Lactobacillus iners and vaginal microbiota diversity as risk factors of uterine cervix dysplasia: a prospective study

Purpose The aim of this study was to observe the vaginal microbiota composition in patients with cervical dysplasia. Methods In this prospective study, 91 samples for vaginal microbial diversity examination were taken from the cervix and posterior vaginal fornix. Eighteen bacterial species, including Lactobacillus species, were identified by real-time PCR. Relative bacterial quantities (RQs) were calculated, and log2-transformed RQs were visualised with boxplots. The relationships between cytological abnormalities and bacterial species were calculated by nonparametric one-way ANOVA (Kruskal–Wallis test). For determination of bacterial diversity, the Shannon index was used. Main finding We demonstrated an increase in the abundance of vaginal microbes dominated by L. iners with increasing severity of cytologically and histologically confirmed cervical lesions, while HPV infection was present in 73.1% of community state type 3 samples. The presence of G. vaginalis and U. parvum in combination with L. iners was statistically significant. Our study also revealed considerably higher bacterial diversity in the community state type IV category. An increasing trend of bacterial diversity with increasing cytological severity of cervical lesions was also observed, although the difference was nonsignificant. Conclusion This study suggests that L. iners has adverse effects on the development of cervical dysplasia, while L. gasseri and L. crispatus may play protective roles. We also pointed out the association of L. iners with anaerobic bacteria, and we suggest the potential role of bacterial diversity in cervical carcinogenesis.