Community acquired pneumonia

COMMUNITY ACQUIRED

PNEUMONIA

UNIT III

DIAGNOSIS AND MANAGEMENT

DIAGNOSIS In addition to a constellation of suggestive clinical features, a

demonstrable infiltrate by chest radiograph or other imaging technique, with or without supporting microbiological data, is required for the diagnosis of pneumonia.

The diagnosis of CAP is based on the presence of select clinical features :

cough, fever, sputum production, pleuritic chest pain

And this is supported by imaging of the lung, usually by chest radiography.

•SIGNS –• Tachypnea• Rales• Bronchial breath sounds

INVESTIGATIONS

CHEST X RAY : All patients admitted to hospital with suspected CAP should have

a chest radiograph performed as soon as possible to confirm or refute the diagnosis. The objective of any service should be for the chest radiograph to be performed in time for antibiotics to be administrated within 4 h of presentation to hospital should the diagnosis of CAP be confirmed.

CHEST X RAY IN PNEUMONIA

Radiologically Pneumonias present as : Areas of increased opacities, which is confined to a

segment or a lobe. Rarely it may involve one or more lobes also. Broadly defined into :

Lobar Pneumonia Bronchopneumonia

INVESTIGATIONS - CHEST X RAY

There are no characteristic features on the chest radiograph in CAP that allow confident prediction of the causative organism.

Multilobe involvement at presentation and pleural effusions were more likely at presentation in Bacteraemic Pneumococcal pneumonia than in non-bacteraemic pneumococcal pneumonia or legionella pneumonia.

Homogenous shadowing was less common in Mycoplasma pneumonia than in the other types.

Lymphadenopathy was noted in some cases of Mycoplasma infections but not in the other types of infection.

CAP due to S aureus appears to be more likely to present with multilobar shadowing, cavitation, pneumatoceles or spontaneous pneumothorax.

K pneumoniae has a predilection for upper lobes (especially the right). A bulging interlobar fissure and abscess formation with cavitation have also been reported.

INVESTIGATIONS - CHEST X RAY

Radiographic changes resolve relatively slowly after CAP and lag behind clinical recovery.

In one study complete clearance were seen duration after initial presentation are by 2 weeks in 51% 4 weeks in 64% 6 weeks in 73%

Clearance rates are slower in Elderly (Major factor { 35%,60%,84% at 3,6,12 weeks respectively}) More than one lobe involvement at presentation Smokers Inpatients rather than outpatients C-Reactive Protein Level >200 mg/L

Pneumonia caused by atypical pathogens clear quickly.

INVESTIGATIONS - CHEST X RAY The chest radiograph need not be repeated prior to hospital discharge in

those who have made a satisfactory clinical recovery from CAP. A chest radiograph should be arranged after about 6 weeks for all those

patients who have persistence of symptoms or physical signs who are at higher risk of underlying malignancy (especially smokers and those aged

>50 years) Further investigations which may include bronchoscopy should be

considered in patients with persisting signs, symptoms and radiological abnormalities at around 6 weeks after completing treatment.

ROUTINE INVESTIGATIONS

General investigations are not necessary for the majority of patients with CAP who are managed in the community.

Pulse oximeters allow for simple assessment of oxygenation. The only other simple non-microbiological tests that influence

immediate management are the UREA, which informs severity assessment, and OXYGEN SATURATION.

The need for an inspired oxygen of 35% or more to maintain the oxygen saturation above 90% implies severe pneumonia.

So does a PaO2 of 60mmHg or less or a PaCO2 of 50mmHg or more. These findings warn that assisted ventilation may become necessary.

ROUTINE INVESTIGATIONS A white cell count of >15 x109 /l strongly implicates a bacterial

(particularly pneumococcal) aetiology. A white cell count of >20 x 109/l or, is an indicator of severity.

All patients with CAP had CRP levels >50 mg/l and 75% of patients had levels >100 mg/l. CRP level of >100 mg/l helped to distinguish CAP from acute

exacerbations of COPD

MICROBIOLOGICAL INVESTIGATIONS

For patients managed in the community, microbiological investigations are not recommended routinely.

Examination of sputum should be considered for patients who do not respond to empirical antibiotic therapy.

More extensive microbiological investigations are recommended only for patients with moderate or high severity CAP.

MICROBIOLOGICAL INVESTIGATIONS

MICROBIOLOGICAL INVESTIGATIONS

MICROBIOLOGICAL INVESTIGATIONS

MICROBIOLOGICAL INVESTIGATIONS

SPUTUM STAINING : Advantages 1. Quick and relatively inexpensive.

2. Can assess quality of samples (cytological content) with rejection of poor quality samples.

3. Can aid the interpretation of culture results and occasionally give an early indication of possible aetiology.

Disadvantages1. Strict criteria for interpretation require appropriate operator training.

2. Validity of results is directly related to the experience of the interpreter

MICROBIOLOGICAL INVESTIGATIONS

SPUTUM CULTURES : Routine sputum cultures are neither very sensitive nor specific. Problems include:

1. Of patients to produce good specimens.

2. Prior exposure to antibiotics.

3. Delays in transport and processing.

4. Difficulty in interpretation due to contamination of the sample by upper respiratory tract flora. (especially in patients already given antibiotics).

MICROBIOLOGICAL INVESTIGATIONS

BLOOD CULTURES Blood cultures are recommended for all patients with moderate

and high severity CAP, preferably before antibiotic therapy is commenced.

MICROBIOLOGICAL INVESTIGATIONS

Other tests Streptococci pneumoniae

Pneumococcal antigen detection Antigen detection is less affected by prior antibiotic therapy. The detection of antigenaemia has a correlation with clinical

severity. The test remains positive in 80–90% of patients for up to 7 days

after starting antimicrobial treatment. May also be applied to other relevant sample types such as

pleural fluid. Pneumococcal PCR

Pneumococcal PCR has little to offer for the diagnosis of CAP at this time, being insufficiently sensitive and specific for routine use.

MICROBIOLOGICAL INVESTIGATIONS

LEGIONELLA Urine antigen detection – EIA, specificity (>95%) & sensitivity

(>80%). CULTURES :

Culture is 100% specific and is the only reliable method of detecting infection with non-pneumophila legionella species.

Problems with culture : The inability of many patients with legionella pneumonia to produce

sputum samples. Prior antibiotic therapy; laboratory time and cost in processing samples. Lack of rapid results (legionella cultures need to be incubated for up to

10 days).

MICROBIOLOGICAL INVESTIGATIONS

SEROLOGICAL TESTING : Standard for diagnosing infection with most atypical pathogens. Relies on Acute and convalescent – phase serological testing. IgM and IgG ELISA for Mycoplasma – IgM is consistent with acute

infection in70% of patients admitted in hospital. Cold Agglutinins are present in 50% of Mycoplasma patients.

MANAGEMENT

SITE OF CARE : Depends on the initial assessment of severity. Many prognostic models have been introduced for severity

assessment. The two most interesting and widely studied are :

Pulmonary Severity Index British Thoracic Society Criteria

PARAMETER SCORE

AGE 1 POINT / YR

FEMALE -10

NURSING HOME RESIDENT +10

NEOPLASTIC DISEASE HISTORY +30

LIVER DISEASE +20

CHF, CEREBROVASCULAR DISEASE, RENAL DISEASE +10,+10,+10

ALTERED MENTAL STATUS +20

RESPIRATORY RATE > 29 +20

SBP > 90 +20

TEMPERATURE > 39.9 C, < 35 C +15

PULSE > 124 +10

pH < 7.35 +30

Bun > 29, Sr Na < 130 +20, +20

Glucose > 249 mg/dL +10

Hematocrit < 30%, PaO2 < 60 mm Hg +10, +10

PLEURAL EFFUSION ON CHEST X RAY +10

PULMONARY SEVERITY INDEX : CLASS I – 0.1% MORTALITY ( score < 51) CLASS II – 0.6% (51 – 70) CLASSIII – 0.9% (71 – 90) CLASS IV – 9.3% (90 – 130) CLASS V – 27% ( > 130 )

Class I – III – Low Risk – Suitable for OP management.

CURB – 65 : C – Confusion U – BUN - > 7mmol / 20 mg/dL R – Respiratory Rate - >_ 30 / mt B – Blood Pressure – SBP < 90mm, DBP < 60mm 65 – Age >_ 65 years

One point for each parameter if present

CURB – 65 SCORE – Mortality 0 – 0.7% 1 – 2.1% 2 – 9.2% 3 – 14.5% 4 – 40% 5 – 57%

Score 0 -1 – OP treatment Score – 2 – Treated in Wards Score 3 or more – ICU care

REASONS FOR ADMISSION OF LOW – MORTALITY RISK PATIENTS :1. Complications of pneumonia itself.

2. Exacerbations of underlying diseases.

3. Inability to reliably take oral medications or receive outpatient care

4. Multiple risk factors falling just above or below thresholds for the score.

TREATMENT

TREATMENT

SWITCHING FROM INTRAVENOUS TO ORAL THERAPY : If patients are hemodynamically stable. Improving clinically. Able to ingest medications. Normally functioning GIT.

Patients should be discharged as soon as they are CLINICALLY STABLE, have no other active medical problems.

In patient observation while receiving oral therapy is not necessary.

DURATION OF ANTIBIOTIC THERAPY Patients with CAP should be treated for a minimum of 5 days. Should be afebrile for 48–72h. Should have no more than 1 CAP-associated sign of clinical

instability before discontinuation of therapy. A longer duration of therapy may be needed if :

Initial therapy was not active against the identified pathogen Or if it was complicated by extrapulmonary infection, such as

meningitis or endocarditis.

NON - RESPONDERS

PROGNOSIS Depends upon :

Age Comorbidities Site of treatment

Young patients without comorbidities recover after 2 weeks. Older patients with comorbidities may take several weeks for

full recovery. Mortality for OP < 1%. Inpatients < 10% (50% deaths direct cause is pneumonia

itself)

PREVENTION

VACCINATION Pneumococcal polysaccharide vaccine Inactivated Influenza Virus Live Attenuated Influenza Virus

Smoking Cessation Respiratory Hygiene Measures

THANK YOU

REFERENCES BRITISH THORACIC SOCIETY - Guidelines for the management

of community acquired pneumonia in adults: update 2009 Infectious Diseases Society of America/American Thoracic Society -

Consensus Guidelines on theManagement of Community-Acquired Pneumonia in Adults

CROFTON AND DOUGLA’S RESPIRATORY DISEASES 5 e HARRISONS PRINCIPLES OF INTERNAL MEDICINE 18 e