STAPHYLOCOCCUS-AUREUS NASAL COLONIZATION IN HIV-SEROPOSITIVE AND HIV-SERONEGATIVE DRUG-USERS

Nasal colonization plays an important role in the pathogenesis of Stap hylococcus aureus infections. To identify characteristics associated w ith colonization we studied a cross-section of a well-described cohort of HIV-seropositive and -seronegative active and former drug users co nsidered at risk for staphylococcal infections. Sixty percent of the 2 17 subjects were Hispanic, 36% were women, 25% actively used injection drugs, 23% actively used inhalational drugs, 23% received antibiotics , and 35% were HIV-seropositive. Forty-one percent of subjects had pos itive nasal cultures for S. aureus. The antibiotic susceptibility patt erns were similar to the local hospital's outpatient isolates and no d ominant strain was identified by arbitrarily primed polymerase chain r eaction (AB-PCR). Variables significantly and independently associated with colonization included antibiotic use (odds ratio [OR] = 0.37; co nfidence interval [CI] = 0.18-0.77), active inhalational drug use with in the HIV-seropositive population (OR = 2.36; CI = 1.10-5.10) and fem ale gender(OR = 1.97; CI = 1.09-3.57). Characteristics not independent ly associated included injection drug use, HIV status, and CD4 count. The association with active inhalational drug use, a novel finding, ma y reflect alterations in the integrity of the nasal mucosa. The lack o f association between HIV infection and S. aureus colonization, which is contrary to most previous studies, could be explained by our rigoro us control for confounding variables or by a limited statistical power due to the sample sizes.