Treating Opportunistic Infections Among HIV-Infected Adults and Adolescents Management of Acute OIs in the Setting of ART      OIs that develop after patients have been started on potent ART can be categorized into three groups. The first group includes OIs that occur shortly after initiating ART (within 12 weeks). These cases are thought to be subclinical infections that have been unmasked by early immune reconstitution and are not considered to be early failure of ART. The second group includes reports of OIs occurring >12 weeks after initiation of ART among patients with suppressed HIV-1 RNA levels and sustained CD4+ T lymphocyte counts >200 cells/µL . Two cases of spinal MAC among patients with nadir CD4+ T lymphocyte counts <50 cells/µL who had sustained CD4+ T lymphocyte count increases to >200 cells/µL are examples. Determining whether these represent a form of immune reconstitution syndrome as opposed to incomplete immunity with the occurrence of a new OI is difficult. The presence of organisms by stain and culture suggests that, in either situation, specific therapy is indicated. The third group includes OIs that develop among patients who are experiencing virologic and immunologic failure while on potent ART. These represent clinical failure of ART.