Characterization of the vaginal fungal flora in pregnant diabetic women by 18S rRNA sequencing

Pregnancy and diabetes are regarded as individual risk factors for vaginal candidiasis. The high prevalence of vaginal candidiasis in pregnant diabetic women can be explained by disruption of the balance of the vaginal normal flora. However, little is known about the overall structure and composition of the vaginal fungal flora in pregnant diabetic women. In the present study, the diversity and richness of the vaginal fungal flora in healthy non-pregnant women (group HN), healthy pregnant women (group HP), women with gestational diabetes mellitus (group GDM), and pregnant women with diabetes mellitus type I (group T1DM) were investigated using an 18S rRNA gene clone library method. Our data demonstrated that the composition of the vaginal fungal flora in the four groups could be divided into two phyla (Ascomycetes, 20/26, and Basidiomycetes, 6/26). The most predominant vaginal fungal species belonged to the Candida and Saccharomyces genera, uncultured fungi, and a large number of low-abundance taxa that were unrecorded or underrepresented in previous studies using cultivation-dependent methods. Variation in operational taxonomic units (OTUs) between the study cohorts was generally high in the clone libraries, as 9, 13, 17, and 20 phylotypes were identified in groups HN, HP, GDM, and T1DM, respectively. The Shannon indices of groups GDM and T1DM (with poorer glycemic control) were significantly higher compared to groups HN and HP (p < 0.05). The data presented here revealed an increased diversity and varied composition of the vaginal fungal flora in pregnant diabetic women and demonstrated that poor glycemic control might be associated with disturbances in the vaginal fungal flora.