Relationship between hydrogen peroxide-producing strains of lactobacilli and vaginosis-associated bacterial species in pregnant women

Abstract

This study was conducted to determine the relationship between lactobacilli and bacterial species associated with bacterial vaginosis in pregnancy and the prevalence of H2O2-producing and non-producing strains of lactobacilli in pregnant women whose vaginal flora had already been analysed. Information was available for 174 pregnant women whose vaginal flora had been evaluated previously by examining gram-stained vaginal smears: 50 had grade III flora (bacterial vaginosis). 50 grade II flora, 41 flora graded as abnormal which then reverted to grade I (revertants) and 33 normal flora (controls). Lactobacilli were isolated from 19 of 50 women whose vaginal flora was grossly abnormal culturally and categorised as grade III by Gram staining. In 6 of these 50 women lactobacilli were isolated in large numbers, i.e. 10(5)-10(6) cfu/ml. H2O2-producing strains of lactobacilli were isolated from 11 of 12 women with grade III flora who were randomly selected from this group. Thus, in those 11 women it appears that H2O2-producing lactobacilli had not protected them from developing bacterial vaginosis. Bacterial species associated with vaginosis were isolated in high numbers from a large proportion of women in the revertant and grade II groups in association with high counts of lactobacilli. Thus, in some women it is possible that a change to an abnormal flora could occur before the complete disappearance of lactobacilli. It is concluded that bacterial vaginosis may develop in some women despite the presence of H2O2-producing strains of lactobacilli and that other factors, as yet unidentified, might be conducive to the appearance of abnormal bacterial flora with progression to vaginosis.

Characterisation and selection of a Lactobacillus species to re-colonise the vagina of women with recurrent bacterial vaginosis

“…Upon exposure to air, colonies producing H 2 O 2 appeared blue. The time taken for the appearance of the blue colouration was recorded and used as an indication of the quantity of H 2 O 2 produced [17].…”

“…H 2 O 2 -producing strains, which are thought to be inhibitory to other bacterial species, have been found signi®cantly more frequently in women with a normal vaginal¯ora than in women with BV [16]. However, the proportion of H 2 O 2 -producing strains isolated from pregnant women with BV may be higher [17].…”

A phase I study of a novel potential intravaginal microbicide, PRO 2000, in healthy sexually inactive women

“…8 Histology was carried out by a single observer (LP) blinded both to the gel used and to whether the specimen was taken before or after exposure. Where evidence of an inflammatory infiltrate was seen, specimens were further assessed using the immunohistological technique previously described.…”

“…8 High vaginal swabs taken at each visit were cultured for a quantitative estimation of vaginal lactobacilli as described previously. 8 Vaginal flora were sampled at 12 hours after the last gel dose during the exposure phase of the study in the UK cohort whereas in the Belgian cohort, sampling was carried out 2 hours after gel insertion.…”

Functional nutrients in infants born by vaginal delivery or Cesarean section

“…The growing presence of Lactobacilli during pregnancy allows maintaining a low pH in the vaginal environment, thus limiting bacterial diversity, reducing the incidence of bacterial vaginosis 12 and preventing the pathogens rise to the uterus, where they may infect amniotic fluid, placenta and foetus. 13,14 Animal studies have shown that changes in the maternal gut microbiota can promote the growth of the mice.…”