Incidence and determinants of Pseudomonas aeruginosa infection among persons with HIV: Association with hospital exposure

Background: Little information exists on risk factors for Pseudomonas aerug inosa infection in persons with HIV. We assessed the incidence and factors associated with P aeruginosa among persons with HIV enrolled in a large obs ervational cohort study in Los Angeles. Methods: Data were analyzed from 4825 persons aged greater than or equal to 13 years with HIV infection enrolled from 4 outpatient facilities from 199 0 to 1998. The association between P aeruginosa infection and demographic, risk behavior, and clinical factors was assessed. Results: P aeruginosa was diagnosed in 72 (1.5%) patients representing a cr ude incidence rate of 0.74 per 100 person-years. The most frequent site of infection was pulmonary (47%). In multivariate analysis, prior hospitalizat ion (adjusted rate ratio = 7.9, 95% CI, 3.8-16.2), and both dapsone (adjust ed rate ratio = 4.0, 95% CI, 2.2-7.4) and trimethoprim-sulfamethoxazole (ad justed rate ratio = 2.5, 95% CI, 1.2-5.3) use were independently associated with higher rates of infection. Increasing days of inpatient stay (P <.01) and decreasing CD4(+) counts (P <less than>.01) were strongly associated w ith P aeruginosa. Azithromycin use decreased the risk of infection by nearl y 70%. Conclusion: Although the overall observed incidence of P aeruginosa was low , hospital exposure, declining CD4(+) levels, and the use of dapsone or tri methoprim-sulfamethoxazole increased the risk of P aeruginosa disease, and azithromycin use was protective in this population. These findings may assi st in the early recognition and diagnosis of persons likely to be at increa sed risk of ip aeruginosa infection.