Studies of introital colonization in women with recurrent urinary infections. II. A comparison of growth in normal vaginal fluid of common versus uncommon serogroups of Escherichia coli.

Vaginal fluid collected from volunteers who denied a history of urinary infections was bactericidal to Escherichia coli at pH 4.0. When the pH was increased to 6.5 with sodium hydroxide, the same vaginal fluids supported bacterial growth. If vaginal fluid was adjusted at pH increments between 4.0 and 5.0, and inoculated with common and uncommon serogroups of Escherichia coli, the uncommon O-groups that never cause urinary infections were significantly (p less than 0.005) more inhibited by the lower vaginal pH than were the common O-groups of Escherichia coli.