The bacterial flora of the vaginal vestibule, urethra and vagina in premenopausal women with recurrent urinary tract infections.

Gram-negative enteric bacteria, mainly Escherichia coli, form the predominant microbial flora of the introitus, vagina and urethra in women with a normal genitourinary tract but who are prone to suffer recurrent urinary infections. The infections in these women tend to occur in greater numbers and persist for long intervals, compared to normal control women who never experience urinary infections and in whom the main introital, vaginal and urethral microbial flora consists of lactobacilli and staphylococci. The appearance of gram-negative enterobacteria in the normal and control subjects usually is a rare and transitory event. The majority of urinary tract infections that developed in our population during this study was preceded by a persistent similar gram-negative vulvovaginal and urethral microbial flora. However, prolonged spontaneous intervals occurred occasionally during which the introital, vaginal and urethral cultures were free of gram-negative bacteria, with simultaneous intervals free of infection. Nevertheless, all of these intervals ended with documented urinary tract infections. The introital culture is a reliable mirror of the vulvovaginal and urethral microbial flora and, therefore, it is adequate in the study of urinary infections in women.