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DEVELOPMENT OF A DELAYED-INCUBATION, MEMBRANE FILTER TEST FOR ENTEROCCI IN WATER.
Citation:
Genthner, F J. AND A P. Dufour. DEVELOPMENT OF A DELAYED-INCUBATION, MEMBRANE FILTER TEST FOR ENTEROCCI IN WATER. Presented at ASM Annual Meeting, Salt Lake City, Utah, May 19-23, 2002.
Description:
A delayed-incubation procedure for assessing bacterial water quality is useful when sampling in remote locations. Although a delayed incubation test for coliforms is available, we are unaware of any published reports of delayed-incubation procedures for enterococci, an EPA recommended indicator. Thus, the availability of such a procedure would aid water monitoring programs. Water samples containing enterococci were filtered through 0.45 ?m membrane filters. Filters were placed immediately on mEI agar and incubated for 24 hr at 41?C to enumerate the enterococci (delayed incubation filtration, DMF). Numbers of enterococci
obtained by IMF were compared to the numbers of enterococci obtained by DMF. In an initial evaluation a holding media developed for coliforms was selected for further testing. The efficacy of this holding media was examined using enterococci from various sources. Tests were also conducted under field-use conditions. Enterococci were enumerated in freshwater samples obtained near Cincinnati, OH by IMF and express-mailed to Pensacola, FL for enumeration by DMF. Conversely, enterococci were enumerated in brackish water samples obtained in the Pensacola area by IMF and express-mailed to Cincinnati for enumeration by DMF. Test data from each sample were analyzed in triplicate and compared for statistical difference (p<0.5) by a two-tailed T-test. With the exception of samples taken from one freshwater location, no significant differences were observed between the IMF and DMF counts. Further testing will be done to determine effectiveness of the holding fluid under a wide variety of conditions.