Exploring potential of vaginal Lactobacillus isolates from South African women for enhancing treatment for bacterial vaginosis

PLoS Pathog. 2020 Jun 4;16(6):e1008559. doi: 10.1371/journal.ppat.1008559. eCollection 2020 Jun.

Abstract

Antibiotics continue to be the standard-of-care for bacterial vaginosis (BV), although recurrence rates are high. Vaginal probiotics may improve durability of BV treatment, although few probiotics for vaginal health contain Lactobacillus spp. that commonly colonize the lower female genital tract. Characteristics of vaginal Lactobacillus strains from South African women were evaluated for their probiotic potential in vitro compared to strains from commercial vaginal products, including growth at varying pHs, ability to lower pH, produce D-/L-lactate and H2O2, influence growth of BV-associated Gardnerella vaginalis and Prevotella bivia, adherence to cervical cells and susceptibility to antibiotics. Fifty-seven Lactobacillus strains were purified from cervico-vaginal fluid, including L. crispatus, L. jensenii, L. gasseri, L. mucosae, and L. vaginalis. L crispatus strains grew better at pHs below 4.5 and lowered pH more effectively than other strains. Production of D-/L-lactate and H2O2 varied between Lactobacillus species and strains. Lactobacillus strains generally inhibited P. bivia more uniformly than G. vaginalis isolates. All vaginal Lactobacillus isolates were resistant to metronidazole while susceptibility to clindamycin varied. Furthermore, vaginal Lactobacillus strains tended to be broadly susceptible to penicillin, amoxicillin, rifampicin and rifabutin. Whole-genome-sequencing of five of the best-performing vaginal Lactobacillus strains confirmed their likely safety, due to antimicrobial resistance elements being largely absent, while putative intact prophages were present in the genomes of two of the five strains. Overall, vaginal Lactobacillus strains largely performed better in these in vitro assays than probiotic strains currently used in probiotics for vaginal health. Including the best-performing vaginal Lactobacillus isolates in a region-specific probiotic for vaginal health may result in improved BV treatment options.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Bacteroidaceae Infections / drug therapy
  • Bacteroidaceae Infections / genetics
  • Bacteroidaceae Infections / metabolism
  • Bacteroidaceae Infections / microbiology*
  • Clindamycin / pharmacology
  • Drug Resistance, Bacterial / drug effects
  • Drug Resistance, Bacterial / genetics
  • Female
  • Gardnerella vaginalis*
  • Gram-Positive Bacterial Infections / drug therapy
  • Gram-Positive Bacterial Infections / genetics
  • Gram-Positive Bacterial Infections / metabolism
  • Gram-Positive Bacterial Infections / microbiology*
  • Humans
  • Hydrogen Peroxide / metabolism
  • Lactic Acid / metabolism
  • Lactobacillus* / genetics
  • Lactobacillus* / isolation & purification
  • Lactobacillus* / metabolism
  • Metronidazole / pharmacology
  • Prevotella*
  • South Africa
  • Species Specificity
  • Vaginosis, Bacterial / drug therapy
  • Vaginosis, Bacterial / genetics
  • Vaginosis, Bacterial / microbiology*

Substances

  • Metronidazole
  • Lactic Acid
  • Clindamycin
  • Hydrogen Peroxide

Supplementary concepts

  • Prevotella bivia

Grants and funding

JSP is supported by EDCTP Strategic Primer SP.2011.41304.038; Poliomyelitis Research Foundation Award 15/23; SA National Research Foundation (NRF) South Africa / France Science and Technology Research collaboration Protea grant FSTR180523333842. AUH is supported by University of Cape Town Post-graduate publication incentive funding; Poliomyelitis Research Foundation Award; SA National Research Foundation (NRF). NW is supported by South African Medical Research Council Division of Research Capacity Development under National Medical Students Research Training Programme. The authors confirm that the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.