Three metronidazole-resistant Prevotella bivia strains harbour a mobile element, encoding a novel nim gene, nimK, and an efflux small MDR transporter

Objectives: In this study we assess the antibiotic resistance genes in three metronidazole-resistant Prevotella bivia clinical isolates.

Methods: Strains were whole-genome sequenced. De novo assembly was performed and genes were annotated in RAST. Manual adjustments were made, when required, to the annotation and length of the genes.

Results: In all three strains a novel nim gene, nimK, was encountered located on a mobile genetic element (MGE). The nimK gene was associated with an IS1380 family transposase. On the same MGE, genes encoding an efflux small MDR (SMR) transporter were present and were associated with a crp/fnr regulator.

Conclusions: This is the first description of the presence of a novel nim gene in metronidazole-resistant P. bivia clinical isolates. This gene is co-located with an efflux SMR transporter on an MGE, which has been named Tn6456 (MG827401). The identification of these resistance genes on an MGE is worrisome, since this indicates the horizontal gene transfer of antibiotic and/or biocide resistance from one strain to the other.