Nasal carriage of and infection with Staphylococcus aureus in HIV-infectedpatients

Background: Staphylococcus aureus is a common cause of serious infection in patients infected with HIV. Objectives: To evaluate risk factors for and quantitative effect of S. aure us infection in HIV-infected patients, with special attention to nasal carr iage. Design: Prospective, multihospital cohort study. Setting: Three tertiary care Veterans Affairs Medical Centers. Participants: 231 ambulatory HIV-infected patients. Results: Thirty-four percent of patients were nasal carriers of S. aureus. Of these patients, 38% were persistent carriers and 62% were intermittent c arriers. Twenty-one episodes of infection occurred in 13 patients: Ten were bacteremias (including 2 cases of endocarditis), 1 was pneumonia, and 10 w ere cutaneous or subcutaneous infections. Seventeen (85%) of these episodes occurred in patients with CD4 counts less than 100 cells/mm(3). Recurrent infections occurred in 3 of 7 patients who survived an initial S. aureus in fection. The mortality rate was higher among patients with S. aureus infect ion than among those without infection (P = 0.03). Factors significantly as sociated with S. aureus infection were nasal carriage, presence of a vascul ar catheter, low CD4 count, and neutropenia. Molecular strain typing indica ted that for 6 of 7 infected patients, the strain of S. aureus isolated fro m the infected sites was the same as that previously cultured from the nare s. Conclusion: Nasal carriage is an important risk factor for S. aureus infect ion in HIV-infected patients. Controlled studies are indicated to determine whether eradication of nasal carriage in a selected subset of patients (fo r example, those with a low CD4 cell count) might prevent invasive S. aureu s infection in patients with HIV infection.