The bacterial pathogenesis of infection following cesarean section.

To further define the bacterial pathogenesis of infections following cesarean section, amnionic fluid was obtained transabdominally at the time of surgery from 56 women whose membranes were ruptured for more than 6 hours. In all specimens, bacterial growth was demonstrated, and 53 of these women developed postoperative myometritis. A mean of 2.5 pathogenic bacteria was isolated from each specimen. More than 90% of the amnionic fluid specimens had polymicrobial anaerobic/aerobic growth (63%) or anaerobes only (30%). Aerobic and anaerobic streptococci accounted for 72% of all bacterial isolates; Bacteroides and Escherichia coli were the next most commonly recovered species. In women treated for myometritis and who subsequently developed a wound or pelvic abscess, cultures from these wounds or abscesses were positive for 1-3 organisms present in amnionic fluid. These data indicate that ascending colonization of flora from the lower genital tract and inoculation into surgically traumatized tissues usually result in polymicrobial pelvic infection with a predominance of anaerobic pathogens. Moreover, abscess development in these women is probably associated with organisms identified in amnionic fluid. Bacterial isolates from these women are remarkably similar to those from women with other pelvic infections.