Abstract
This study was performed to comparatively evaluate the enumeration methods for enterococci by using standard strains, 16S ribosomal RNA gene approaches, and the biochemical profile method. The Enterolert QT and mE method are effective procedures for enumerating enterococci in water because the correlation coefficient was high and the recovery efficiencies were almost 100% when using E. faecalis (JCM5803T) as a standard strain. Furthermore, false-positive organisms, such as Aerococcus viridans and Streptococcus bovis, appeared not to affect the enumeration results of the Enterolert QT method and the mE method. The Enterolert QT is equivalent in sensitivity to the mE method in the experiment using surface-water samples. In spite of the rain event, most of both the positive wells from the Enterolert QT and the positive colonies from the mE method were identified to species levels where possible by 16S rRNA gene sequencing. However, when the surface-water samples were enumerated after the rain event using the Enterolert QT method, although enterococci were identified by 16S rRNA gene sequencing, the rate of biochemical identification by the API Strep test diminished, which indicates the need for further study.
