genotyping clusters, one preventable outbreak. Public Health Rep. 2009;124:490–494.


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