Urinary Tract Infections Chromogenic Agar (UTIC) is a chromogenic medium for the presumptive identification and confirmation of microorganisms causing urinary tract infections. The microorganisms which cause infections in the urinary tract are generally abundant and of only one species: E. coli is the organism most frequently isolated. Peptone mixture provides nitrogen, vitamins, minerals and amino acids essential for growth. The medium includes two chromogenic substrates which are cleaved by enzymes produced by Enterococcus spp, Escherichia coli and coliforms. It also includes phenylalanine and tryptophane providing a presumptive indication of the tryptophane deaminase activity, which illustrates the presence of Proteus spp., Morganella spp, and Providencia spp.(brown colonies). This is based on CLED Agar. Bacteriological agar is the solidifying agent. One of the chromogenes is metabolised by ÃŸ-glucosidase enzyme activity, allowing the specific detection of enterococci which form blue or turquoise colonies. The other chromogen is cleaved ÃŸ-galactosidase, an enzyme produced by E. coli which grows as pink colonies. (In case of unreliable colony results, carry out Indol test). When bacteria cleaves both chromogenic substrates, it results in dark blue - purple colonies, characteristical of coliforms bacteria as E. aerogenes, K.pneumoniae and C. freundii. It should be noted that, as with all chromogenic media, microorganisms with atypical enzyme patterns may give anomalous reactions. For example 45% of Enterobacter cloacae do not contain ÃŸ-glucosidase, therefore resulting in pink colonies not distinguishable from E. coli. For confirmation, the Indol test must be performed.
Write Your Own Review