Amniotic fluid interleukin-1 beta and interleukin-6, but not interleukin-8 correlate with microbial invasion of the amniotic cavity in preterm labor.

PROBLEM: We compared the frequency of intra-amniotic infection in preterm labor (PL) with women not in labor, and correlated infection with amniotic fluid (AF) cytokines. Detailed identification of species, especially mycoplasmata, was tried to improve our understanding of the pathogenesis of PL.

METHOD OF STUDY: AF from 20 women with PL and 20 controls were evaluated. Infection was detected by PCR for Mycoplasma hominis, Ureaplasma urealyticum and 16S rRNA bacterial gene, which was cloned and sequenced for bacterial identification. Interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor (TNF)-α levels were measured by ELISA.

RESULTS: Frequency of intra-amniotic infection is higher in PL (40.0%). Sequencing-based method identified Bacteroides fragilis, Prevotella bivia and Leptotrichia amnionii, in addition to Mycoplasma species detected by PCR. AF infection correlated with increased IL-1β and IL-6 levels.

CONCLUSION: The frequency of intra-amniotic infection, especially M. hominis, in PL women who delivered with 7 days, is high and correlates with high IL-1β and IL-6 levels, but not IL-8.