Clinical Microbiology

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The emergence of antibiotic resistance has complicated the role of clinical microbiology laboratories.  Screening for resistant organisms has become increasingly important.  CHROMagar has several products specifically for screening for antibiotic resistant organisms.  These products have been designed to be user friendly with very high sensitivity and specificity for the target organism.  In most cases, the CHROMagar product improves the turnaround time dramatically compared to the traditional techniques.  CHROMagar also has products for the direct identification of several organisms which simplifies traditional identification protocols  The list below gives some examples of the products available.  For more CHROMagar products, detailed descriptions and literature, go to www.chromagar.com

CHROMagar Candida

Plate reading

  • Candida albicans – green
  • Candida tropicalis – metallic blue
  • Candida krusei – pink, fuzzy
  • Other species – white to mauve
  • Intense colony colouration helping to differentiate species
  • 36-48 h incubation at 35 °C or higher
  • specificity and sensitivity exceeds 99% for Candida albicans, Candida tropicalis and Candida krusei
CHROMagar ESBL

Plate reading

  • E.coli ESBL – Dark pink to reddish
  • Sensitive Gram negative strains – inhibited
  • Klebsiella, Enterobacter, Citrobacter – metallic blue
  • Proteus – brown halo
  • Detection after overnight incubation
  • Good species identification – based on CHROMagar Orientation
  • High sensitivity (99,2%) and Specificity (89%)
  • No selective pre-enrichment required
CHROMagar KPC

Plate reading

  • E.coli CarbapenemR – Dark pink to reddish
  • Klebsiella, Enterobacter, Citrobacter CarbapenemR – Metallic blue
  • Pseudomonas CarbapenemR – Cream, translucent
  • Other bacteria – Usually inhibited
  • Detection of NDM-1: Bacteria harbouring this resistance mechanism (a metallo-betalactmase) can easily be screened with CHROMagar KPC
  • Species identification thanks to the CHROMagar Orientation base
  • Direct plating of the sample
  • Requires only 18-24 hours of incubation
CHROMagar MRSA

Plate reading

  • Methicillin Resistant Staphylococcus aureus (MRSA) – rose to mauve
  • Methicillin Susceptible Staphylococcus aureus (MSSA) – inhibited
  • Other bacteria – blue, colourless or inhibited
  • Easy interpretation – intense mauve colony colour
  • MRSA colonies in 18-24h
  • Detects strains with heterogeneous resistance with better sensitivity than oxacillin
  • Sensitivity and specificity values close to 100%
CHROMagar Orientation

Plate reading

  • E.coli – dark pink to reddish
  • Enterococcus – turquoise blue
  • Klebsiella, Enterobacter, Citrobacter – metallic blue
  • Proteus – brown halo
  • Pseudomonas – cream, translucent
  • S.aureus – golden, opaque, small
  • S.saprophyticus – pink, opaque, small
  • Isolation of a variety of microorganisms from urine specimens
  • Reliable detection, enumeration and presumptive identification of urinary tract pathogens
  • Full differentiation of pathogens in most cases
  • Easier recognition of mixed growth
  • Provides higher detection rates, especially of minor populations
  • Specificity of 99,3%* for E.coli, which is found in 40-70% of urinary tract infections
CHROMagar Salmonella Plus    

Plate reading

  • Salmonella (including S.typhi, S.paratyphi A and lactose positive Salmonella) – mauve
  • E.coli – colourless
  • Coliforms, etc – blue
  • Proteus, etc – colourless or inhibited
  • Detects lactose positive Salmonella
  • Easy to read with the naked eye: E.coli are colourless and cannot hide suspect colonies.
  • High sensitivity and specificity compared to other chromogenic media
  • Decreases workload – fewer false positives
CHROMagar STEC

Plate reading

  • Most common Shiga-Toxin E.coli serotypes – mauve
  • Other Enterobacteriacae – colourless, blue or inhibited
  • Gram positive bacteria – inhibited
  • Detects all shiga toxin producing E coli serotypes not only E O157
  • Highly selective – excellent for screening
  • PCR can be performed directly from colonies
CHROMagar StrepB

Plate reading

  • Streptococcus B – Mauve
  • Other Microorganisms – blue, colourless or inhibited
  • Detection of Streptococcus agalactiae, AKA Group B Streptococci (GBS)
  • Detection of GBS, including non-haemolytic strains, with sensitivity close to 100 %
  • Aerobic incubation compared to anaerobic incubation for Granada medium
  • Results in 18-24 hours compared to 24-48 hours for Granada medium