What are the solutions for the problems in lower respiratory infections? : GEORGIA
Lower Respiratory Infections
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Transcript of Lower Respiratory Infections
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Dr.T.V.Rao MD
LOWER RESPIRATORY
BACTERIAL INFECTIONS
AETIOLOGY, DIAGNOSIS
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RESPIRATORY SYSTEM
ENVIRONMENT IS DIVERSE
Upper respiratory system
Nose, pharynx, associated structures
Purpose: to take in, warm and moisten air Most common site of infections
Lower respiratory system
Larynx, trachea, bronchi, alveoli
Purpose: ventilation, gas exchange
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ANATOMY OF THE RESPIRATORY
SYSTEM (AND SITES OF INFECTION)
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CLINICAL PRESENTATION:
LOWER RESPIRATORY TRACT INFECTION
Acute Infection:
Fever, chills
Back pain, myalgias, arthralgias
Headache, malaise, chills
Nausea, vomiting
Chest Infection:
Cough
Chest pain
Rales, wheezing, noisy chest
Characteristic changes on chest x-rays
Increasing respiratory distress, may require mechanical ventilation
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LOWER RESPIRATORY TRACT INFECTIONS
EPIDEMIOLOGY
Pneumonia is the sixth leadingcause of death in US
Increasing numbers of patients at risk Aging population
Increase in patients with
immunocompromising conditions
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DIAGNOSIS DEPENDS ON CLINICAL
PRESENTATION AND AGE TOO
Most of these cases diagnosis depends on
clinical presentation and minimum laboratory
and radiologic investigations may be needed
most of these cases recovered smoothly with
appropriate management unless an underlying
lung pathological or systemic disease may
worsen the condition or continue with chronicityappropriate follow-up of these patients in OPC is
appreciated especially after discharge from
hospitalDR.T.V.RAO MD 6
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Infections of the lowerrespiratory tract are the
leading cause of cause
of mortality world wide.
Streptococcus
pneumoniae is the
leading bacterial agent
of community acquiredpneumonia along with
Haemophilus
influenza and
Moraxella catarrhalis
LOWER RESPIRATORY TRACT
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Pneumococcus is the
most common bacterial
pathogen causing
febrile pneumonia inchildren and adults
The clinical syndrome
is characteristic and
distinctive : acute
onset of high, spiking
fever, with chills, cough,
and sputum production
PNEUMOCOCCUS A SIGNIFICANT PATHOGEN
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Acute bronchitis
Community
acquired pneumonia Hospital acquired
pneumonia
Pneumonia in theimmunocompromisedhost
CATEGORIES OF LOWER
RESPIRATORY TRACT INFECTIONS
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COMMUNITY ACQUIRED PNEUMONIA
ETIOLOGIC AGENTS
Pathogen Frequency (%)Streptococcus pneumoniae 66
Haemophilus influenza 1-12
M catarrhalis 10
Legionellaspecies 2-15Mycoplasma pneumoniae 2-14
Klebsiellaspecies 3-14
Enteric gram negative bacilli 6-9
Staphylococcus aureus 3-14
Chlamydiaspecies 5-15
Influenza viruses 5-12
Other viruses
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SPECIMEN COLLECTION:
The patient should be standing, If possible or sitting upright in
bed.
He or she should take deep breath to full the lungs, and emptythen in one breath, coughing as hard and as deeply as
possible.
Sputum brought up should be spit into screw capped
container.Visually inspect the specimen.
Tighten the cap of the container and send immediately to lab.
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Sputum of less than 2ml
should not be processed
unless obviously purulent
Only 1 sputum per 24hr.submitted
Some scoring system
should be used to reject
specimen that re oralcontamination.
SPUTUM COLLECTION
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TRANSPORTATION OF SPUTUM
Transportation in
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INDUCED SPUTUM
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Patients who are unable to produce sputum may beassisted by respiratory therapy technician. Aerosolinduced specimen are collected by allowing thepatient to breath aerosolized droplets of a solution
of 15% sodium chloride and 10% glycerin forapproximately 10 minute obtaining suchspecimen may avoid the need for a more invasiveprocedures ,such as bronchoscopy or needle
aspiration, in many cases.
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BRONCHOALVEOLAR LAVAGE (BAL)
SPECIMEN ACCEPTABILITY
Microscopic examination of Gram-stained smear
Acceptable
1% of cells present are squamous epithelial
cells
Thorpe JE et. al. 1987. Bronchoalveolar lavage for diagnosing acute bacterialpneumonia. J. Infect. Dis. 155:855-861DR.T.V.RAO MD 15
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METHODS OF COLLECTION IS
IMPORTANT..
Sputum collected under supervision of nurse or resident
Samples were processed immediately
Screened for epithelial cells
Screened for predominant morphotype (> 75% of the
organisms seen)
Sputum planted to blood agar, chocolate agar and MacConkey
agar Strictly defined clinical and diagnostic parameters
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Prepare a gram stain smear for
all lower respiratory tract
specimens to determine the
presence of oropharyngeal
contamination (indicated by
squamous epithelial cells) andlower respiratory tract secretions
(indicated by WBCs) as well as
to identity the most likely
pathogens (Indicated by the
predominant organismsassociated with WBCs).
MICROSCOPIC EXAMINATION
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SPUTUM GRAM STAIN
Good quality specimens
Quantify number and types of inflammatory cells
Note presence of bronchial epithelial cells
Concentrate on areas with WBCs when looking for
organisms
Determine if there is a predominant organism (> 10 per oil
immersion field) Semiquantitate and report organism with descriptive
If no predominant organism is present, report mixed gram
positive and gram negative floraDR.T.V.RAO MD 18
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SPUTUM GRAM STAIN IS HELPFUL - YES
Proponents
Demonstration ofpredominant
morphotype on Gramstain guides therapy
Accuracy is good when
strict criteria are used Cheap, so why not?
Antagonists
Poor specimen collection
Intralaboratory variability
(Gram stain interpretation) Low sensitivity and
specificity
Empiric treatment
guidelines Do much dependence ???
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STUDIES PROVE ... Overall sensitivity and specificity for pneumococcal
pneumonia: 57% and 97%
Overall sensitivity and specificity forH. influenza
pneumonia: 82 % and 99%
Gram stain gave presumptive diagnosis in 80% of
patients who had a good specimen submitted
> 95% of patients in whom a predominant morphotypewas seen on Gram stain received monotherapy
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REPORT GRAM STAINING WITH
CAUTION
Be as descriptive as possible
Moderate neutrophils
Moderate Gram positive diplococcic suggestiveofStreptococcus pneumoniae
Few bacteria suggestive of oral flora
Keep report shortavoid line listing of all
morphotypes present
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If no squamous epithelial cell are
found, report No epithelial cells
seen
If only a few epithelial cells are
found report Few epithelial cellsseen
If abundant epithelial cells seen,
indicating oropharyngeal
contamination, such specimens
are graded as unsatisfactorysample.
SQUAMOUS EPITHELIAL CELLS
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If no WBC are foundreport No WBCs
seen
If WBCs are present
in any amount state
as few, moderate or
numerous WBCsseen.
REPORTING THE PRESENCE OF LEUCOCYTES:
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INTERPRETATION OF GRAM STAIN:
None Few Moderate Numerous
Squamous epithelial cells/ LPF* 0 1-9 10-24 >25
Neutrophils/LPF* 0 1-9 10-24 >25
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GRAM STAINING REPORTING MICROBIAL
OBSERVATIONS
Type / Number of organisms / HPF**
Gram-positive cocci
Gram-negative cocci
Gram-negative rods
Gram-positive rods
PF*: (low power field) x 10 (examine 10-20 fields)
HPF**: (high power field) oil immersion
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PROCESSING SPECIMENS FOR CULTURE
Process specimens in biological safety cabinet, asaerosol can result in laboratory-squired respiratoryinfections.
Process all specimens as rapidly as possible,
especially specimen from emergency department, andinpatients. Select the most purulent or most blood-tinged portion of the specimen. Significant growthabove the cutoff should be reported; however if more
than one pathogen is isolated than it is suggestive oforopharyngeal contamination and clinical correlationshould be done before reporting the samples.
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Sheep Blood
Agar
MacConkeyagar
Chocolateagar
CHOOSING CULTURE MEDIA:
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Most of the commonlysought etiologic agents oflower respiratory tractinfection will isolated on
routinely used media : 5%sheep blood agar,MacConkey agar forisolation and differentiationof gram-negative bacilli
,and chocolate agar forNeisseria spp andHaemophilus .
ROUTINE CULTURE
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CONTAMINATION WITH ORAL FLORA
INTERFERES RESULTS
Because of contaminating oral flora ,sputum specimens,
specimens obtained by bronchial washing, and lavage
tracheostomy, or endotracheal tube aspirates are not
inoculated to enriched broth or incubated anaerobically.Only specimens obtained by percutaneous aspiration
(including trans tracheal aspiration )and by protected
bronchial brush are suitable for anaerobic culture: he
latter must be done quantitatively for properinterpretation.
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CULTURING SPECIMENS FROM CYSTIC
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CULTURING SPECIMENS FROM CYSTIC
FIBROSIS
Sputum specimens from patients known tohave cystic fibrosis should be inoculated to
selective agar ,such as manitol salt agar for
recovery ofS .aureus and selective horseblood-bacitracin ,incubated anaerobically and
aerobically ,for recovery ofH,influenzae that
may be obscured by the mucoid
P,aeroginosa on routine media.
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SPUTUM AND ENDOTRACHEAL SUCTIONCULTURE EVALUATION
Identify and perform susceptibility testing on 2-3 potentialpathogens seen as predominant on Gram stain
Alpha streprule out S. pneumoniae
Yeastrule out Cryptococcus neoformans only
S. aureus, Gram negative bacilli
< normal flora, quantify and limit ID; no susceptibility
Add comment that organism not predominant on stain
ID mould, Mycobacteria orNocardia spp.
Modified from Sharp SE, et. Al. 2003. Cumitech 7B. ASM Press.DR.T.V.RAO MD 31
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INTERPRETATION OF QUANTITATIVE
PSB/BAL
Dilution Method
Quantify each morphotype present and express as CFU/ml
Calibrated Loop Method
Quantify each morphotype present and express as log10 colonycount ranges
Thresholds for significance
PSB > 103 CFU/ml
BAL > 104 CFU/ml
Baselski and Wunderink. 1994. ClinMicro Rev7:547
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EXAMINE FOR AND ALWAYS REPORT.
Streptococcus pyogenes
Group B streptococci in pediatric population
Francisella tularensis
Bordetella spp., especially Bordetella bronchiseptica
Yersinia pestis
Nocardia spp.
Bacillus anthracis
Cryptococcus neoformans
Molds, not considered saprophytic contaminants
Neisseria gonorrhoeaeDR.T.V.RAO MD 33
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Streptococcuspneumoniae
Haemophilusinfluenza reportbeta-lactamase
ALWAYS REPORT, BUT DO NOT MAKE AN EFFORT TO FIND
LOW NUMBERS, UNLESS THEY ARE SEEN IN THE SMEAR.
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REPORT IF PRESENT IN SIGNIFICANT
AMOUNTS, EVEN IF NOT PREDOMINANT
1 Moraxella catarrhalis
2 Neisseria meningitides
Report the following for nosocomialinfections:
3. Pseudomonas aeruginosa
4. Stenotrophomonas maltophilia
5. Acinotobacterspp.
6. Burkholderia spp.DR.T.V.RAO MD 35
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REPORT IF PRESENT IN SIGNIFICANT AMOUNT AND IF IT IS
THE PREDOMINANT ORGANISM IN THE CULTURE,
PARTICULARLY IF SUGGESTS INFECTION WITH
MORPHOLOGY CONSISTENT WITH ISOLATE.
Staphylococcus aureus
Beta-hemolytic streptococcus B (adults), C, or G
Single morphotype of gram-negative rod (especiallyKlebsiella pneumoniae)
Fastidious gram-negative rods; usually report beta-lactamase
Corynebacterium spp. if urea positive or from ICU
Rhodococcus equiin immunocompromised patients
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ATS GUIDELINES
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ATS GUIDELINES
DIAGNOSTIC TESTS FOR CAP
Empiric therapy for outpatients
Macrolide or tetracycline
Hospitalized patients with CAP
2 sets of pre-treatment blood cultures Pleural fluid Gram stain/culture when appropriate
Studies for Legionella, Mtb, fungi in select patients
Sputum Gram stain/culture only if resistant or unusual pathogen issuspected
Avoid extensive testing
ATS. 2001.Am J Respir Crit Care Med163: 1730-1754.
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CRITERIA FOR REJECTING
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CRITERIA FOR REJECTING
SAMPLES
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Mismatch of information on the label and the request
Inappropriate transport temperature
Excessive delay in transportation
Inappropriate transport medium
specimen received in a fixative
dry specimen
sample with questionable relevance
Insufficient quantity
Leakage
IM
MUNOCOMPROMISED PATIENTS
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Aerobic Gram stainquantitative bacterialculture
Fungal stain and culture
Mycobacterial stain andculture
Viral culture/RespiratoryDFA
Pneumocystis DFA
Legionella culture
IMMUNOCOMPROMISED PATIENTS
SUGGESTED BAL PROTOCOL
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MANY OTHER CAUSES OF PNEUMONIA WITH
ACUTE RESPIRATORY DISEASE & FEVER
Plague Tularemia RICIN toxin
StaphylococcalEnterotoxin B
TBLegionella
SARS
S.Pneumoniae
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SUMMARY Respiratory system can host a variety of microbes
Normal flora in restricted areas
Susceptibility depends on age, immune system
Some organisms are adept at evading immune
system
Damage generally due to cytotoxicity andinflammation
Vaccines are available for some organismsDR.T.V.RAO MD 41
CHILDHOOD IMMUNIZATIONS CAN REDUCE
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CHILDHOOD IMMUNIZATIONS CAN REDUCERESPIRATORY INFECTIONS FOLLOW THE SCHEDULES
Birth 1m 2m 3m 4m 6m 12m 15m 18m 4-6y 11-12y
HBV3
DTP
HBV1HBV2
DTP
DTP DTP
Hib
Hib
Hib Hib
Polio Polio Polio
MMR MMR or MMR
Varicella Varicella
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DO REMEMBER
The culture of lower respiratory
specimens may result in more
unnecessary microbiologic effort
than any other type of
specimen.Raymond C Bartlett
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Programme created byDr.T.V.Rao MD for Medical and
Health Workers in theDeveloping World
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