Selection of Vaginal H sub(2)O sub(2)-Generating Lactobacillus Species for Probiotic Use

• Published in: Current microbiology 1999-01, Vol.38 (5), p.279-284
• Main Authors: Ocana, V S, de Ruiz Holgado, AAP, Nader-Macias, ME
• Format: Article
• Language: English
• ISSN: 0343-8651

Lactobacilli are believed to contribute to the control of the vaginal microflora by different mechanisms such as production of antagonistic substances like lactic acid, bacteriocins, and H sub(2)O sub(2). This paper describes the selection of H sub(2)O sub(2)-generating lactobacilli among 35 hydrophobic isolates from the human vagina. Lactobacillus crispatus F117, which generated the highest H sub(2)O sub(2) level, was chosen to study: (a) the kinetics of H sub(2)O sub(2) production considering different culture conditions, and (b) the effect of this metabolite on the growth of urogenital tract pathogens. The levels of H sub(2)O sub(2) in L. crispatus supernatant increased during its growth and were maximum at the early stationary phase (3.29 mmol H sub(2)O sub(2)L super(-1)) under aerated conditions (agitated cultures). In nonagitated cultures there were no detectable levels of H sub(2)O sub(2). L. crispatus F117 spent supernatant inhibited Staphylococcus aureus growth in plaque assay. Inhibition was due to H sub(2)O sub(2) since catalase treatment of the supernatant suppressed inhibition. In mixed cultures performed with L. crispatus and S. aureus a significant decrease in pathogen growth was observed. The inhibitory effect depended on the initial inoculum of S. aureus. Further evaluation of the properties of L. crispatus F117 will be performed to consider its inclusion in a probiotic for local use in the vaginal tract.