COMMUNITY AQUIRED PNEUMONIA

Dr. Devawrat Buche, MDFNB Fellow ( CCM )

• Definition• Epidemiology• Signs and symptoms• Investigations• Microbiology• Risk stratification• Treatment • Prevention

DEFINITION

It is a syndrome in which acute infection of lung develops in persons who have not been previously hospitalized , with no regular exposure to health care system.

Traditional definition ( NEJM, oct 2014 )Newly developed lung infiltrate on chest imaging along with fever, cough, sputum production, shortness of breath with physical findings of consolidation and leucocytosis.

• Joint ICS/ NCCP (I) Definition:1. In the absence of CXR-• Symptoms of acute LRTI for less than 1 week • At least 1 systemic feature ( temp >37.7, chills and

rigors, severe malaise )• New focal chest signs ( bronchial breath sounds/

crackles)• No other explaination for the illness2. In the presence of CXR – • Above symptoms• New radiologic shadowing • With no other explaination ( edema / infarction)

EPIDEMIOLOGY• World • Social burden• US stats : > 9 lakh cases/ year in > 65 yr age• High rates of hospital admissions , prolonged inactivity :

health care burden

• INDIA• NO large studies, data limited• Attributable mortality to LRTI is around 20%

2008 stats :• Mortality due to LRTI : 35.1/ lakh• Mortlaity due to TB : 35.8 / lakh

ETIOLOGY

• Etiology in India (based on blood cultures ) :S. Pneumoniae ( 35.3% )s. Aureus ( 23.5%)Kleb. Pneumoniae ( 20.5%)H. Influenzae ( 8.8%)• Legionella is often not considered in Indian

setting : 1 study found 27% patients seropositive and 18 % urine ag positive

• No large studies to specifically address viruses as the cause.

• Etiology in specific population groups : 1. Elderly• S. pneumonia : 19- 58% of hospitalized pt.• H. influenzae : 5- 14 %2. AlcoholismIncreased CAP risk with dose response relationship• S. pneumoniae: most common• High incidence of bacteremia and increased severity• Mortality rates similar to other groups.3. COPD• Increased incidence of pseudomonas and GNB4. Diabetes mellitus• Increased bacteremia, higher mortality rates.• Pneumococcal pneumonia (m.c. )

• Risk factors for pseudomonas pneumonia : 1. Immunocompromiosed2. Chronic respiratory disease3. Enteral tube feeding4. Cerebrovascular disease5. Chronic neurological disorders6. Structural respiratory disease : bronchiectasis

DIAGNOSTIC TESTING

• Physical examination• Routine investigations • Chest X ray• Microbiological studies • Immunological studies

Clinical diagnosis is based on:• Presence of clinical features : cough, fever,

sputum production, pleuritic chest pain• Physical examination: rales, bronchial breath

sounds, tachypnea, tachycardia, fever.• Pulse oximetry : desaturation s/o severity• Other : plasma glucose, CBC, LFT, KFT,

electrolytes

Chest radiography• CXR useful in suggesting etiologic agents, prognoses,

alternative diagnosis and associated conditions

• A demonstrable infiltrate by chest radiograph or other imaging technique is required for diagnosis of pneumonia ( level III evidence ) – should be done whenever possible.

• For hospitalized patients with suspected pneumonia having negative CXR: continue empirical therapy and repeat CXR in 24-48 hrs.

• Salient findings :1.Asymmetric lung opacification with air bronchogram2. Presence of silhouette sign3. Increased opacity with well defined interface

• HRCT salient findings :1. Air space considation2. Ground glass attenuation3. Thickening of bronchovascular bundle• Low sensitivity and specificity to discrimnate

bacterial from non bacterial etiology

• Recommendation :1. Should not be routinely performed2. Should be performed in those with nonresolving

pneumonias and for assessment of complications.

Microbiological studies

1. Blood culture • Low sensitivity , high specificity : for etiology• Low yield : 5 – 33 % Recommendations :A. Should be obtained in all hospitalized

patients ( 2A )B. Not required in routine outpatient

management ( 2A).

2. Sputum Gram stain and culture• Yield : 34 – 86 %• Provides rapid results, narrows down etiology

SAMPLING• 20 – 40 fields examined under low power• If epithelial cells > 10/lpf : sample rejected• If no. of pus cells is 10 times epi. Cells, with 3+ or4+ single

bacterial morphology : sample accepted

Recommendations : 1. Initial gram stain and culture obtained from all hospitalized

patients with CAP ( 2A)2. Sputum for AFB obtained as per RNTCP guidelines ( 2A)3. Sputum quality should be ensured for interpreting results ( 2A )

Other cultures1.Thoracocentesis • Pleural effusions >5 cm in lateral upright CXR• Undergo thoracocentesis, GS and culture• Yield is low• But can impact management2.BAL / tracheal aspirate.• Not been studied prospectively in initial magt of

CAPBest indications are : • Immunocompromised patients with CAP• Patients of CAP with failure of t/t

Immunological testing

1. Urinary pneumococcal Ag• Rapid immunochromatographic membrane

tests• Unfavourable cost : benefit ratio• Only confirms etiology, no change in t/t

protocol.Currently, not recommended routinely.

2. Legionella urine Ag test• High specificity ( 99 %), low sensitivity ( 74 %)• Positive test is highly specific, changes duration of

antibiotic therapyCurrently recommended for patients with severe CAP ( 1B)

3. Atypical pathogens • Mycoplasma, chlamydia, viruses• Serological assays used : variable results• Currently not recommended for routine diagnosis

( 2A)

4. Biomarkers • Procalcitonin• C reative protein

• Considered adjunct to clinical diagnosis.• PCT can help to differentiate between bacterial

and viral etiology : aid in t/t protocols

Currrently not recommended for routine investigations (2A)

Risk stratification

NEED: • For triaging the site of treatment : OPD vs. IPD,

ward vs. ICU• For ordering diagnostics• For starting empirical treatment• For prognosticationAided by various scoring systems .

Scoring systems

• Well validated scoring systems :1. CURB 652. Pneumonia severity index ( PSI )3. SMART COP4. ATS/ IDSA criteria

Other ( poorly validated ):5. A DROP6. REA- ICU index7. CAP – PIRO8. ESPANA scale

1. CURB-65 SCORE

• Severity of illnes score• Derived from pooled data from UK, NZ and Netherland• Guide in triaging : for site of careScore 0 – 1 : OPD Score 2 : WardsScore ≥ 3 : ICU

Modification is CRB 65: requires only clinical examination.

2. Pneumonia Severity Index

• Prognostic prediction rule• Defines severity of illness based on predicted

risk of mortality at 30 days.• Includes 20 variables , stratified into 5 classes:0-50 points : 0.1 % mortality51 – 70 : 0.6 % mortality71 -90 : 0.9 %91 – 130 : 9.3 %130 – 395 : 27 %

3.IDSA/ATS CRITERIA

• Helps triaging site of care • Criteria for ICU admission :Any major criteria , orAt least 3 minor criteria

Definition of severe CAP : presence of both major criteria ( need for ventilation and vasopressors )

4.SMART COP score

• Derived from Australian CAP study• Point based severity score• Score ≥ 3 : 92 % pt. require invasive ventilation and

vasopressors.

Treatment

1. Empirical 2. Definitive The empirical t/t is guided by :• Knowledge of most likely pathogen• Local susceptibility patterns• Pk/pd profile of antibiotics• Compliance , safety and cost of drugs• Any ongoing medical therapy / comorbidities..

Timing

• As soon as possible after CAP diagnosis is established

• In severe CAP : asap, preferably within 1 hr.

A. OUTPATIENT • Previously healthy & no antimicrobials within 3 months 1. Macrolide ( level I )2. Doxycycline ( level III)

• comorbidities present / antibiotic use:1. A respiratory FQ ( levofloxacin ) ( level I)2. A β lactam + macrolide ( level I)

• For high infection rates( >25 %) or high resistance for S. pneumoniae ( MIC ≥ 16 µg/ml)

- ceftriaxone/cefpodoxime/cefuroxime- doxycycline

Joint ICS/NCCP (I) Recommendations : • Stratification into patients with or without

comorbidities.• Patients without comorbidity : monotherapy

with oral macrolides/ oral β lactam • Patients with comorbidities : oral combinaton

therapy ( β lactam + macrolides )• NO FQ

B. INPATIENT , NON ICU• Respiratory FQ ( Level I evidence)-moxifloxacin-Gemifloxacin, or- levofloxacin• A β lactam + macrolide ( Level I evidence)- cefotaxim/ ceftriaxone/ ampicillinJoint ICS/NCCP (I) Recommendations:• Resp. FQ can be used if TB is not a diagnostic

consideration.• Patients should undergo testing for sputum AFB.• Route of medication decided by the clinical condition

C. ICU PATIENTS

• A β lactam ( cefotaxim/ceftriaxone / ampicillin) +• Macrolide ( azithromycin ) / resp. FQFOR PENICILLIN ALLERGY • A resp. FQ + Azetreonam

Joint ICS/NCCP (I) Recommendations:• β lactam ( ceftriaxone/ amox-clav) + macrolide

D. HIGH RISK FOR PSEUDOMONAS• Antipseudomal, antipneumococcal β lactam ( piperacillin

tazobactam/ cefepime/ imipenem/ meropenem ) OR• β lactam ( as above ) + AG + MACROLIDE OR• β lactam ( as above ) + AG + antipneumococcal FQFOR PENICILLIN ALLERGY : substitute Azetreonam for β lactam

Joint ICS/NCCP (I) Recommendations:β lactam ( as above ) + AG + antipneumococcal FQ• Resp. FQ can be used if TB is not a diagnostic consideration.• Patients should undergo testing for sputum AFB

E. HIGH RISK FOR CA-MRSA

• Risk factors for S.aureus infection are :1. ESRD2. Injectable drug abuse3. Prior influenza4. Prior antibiotic t/t esp. with FQ.

EMPIRICAL TREATMENT : β lactam + vancomycin / linezolid

F. ANAEROBIC COVER

• Indicated only in classic aspiration cases in patients with :

• Loss of consciousness• Alcohol/ drug overdose• Post ictal• Seizures in patient with gingival disease• Loc/ seizures in patient with esophageal

motility disorder.

Pathogen directed treatment

• Switching from IV to Oral t/t :• Hemodynamically stable• Able to accept orally• Normal functioning GI tract

• Duration of treatment • minimum of 5 days • Criteria before discontinuation is as below.

Patient should have these for 48 -72 hrs.

Reasons for lack of response

Outcomes ( NEJM Oct. 2014 )

• 30 day death rates in hospitalized : 10 -12 %• Post hospital discharge : redamission within 30

days is 18 %• Functional disability esp. in elderly• Survivors after 30 days : mortality remains

elevated at 1 year, and in pneumococal pn. It is elevated for 3 -5 years.

References

• IDSA/ ATS guidelines, 2007• Joint ICS/NCCP (I) guidelines, Lung India, 2012• BTS guidelines,2009• NEJM Review article on CAP, Oct. 2014

THANK YOU !!