Since potent
HIV protease inhibitor drugs became widely available in early 1996, many HIV clinical specialists have noted a marked decrease in the occurrence of
AIDS-related opportunistic infections, and some specialists have reported unusual clinical presentations and manifestations of previously common
opportunistic infections. In this article, we will review (1) the available data regarding recent trends in
AIDS-related opportunistic infections incidence and manifestations, (2) clinical and immunologic evidence that potent
combination antiretroviral therapy can alter the natural history of these
opportunistic infections, and (3) the implications of these findings for current patient management practice and future clinical and immunologic research. As a preface to this review, however, it is important to acknowledge that any evaluation of the potential benefit of potent
combination antiretroviral therapy in reducing the risk of serious
opportunistic infections can be confounded by the concomitant use of prophylactic
antimicrobial agents co-administered to prevent specific
opportunistic infections. For example, it is standard clinical practice to administer
trimethoprim-sulfamethoxazole (or another agent if
trimethoprim-sulfamethoxazole cannot be tolerated) to patients with an absolute CD4 lymphocyte count < 200 cells/microliters, unexplained chronic
fever or a history of oropharyngeal
candidiasis. Similarly, specific antimicrobial prophylaxis to prevent disseminated Mycobacterium avium complex (MAC)
infection in patients with absolute CD4 counts < 50 cells/microliters is also a widely recommended guideline. Although the relative efficacies of specific antimicrobial prophylaxis regimens in preventing the most common life- and sight-threatening opportunistic infectious complications of
AIDS [
Pneumocystis carinii pneumonia (PCP), disseminated MAC
infection, and cytomegalovirus (CMV)
retinitis] are now well established, these relative efficacies were established in the era before potent
combination antiretroviral therapies became available and may not be generalizable to the current era. Nevertheless, for perspective, the reported efficacies of prophylaxis for PCP, disseminated MAC
infection, and CMV end-organ disease are summarized in Table 1.