HIV-related Pneumonias

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

HIV-related pneumonias refer to a spectrum of lung infections seen in individuals with HIV, ranging from common bacterial pneumonias to opportunistic infections such as Pneumocystis jirovecii pneumonia (PJP) and fungal infections. These infections are associated with immune suppression due to low CD4 counts.

Aetiology

The causes of HIV-related pneumonias include:

  • Bacterial: Streptococcus pneumoniae, Haemophilus influenzae.
  • Opportunistic:
    • Pneumocystis jirovecii pneumonia (PJP): The most common opportunistic infection in HIV.
    • Fungal infections (e.g., aspergillosis, cryptococcosis).
  • Mycobacterial: Mycobacterium tuberculosis or non-tuberculous mycobacteria (NTM).
  • Viral: Cytomegalovirus (CMV) pneumonitis.

Pathophysiology

The development of HIV-related pneumonias is linked to immunosuppression caused by the HIV virus, particularly when CD4 counts drop below 200 cells/µL. This leads to impaired immune responses and an increased risk of opportunistic infections.

Risk Factors

  • CD4 count < 200 cells/µL (advanced HIV or AIDS).
  • Lack of antiretroviral therapy (ART) or poor adherence to ART.
  • History of previous opportunistic infections.
  • Smoking or chronic lung disease.

Signs and Symptoms

Symptoms may vary depending on the causative organism:

1. Bacterial Pneumonias:

  • Acute onset of fever, productive cough, and pleuritic chest pain.
  • Dyspnoea and systemic symptoms such as fatigue.

2. Opportunistic Infections (e.g., PJP):

  • Gradual onset of fever, non-productive cough, and worsening dyspnoea.
  • Hypoxaemia, which may worsen with exertion.

3. Tuberculosis:

  • Persistent cough, haemoptysis, weight loss, and night sweats.

Investigations

Key investigations include:

  • Chest X-ray:
    • Bacterial: lobar consolidation.
    • PJP: bilateral interstitial infiltrates (ground-glass opacities).
    • Tuberculosis: cavitation or apical changes.
  • Sputum Culture and Sensitivity: to identify bacterial or fungal pathogens.
  • Blood Tests:
    • Full blood count (FBC) to assess for anaemia or leukopenia.
    • CD4 count and HIV viral load to assess immune status.
  • Bronchoalveolar Lavage (BAL): for PJP diagnosis if sputum is non-diagnostic.
  • Pulse Oximetry: to assess oxygen saturation, which may drop significantly on exertion in PJP.

Management

1. Bacterial Pneumonia:

  • Antibiotics:
    • Amoxicillin 500 mg TDS for 7 days (first-line).
    • For penicillin allergy: Clarithromycin 500 mg BD for 7 days.

2. Pneumocystis jirovecii Pneumonia (PJP):

  • First-Line: Co-trimoxazole (trimethoprim-sulfamethoxazole) 120 mg/kg/day in 2–3 divided doses for 21 days.
  • Adjunctive Therapy: corticosteroids (e.g., prednisolone) if hypoxaemia (PaO₂ < 9.3 kPa).

3. Tuberculosis:

  • Start standard anti-tuberculous therapy (e.g., rifampicin, isoniazid, pyrazinamide, ethambutol) based on local guidelines.

4. Supportive Care:

  • Oxygen therapy for hypoxaemia.
  • Hydration and nutritional support.

Referral

Consider referral to secondary care for the following:

  • Respiratory Specialist: for patients with PJP or suspected fungal infections requiring bronchoalveolar lavage.
  • HIV Specialist: for management of advanced HIV and initiation or optimisation of antiretroviral therapy (ART).
  • Infectious Disease Specialist: for multidrug-resistant tuberculosis or atypical infections.
 
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