A comperative study of media for detection of enterococci in water.

Abstract

THE FECAL STREPTOCOCCI, or enterococci, have received increasing attention as indicators of pollution. Determination of enterococci may supplement information provided by the coliform group of organisms in water. The previous lack of a generally accepted and a suitable medium has, in part, been responsible for the infrequency of their use as supplementary indicators of pollution. The statements of Suckling' that enterococci are present in feces and sewage and are found in polluted water; that they are not found in pure water and sites away from human and animal life; and that enterococci do not multiply outside the animal body in water or soil have been amply confirmed.2-4 Recent editions of Methods for the Examination of Water, Sewage, and Industrial Wastes have not included methods for enterococci, but reference has been made to British work. The latest issue of British methods5 includes a section on fecal streptococci using tellurite or azide media for their detection. It was with the intent of rectifying this omission that the present study was encouraged by the Standard Methods Committee. Media for enterococci were selected for this collaborative project which were either new and untested, or which had been found highly productive in previous comparisons. The practicality of the method for widespread use was likewise considered. This study was designed to compare the productivity of various media for enterococci. Tube dilution and membrane filter technics were performed in eight laboratories* with untreated natural waters from widely separated parts of the country and collected during cold and warm seasons. In addition the relationship, if any, between the coliform bacteria and enterococci in these waters could be studied.