Diversity of Cervicovaginal Microbiota Associated with Female Lower Genital Tract Infections

The female genital tract (FGT) harbors very large numbers of bacterial species that are known to play an important role on vaginal health. Previous studies have focused on bacterial diversity in the vagina, but little is known about the ectocervical microbiota associated with FGT infections. In our study, vaginal swabs and ectocervical swabs were collected from 100 participants in China, including 30 women with bacterial vaginosis (BV; BV group), 22 women with cervicitis (Cer group), 18 women with BV in combination with cervicitis (BC group) and 30 healthy control women (CN group). The diversity and richness of cervicovaginal microbiota were investigated with culture-independent polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR) targeting 11 microorganisms that have been associated with FGT infections. Despite significant interpersonal variations, the PCR-DGGE profiles revealed that vaginal microbiota and ectocervical microbiota were clearly much more complex in the BV group, while the ectocervical microbiota showed no significant difference between healthy and diseased participants. Using species-specific qPCR, BV and cervicitis were significantly associated with a dramatic decrease in Lactobacillus species (p < 0.05), and potential pathogenic species such as Gardnerella, Atopobium, Eggerthella, Leptotrichia/Sneathia, and Prevotella were more common and in higher copy numbers in BV than in CN samples (p values ranged from 0.000 to 0.021). No significant differences were observed between healthy and cervicitis samples (p > 0.05) in ectocervical microbiota. The total numbers of bacteria were significantly lower in the ectocervix as compared in the vagina (p < 0.05). Intriguingly, vaginal microbiota from participants with BV in combination with cervicitis was quite different from that of participants with BV or cervicitis alone. Our study demonstrated that the cervicovaginal microbiota was actively involved in the process of FGT infections. The predominant bacteria of the cervicovaginal communities were clearly associated with BV; however, there was not sufficient evidence that the ectocervical microbiota is directly involved in the development of cervicitis.