Black-pigmented gram-negative anaerobes in genito-urinary tract and pelvic infections.

Black-pigmented Gram-negative anaerobes are part of the normal vaginal flora and contribute to a range of superficial and deep genital infections. Prevotella melaninogenica is found in moderate numbers (10(4-6) cfu/g) in healthy women; the numbers and detection rates increase in anaerobic vaginosis (where it may be a significant contributor to changed microbial metabolic activity that gives the signs and symptoms of this condition) and in other vaginal infective conditions. Pr. melaninogenica is also part of the mixed flora in deep pelvic infections: endometritis, post-partum and post-abortal uterine infections; salpingitis and tubo-ovarian abscesses; PID and pelvic abscesses. Porphyromonas asaccharolytica is probably not a vaginal commensal, but may be isolated from patients with vaginal or pelvic disease. It is more specifically associated with superficial abscesses (e.g. Bartholin's abscess) and ulcers of the genitalia and perineum. P. asaccharolytica was the commonest species isolated from men with genital ulcers of various primary causes and ranging in severity from superficial balanitis/balanoposthitis to synergic gangrene.