The Lactobacillus flora in vagina and rectum of fertile and postmenopausal healthy Swedish women

Abstract
Background: Lactobacillus species are the most often found inhabitants of vaginal ecosystem of fertile women. In
postmenopausal women with low oestrogen levels, Lactobacillus flora is diminishing or absent. However, no
studies have been performed to investigate the correlation between oestrogen levels and the lactobacilli in the
gut. The aim of the present study was to investigate the relation in healthy women between vaginal and rectal
microbial flora as well as possible variations with hormone levels.
Methods: Vaginal and rectal smears were taken from 20 healthy fertile women, average 40 years (range 28-49
years), in two different phases of the menstrual cycle, and from 20 postmenopausal women, average 60 years
(range 52-85 years). Serum sex hormone levels were analyzed. Bacteria from the smears isolated on Rogosa Agar
were grouped by Randomly Amplified Polymorphic DNA and identified by multiplex PCR and partial 16S rRNA
gene sequencing.
Results: Lactobacillus crispatus was more often found in the vaginal flora of fertile women than in that of
postmenopausal (p = 0.036). Fifteen of 20 fertile women had lactobacilli in their rectal smears compared to 10
postmenopausal women (p = 0.071). There was no correlation between the number of bacteria in vagina and
rectum, or between the number of bacteria and hormonal levels. Neither could any association between the
presence of rectal lactobacilli and hormonal levels be found.
Conclusion: Lactobacillus crispatus was more prevalent in the vaginal flora of fertile women, whereas the
Lactobacillus flora of rectum did not correlate to the vaginal flora nor to hormonal levels.