Genotyping of gardnerella vaginalis from pregnant women in Durban by amplified ribosomal DNA restriction analysis.

Abstract

Gardnerella vaginalis is one of the most frequently isolated microorganisms associated with bacterial vaginosis (BV). However, limited information concerning the genetic diversity of G. vaginalis isolated from BV positive and intermediate cases, has been documented. This study investigated the diversity of G. vaginalis in pregnant women, a currently under-researched area in South Africa. The study population included pregnant women recruited from a public hospital in Durban, South Africa. The women provided 2 self-collected vaginal swabs for microscopy and the genotyping assays. The BV status of the women was determined using Nugent scoring. A total sample of n=137 specimens was selected for analysis. The 16S ribosomal ribonucleic acid (rRNA) gene of G. vaginalis was used for the genotyping assays. The 16S rRNA gene polymerase chain reaction products were digested with TaqI to generate genotyping profiles and genotypic subtypes were determined by correlating BamHI and HindIII digestion profiles. Phylogenetic analysis was performed on the 16S rRNA gene sequences. The data analysis was performed in R Statistical Computing software, version 3.6.2. Restriction digestion with TaqI revealed the presence of two different genotypes i.e. GT1 and GT2. Within both BV positive and intermediate sample groups, GT1 was the most prevalent genotype (54%). Overall, 4 subtypes (1, 2B, 2AB and C) were shown to be present in the sample population. The most prevalent subtype was 2B (15/37, 40.5%), followed by subtypes 1 (11/37, 29.7%), 2C (4/37, 10.8%) and 2AB (4/37, 10.8%). The phylogenetic analysis of the 16S rRNA genes showed the presence of 5 clusters. The tree displayed clusters which contained groups of specimens from the same BV group with different genotypes and subtypes present. There were also clusters which contained specimens from across the BV groups carrying the same genotype and subtype. Finally, the study did not find a significant association (p>0.05) between reported symptoms of discharge and genotype harboured. This study provides the first report on the diversity of G. vaginalis in South African pregnant women. Diversity assessments of G. vaginalis with respect to genotypes and subtypes may aid in a greater understanding on the pathogenesis of this microorganism.