Background:  In July 2003, the Centers for Disease Control, Health Resources and Services Administration, National Institutes of Health, and the Infectious Disease Society of America published Incorporating HIV Prevention into the Medical Care of Persons Living with HIV. Recommendations included baseline and regular sexually transmitted disease (STD) screening for syphilis; throat, rectal, and urine screening for gonorrhea; and rectal and urine screening for chlamydia. STD screening may identify patients with ongoing risk behavior and enable the treatment of STD, both of which could result in decreased HIV transmission.

Methods:  In Spring 2003, we implemented STD screening at the UCSF Positive Health Program San Francisco General Hospital. Providers categorized patients into risk groups based on the number of recent sex partners in the past 3 months. We used rapid plasma reagin testing for syphilis with the Treponemal pallidum particle agglutination assay for confirmation. We used nucleic acid amplification testing (BD ProbeTec, Franklin Lakes, NJ) for the diagnosis of urethral (urine), rectal and pharyngeal chlamydia and gonorrhea infection based on prior experience demonstrating the superior performance of nucleic acid amplification testing versus culture.

Results:  During this period, 814 asymptomatic HIV-infected patients underwent screening:  15 (1.8%) new syphilis infections were found. Of 586 urine samples tested, 7 (1.2%) were positive for chlamydia, none for gonorrhea. Of 494 who had either pharyngeal or rectal screening, 39 (7.9%) had either chlamydia or gonorrhea infection:  24 (5.1%) of 474 persons tested positive for pharyngeal infection and 18 (5.0%) of 363 persons tested positive for rectal infection. The prevalence of pharyngeal chlamydia was 7 (1.5%) of 472; pharyngeal gonorrhea was 18 (3.8%) of 474; rectal chlamydia was 15 (4.2%) of 361; and rectal gonorrhea 6 (1.7%) of 363. There were no differences in the prevalence of infection by risk group. Women had no rectal infections but the prevalence of pharyngeal infection was 3 (6.5%) of 46.

Conclusions:  Amplification testing detected asymptomatic carriage of chlamydia or gonorrhea in HIV-infected patients. Rectal and pharyngeal screening identified 5 times more infected patients than urine screening alone. Stratifying patients by reported risk behavior did not correlate with STD prevalence. HIV care providers should assess STD prevalence rates in all patients at all possibly relevant anatomic sites.

Keywords: HIV Prevention; STD Diagnosis; HIV Care