Other factors that promote virulence are hematomas and devitalized tissue. Although the cervix and vagina routinely harbor such bacteria, the uterine cavity is usually sterile before rupture of the amnionic sac. As the consequence of labor and delivery and associated manipulations, the amnionic fluid and uterus become contaminated with anaerobic and aerobic bacteria. Intraamnionic cytokines and C-reactive protein are also markers of infection (Combs, 2013; Marchocki, 2013). In studies done before the use of antimicrobial prophylaxis, Gilstrap and Cunningham (1979) cultured amnionic fluid obtained at cesarean delivery in women in labor with membranes ruptured more than 6 hours. All had bacterial growth, and on average, each specimen contained 2.5 organisms. Anaerobic and aerobic organisms were identified in 63 percent, anaerobes alone in 30 percent, and aerobes alone in only 7 percent. Anaerobes included Peptostreptococcus and Peptococcus species in 45 percent, Bacteroides species in 9 percent, and Clostridium species in 3 percent. Aerobes included Enterococcus in 14 percent, group B streptococcus in 8 percent, and Escherichia coli in 9 percent of isolates. Sherman and coworkers (1999) later showed that bacterial isolates at cesarean delivery correlated with those taken from women with metritis at 3 days postpartum. Group B streptococci, E coli, and enterococci are some of the more common blood culture isolates with metritis (Cape, 2013; O'Higgins, 2014). Although important because of the severity of infections they cause, clostridial species rarely cause puerperal infections (Chong, 2016).
he role of other organisms in the etiology of these infections is unclear. Observations of Chaim and colleagues (2003) suggest that when cervical colonization of U ureayticum is heavy, it may contribute to the development of metritis. To add evidence to these observations, Tita and associates (2016) recently reported that azithromycin-based extended-spectrum antimicrobial prophylaxis reduced postoperative cesarean delivery infections from 12 to 6 percent compared with j-Iactam agents given alone. Chlamydial infections have been implicated in late-onset, indolent metritis (Ismail, 1985). Finally, Jacobsson and associates (2002) reported a threefold risk of puerperal infection in a group of Swedish women in whom bacterial vaginosis was identified in early pregnancy (Chap. 65, p. 1245).
Bacterial Cultures. Routine genital tract cultures obtained before treatment serve little clinical use and add significant costs. Similarly, routine blood cultures seldom modiy care. In two earlier studies done before perioperative prophylaxis was used, blood cultures were positive in 13 percent of women with postcesarean metritis at Parkland Hospital and 24 percent in those at Los Angeles County Hospital (Cunningham, 1978; DiZerega, 1979). In a later Finnish study, Kankuri and associates (2003) identified bacteremia in only 5 percent of almost 800 women with puerperal sepsis. Blood cultures might be reasonable in women with exceedingly high temperature spikes that may signiy virulent infection with group A streptococci.