[Choice of media for detection of Streptococcus faecalis in routine water testing]

The aim the study was to find a medium for routine water testing for detection of Streptococcus faecalis which could be used by water supply laboratories and sanitary services. In the study dry ready Merck media were used: Mf-enterococcus agar, MF-enterococcus agar base, K-F-streptococcus agar, and Azide Nutrient Pad Sets (of Sartorius). The Slanetz-Bartley medium prepared in our laboratory National Institute of Hygiene (PZH). Method served as control. The usefulness of media for the isolation of Str. faecalis was tested in waters of household wells in the environs of Warsaw. Water from 50 wells was tested; from each well two samples of 10 ml and 100 ml were filtered. The filters were placed on the tested media and incubated at 37 degrees C for 48 hours. Colonies with characteristic pink or orange brown colour were counted. From each plate 3-5 colonies were taken for verification tests. For verification tests 609 bacterial colonies showing characteristic growth on tested media were taken. For the statistical analysis of the results variance analysis was used which showed no significant differences between the control Slanetz-Bartley medium and the ready Merck media. These media can be used alternatively for routine water testing for detection of Str. faecalis. The Azide medium is not recommended since 96% of colonies showing in this test the growth characteristic of Str. faecalis were negative in verification tests. In routine water testing in case of growth of characteristic colonies on isolation media, it is recommended to carry out verification tests including, at least, a test for catalyse production, and culture on Litsky liquid medium or agar medium with bile salts and aesculin.