Risk profile of female sex workers who participate in a routine penicillin prophylaxis programme in Surabaya, Indonesia.

We conducted a sexually transmitted disease (STD) prevalence survey of 1867 female sex workers in Surabaya, Indonesia, some of whom reported participation in a routine penicillin prophylaxis programme. In Surabaya, 34% of female sex workers had received a prophylactic penicillin injection programme from the government within 28 days. Sex workers who had received routine prophylaxis injection were more likely to be less educated, to work in brothel complexes, and to have more customers per week than other sex workers. The prevalence rates of syphilis, gonorrhoea, chlamydia, and trichomoniasis were higher among sex workers who received the routine penicillin treatment than among those who had not received antibiotic treatment in the last 28 days. However, after adjustment for age, education, fee per sex act, number of customers, and condom use in the previous 7 days, only trichomoniasis was still significantly different (adjusted odds ratio of 3.2). High-risk women were more likely to participate in the routine penicillin prophylaxis programme. The lack of a demonstrable individual-level protection from this prophylaxis treatment programme in this cross-sectional study appears due to differential uptake of penicillin prophylaxis by women at higher presumptive risk for STD. Randomized clinical trials and mathematical modelling, together with observational data such as presented here, all can contribute to optimal understanding of a complex intervention like mass chemoprophylaxis for STD among female sex workers.