Identification of Escherichia coli O157:H7 Meat Processing Indicators for Fresh Meat through Comparison of the Effects of Selected Antimicrobial Interventions

Abstract

Fresh meat products can become contaminated with the pathogen Escherichia coli O157:H7 during the slaughter process; therefore, an E. coli O157:H7 indicator to verify the effectiveness of process controls in slaughter establishments would be extremely useful. The hides of 20 beef cattle were sampled, and 113 bacterial isolates were obtained. Thirteen of these isolates representing four genera, Escherichia, Enterobacter, Providencia, and Serratia, were selected based on growth and biochemical characteristics similar to those of five clinical strains of E. coli O157:H7. The temperature sensitivity was determined for the individual isolates and the five E. coli O157:H7 strains at 55 and 65 degrees C. D65-values for all 13 isolates were not significantly different from D65-values of the E. coli O157:H7 strains. E. coli isolates were the only isolates whose D55-values were not significantly different from those of the E. coli O157:H7 strains. E. coli isolates P3 and P68 were more resistant to the effects of 55 degrees C than were the other E. coli isolates but were not significantly different from E. coli O157:H7 WS 3331 (P > 0.05). The remaining E. coli isolates (P1, P8, and P14) were not significantly different from E. coli O157:H7 strains ATCC 35150, ATCC 43894, ATCC 43895, and WS 3062 (P > 0.05). Prerigor lean and adipose beef carcass tissue was artificially contaminated with stationary-phase cultures of the five E. coli beef cattle isolates or a cocktail of five E. coli O157:H7 strains in a fecal inoculum. Each tissue sample was processed with the following microbial interventions: 90 degrees C water; 90 degrees C water followed by 55 degrees C 2% lactic acid; 90 degrees C water followed by 20 degrees C 2% lactic acid; 20 degrees C water followed by 20 degrees C 2% lactic acid; 20 degrees C water followed by 20 degrees C 20 ppm chlorine; and 20 degrees C water followed by 20 degrees C 10% trisodium phosphate. The appropriateness of the E. coli isolates as potential E. coli O157:H7 indicators was dependent upon the microbial intervention utilized. For all microbial intervention methods applied irrespective of tissue type, the mean log reductions of at least two E. coli isolates were not significantly different from the mean log reduction of the E. coli O157:H7 cocktail (P > 0.05). Because of the frequent employment of multiple microbial interventions in the cattle industry, no single isolate can realistically represent the effectiveness of all microbial interventions for reduction of E. coil O157:H7. Thus, the use of a combination of E. coli isolates may be required to accurately predict the effectiveness of microbial intervention methods on the reduction of E. coli O157:H7 in beef carcass tissue.

Pulsed electric field inactivation of E. coli O157:H7 and non-pathogenic surrogate E. coli in strawberry juice as influenced by sodium benzoate, potassium sorbate, and citric acid

“…This difference may, again, be attributed to the protective effects of the increasing electrical conductivity induced by the addition of the sodium and potassium salts. The addition of preservatives þ 2.7% citric acid effected greater injury (100%) in E. coli 35218 than occurred in the acid-resistant enterohemorrhagic E. coli (96%), which may be attributed to the acid-resistant nature of E. coli O157:H7 (Cheng et al, 2002;Duffy et al, 1999;Marshall et al, 2005Yu et al, 2001. …”

Antibacterial activity of decontamination treatments for cattle hides and beef carcasses

“…The different chemicals were mainly investigated in only one single study and under laboratory conditions. In the study of Castillo et al (1999b) (Cabedo et al, 1996;Castillo et al, 2003;Cutter, 1999;Gorman et al, 1995b;Marshall et al, 2005), whereas chlorine or a commercial sanitizer (RPM acid sanitizer, WestAgro Inc., Kansas City, MO, USA) mainly yielded reductions between 1.2 and 1.7 orders of magnitude (Gorman et al, 1995b;Marshall et al, 2005).…”

“…Highest reductions of aerobic bacteria and Enterobacteriaceae were thereby obtained by pre-evisceration spraying (Bosilevac, Nou, Barkocy-Gallagher, Arthur, & Koohmaraie, 2006), whereas in the other studies washing was applied at the end of slaughter. In comparison with hot water spraying, cold and warm water yielded reductions of aerobic bacteria, coliforms and E. coli by 0.3-2.9, 0.4-3.0 and 0.3-3.5 orders of magnitude, respectively (Cabedo et al, 1996;Cutter, 1999;Cutter, Dorsa, & Siragusa, 1997;Cutter & Rivera-Betancourt, 2000;Cutter & Siragusa, 1995;Cutter et al, 2000;Dorsa et al, 1996b;Gill & Landers, 2003;Gorman, Morgan, Sofos, & Smith, 1995a;Gorman et al, 1995b;Marshall, Niebuhr, Acuff, Lucia, & Dickson, 2005;Reagan et al, 1996). Under commercial conditions, cold and warm water spraying using wash cabinets reduced aerobic bacteria, coliforms and E. coli on beef carcasses by 0.5-1.0 orders of magnitude (Gill & Landers, 2003;Reagan et al, 1996).…”

“…However, supplementary hot water spraying (95 °C) did not further enhance the efficacy (Castillo et al, 1999a). Besides, in the study of Phebus et al (1997) Occasionally, the antibacterial activity of water spraying in combination with chemicals as ASC, chlorine, H 2 O 2 , ozone, peroxyacetic acid, saponin, TSP or commercially available preparations was investigated on inoculated beef carcass surface parts (Cabedo et al, 1996;Castillo et al, 1999b;Castillo et al, 2003;Cutter, 1999;Gorman et al, 1995b;Marshall et al, 2005;Penney et al, 2007). The different chemicals were mainly investigated in only one single study and under laboratory conditions.…”

Radiofrequency pasteurization of inoculated ground beef homogenate

“…All isolates were obtained from cattle and known to exhibit characteristics relatively similar to E. coli O157:H7 (Niebuhr, Laury, Acuff and Dickson, 2008;Marshall, Niebuhr, Acuff, Lucia and Dickson, 2005).…”