Clinicobacteriological Study on Microbial Flora in the Vagina

(1) Variations of Vaginal Microbial Flora according to the Menstrual Cycle

Abstract

This study was done to assess the variations of vaginal microbial flora according to the menstrual cycle. In order to be prepared for the study of correlativities of vaginal bacterial flora to the menstrual cycle, relations between vaginal bacterial flora vs. ovarian functions and between microbial flora vs. vaginal pH were studied.
The subjects of the study were normal and healthy women who visited the Department of Gynecology at the Central Hospital of Japanese National Railways between October 1977 and September 1979.
At first, by discharge samples obtained from the vaginal lateral wall, fornix and endocervix, pH and microbial isolation rates were studied in relation with the sites of sampling. PH was, in the higher to lower order, endocervix, fornix, vaginal lateral wall while the microbial isolation rates were, adversely, vaginal lateral wall, fornix, endocervix. As the types of bacteria were equal in three sites, the vaginal lateral wall was decided as the site of vaginal discharge sampling for the study, as follows.
The study consisted of search for relations between the ovarian function and vaginal microbial flora variations at women of regular menstruation in sexually active phase of life, at climacteric women of irregular menstruation and also at postmenopausal women by determining their bacterial isolation rates and vaginal PH, as well as the predominant organism of vaginal microbial flora. The results shoved that the number of bacteria and the number of types of bacteria were both greatly reduced in climacteric and postmenopausal women. The vaginal PH of women in sexually active phase was low, and the predominant microorganism in them was lactobacillus, while in climacteric and postmenopausal women, the vaginal PH became higher and lactobacillus became less predominant. In many cases, no predominant organism could be determined in them.
The variations of vaginal PH vs. menstrual cycle and PH vs. microbial flora were not found significantly correlative.
The variation of vaginal microbial flora according to the menstrual cycle was studied in view of the following three facters.
1) In view of the bacterial isolation rates: The 42 women of normal menstrual cycle were asked to visit the hospital in their first haif of follicular phase, second half of follicular phase, first half of luteal phase and second half of luteal phase for vaginal microbial study, and 168 samples obtained from them were studied. For anaerobic bacteria, the samples obtained were 120 from 30 of the women.
The resulted isolation rates almost did not show any significant differences from phase to phase. But only Bacteroides increased in the luteal phase.
2) In view of the bacterial amounts: The microbial amounts were studied by giving a score to each bacteria, and its found that Bacteroides increased in the luteal phase, but others did not show any significant differences from phase to phase.
3) In view of the positive rates of Doderlein bacilli (Lactobacilli) by vaginal smear: The Doderlein bacilli on the smear were studied by vaginal cytological examination, but no significant variation of them in accordance with the menstrual cycles was recognized.
The conclusion from the above study was that the increase or decrease of vaginal microbial flora is under influences of the ovarian function (estrogen) and vaginal PH variations. But there was no variation of them almost to follow the menstrual cycles, but only Bacteroides increase in the luteal phase.