In Vitro Susceptibility of Iranian Isolates of Trichomonas vaginalis to Metronidazole.
BACKGROUND
Metronidazole, a 5-nitroimidazole derivative, is the main antitrichomonal agent of choice for treatment of trichomoniasis. Since 1962, some cases of treatment failure with metronidazole have been reported and recently drug resistance is now on the rise in the world. This study was aimed to determine current susceptibility of Iranian isolates of Trichomonas vaginalis to metronidazole.


METHODS
This study was performed on 50 T. vaginalis isolates collected from west and central areas of Iran. After axenisation of the parasites, susceptibility testing was carried out by using serial twofold dilutions of metronidazole (400 to 0.1 μg/ml). The minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC) of the trichomonads were determined after 48 h incubation at 35.5 °C. Drug susceptibility assays of the all isolates were carried out two times in triplicate under aerobic and anaerobic conditions.


RESULTS
Ninety-eight percent of the T. vaginalis isolates (49/50) were sensitive to metronidazole. Metronidazole resistance was defined as aerobic MIC ≥50 μg/ml, detected in one isolate. The means of aerobic MICs and MLCs and that of anaerobic MICs of the parasites were 2.91, 1.95 and 0.28 μg/ml, respectively.


CONCLUSIONS
This investigation showed in vitro low-level tolerance to metronidazole in a few T. vaginalis isolates that may be leading to the development of drug resistance.
Dept. of Medical Parasitology and Mycology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; Dept. of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Mohammad
M
Matini
Dept. of Medical Parasitology and Mycology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
Amir-Hossein
AH
Maghsood
Dept. of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; Center for Research of Endemic Parasites of Iran (CREPI), Tehran University of Medical Sciences, Tehran, Iran.
Mahdi
M
Mohebali
Dept. of Obstetrics and Gynecology, Fatemieh Women Hospital, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
Soghra
S
Rabiee
Dept. of Medical Parasitology and Mycology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
Mohammad
M
Fallah
Dept. of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Sassan
S
Rezaie
Dept. of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; Center for Research of Endemic Parasites of Iran (CREPI), Tehran University of Medical Sciences, Tehran, Iran.
Mostafa
M
Rezaeian
In vitro; Iran; Metronidazole; Parasitic sensitivity tests; Trichomonas vaginalis