Role of aerobic gram-negative bacilli in endometritis after cesarean section.

Endometritis is considered to be a polymicrobial infection, involving aerobes, anaerobes, and genital mycoplasmas. Aerobic gram-negative rods make up 7%-25% of all genital isolates, but findings from studies in which special collection techniques were used suggest that many of these may be contaminants from the lower genital tract. Bacteremia occurs in 4%-30% of patients with endometritis, and aerobic gram-negative rods account for approximately 25% of blood isolates. Both selected therapy studies and studies of intrauterine cultures collected at surgery from patients at risk for endometritis suggest the significant role of aerobic gram-negative rods. Among them Escherichia coli is the most common isolate in both genital and blood cultures. Klebsiella pneumoniae and Proteus mirabilis rank next, followed by Enterobacter species. Pseudomonas species account for fewer than 0.6% of genital isolates. Overall, aerobic gram-negative rods are causally involved in 10%-20% of cases of endometritis following cesarean section.