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Vancomycin-resistant Enterococcus (VRE) infections are especially aggressive and have been associated with mortality rates approaching 60% to 70%. They are now the second-leading cause of nosocomial infections in the U.S., and their prevalence is increasing worldwide. Resistance to vancomycin has the potential to be transferred from bacteria to bacteria. Cross-resistance is mediated by plasmids and transposons, which may transfer the genes associated with resistance to other much more aggressive pathogens, such as staphylococci and streptococci. Three principal types of vancomycin resistance are found in Enterococcus spp.; VanA, VanB and VanC genotypes. VanA and VanB types account for most significant infections in clinical settings, involving E.faecium and E.faecalis. VanC resistance is a low-level intrinsic resistance found in other Enterococcus spp. The Colorex™ VRE media is another chromogenic media in the Colorex™ range, enabling presumptive identification of vancomycin resistant Enterococci by the formation of mauve/pink coloured colonies (for VanA and VanB genotypes) and blue coloured colonies (for VanC genotypes) after 18-24 hours incubation. -
This is a defined medium primarily for the cultivation of fungi and bacteria that are capable of utilising Sodium Nitrate as their sole source of Nitrogen. If made more acidic by adjusting to pH 3.5 it can also be used for isolation of yeasts. It has also been used for the identification of Candida albicans by chlamydospore production. -
This medium is used for the presumptive identification of Pseudomonas aeruginosa from water and environmental samples. Pseudomonas aeruginosa is presumptively identified by the characteristic green pigmentation of the colonies with hydrolysis of casein (clear zones around each colony). -
This is best described as a multi-purpose medium for differentiation of enterobacteriacae that combines three individual tests into a single medium. For use the medium is inoculated by making a single stab into the medium with a straight wire (or equivalent) using a pure culture (or discrete single colony) of the test organism. Following incubation it is recommended that the medium should first of all be examined to determine whether or not the organism is motile. The presence of motility is apparent by the organism tracking out from the line of inoculation and often turning the medium turbid. Non-motile organisms generally grow within the stab line leaving the surrounding medium clear. Urease positive organisms (e.g. Proteus spp) turn the medium bright red due to the hydrolysis of the Urea in the presence of the Phenol Red Indicator often making it difficult to determine the other parameters.Indole is tested for by layering a small amount of Indole Reagent (Erlich’s or Kovac’s appear to work equally well) onto the surface of the medium and allowed a few minutes to react. A positive result is indicated by the formation of a red line at the interface of the reagent and the medium. -
BM1359 Phosphate Buffer (0.067M) is a standard biochemical reagent suitable for a variety of uses, primarily the neutralisation of sterilised sputum samples, and is recommended by the UK Standards for Microbiology Investigations for the investigation of specimens for Mycobacterium species. -
Chromogenic Coliform Agar (CCA) Chromogenic Coliform Agar (CCA) conforms to the ISO 9308-1 guidelines for the detection, enumeration and isolation of coliforms and more specifically Escherichia coli in water samples by the membrane-filtration technique. The colonial differentiation is provided by the chromogenic substrates, Salmon-GAL and X-glucuronide. Salmon-GAL is used for the detection of β-D-galactosidase enzymatic activity. X-glucuronide is used for the detection of β-D-Glucoronidase enzymatic activity. β-D-galactosidase, expressed by all coliforms, cleaves the Salmon-GAL substrate and producing red/pink coloured colonies. Unlike other coliforms, Escherichia coli leaves both Salmon-GAL and X-glucuronide producing a violet/blue coloured colonies. Tryptophan is used to increase detection reliability by improving the indole reaction. The peptones, sodium pyruvate and sorbitol support bacterial growth and simple recovery of sub-lethal thermally injured coliforms. Sodium di-hydrogen phosphate and di-sodium hydrogen phosphate phosphate buffer the medium and sodium chloride is used to achieve osmotic balance. The selectivity is attained by the addition of Tergitol® 7 as it inhibits the growth of Gram positive bacteria. -
Based on Christensen’s Medium this medium is generally used to detect rapid urease activity of Proteus spp although it can be used to detect urease activity of other Enterobacteriaceae. When used for the later purpose it is necessary to increase the incubation time to as long as 48 hours. -
A modification of Christensen’s Medium by Maslen this medium is generally used to detect rapid Urease activity of Proteus spp although it can be used to detect Urease activity of other Enterobacteriaceae including Urease producing Salmonella and Shigella. Unlike Christensen’s Medium when used for the later purpose it is not necessary to increase the incubation time.
