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s.b. o'brien, g. duffy, d. daly, j.j. sheridan, i.s. blair and d.a. mcdowell. 2005. To assess the detection and recovery rates achieved with commonly used cultural methods for the enumeration and recovery of Escherichia coli O157:H7 from minced beef and bovine hide. Minced beef and bovine hide were inoculated with varying concentrations (log10 1·58–2·58 CFU g−1 and log10 2·42–4·49 CFU 100 cm2 respectively) of E. coli O157:H7 and recovered using a direct plate method or an enrichment/immunomagnetic separation (IMS) method and then plated onto SMAC or SMAC-CT in both cases. The direct plate method detected the pathogen consistently from minced beef samples with an average recovery of 69·2–91·2%. From faecal material on the bovine hide the recovery of the pathogen ranged from 1·80 to 64·5% with fresh faeces depending on the inocula while from dried faeces on hide the results ranged from no recovery at all to 25·1%. Enrichment/IMS recovered E. coli O157:H7 at all inocula levels tested in minced beef while the pathogen was only detected consistently at an average inocula level of log10 2·73 CFU 100 cm2 from fresh faeces and log10 4·49 CFU 100 cm2 from dried faeces on bovine hide. The direct count enumeration method for E. coli O157:H7 underestimated the numbers of pathogens present. The enrichment/IMS procedure consistently detected the pathogen from minced beef but did not always detect E. coli O157:H7 from faeces on bovine hide. Overall this study highlights that any microbial data, used in either predictive microbiology or risk assessment, must take account of the sensitivity and associated performance of the methods employed, in order to make an accurate reflection of the true microbiology of the examined sample. [ABSTRACT FROM AUTHOR]

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 degrees C for 2 h) resulted in a decrease of approximately 6 log10 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.

Aims: The survival characteristics of Escherichia Coli O157:H7 were investigated in bovine slurry from cattle fed two different diets: (i) silage and (ii) silage + concentrates., Methods and Results: Slurry samples collected from freshly-agitated tanks were inoculated at a level of log10 6.0 cfu g(-1) and stored in the laboratory at 10 degrees C. Over a 12 week storage period, a 3.5 and 5.5 log reduction was observed in slurry from cattle fed a silage and silage plus concentrate diet, respectively., Conclusions: The persistence of E. coli O157:H7 in slurry over a 3 month storage period indicates its potential for transmitting the organism back into the environment., Significance and Impact of the Study: The discussion concludes however, that despite pathogen survival in slurry, it may not represent a major source of transmission in the farm environment.

A new method of separating bacteria from beef mince has been developed, in which an alkaline protease, Alcalase 0.6 L, was used to degrade the meat proteins, leaving micro-organisms in suspension. The organisms were then counted, using a membrane filtration-epifluorescent microscopy technique. A correlation coefficient of 0.97 was obtained between this method and the standard plate count, indicating its suitability for use in quality control.