Chromogenic selective medium for detection of carbapenem-resistant Enterobacteriaceae directly from clinical specimens

DESCRIPTION
ChromaticTM CRE Agar Base is a chromogenic selective medium used with supplements for detection of carbapenem-resistant Enterobacteriaceae directly from clinical specimens. Carbapenems (imipenem, meropenem, ertapenem and doripenem) are the last shelter from multi-resistant Gram-negative bacterial
infections. Carbapenemase is an enzyme class which can be produced by Klebsiella pneumoniae and by other organisms including Serratia spp, Enterobacter spp, Escherichia coli and Citrobacter freundii. Early detection of carbapenems resistance is essential in order to limit the spread of these pathogens.

PRINCIPLE
Peptone mix is a source of amino acids, nitrogen, minerals, vitamins, and other factors which increases the growth of bacteria. Chromogenic and selective mix facilitates the identification of bacteria on the basis of the color and colony morphology. Agar is the solidifying agent. Supplementation with ChromaticTM CRE Supplement (ref. 81088) inhibits most of the non-Enterobacteriaceae and the carbapenemsensitive organisms.

TYPICAL FORMULA (g/l)

PREPARATION
Suspend 56.8 g of powder in one liter of deionized or distilled water. Bring to boil and shake until completely dissolved. Sterilize at 121°C for 15 minutes. Cool up to 45-50°C. Aseptically, add the contents of 2 vials (10 ml) of ChromaticTM CRE Supplement (ref. 81088) reconstituted as directed in the instructions for use that accompany the product. Pour in Petri dishes.

TECHNIQUE
Inoculate the medium directly from faecal screening swabs, or using a sterile loop previously dipped in liquid suspension of the sample, by streaking the specimen onto the agar surface. Incubate aerobically at 37°C for 18-24h.

INTERPRETATION OF RESULTS
K. pneumoniae produces blue-violet colonies.
E. coli produces red colonies.
Enterobacter spp, produces blue-green colonies.
Citrobacter spp, produces blue colonies with red halo.
Non-Enterobacteriaceae (if not inhibited) produce white to naturally pigmented colonies.

STORAGE CONDITIONS
The powder is very hygroscopic, store the powder at 10-30°C, in a dry environment, in its original container tightly closed and use it before the expiry date on the label or until sings of deterioration or contamination are evident. Store prepared plates at 2-8°C away from light.

WARNING AND PRECAUTIONS
The product does not contain hazardous substances in concentrations exceeding the limits set by current legislation and therefore is not classified as dangerous. it is nevertheless recommended to consult the safety data sheet for its correct use. The product is designed for In vitro diagnostic use and must be used only by properly trained operators.

DISPOSAL OF WASTE
Disposal of waste must be carried out according to the national and local regulations in force.

STORAGE
10-30°C

PACKAGING

APPEARANCE OF THE MEDIUM
Powder medium
Appearance: fine, dry, homogeneous, free of extraneous material
Colour: beige
Ready-to-use medium
Appearance: slightly opalescent
Colour: amber

SHELFLIFE
2 years

QUALITY CONTROL

1. Control of general characteristics, label and print
2. Microbiological control
   Inoculum for productivity: 50-100 CFU
   Inoculum for selectivity: 10⁴-10⁶ CFU
   Incubation Conditions: 18-24 h at 35 ± 2°C, in aerobiosis

REFERENCES

1. EUCAST guidelines for detection of resistance mechanisms and specific resistances of clinical and/or epidemiological importance. Version 1.0, 2013.
2. Podschun R, Ullman U (1998). Klebsiella spp as Nosocomial Pathogens: Epidiemology, Taxonomy, Typing Methods, and Pathogenicity Factors. Clinical Microbiology Reviews 11 (4): 589–603.
3. Kochar S, Sheard T, Sharma R, Hui A, Tolentino E, Allen G, Landman D, Bratu S, Augenbraun M, Quale J. Success of an infection control program to reduce the spread of carbapenem-resistant Klebsiella pneumoniae. Infect. Control Hosp. Epidemiol. 2009 30(5):447-52.

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