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 41AE5°C in tryptone soya broth supplemented with cefixime (50 lg l )1 ), vancomycin (40 mg l )1 ) and potassium tellurite (2AE5 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 lg ml )1 ) and potassium tellurite (2AE5 mg l )1 ). Optimum recovery of E. coli O111 was on chromocult agar, supplemented with cefixime (50 lg 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 ¼ 9) and O111 (n ¼ 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.

The enrichment, isolation and detection procedures used in this study provide a rapid routine-based molecular method for the detection and differentiation of E. coli O26, O111 and O157 from minced meat.

A real‐time polymerase chain reaction (PCR) method developed in this study was compared with a conventional International Organization for Standardization culture method for the detection of Salmonella in Irish beef, chicken, pork and turkey. This also provided a snapshot of the incidence of Salmonella in such products. After selective enrichment, all meat samples (n = 100) were: (1) subjected to DNA extraction and real‐time PCR analysis using primers against Salmonella spp. specific gene (16S rRNA) or the invA virulence gene; and (2) plated on differential media and identified as Salmonella using immunological and sub‐typing methods. Retail samples (5/100) were shown to contain Salmonella using the 16S rRNA gene‐based real‐time PCR assay and the standard culture method. However, only two (of five) samples were shown to contain Salmonella using the invA gene‐based real‐time PCR assay. For the sample set examined, the developed 16S rRNA gene‐based real‐time PCR assay demonstrated comparable specificity and sensitivity to the currently used standard culture method but was considerably more rapid.

Aims: The objective of this study was to investigate the potential value of individual and combined applications of some GRAS (generally regarded as safe) additives with freezing and pulsed electric field (PEF) application, in reducing the risks associated with the presence of E. coli O157:H7 in beef burgers. Methods and Results: Beef burgers, trimmings and filter paper were inoculated with E. coli O157:H7 and subjected to a range of chemical and physical treatments. Sequential application of 2% (v/v) lactic acid and freezing (at ) 20°C for 2 h) resulted in a decrease of approximately 6 log 10 cfu cm )1 in E. coli O157:H7, but only on filter paper. All other treatments were ineffective. Conclusions: Currently available methods for controlling E. coli O157:H7 in beef burgers during production are ineffective. Significance and Impact of the Study: Further research is needed to develop controls for E. coli O157:H7 during beef burger production.

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