Community-Acquired Community-Acquired PneumoniaPneumonia

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:

• 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 COMMUNITY-ACQUIRED 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)

Bacteria (Chlamidia.tracho, Bordetella)

• 3m -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• 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)

lateralPosteroanterior

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 sputumGram'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 – age– sex– comorbid illnesses– physical findings– selected laboratory findings

• The PSI is applied in two steps

PNEUMONIA SEVERITY INDEX

Step 2 of prediction rule

• Age (age years)

• Coexisting illnesses (10 – 80)

• Physical examination findings (10-65)

• Laboratory and radiographic findings (10 – 110)

STRATIFICATION OF RISK SCORE

Risk Risk classclass

No. of pointsNo. of points Mortality Mortality (%)(%)

Recommendations Recommendations for site of carefor site of care

I No predictors 0.1 % Outpatient

II </= 70 0.6 % Outpatient

III 71 - 90 2.8 % Inpatient (briefly)

IV 91 - 130 8.2 % Inpatient

V > 130 29.2 % 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

ManagementAntibiotic 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%

a) coexisting illness and/or bacteremia

b) the severity of illness at the onset of antibiotic therapy

c) the subsequent hospital course organism duration of treatment organism duration of treatment

S. pneumoniae 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

DURATION OF TREATMENT

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