BACTERIAL PNEUMONIA IN ADULT PATIENTS WITH HIV-INFECTION

Patients with HIV infection are at increased risk for community-acquir ed bacterial pneumonias, due in part to their defects in B-cell functi on. Streptococcus pneumoniae is the commonest cause of community-acqui red pneumonia, with the second most common bacterial agent being Haemo philus influenzae. These two organisms account for about two-thirds of community acquired bacterial pneumonias. Frequently bacterial pneumon ias appear difficult to distinguish from Pneumocystis carinii pneumoni a or other opportunistic lung infections, because of their atypical cl inical and radiologic presentations. Community-acquired pneumonias may be recurrent but have low fatality rates. In comparison, nosocomial p neumonias occur primarily in patients with AIDS and are usually due to Staphylococcus aureus, Pseudomonas aeruginosa and other aerobic gram- negative bacilli. Nosocomial pneumonias have high fatality rates. S. a ureus is an important cause of morbidity and mortality in patients wit h AIDS and has emerged as a secondary opportunist in lungs of patients with opportunistic diseases. While appropriate laboratory study is be ing done, empiric antibiotic therapy should be directed against the mi croorganisms above described.