Use of esterase inhibitors and zone electrophoresis to define bacterial esterases in amniotic fluid.

OBJECTIVE

The purpose of our study was to define further the role of bacterial esterases in amniotic fluid obtained from women with chorioamnionitis.

STUDY DESIGN

Amniotic fluid samples from 39 patients with chorioamnionitis were submitted for bacterial cultures and in vitro assay. Esterase inhibitors diisopropyl fluorophosphate and iodoacetic acid were added and the degree of inhibition calculated. These results were compared with the amniotic fluid culture results. Chi square analysis was performed to compare the results of the esterase assay and the inhibition assay between the uninfected and infected amniotic fluid samples.

RESULTS

Thirty-one patients had positive bacterial cultures, with 21 being infected with gram-negative organisms. All samples showed significant inhibition (range 55% to 82%) with diisopropyl fluorophosphate. There was partial inhibition with iodoacetic acid (range 10% to 30%) in the gram-negative samples but no inhibition in the gram-positive and uninfected samples. Six infected and two uninfected samples were analyzed by using zone electrophoresis with human plasma as a control. Minimal esterase motility was noted in the amniotic fluid samples as compared with that in plasma.

CONCLUSION

The esterases in amniotic fluid appeared to be of bacterial, not human, origin. Furthermore, different groups of bacteria appeared to produce different esterases in infected amniotic fluid.