Prevalence of self-medication with antibiotics among patients attending a clinic for treatment of sexually transmitted diseases.

To ascertain the prevalence of self-medication with antimicrobial agents among patients attending a clinic for treatment of sexually transmitted diseases (STDs), we administered a questionnaire to and collected a urine specimen for antimicrobial testing from 551 patients before treatment. We defined self-medication as an antimicrobial agent taken on the patient's own initiative by self-report during the week before the visit to the clinic or a positive urine assay for antimicrobial agents at the time of the clinic visit. We tested urine for the presence of antimicrobial agents by a disk diffusion method using Sarcina lutea as the test organism. A total of 75 (14%) of the 551 participants were self-medicators: 19 reported antimicrobial use and had a positive urine test, 27 reported antimicrobial use but had a negative urine test, and 29 denied antimicrobial use but had a positive urine test. Thus, 29 (60%) of the 48 patients with antimicrobial agents detected in their urine at the time of the clinic visit denied self-medication. Self-medicators acquired their antibiotics either from their medicine cabinet (44%) or from a family member or friend (56%). Self-medication was associated with self-report of prior use of unprescribed antimicrobial agents (P < .0001). We concluded that use of unprescribed antimicrobial agents (usually beta-lactam agents or tetracyclines) among STD clinic attendees in our study was common and that self-reporting was not a reliable method of screening for self-medicators.