[Comparative evaluation of membrane filter methods for enumeration of enterococci in water]

Many laboratory methods for the assay of viable counts of enterococci in water have been reported, but the evaluation or verification of the methods have yet to be reported. The three most commonly used membrane filter methods were selected and compared in terms of the verification of enterococci counts in environmental water. The verified percentages, i.e. identified enterococci count versus apparent enterococci count, assayed by each method, were as follows: KF.MF (membrane filter cultured on KF agar) method 64.5%; mENT.MF (membrane filter cultured on mENT agar) method 80.7%; and mE.MF (membrane filter cultured on mE agar) method 63.4%. The AC.MF (membrane filter cultured on AC agar) method which we reported previously (Koujima I, et al. Jap J Bact, 1989; 44: 813-816) consistently gives 100% verification and therefore is the most consistent method and superior in accuracy to the other three methods.