Elimination of vaginal colonization with Escherichia coli by administration of indigenous flora

A persistent vaginal colonization with a pyelonephritogenic strain of Escherichia coli, induced by administration of amoxicillin, was established in four adult cynomolgus monkeys. This colonization mimicked the one seen in urinary tract infection-prone human females. Attempts to eliminate the E. coli colonization and restore normal conditions were made. Either suspensions of lactobacilli or vaginal fluid from a healthy unmanipulated monkey was administered as repeated vaginal flushes for 5 to 9 days. A total elimination of vaginal E. coli was observed in two of six experiments with lactobacilli, and a decrease was observed in the other four. A better result was obtained with flushes of vaginal fluid, which eliminated the E. coli colonization in eight of eight experiments. In two of these, a single flush was sufficient to obtain a decolonization. The ability of fresh vaginal fluid to eliminate E. coli from the vagina could be transferred from one monkey to another. This study demonstrates the role of the normal flora in the defense against genital colonization with potentially pathogenic adhering E. coli. The possible clinical relevance of these findings must be further examined.