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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. -
This is a selective chromogenic medium for the detection of Malassezia spp., especially M.restricta and M.globosa, in veterinary or clinical specimens. Malassezia spp. is a commensal organism in humans and animals that can cause severe dermatitis or otitis infections. The medium is supplemented with Glycerol and Tween 40 to enhance the in-vitro growth of Malassezia spp. due to the complex lipid requirements of these yeasts. Appearance and differentiation of Malassezia spp. is readily apparent by the distinctive colonial colours allowing for differentiation from Candida spp. in specimens. The inclusion of chloramphenicol ensures the inhibition of bacterial species during incubation of specimens. -
Colorex™ MRSA is a chromogenic medium for the selective isolation of Methicillin-Resistant Staphylococcus aureus (MRSA). The medium can be used for the routine screening of clinical specimens for MRSA from a variety of sampling sites such as the nose, throat and groin. The medium incorporates a nutritious peptone base medium and a number of selective agents to inhibit most Gram-negative and Gram-positive bacteria as well as yeasts and moulds. The chromogenic detection of specific enzyme activity leads to the formation of pink/mauve colonies indicating MRSA (including low level resistant and hetero-resistant strains) following incubation at 37°C for 18-24 hours. Other organisms, if present are indicated by blue or colourless colonies. Any presumptive isolates must be confirmed using serological and/or biochemical techniques available to the laboratory. The use of this chromogenic medium does not diminish the requirement for conventional antimicrobial susceptibility tests for the confirmation of methicillin resistance. Limitations: 1. S.aureus strains that possess a low MIC to the selective agent present in the medium but are mec A negative may form colonies on the medium. 2. Some MRSA strains may form typical colonies surrounded by a matte halo. The formation of the halo serves no diagnostic function. 3. Certain methicillin-resistant coagulase-negative staphylococci (CNS) may produce characteristic colonies. In some cases differentiation may be achieved by examination of the colour of these colonies, as they may be considerably darker in colour (bluish purple to a very dark pink/magenta). 4. Certain bacterial species other than staphylococci may produce colonies with a characteristic colour. -
Colorex™ MRSA is a chromogenic medium for the selective isolation of Methicillin-Resistant Staphylococcus aureus (MRSA). The medium can be used for the routine screening of clinical specimens for MRSA from a variety of sampling sites such as the nose, throat and groin. The medium incorporates a nutritious peptone base medium and a number of selective agents to inhibit most Gram-negative and Gram-positive bacteria as well as yeasts and moulds. The chromogenic detection of specific enzyme activity leads to the formation of pink/mauve colonies indicating MRSA (including low level resistant and hetero-resistant strains) following incubation at 37°C for 18-24 hours. Other organisms, if present are indicated by blue or colourless colonies. Any presumptive isolates must be confirmed using serological and/or biochemical techniques available to the laboratory. The use of this chromogenic medium does not diminish the requirement for conventional antimicrobial susceptibility tests for the confirmation of methicillin resistance. Limitations: 1. S.aureus strains that possess a low MIC to the selective agent present in the medium but are mec A negative may form colonies on the medium. 2. Some MRSA strains may form typical colonies surrounded by a matte halo. The formation of the halo serves no diagnostic function. 3. Certain methicillin-resistant coagulase-negative staphylococci (CNS) may produce characteristic colonies. In some cases differentiation may be achieved by examination of the colour of these colonies, as they may be considerably darker in colour (bluish purple to a very dark pink/magenta). 4. Certain bacterial species other than staphylococci may produce colonies with a characteristic colour. -
Colorex™ mSuperCARBA™ is a selective chromogenic medium that has been developed for the detection and isolation of carbapenemase producing Enterobacteriaceae (CPE). Nosocomial infections due to CPE are particularly difficult due to the limited treatment options. Therefore, this medium is designed to simplify the detection of CPE carriers and to allow for improved monitoring of high risk patient groups. 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. All presumptive positive colonies should be confirmed for carbapenemase production. Typical colour reactions are as follows: Escherichia coli – Red/Pink colonies; Klebsiella spp., Enterobacter spp., & Citrobacter spp. – Metallic blue colonies; Other Gram –ve CPE – Colourless colonies; Carbapenem sensitive bacterial species, Gram +ve bacterial species & yeasts – Inhibited. -
Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria particularly among the coliform group of organisms. Colorex™ UTI has been developed primarily for use in the examination of urine specimens with the aim of simplifying the differentiation and presumptive identification of the main organisms, gram negative and gram positive, usually found in Urinary Tract Infections. It can however be used to differentiate organisms in other types of clinical specimens. 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. -
Colorex™ Salmonella Plus is a chromogenic media for the isolation and presumptive identification of Salmonella spp, S typhi, S.paratyphi and lactose positive Salmonella from foodstuffs. Any presumptive Salmonella spp. will produce a mauve colouration; other organisms will be blue or colourless in appearance. Cefsulodin is added as a selective agent to inhibit the growth of Pseudomonas and Aeromonas species. Any presumptive isolates must be confirmed using serological and biochemical techniques available to the laboratory. This product meets the requirements of ISO 6579:2002 standard. -
This is a chromogenic medium for the isolation and presumptive identification of Staphylococcus aureus. Mauve colonies indicate Staph aureus following incubation (18 – 24 hours) at 37°C, other organisms, if not inhibited, are indicated by blue or colourless colonies. Studies have suggested that this media has a specificity and sensitivity of 99.4% and 95.5% respectively (Gaillot et al 2000). -
About a quarter of pregnant women in the UK are estimated to carry Streptococcus agalactiae. As a result of this, babies become colonized with Streptococcus agalactiae (GBS) during labour and birth; the vast majority are unaffected by this colonization, however, a small percentage become infected with conditions such as eye infections, pneumonia, septicaemia or meningitis. Colorex™ StrepB Agar is a chromogenic media that presumptively identifies Streptococcus agalactiae (mauve/red colonies) after 18-24 hours incubation in aerobic conditions. Enterococci are differentiated by the formation of blue colonies; other organisms are inhibited or colourless. NB: Some strains of Group A, C & G streptococci may also produce mauve colonies. Therefore, final identification may require additional testing. -
Traditional methods for the isolation of Vibrio spp. (e.g. TCBS medium) are labour intensive and not particularly sensitive. Colorex™ Vibrio allows for the easy differentiation of V.parahaemolyticus from V.cholerae and V.vulnificus and other Vibrio spp. at the initial isolation stage while retaining a higher level of sensitivity than conventional methods. V.parahaemolyticus produces colonies with a mauve colouration while V.cholerae and V.vulnificus produce colonies with a blue colouration. Colorex™ Vibrio is a highly selective medium with most major Enterobacteriaceae spp. and Gram positive organisms being inhibited during incubation. -
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. -
A basic general-purpose blood free medium, capable of supporting the growth of most micro-organisms, including many fastidious organisms that do not require blood. -
A general purpose medium enriched with 5% Defibrinated Horse Blood, suitable for the isolation of most organisms including many fastidious anaerobes. -
Columbia Agar Base with 5% Horse Blood & Streptococcal Selective Supplement This is a medium for the selective isolation of Streptococcus spp. from clinical samples. Based on Columbia Agar Base enriched with 5% Horse Blood it is made selective by the addition of Colistin and Oxolinic Acid. -
A very nutritious general-purpose medium based on Columbia Agar Base enriched with 5% Sheep Blood, suitable for the isolation of most organisms including most fastidious anaerobes of clinical significance. Many workers claim that β-haemolysis is more readily apparent, particularly in group A streptococci, when Sheep Blood is used in place of Horse Blood.
