Characterisation of the oral, vaginal and rectal Lactobacillus flora in healthy pregnant and postmenopausal women

Abstract

Objective: To investigate the hypothesis that the rectum may be an important reservoir for vaginal colonisation by Lactobacillus species.

Study design: We included 60 pregnant women aged 18-35 years and 80 postmenopausal women aged 55-65 years in this cross-sectional observational study. Participants had to be without clinical signs of vaginal infection and without hormone replacement therapy. Only women with normal vaginal microflora (Nugent scores 0-3) were included in the evaluation. The first oral, vaginal, and rectal smears were taken for the enumeration of lactobacilli by cultural methods and identification of dominating lactobacilli based on multiplex polymerase chain reaction (PCR). The second oral, vaginal, and rectal smears were taken for molecular lactobacilli profiling using PCR denaturing gradient gel electrophoresis (DGGE).

Results: 30 pregnant and 30 postmenopausal women were evaluated. On multiplex PCR, 99 colonies isolated from 30 pregnant women and 37 colonies isolated from 30 postmenopausal women were identified as being members of the genus Lactobacillus: 50% of pregnant and 33% of postmenopausal women had one or more Lactobacillus spp. recovered from their oral specimens. Around 80% of pregnant and 40% of postmenopausal women harboured one or more Lactobacillus spp. in the vagina and rectum. On PCR-DGGE, 80% of pregnant and 40% of postmenopausal women harboured the same lactobacilli isolates in both the vagina and rectum.

Conclusion: This study supports the hypothesis that the rectum may play an important role as a reservoir for some strains of lactobacilli that colonise the vagina.