CHROMOCULT ENTEROCOCCI BROTH 500GR MERCK

CHROMOCULT ENTEROCOCCI BROTH MERCK RENDIMENTO 18g (CALDO SIMPLES) OU 36g (CALDO DUPLO) EM 1L EMBALAGEM 500GR Use as a test for enterococci and also for their selective enrichment in the bacteriological water examination. Mode of Action The presence of enterococci (as well as the less frequent D-streptococci), which account for most of the faecal streptococci, serves as an indicator for faecal contamination. This is, in some respect, more specific than the presence of coliforms which may originate from non-faecal sources, whereas enterococci can come only from faeces of human or animal origin. The concentration of sodium-azide present in this medium largely inhibits the growth of the accompanying, and especially the Gram-negative microbial flora while sparing the enterococci. The substrate X-GLU (5-bromo-4-chloro-3-indolyl-ß-Dglucopyranoside) is cleaved, stimulated by selected peptones, by the enzyme ß-D-glucosidase which is characteristic for enterococci. This results in an intensive blue-green colour of the broth. Azide, at the same time, prevents a false positive result by most other ß-D-glucosidase positive bacteria. Therefore, the colour-change of the broth largely confirms the presence of enterococci and D-streptococci in water. Typical Composition (g/litre) Peptones 8.6; sodium chloride 6.4; sodium azide 0.6; 5-bromo-4-chloro-3-indolyl-B-D-glucopyranoside (X-GLU) 0.04; Tween® 80 2.2. Preparation Suspend 18 g (single-strength) or 36 g (double-strength) in 1 litre of demin. water, dispense into suitable vessels, autoclave (15 min at 121 °C). pH: 7.5 ± 0.2 at 25 °C. The prepared broth is clear and yellowish.