Anaerobic periurethral flora of healthy women and women susceptible to urinary-tract infection.

The anaerobic periurethral microbial flora of 25 healthy women was compared with that of 29 women attending the urinary-tract-infection clinic at the Royal Free Hospital. The latter group consisted of 19 patients receiving long-term prophylactic antimicrobial therapy and 10 with proven recurrent urinary-tract infection not receiving prophylactic treatment. The numbers and species of anaerobes isolated from each group were similar. Lactobacillus spp. were the most frequently isolated organisms in each group and the most numerous. Bacteroides spp. were the next most frequently isolated. In any one subject, the anaerobic flora varied considerably during the study period of approximately 6 months. Thus, the anaerobic flora is not affected by recurrent urinary-tract infection in the past nor by the use of prophylactic chemotherapy. It does not appear to exert a protective role against the initiation of urinary-tract infection.