Prevalence of metronidazole-resistant Trichomonas vaginalis in a gynecology clinic.
OBJECTIVE
To determine the prevalence of in vitro resistance to metronidazole among unselected isolates of Trichomonas vaginalis and correlate in vitro findings with response to metronidazole therapy.


METHODS
Vaginal fluid from women attending a gynecology clinic at an urban hospital was cultured, isolates were tested for in vitro resistance to metronidazole, and these results were correlated with therapeutic outcome.


RESULTS
Among 911 women, T vaginalis was detected by culture in 82 (9.0%). Of the 82 isolates, 2 (2.4%; 95% CI, 0.3-8.5%) had low-level in vitro resistance (minimum lethal concentration, 50 micrograms/mL). Women with positive wet mount examinations were treated with metronidazole, 2 g, once and asked to return in one week. Of the 42 infected women agreeing to return for a repeat examination and culture, 26 (61.9%) did, and all (including one woman with a resistant isolate) were cured.


CONCLUSIONS
Isolates of T vaginalis resistant to metronidazole occur widely throughout the United States. Although the in vitro susceptibility of T vaginalis to metronidazole has been very poorly studied, our study is consistent with a decade-old prevalence estimate of in vitro resistance (5%), and suggests that high-level resistance is uncommon. This study confirmed, in the absence of reinfection, the continuing clinical effectiveness of single-dose metronidazole for the large majority of trichomoniasis cases.
Schmid
G
G
Centers for Disease Control and Prevention and Grady Memorial Hospital, Emory University School of Medicine, Atlanta, Georgia, USA. gps1@cdc.gov
Narcisi
E
E
Mosure
D
D
Secor
W E
WE
Higgins
J
J
Moreno
H
H
D000328:Adult; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D004351:Drug Resistance; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D008795:Metronidazole / Q000494:pharmacology*; D015995:Prevalence; D014247:Trichomonas Vaginitis / Q000188:drug therapy*; D014246:Trichomonas vaginalis / Q000187:drug effects* / Q000302:isolation & purification / Q000472:pathogenicity
D000890:Anti-Infective Agents; D008795:Metronidazole