Microbiology of the female genital tract.

Patients who contract genital tract infections are predominantly young, are otherwise healthy, and generally respond well to treatment for bacterial infections. These infections are most commonly polymicrobial in etiology, with several noteworthy exceptions. Often there is an inciting event such as childbirth, surgical intervention, pregnancy termination or intrauterine contraceptive device insertion. With treatment, prognosis for cure is excellent; however, sequelae such as recurrent infections, infertility, or ectopic pregnancy can be serious. Bacteria encountered in the female genital tract can be divided into aerobic and anaerobic organisms. Among the aerobic gram-positive organisms, several varieties of streptococci such as Group B streptococci and enterococci occur frequently. Staphylococcus aureus is an infrequent but important pathogen. Among the aerobic gram-negative organisms, the most common is Escherichia coli. Klebsiella sp. and Proteus sp. occur in about 5% of genital tract infections. Species that are more resistant to antibiotics, such as Pseudomonas aeruginosa and Enterobacter sp., occur in approximately 1% or 2% of these cases and are more likely to appear in patients who have previously received antibiotic therapy or who have been hospitalized for some time. Among the anaerobic organisms, the most common gram-positive isolates are Peptostreptococci and Peptococci. Clostridia sp. occurs less frequently. Among the anaerobic gram-negative organisms, the Bacteroides sp. most frequently encountered are Bacteroides bivius and Bacteroides disiens. Bacteroides fragilis is still a common problem but appears to be less predominant. Other organisms encountered are Chlamydia trachomatis, the genital mycoplasmas, yeasts, protozoa, and viruses.