Comparison of quantitative and qualitative methods of detecting hydrogen peroxide produced by human vaginal strains of lactobacilli

摘要

A quantitative method was developed for the measurement of micromolar quantities of H2O2produced in Rogosa broth and peptonized milk broth by vaginal strains of lactobacilli isolated from women. The production of substantial amounts reproducibly was dependent on the growth of the organisms in acid media (pH ≤6.0) under anaerobic or micro‐aerophilic conditions with continuous agitation. The addition to the media of the enzyme inhibitor, 3‐amino‐l,2,4‐triazole, with or without catalase sometimes induced the production of H2O2especially in non‐agitated cultures. However, other agents such as concanavalin ando‐dianisidine had no enhancing effect, and catalase or peroxidase alone completely inhibited H2O2production.The H2O2produced in the acid media was stable for more than a month at 5°C but not in media at pH ≥ 7.0. Of five strains of lactobacilli tested by the quantitative method and by a chromogenic qualitative method (Rogosa‐catalase or ‐peroxidase agar), three consistently produced H2O2measurable by the former method, but none did so after growth of the organisms on Rogosa‐catalase/peroxidase agar which suggested that the qualitative method was unreliable. The fact that H2O2was produced in substantial quantities by some strains and not at all by others enabled H2O2‐producers and non‐producers