Prior to the introduction of antiretroviral therapy (ART), treatment and prevention of opportunistic infections (OIs) were the main-stays of reducing morbidity and mortality in people living with human immunodeficiency virus (HIV). While the widespread use of ART has greatly decreased the frequency of OIs, a sizeable number of HIV-infected individuals are either not taking ART or do not have an adequate immune response to ART. Thus OIs continue to cause a significant burden of disease in people living with HIV, and prophylaxis against OIs remains a major component in the management of HIV. The guidelines for OI prophylaxis in HIV-infected individuals are published by the Centers for Disease Control and Prevention, National Institutes of Health, and HIV Medicine Association of the Infectious Disease Society of America. The newest version of the guidelines was published in 2013 and includes revisions on the vaccination strategies for HIV-infected people.

Primary prophylaxis refers to treatment given to prevent development of infection. The most influential example of primary prophylaxis in HIV is the use of trimethoprim–sulfamethoxazole (TMP–SMX) in immune compromised individuals to prevent development of Pneumocystis jirovecii (carinii) pneumonia (PCP).

Secondary prophylaxis refers to continued treatment given after the acute course of treatment is complete in order to decrease the risk of relapse. Depending on the infection, secondary prophylaxis is sometimes referred to as maintenance or chronic suppressive therapy for difficult-to-treat OIs. The timing of primary prophylaxis and recommended vaccinations is summarized in Table 102.1. The preferred and alternative agents and dosages for primary and secondary prophylaxis are summarized in Tables 102.2 and 102.3.