A 28-year-old woman is evaluated following the diagnosis of HIV infection discovered during a routine screening examination.
On examination, the patient appears well. Temperature is 37.1°C (98.8°F), blood pressure is 105/70 mm Hg; pulse rate is 88/min, and respiration rate is 10/min. The remainder of her examination is normal.
Her CD4 cell count is 77/μL and her HIV-1 RNA level is 200,000/mL. Her toxoplasma antibody is positive, and her tuberculin skin test is negative. All of her immunizations are up to date.
The patient agrees to begin antiretroviral drug therapy.
This patient should receive trimethoprim-sulfamethoxazole. Several drugs have been shown to provide effective prophylaxis against opportunistic infections in patients with HIV infection and to prolong life in some patients. The CD4 cell count is an indicator of immune competence. Recommendations regarding when to initiate prophylaxis are based on CD4 cell count levels. The threshold for Pneumocystis and toxoplasmosis prophylaxis is 200/μL and 100/μL, respectively. The patient's CD4 cell count is 77/μL, and she should receive prophylaxis for Pneumocystis and for toxoplasmosis if her antibody titer is positive (demonstrating previous infection but not immunity). Trimethoprim-sulfamethoxazole is the first-line agent for both.
Azithromycin is used for prophylaxis against Mycobacterium avium complex in patients with a CD4 cell count less than 50/μL. This patient's CD4 cell count is not at this threshold and, therefore, prophylactic azithromycin therapy is not recommended. Fluconazole is not recommended for the primary prophylaxis of Candida infections despite its effectiveness in this role. The potential for drug resistance, numerous potential drug-drug interactions, the ease and effectiveness of treating infection when it does occur, and lack of survival benefit argue against prophylactic use. Isoniazid would be indicated if the patient were found to have a positive tuberculin skin test greater than 5 mm and a negative chest x-ray excluding active tuberculosis. There is no reason to provide prophylactic isoniazid therapy for patients who have not been exposed to Mycobacterium tuberculosis. Although valganciclovir is effective in preventing cytomegalovirus (CMV), infection, decisions regarding prophylaxis are complex. Valganciclovir is expensive, a theoretical concern about the development of drug resistance exists, it is toxic to the bone marrow, and treatment of early infection is very effective. Finally, no proven survival benefit is associated with CMV prophylaxis.
- In patients with HIV infection, prophylactic therapy for Pneumocystis, toxoplasmosis, and Mycobacterium avium complex are determined by the CD4 cell count.