Antibacterial activity of amniotic fluid in the early third trimester. Its association with preterm labor and delivery

Abstract

The purpose of this study was to determine the bacterial growth inhibitory property of amniotic fluid (AF) from patients in the early third trimester and to examine its relationship to preterm labor and delivery. A total of 38 AF samples from patients between 27 and 35 weeks gestation with intact membranes were studied. Antibacterial activity was tested against Escherichia coli, Staphylococcus aureus, and Bacteroides fragilis. Fifteen fluids were from patients in preterm labor who delivered near term after successful inhibition of labor. Five of these fluids (33%) were inhibitory to E. coli, five (33%) to S. aureus, and 11 (73%) to B. fragilis. Nine fluids were from patients who failed inhibition of labor and delivered preterm; none of these were inhibitory to E. coli, two (22%) to S. aureus, and only one (11%) to B. fragilis (P less than 0.005). Two of the nine fluids from patients who failed inhibition of labor also yielded fusobacteria. The remaining 14 fluids were obtained from patients without preterm labor and exhibited antibacterial activity similar to that from patients with successful labor inhibition. Results suggest a relationship between the absence of AF antibacterial activity against B. fragilis and preterm delivery in patients with preterm labor and intact membranes.