Antimicrobial activity of amniotic fluid obtained vaginally.

Twenty-nine amniotic fluid samples were aspirated from pregnant women at term (38-40 weeks' gestation) by tapping the bulging membrane vaginally, and their effects on Escherichia coli, Staphylococcus aureus and Candida albicans were studied. Inhibition rates were 72.41% for E coli, 68.96% for S aureus and 79.31% for C albicans. Two samples (6.90%) affected only a single organism, 18 (62.07%) affected two organisms and eight (27.59%) affected all three. Only one sample (3.45%) had no inhibitory effect on the microorganisms studied. Thus, 28 of 29 samples (96.55%) inhibited the growth of at least one of the microorganisms tested. These results are also significant because there is a high risk of contamination of amniotic fluid samples obtained through the vaginal route, although they can be obtained easier that way than through amniocentesis.