HIV Opportunistic Infections & Prophylaxis

A client with HIV whose CD4+ count drops below 200 cells/mm³ doesn't die from HIV itself — they die from infections a healthy immune system would easily handle. Knowing which infections strike at which thresholds changes everything.

Opportunistic infections (OIs) are the primary cause of morbidity and mortality in HIV/AIDS. They emerge predictably based on CD4+ count thresholds. At CD4+ < 200 cells/mm³, Pneumocystis jirovecii pneumonia (PJP) becomes the most common and most tested OI — presenting with dry nonproductive cough, progressive dyspnea, and fever. Prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) begins when CD4+ falls below 200. At CD4+ < 100, Toxoplasma gondii encephalitis and Cryptosporidium emerge. At CD4+ < 50, Mycobacterium avium complex (MAC) and cytomegalovirus (CMV) retinitis become threats — MAC prophylaxis with azithromycin starts at this threshold. Oral candidiasis (thrush) and esophageal candidiasis can appear at higher CD4+ counts and often signal disease progression. Kaposi sarcoma — purple-red vascular skin lesions — is an AIDS-defining malignancy. Nursing priorities include strict infection precautions, respiratory isolation for active TB coinfection, meticulous oral and skin assessment, calorie-dense nutrition support, and monitoring for medication interactions between OI prophylaxis and antiretroviral therapy.

Key Distinctions

Don't confuse PJP (dry cough, dyspnea, no sputum) with bacterial pneumonia (productive cough, purulent sputum, high fever) — PJP is insidious and progressive. Students mix up prophylaxis thresholds: PJP prophylaxis starts at CD4+ < 200, MAC prophylaxis at CD4+ < 50. Oral thrush is not the same as esophageal candidiasis — thrush is visible white patches you can scrape; esophageal candidiasis causes painful swallowing and requires systemic antifungal treatment.

Clinical Pearl

Think "200-100-50": PJP at 200, Toxo at 100, MAC and CMV at 50. The lower the count, the more dangerous and disseminated the infection.