Molecular Detection, Antimicrobial Resistance Genes, and Phylogenetic analysis of Gardnerella vaginalis in Women with Bacterial Vaginosis

Abstract

Gardnerella vaginalis is gram-negative to gram-variable, small, pleomorphic rods that is non motile and does not have endospores, or capsules. It is a part of the female vaginal microflora. This bacterium is associated with a condition called bacterial vaginosis (BV). The treatment of bacterial vaginosis is by metronidazole and/or clindamycin according to the recommendations of centers for disease control and prevention (CDC).
Amis: To determine the prevalence of Gardnerella vaginalis among women with bacterial vaginosis, assess the association between intrauterine device (IUD) use and bacterial vaginosis, identify the prevalence of metronidazole and clindamycin resistance genes among the isolates and to investigate the genetic diversity using 16S rRNA gene sequencing and phylogenetic analysis.
Methods: 224 high vaginal swabs were collected from symptomatic women. Amsel´s criteria were used to diagnose bacterial vaginosis. PCR was performed in order to detect Gardnerella vaginalis, also metronidazole and clindamycin resistance genes were detected. 16SrRNA gene sequencing was done to investigate genetic diversity and phylogenetic analysis.
Results: Out of 224 vaginal specimens, bacterial vaginosis was diagnosed in (25%). G. vaginalis was detected in (81.48%) of the BV positive samples. Erm a gene was detected in (50%) of the isolates while Rdx genes was not detected in all bacterial isolates (100%). 16 S rRNA gene sequencing confirmed all G. vaginalis isolates (98.18%-100%) identity, and phylogenetic tree analysis showed close genetic relatedness with minor sequence variation.
Conclusions: Gardnerella vaginalis was prevalent in women with bacterial vaginosis. No significant relationship was found between the use of intrauterine device (IUD) and the occurrence of bacterial vaginosis. G. vaginalis isolates harbored Erm a gene which suggest a potential risk of clindamycin resistance among the isolates, Rdx gene was absent in all isolates. 16S rRNA gene sequencing and phylogenetic tree confirmed the identity of the isolates and revealed minor genetic variation.