Azithromycin, also known as Zithromax, belongs to the class of medicines known as antibacterials orantibiotics. These medicines kill bacteria (small organisms that can cause infection in humans) or stopbacteria from growing. Patients with weakened immune systems, includingpeople with HIV, tend to have more frequent andmore serious bacterial infections. Azithromycinwas approved by the FDA on June 14, 1996, formany uses, including the prevention and treatmentof Mycobacterium avium complex (MAC) inpersons with advanced HIV infection. It is alsobeing investigated to see how well it works inpreventing other kinds of bacterial infections inpeople with HIV.