CHORIOAMNIONITIS CAUSED BY GRAM-NEGATIVE BACTERIA AS AN ETIOLOGIC FACTOR IN PRETERM BIRTH

The role and microbiological causes of infection and inflammation of t he chorioamnion were studied in 85 patients with spontaneous preterm d eliveries (< 37 weeks) and in 85 control patients with full term deliv eries. Microorganisms were isolated from the freshly separated chorioa mnion in 55% of preterm and 26% of term deliveries (p < 0.001), Isolat ion rates of gram-negative enteric bacteria were significantly higher in preterm deliveries than in term deliveries (p < 0.001), whereas dif ferences in the isolation of other bacterial species were not signific ant, Histological chorioamnionitis was noted in 49% of preterm and 14% of term deliveries (p < 0.001), and was strongly associated with a po sitive chorioamniotic culture in both groups (p < 0.001), Histological chorioamnionitis was noted in 94%, 54%, and 4% of membranes with gram -negative rods, other microbial species and negative cultures, respect ively (p < 0.001). Preterm deliveries were also associated with signif icantly higher rates of bacterial vaginosis (38% vs, 14%) and isolatio n of vaginal pathogens (85% vs. 65%), In the case of the majority (88% ) of chorioamniotic isolates the same species was isolated in the vagi na, The findings suggest that gram-negative enteric rods are important placental pathogens responsible for subclinical chorioamnionitis and possibly preterm birth. The findings support the concept that microorg anisms ascending from the lower genital tract produce local inflammati on, which may result in preterm labour and delivery.