New concepts of obstetric and gynecologic infection.

Multiple organisms are usually recovered from patients with acute pelvic inflammatory disease (PID). The sexually transmitted organisms Neisseria gonorrhoeae, Chlamydia trachomatis, and genital mycoplasmas frequently initiate infection. Although aerobic and anaerobic bacteria that constitute the normal vaginal flora are frequent secondary invaders following an initial sexually transmitted infection, these bacteria can also primarily cause PID. Early postpartum endometritis, the most common postpartum infection, amniotic fluid infection, and infection following hysterectomy are usually caused by the aerobic and anaerobic bacteria that constitute the normal vaginal flora. Because the organisms that cause the various obstetric-gynecologic infections are often found in combination, it is necessary to begin therapy with broad-spectrum antibiotics. Many of these infections are caused by anaerobic bacteria and it is often necessary to select antibiotics that inhibit anaerobes.