Pneumocystis Pneumonia

Pneumocystis pneumonia is a life-threatening condition found mainly in the immunosuppressed. It’s caused by Pneumocystis jirovecii and is transmitted by the airborne route.

Immunocompetent individuals may remain carriers.

Risk factors

• HIV patients with a low CD4 count(<200 cells/mm³)
• Malignancy, particularly hematologic
• History of pneumocystis pneumonia
• Transplant patients
• Patients on steroids
• Premature and malnourished infants
• Treatment of inflammatory conditions. E.g. rheumatoid arthritis
• Severe malnutrition

Clinical presentation

• The main one is progressive dyspnoea of duration <12 weeks
• Initially maybe asymptomatic
• Low-grade fever, malaise, fatigue, weight loss and chills
• Non-productive cough
• May progress to fulminant respiratory failure

Physical exam

• Crackles bilaterally
• Low oxygen saturation

Investigations

1. Lactate dehydrogenase assay- elevated(significant in HIV)
2. Beta D glucan assay- elevated
3. ABG analysis- low PaO²
4. Low CD4 count
5. Definitive diagnosis- silver stains, PCR and immunofluorescence. Done on induced sputum
6. Chest Xray- bilateral interstitial infiltrates. It may be normal in the early stages. May also show pneumothorax
7. HRCT- ground-glass infiltrates. Pneumatoceles may also be present

Management

1. Supportive- Oxygen and intravenous fluids
2. High dose cotrimoxazole for 21 days. It can be started when there is high clinical suspicion, even before definitive confirmation has been made

Classification;

1. Mild disease- PaO₂ ≥70 mmHg and Aa gradient of <35 mm

2. Moderate to severe disease- PaO₂ <70 mmHg and Aa gradient≥35mm.

• Mild disease- oral medication
• Moderate to severe disease- intravenous medication. In HIV, add prednisone, and start ART in those who haven’t started in consultation with the infectious disease unit

Prevention

1. Prophylaxis;

• Primary- HIV with CD4 count <200
• Secondary- history of PCP with immunosuppression

Regimens;

• Low dose cotrimoxazole
• Alt- dapsone, atovaquone

Complications

• Respiratory failure
• acute respiratory distress syndrome
• Pneumothorax
• Pleural effusion