-
CLED Agar (Bevis) A modification by Bevis of the original CLED medium of Mackey & Sandys. This formulation uses a double indicator system (Andrade’s (Acid fuchsin) and Bromothymol blue) to improve differentiation of Lactose and Non-lactose fermenting organisms. The lack of Sodium Chloride also prevents the swarming of Proteus spp. -
Colorex 0157 with Cefixime & Tellurite This medium replaces the conventional Sorbitol MacConkey Agar that is reputed for high levels of false positives and the difficulty of colonial interpretation and differentiation. Colorex O157 is a chromogenic medium with a very high specificity (98% according to K.A. Bettelheim, 1998 J.Appl.Microbiol.85:425-428) for E.coli O157. To reduce the level of background flora, the medium is made selective by the addition of Cefixime and Potassium tellurite. Positive colonies exhibit a mauve colouration enabling easy interpretation amongst blue or colourless colonies of other bacteria. -
Colorex™Acinetobacter MDR is a chromogenic medium for the detection of multi-drug resistant (MDR) Acinetobacter spp. Positive colonies exhibit a distinct red colouration with a pale grey centre enabling easy interpretation amongst blue, violet or colourless colonies that may be produced by other Gram –ve bacteria. Gram +ve bacteria and yeast are inhibited on this medium. Limitations: 1. Some Pseudomonas, Stenotrophomonas and Burkholderia spp. may form pale red colonies on this medium but are readily distinguishable due to differences in colonial morphology compared to the Acinetobacter spp. An oxidase test will readily differentiate any Pseudomonas spp. 2. Some Enterobacteriaceae isolates may form blue colonies on this medium. 3. Definitive MDR characterisation may require additional antibiotic susceptibility testing. -
Colorex C3GR is a chromogenic screening medium for the detection of β-Lactamase producing Gram-negative bacteria in clinical specimens. The selectivity of the medium allows for detection of ESBL and/or AmpC producing isolates that exhibit a reduced susceptibility to 3rd generation cephalosporin antibiotics. The chromogenic reactions allow for species differentiation on presumptive positive isolates. -
Colorex™ Campylobacter is a chromogenic media for the isolation and presumptive identification of Campylobacter spp, from clinical specimens and food samples. Any presumptive Campylobacter colonies will produce a red colouration whilst most other organisms will be inhibited. Typical colour reactions are as follows – Campylobacter jejuni – Red colonies; Campylobacter coli – Red colonies; Campylobacter lari – Red colonies; Other Gram –ve bacteria – Blue colonies or inhibited; Gram +ve bacteria & yeasts – Inhibited. Presumptive positive Campylobacter colonies must be confirmed using serological and biochemical techniques according to the method / procedure being followed. -
In recent years there has been an increase in the number of immuno-compromised patients, which has in turn led to an increased rate of infections associated with Candida species. There were 2151 reported cases of candidaemia in 2016 with C.albicans accounting for 42%, C.glabrata for 25%, C.parapsilosis for 9% and C.tropicalis for 3% of infections in England, Wales and Northern Ireland.(1) COLOREX™ Candida was formulated specifically for the detection and isolation of clinically significant Candida spp. by means of colonial colour and morphology within 48hrs. COLOREX™ Candida allows for the recognition of a minor Candida population within a mixed population as well as the pre-dominant species thereby allowing for a patient specific treatment plan at the earliest possible opportunity. Most bacterial species will be inhibited due to the inclusion of chloramphenicol. C.albicans – Green colonies C.tropicalis – Metallic blue colonies C.glabrata – Mauve to pink colonies C.krusei – Large fuzzy pink colonies Limitations Definitive identification requires additional testing of isolates (e.g. MALDI-TOF). C.glabrata and C.parapsilosis cannot be readily distinguished on this particular medium. C.dubliniensis will form dark green colonies on COLOREX™ Candida so additional testing is required to confirm presence in the specimen. C.auris isolates will grow on this medium but the colony colour may vary from white to pale purple/pink so further testing will be required to confirm identification. -
Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria particularly among the Enterobacteriaceae. Colorex™ ESBL (Extended Spectrum Beta-Lactamase) medium has been developed for the isolation of ESBL – producing organisms with the aim of simplifying the differentiation and presumptive identification of the causative organism. It should be noted that other non-ESBL and AmpC isolates will be inhibited on this medium reducing the incidence of false positives. The distinctive colonial colouration of the various species can reduce the need for additional follow up testing allowing many positive results to be issued within 24 hours of receipt of the sample. If necessary an Indole test for confirmation of Escherichia coli and TDA test for Proteus spp. can be performed directly from the medium. Typical colour reactions are as follows: Escherichia coli – Red colonies; Proteus spp., Providencia spp. & Morganella spp. – Clear colonies with a brown halo; Klebsiella spp., Enterobacter spp, Serratia spp. & Citrobacter spp. – Metallic blue colonies; Salmonella spp. & Acinetobacter spp. – Clear colonies; Gram +ve bacterial species and yeasts – Inhibited. -
Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria. This is one such medium and is a selective medium for the isolation and presumptive identification of Listeria monocytogenes from clinical and food samples. The medium is made selective by the inclusion of Lithium chloride, Ceftazidime, Polymixin B, Nalidixic acid (to suppress other bacteria) and Amphotericin B (to suppress yeasts and fungi). With the combination of both the chromogenic substrate and phospholipase C enzyme reactions, it is possible to differentiate L.monocytogenes from other Listeria spp. Users should be aware that some strains of L.ivanovii are capable of producing an opaque halo, highlighting the need to confirm presumptively identified colonies.
