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Community-Acquired
Pneumonia
B.Hajikarim
ZUMS
2010
Importance of CAP
• A major cause of death globally
» Death rate due to pneumonia: 75000
• High incidence & mortality
» patients per year: 4,000,000
» Mortality Rate: 2-30%
• High rate of hospitalization
» (600,000/15%)
CAP In The Past DECADE
Dramatic changes
in the etiology
(Emerging pathogens)
Growth of antimicrobial
resistance
Dramatic changes in the
diagnosis & management
Pathogenesis
• Defense mechanisms:
• Filtering system
– cough, sneezing, & reflex glottis
– ciliated cells
• Clearing system
– Macrophages
– T & B lymphocytes
Transmission routes:
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Aspiration of oropharyngial colonization
Inhalation of infectious aerosols
Hematogenous dissemination
Direct inoculation
ETIOLOGY OF COMMUNITY-ACQUIRED
PNEUMONIA
• Pathogen not defined in as many as 50 %
patients even with extensive diagnostic
testing
• S. pneumonia is the leading cause of CAP
• H. influenzae ( type B), S. aureus, and gram
(-) bacteria each account for 3 to 10 %
• Staph aureus CAP is usually seen in the
elderly and as post-influenza pneumonia
ETIOLOGY OF COMMUNITYACQUIRED PNEUMONIA
• P. aeruginosa causes CAP in neutropenia,
cystic fibrosis, HIV infection &
bronchiectasis
• N. meningitidis, M. catarrhalis & S. pyogenes
can occasionally cause CAP
• Anaerobic organisms are implicated in
aspiration pneumonia and lung abscess
• MRSA, M. tuberculosis & certain viral agents
are common in nursing-home patients
Community acquired
pneumonia (CAP)
• Definition:
– Acute signs & symptoms
(respiratory or nonrespiratory)
– New radiographic infiltrate
– Acquisition of infection from
outside the confines of a hospital
Clinical approach to pneumonia
–History
–Physical examination
–Age
–Epidemiologic data
–Predisposing conditions
History
• Typical or atypical pneumonia syndromes
• Host consideration:
– Neonates (no fever, mild & prolonged
symptoms)
– Young infants (viral pneumonia with
respiratory distress & fever +/- sepsis)
– Elderly (Changes in eating habit or mental
function, minimum of respiratory symptoms)
History
• Special considerations by organism:
– M.TB & fungal pneumonia (gradual onset)
– Mycoplasma & Chlamydia pneumonia
(protracted cough, minimum sputum)
– Legionnaires’ disease (relative bradycardia,
renal, liver. Mental & GI abnormalities)
Physical examination
• Signs of nonpneumonic infection
• Signs of pleural effusion
• Signs of anomalies lead to
intrapulmonary process (DVT, clubbing, …)
• Host considerations (very young & very
old patients ,immune status)
Epidemiologic data
• Family history (RSV, Mycoplasma.p,
Influenza)
• Travel history
• Unusual contact (with animal, birds,
excavation)
• Seasonal & geographic differences
• Patients living circumstances
Age
• Newborn: Viruses (CMV,Rubella,HSV)
Bacteria (GBS)
• 1 - 3 m: Viruses (RSV, influenza & Para.inf)
• 3m
Bacteria (Chlamidia.tracho, Bordetella)
-5Y: Viruses (RSV, Para.in, Adeno, Influ)
Bacteria (S.Pneu, H.inf, Chla.P, Myco.P)
Age
• 5 - 18Y: Viruses( Para.inf, Influ, Adeno)
Bacteria (Myco, Chla, Pneu)
• 18 -65Y: Viruses (Para.inf, Influ, Adeno)
Bacteria(Myco.P, Chla.P, S.Pneu)
• Over 65Y: Bacteria (S.Pneumo, H.inf, gr
neg,Staph, mora.C,Legio.P
Viruses
Predisposing conditions
• In alcoholics:
S.pneumonia, K.pneumonia, H.Influenza, M.Tuberculosis
• Aspiration Of URT secretions
• Chronic obstructive pulmonary disease:
H.influenza, S.pneumonia, Moraxella catarralis
• Cystic fibrosis:
Staphylococcal & Pseudomonas infection
• Post influenza bacterial pneumonias
Predisposing conditions
• Immune status (including HIV/AIDS):
– Hypogammaglubolinemia: Encapsulated
bacteria
– Sever neutropenia:
Pseudomonas, Staphylococcal & Fungal inf.
– HIV & AIDS :Consider CD4 count
– Corticosteroid therapy: M.TB, Nocardial
infections
Clinical approach to pneumonia
(Review)
–History
–Physical examination
–Age
–Epidemiologic data
–Predisposing conditions
Diagnostic evaluation
• Baseline assessment
• Outpatient assessment
• Inpatient assessment
Baseline assessment
• Chest X.ray useful for:
– Diagnosis of pneumonia
– Diagnosis of etiologic agents
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Location of infiltration
Cavitations
Volume loss
Pleural effusion
Mediastinal adenopathy
Baseline assessment
• Chest X.ray useful for:
– Detecting associated conditions
– Follow up (rapid changes over 8-36 h)
• Patients clinically improving (gradually or
even longer clearing)
• Patients not improving (bronchial obstruction,
super infection, associated effusion, abscess)
Pneumococcal pneumonia: lobar consolidation
affecting both lungs. An air bronchogram is
easily seen in the left middle zone
Mycoplasma pneumonia: patchy
consolidation in several areas in both lungs
Staphylococcal pneumonia: pneumatoceles
(arrowed) in right middle and lower lobes
and in left lower lobe (infant)
Posteroanterior
lateral
Pulmonary tuberculosis: consolidation &
cavitation of left upper lobe
Pulmonary tuberculosis: extensive consolidation
of the left lung with partial collapse. Less severe
changes are seen on the right
Tuberculosis of mediastinal glands:
widening of superior mediastinum by
enlarged right paratrachael lymph nodes
Tuberculous pleurisy: small right
pleural effusion
Lung abscess: abscess cavity in
lower lobe of right lung.
posteroanterior
lateral
Chest x-ray
• False negative results
• High resolution CT (HRCT) is more
sensitive for the evaluation of:
– interstitial disease
– bilateral disease
– cavitations
– empyema
– hilar adenopathy
Outpatient assessment
• Sputum stains:
– gram staining of sputum
• Appearance
• Adequacy
• Unsuspected gram negative organisms
– Acid fast smear & culture
Gram's stain of expectorated sputum
• Sensitivity and specificity vary widely depending
on the criteria used to define a "positive” stain
• > 25 neutrophils and < 10 squamous epithelial
cells per low power field
• Cytologic screening criteria not evaluated for
Legionella, mycobacteria or viral infections
• Direct staining of sputum may be diagnostic for
Mycobacterium sp., endemic fungi, Legionella
sp. (DFA stain) & P. carinii
Sputum Gram stain
Sputum Gram Stain
Inpatient assessment
Recovery of the organism
• Obtaining of different diagnostic specimens
before treatment:
• Blood culture
• A good sputum for smear & culture
• Aspiration & culture of pleural fluid
• Other body secretion cultures
Invasive diagnostic techniques
• Transtracheal aspiration
• Bronchoscopy with a protected
brush catheter
• Bronchoalveolar lavage with or
without balloon protection
• Direct needle aspiration of the lung
Diagnostic evaluation
(Review)
• Baseline assessment
• Outpatient assessment
• Inpatient assessment
Management
• Choose the Environment of
management
By:
Pneumonia Severity Index.
PNEUMONIA SEVERITY INDEX (PSI)
CLINICAL PREDICTION RULE
• The PSI rule stratified adults with radiographic
evidence of CAP into five classes for risk of
death from all causes within 30 days of
presentation
• Predictor Variables
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age
sex
comorbid illnesses
physical findings
selected laboratory findings
• The PSI is applied in two steps
PNEUMONIA SEVERITY INDEX
Step 2 of prediction rule
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Age (age years)
Coexisting illnesses (10 – 80)
Physical examination findings (10-65)
Laboratory and radiographic findings
(10 – 110)
STRATIFICATION OF RISK SCORE
Risk
class
I
No. of points
No predictors
Mortality
(%)
0.1 %
Recommendations
for site of care
Outpatient
II
</= 70
0.6 %
Outpatient
III
IV
V
71 - 90
91 - 130
> 130
2.8 %
8.2 %
29.2 %
Inpatient (briefly)
Inpatient
Inpatient
SEVERE COMMUNITY-ACQUIRED
PNEUMONIA
There is no universally accepted definition of
severe CAP:
ATS definition:
1. Requirement for mechanical ventilation
2. Requirement for vasopressors for more than 4 h
3. SBP < 90 mmHg
4. Severe respiratory failure defined by a Pao2/Flo2
ratio <250
5. Multilobar involvement
Management
Antibiotic choices
outpatient < 60 yrs
– Amoxicillin (500mg TDS)
– Macrolides
Erythromycin (500mg Qid)
Azithromycin (500mg then 250mg
daily)
Clarithromycin (500mg BD)
– Doxycycline (100mg BID)
– Flouroquinolone (IDSA)
outpatient 60 yrs or > or adult with
preexisisting disease
1. beta-lactam ( cefpodoxime, high dose
amoxicillin, amox-clav., ceftrioxone)
PLUS
macrolide or doxycycline
2. antipneumococcal quinolone (only
IDSA)
Pathogen Resistance in CAP
• Three specific pathogen:
H.inf, S.pneu, M.cata
• Linear increase in the magnitude of ampicillin
resistance with: H.inf=33%, M.cata=100%
• High prevalence of penicillin resistance with
S.pneu=35%
• Non-betalactam resistance with S.pneu:
Macrolides=26% clindamycin=9%
Tetracycline=16% Chloramphenicole=8%
TMP-SMZ=30% Fluoroquinolones=0.2%
DURATION OF TREATMENT
a) coexisting illness and/or bacteremia
b) the severity of illness at the onset of antibiotic therapy
c) the subsequent hospital course
organism
S. pneumoniae
duration of treatment
approximately 7 to 10 days
M. pneumoniae
10 to 14 days
C. pneumoniae
10 to 14 days
Legionnella pneumonia
14 days
21 days if immunocompromised
Response to treatment
• Subjective feelings of improvement
– Within 1-3 days
• Fever
– Within 2-5 days
• Chest examination findings
– Longer than 1 week
• Leukocytosis
– Within 3-4 days
• Bacteremia
– Less than 24-28 hours
• Radiographic improvement
PREVENTION
• Pneumococal Vaccine
• Influenza Vaccine
Pneumoccal vaccine
• 23-valent polysaccharide pneumoccal
vaccine:
– 90% of the serotypes are included in the 23 valiant
vaccine
– 70% response in the general population
– Lower in immunocompromised patients and those on
maintenance dialysis
• Target hosts at greatest risk for
pneumococcal disease:
– > 65 yrs
– chronic cardiovascular and pulmonary disease
– metabolic diseases, alcoholism, cirrhosis,
nephrotic syndrome
– immunosuppression, asplenia
– lymphoma, multiple myeloma