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

This paper reports the results of characterising and selecting a strain of Lactobacillus for potential use as a probiotic in regenerating the vaginal flora of women with recurrent episodes of bacterial vaginosis (BV). BV is a condition characterised by a depiction of vaginal lactobacilli accompanied by an overgrowth of a mixed vaginal flora of aerobic, anaerobic and micro- aerophilic species in very large numbers. BV has been associated with vario us gynaecological and obstetric complications and has an extremely high rec urrence rate, due in part to the failure to establish a normal vaginal flor a after antimicrobial therapy. A total of 60 vaginal isolates of lactobacil li was assessed for characteristics considered important for vaginal re-col onisation. The characteristics studied were the in-vitro inhibitory activit y of the lactobacilli against bacterial species isolated from women with re current BV, acid production after growth of the lactobacilli in liquid cult ure, production of hydrogen peroxide (H2O2) and adhesiveness of the lactoba cilli to exfoliated vaginal epithelial cells (VEC). Four strains of lactoba cilli, L. acidophilus (61701 and 61880), L. crispatus (55730) and L. delbru eckii subsp. delbrueckii (65407), demonstrated the greatest inhibitory acti vity against the BV-associated bacterial species. Two of these isolates (55 730 and 61880) produced H2O2 All four isolates produced a highly acidic env ironment after growth in liquid medium (pH < 4). Only one of these (strain 61701) was strongly adherent to VEC (>100 bacteria/VEC). A further Isolate (L. acidophilus 48101) did not demonstrate maximum inhibitory activity agai nst BV-associated bacteria, but was found to be a strong producer of H2O2 a nd was also highly adherent to VEC. Isolates 61701 and 48101 could be candi dates for use as probiotics for vaginal re-colonisation.