Identification of intrinsically metronidazole-resistant clades of Gardnerella vaginalis.

Abstract Gardnerella vaginalis is associated with bacterial vaginosis (BV), the most common cause of vaginal discharge. Metronidazole is a front-line therapy for BV, and treatment failure and recurrent disease are common problems. Whole-genome sequencing studies have revealed that G. vaginalis has a population structure that consists of 4 clades: clades 1 and 3 are associated with BV, whereas clades 2 and 4 are not. To determine if metronidazole susceptibility is associated with population structure, we analyzed 87 clinical isolates and found that metronidazole resistance (MIC ≥32μg/mL) was highly associated with clade ( P G. vaginalis clades will facilitate future studies on the relationship between metronidazole resistance and BV treatment failure.