Micromethod for Determination of Antibacterial Capacity in Amniotic Fluid

Abstract

A new method for assessing antibacterial activity in amniotic fluid (AF) is presented. Sample sizes of 100 microliter were incubated at 37 degrees C in an equal amount of growth medium with inoculated bacteria. The quantification of bacterial growth was established by measuring the change in optical density with an automated spectrophotometer. In this study, Escherichia coli, type K 12, was used for inoculation and the bacterial growth was assessed after 6, 18, 30, 42, and 54 hours' incubation. The variation coefficients in intra-assay and interassay measurements were 3.8 and 5.2%, respectively. Shaking of the incubated sample significantly changed the results by increasing the number of viable cells in the most probable number method and decreasing the optical density difference in the spectrophotometric method. Nevertheless, the correlation between the results in both methods was good (r = 0.94, p less than 0.05, and r = 0.98, p less than 0.01, respectively). By filtering the AF sample before incubation, a great deal of antibacterial activity was removed. The reproducibility, simplicity, and rapidity of this spectrophotometric method of assessing antibacterial activity in AF may make it a useful clinical tool.

Trace Elements and Antibacterial Activity in Amniotic Fluid

“…The antibacterial capacity was given as the difference between optical density (ODD) o f amniotic fluid-growth medium solution with and without bacteria. Complete information on the method is given in an earlier report [10].…”

“…In some other investigations [7][8][9] this correla tion was not found. We have developed a rapid micromethod for assessing antibacte rial activity in A F [10]. In this report we present the results o f a study o f the presence of various trace elements (zinc, phosphate, iron, copper, calcium, potassium and bro mine) in A F and their possible correlation to antibacterial activity in AF.…”