Catarame TMG, O'Hanlon KA, Duffy G, Sheridan JJ, Blair IS, McDowell DA. Optimization of enrichment and plating procedures for the recovery of Escherichia coli O111 and O26 from minced beef.
J Appl Microbiol 2003;
95:949-57. [PMID:
14633022 DOI:
10.1046/j.1365-2672.2003.02065.x]
[Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIM
Optimization of enrichment media and selective agars for the detection of Escherichia coli O26 and O111 from minced beef.
METHODS AND RESULTS
This study compared a number of different enrichment conditions and plating media for the recovery of E. coli O26 and E. coli O111 from minced beef. The optimum enrichment conditions for E. coli O26 was observed in beef samples enriched at 41.5 degrees C in tryptone soya broth supplemented with cefixime (50 microg l(-1)), vancomycin (40 mg l(-1)) and potassium tellurite (2.5 mg l(-1)). Similar enrichment conditions were optimal for E. coli O111 with the omission of potassium tellurite. The optimum agar for recovery of E. coli O26 and giving the most effective suppression of contaminants was MacConkey agar [lactose replaced by rhamnose (20 g l(-1))] and supplemented with cefixime (50 microg ml(-1)) and potassium tellurite (2.5 mg l(-1)). Optimum recovery of E. coli O111 was on chromocult agar, supplemented with cefixime (50 microg ml(-1)), cefsulodin (5 mg l(-1)) and vancomycin (8 mg l(-1)). Minced beef samples were inoculated with a number of strains of E. coli O26 (n=9) and O111 (n=8), and the developed enrichment and plating methods, used in combination with immunomagnetic separation, were shown to be an effective method for the recovery of all strains.
CONCLUSIONS
Routine cultural methods for the recovery of E. coli O26 and O111 from minced beef are described.
SIGNIFICANCE AND IMPACT OF THE STUDY
The optimized enrichment and plating procedure described for the recovery of E. coli O111 and O26 from meat can be used to extend research on these emerging pathogens in beef.
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