Removal of Escherichia coli O157:H7 from Surface Tissues of Beef Carcasses Inoculated with Wet and Dry Manure

Abstract

Beef tissues were contaminated with wet and dry manure. The manure was previously inoculated with Escherichia coli O157:H7 GFP, genetically modified with a plasmid encoding a protein that fluoresces green when exposed to long-wave ultraviolet light. After incubation at 37 degrees C for 5 days, the wet manure was spread on the surface of beef tissues at an average E. coli O157:H7 GFP level of 6.62 log CFU/cm2. Dry manure was obtained by subjecting wet manure to natural drying (simulating dry manure adhering to the hides of cattle) and was also applied to the surfaces of beef tissues. The degree of removal of E. coli O157:H7 GFP by washing was compared to the removal of cells of the same strain that had been inoculated as a suspension. The E. coli O157:H7 mixed into feces of cattle adhered more strongly to meat surfaces than that applied as a suspension, complicating the removal by conventional washing procedures. The fate of the bacterium mixed into wet or dry manure was evaluated. An initial decrease of the inoculated population was observed; this was probably an effect of the changed environment represented by the manure. After adaptation, the inoculated bacteria grew in the wet manure; a maximum population was reached in 5 days at 37 degrees C; levels declined with drying. The use of the GFP marker was of great value, since it allowed enumeration of E. coli O157:H7 in the presence of the natural flora of manure.

Escherichia coli O157 in Ground Beef from Local Retail Markets in Pachuca, Mexico

“…This higher frequency could be due to the combination or interaction of different factors; partic ularly animal-handling practices immediately before, dur ing, and after slaughter, (e.g., inadequate slaughterhouse hygiene) (11,31). Another possible reason for discrepancies between the present study results and those of other studies done in Mexico is the use of different analytical methods (12,24).…”

Growth and survival of non-O157:H7 Shiga-toxin-producing Escherichia coli in cow manure

“…The eight STEC strains were electroporated in the presence of a plasmid vector pGFPuv (Ozyme, Montigny‐Le‐Bretonneux, France) carrying ampicillin resistance gene and the green fluorescent protein (GFP) open reading frame, according to the protocol described by Delazari et al. (1998) with minor changes.…”

Escherichia coliO157:H7: Animal Reservoir and Sources of Human Infection

“…EHEC survive well and multiply in raw manure and bedding, but do not survive proper composting or waste treatment. EC O157:H7 inoculated in moist bovine manure initially declined, but subsequently grew to a maximum in 5 days at 378C (Delazari et al, 1998); EHEC O157:H7 human strain 932 survived best at 228 and 378C for up to 70 days (Wang et al, 1996), and EC O157 survived up to 18 weeks at 158C, and 14 weeks at 258C; the best survival occurred with high concentrations of inocula (Fukushima et al, 1999). In a 3-month cattle study, EC O157:H7 were frequently cultured from cedar chip bedding that supported growth of the bacteria when moistened with bovine urine, and samples from the ambient environment were positive when the animals did not carry the bacteria (Davis et al, 2005).…”