Background:
Postexposure prophylaxis (PEP) has been used to prevent HIV infection among healthcare workers exposed to HIV via needle stick injuries. In 1999, PEP was expanded to possible nonoccupational HIV exposures in San Francisco. This analysis includes patients enrolled in PEP since August 2003 at the municipal STD clinic.

Objective:
To describe a PEP program at an STD clinic.

Method:
Patients reporting high-risk sexual or syringe-sharing behavior (within 72 hours) with partner(s) with positive or unknown HIV serostatus are offered PEP. In addition to STD testing, patients are tested for HIV by either standard or rapid antibody test methods. HIV antibody negative specimens are tested for HIV ribonucleic acid (RNA) to detect acute HIV infection. Patients receive a 2-day starter pack of zidovudine plus lamivudine (Combivir, GlaxoSmithKline), a prescription for the remaining 26 days of therapy, and extensive counseling. Staff contact patient one day after enrollment to confirm prescription has been filled, and check-in again one week later. At the completion of the 28-day course of treatment, patients are contacted for follow-up HIV antibody and RNA testing and counseling.

Result:
From August 2003 through November 2005, 387 STD clinic patients were given PEP. Eighty-nine percent were men, 3.4% were transgender and 81.6% percent were men who have sex with men. On the day of PEP enrollment, 5.9% had gonorrhea, 7.5% had chlamydia, and 2.6% were HIV positive (n= 10). Thirty-three percent (n=127) returned to the clinic for one-month follow up testing; however an undocumented number of patients sought HIV testing elsewhere. None of the PEP participants returning for the one-month follow-up seroconverted or had acute HIV infection.

Conclusion:
PEP might be an important secondary prevention intervention for patients who are at high-risk of HIV infection to prevent seroconversion following nonoccupational HIV exposures

Implications:
STD clinics can successfully incorporate PEP into their standard HIV testing services.