The Effect of Filtration of Amniotic Fluid on the Growth of Chlamydia Trachomatis and Escherichia Coli

There is increasing concern about Chlamydia trachomatis infection during pregnancy, because of reports of increased maternal, fetal, and neonatal risks. Amniotic fluid is known to possess antibacterial activity and has recently been shown to inhibit formation of chlamydial inclusions in McCoy cell culture. To further characterize the anti-chlamydial factor, we investigated the effect of filtering the fluid (0.45 microns pores) prior to incubation. Amniotic fluid was obtained from 12 women at term gestation, either by amniocentesis, or at cesarean section, Chlamydial inclusion formation was studied in McCoy cell cultures, and Escherichia coli growth was studied by a plate-count method. Filtered amniotic fluid had significantly less inhibitory activity against chlamydial inclusion formation than nonfiltered fluid did. Both filtered and nonfiltered amniotic fluid were equally effective in inhibiting E. coli colony growth. These data suggest that the chlamydial inhibitor in amniotic fluid does not pass through 0.45 microns pores and is larger than the bacterial inhibitor that was reported to be a peptide of low molecular weight.