Makindo Medical Notes.com

HIV patients at increased risk of Strep pneumoniae, Haemophilus Influenzae and Moraxella catarrhalis infection

About

• Pneumocystis carinii was renamed Pneumocystis jirovecii after the physician who reported P. carinii as the cause of interstitial pneumonia in neonates. However, the term PCP still remains.
• Pneumocystis jirovecii is a fungus that lacks ergosterol and so it is not susceptible to the usual antifungal drugs.

Aetiology

• Is seen in immunosuppressed patients and those with HIV with CD4 < 200 cells/mm3
• May be seen at presentation or those who have stopped medications

Clinical

• Insidious breathlessness, high fever, dry cough
• Hypoxia and bibasal crackles
• Exercise induced drop in O₂ sats
• Signs suggestive of HIV infection e.g., oral candida
• Pneumothorax is not uncommon

Investigations

• Sputum generation using hypertonic saline and Immunofluorescence of sputum will identify the organism.
• Bronchoscopy and lavage may be needed to show the organism.
• HIV test, CD4 count, Viral load
• CXR/CT chest shows interstitial shadowing and may be reported as pulmonary oedema or may indeed be normal. Ground glass appearance of lung fields. Bilateral and perihilar shadowing
• Elevated lactate dehydrogenase level (LDH)
• ABG may show Type 1 respiratory failure

Differentials

• Bacterial or other viral pneumonia
• Pulmonary embolism if CXR normal
• Asthma but wheeze is minimal
• Pulmonary oedema on CXR
• COVID pneumonia
• HIV infection and TB

Management

• ABC. High flow Oxygen. Get HIV test. Refer to an HIV specialist
• PCP Prevention: Co-trimoxazole 960 mg OD, reduced if not tolerated to 480 mg OD, alternatively 960 mg OD on alternate days, alternate day dose to be given 3 times weekly, alternatively 960 mg BD on alternate days, alternate day dose to be given 3 times weekly.
• PCP Treatment Mild to Moderate:
  • Co-trimoxazole PO 1920mg TDS or 90mg/kg/day in 3 divided doses (rounded to nearest 480mg) Duration: 21 days
  • Atovaquone 750 mg BD for 21 days, dose to be taken with food, particularly high-fat food. Atovaquone has poor bioavailability. Presence of food (particularly high fat) increases the absorption2-3-fold.
  • Dapsone 100mg PO OD + Trimethoprim oral 20mg/kg/day in 3divided doses rounded to nearest 50mg
• PCP: Severe
  • High dose Co-trimoxazole IV infusion 120mg/kg/day for 3 days then reduce to 90mg/kg/day for 18 days. The total daily dose may be divided in 3-4 doses. + steroids (see further information box) Switch to oral co-trimoxazole at same dose when appropriate after clinical improvement to complete course.
  • Clindamycin IV infusion 600 QDS or 900mg TDS + Primaquine* PO 30mg OD
  • Pentamidine 4 mg/kg IV OD for at least 14 days.
• If O₂ saturations <92% or PaO₂ =9.3kpa on room air start steroids at the same time as treatment (or within 72 hours). Prednisolone oral 40 mg BD for 5 days, 40mg od for 5days then 20 mg daily for 11 days then stop. Alternative is IV methylprednisolone 40 mg QDS for 5 days)
• Pneumothorax is a common complication of severe disease and carries a poor prognosis. CXR is required if deterioration and/or chest pain.
• Some patients may need ventilatory support due to respiratory failure. Note the high risk of pneumothorax.
• Patients who are HIV positive will need commenced on HAART to get CD4 count > 200 cells/mm³

References

• Pneumocystis pneumonia
• Treatment table