[Reactions of different Enterobacteriaceae and Vibrionaceae species in BRILA-MUG (Fluorocult) bouillion]

In order to test the usefulness of BRILA-MUG (= Fluorocult) medium (Merck) for isolation and identification of total coliforms and faecal coliforms in surface water according to the EC guidelines for bathing waters a total of 969 strains of different Enterobacteriaceae and Vibrionaceae species was examined under different culture conditions. These included 486 E. coli (reference strains of O-groups 1-170, enterotoxin and Verotoxin-producing strains), 149 Salmonella (subspecies I-VI), 92 Yersinia, 44 Shigella, 64 Vibrio, 16 Aeromonas, and 118 strains of other Enterobacteriaceae species. After 48 h incubation at 36 degrees C 372 (82.0%) of 486 E. coli showed the typical reactions of gas formation, fluorescence (beta-glucuronidase activity), and indole production. Examination of fluorescence after addition of 1 N NaOH (0.5 ml), or testing of indole production after subculture in tryptophane containing broth improved the amount of typical reactions to 434 (95.4%). Incubation at 44 degrees C for 48 h gave less favourable results as compared with that at 36 degrees C. Out of 483 strains of other species 3.9% Salmonella strains of subspecies II-IV, 6.25% Citrobacter freundii, and 50% Edwardsiella tarda strains yielded reactions typical of E. coli. Shigella and Yersinia strains occasionally produced indole or fluorescence, but never visible gas.