|Rivera Betancourt, Mildred|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2000
Publication Date: N/A
Interpretive Summary: Unlike other strains of Salmonella spp., Salmonella Typhimurium definitive type 104 (S. Typhimurium DT 104) exhibits resistance to many antibiotics. Because of its resistance to many antibiotics, treating S. Typhimurium DT 104 infections in animals and humans is difficult. Since the 1980s the pathogen has been associated with foodborne outbreaks of unpasteurized dairy products, chicken, and pork sausages. Most outbreaks associated with pathogenic Escherichia coli have been caused by O157:H7 strains. However, numerous strains of non-O157 E. coli have emerged as important human pathogens. Non-O157 E. coli have been implicated in foodborne outbreaks associated with sausages, ground beef, and unpasteurized milk, as well as with water, person-to-person transfer, or contact with cattle or cattle manure. This study was conducted to determine if slaughter interventions (water, hot water, organic acids, and alkaline treatments) that are used by the meat industry to reduce Salmonella spp. and E. coli O157:H7 are effective against S. Typhimurium DT104, E. coli O111:H8, and E. coli O26:H11. Spray washing (125 psi, 15 sec, 121 deg F) with the interventions was performed with a carcass washer especially designed for research purposes. Results demonstrated that interventions used by the meat industry to reduce Salmonella spp. and E. coli O157:H7 appear to be effective against DT104 and other pathogenic E. coli. Another finding from this study indicated that researchers should not rely upon visual confirmation of the organism, but should utilize diagnostic tools such as antibody-based assays to identify pathogens in the laboratory.
Technical Abstract: A study was conducted to determine if slaughter interventions currently used by the meat industry are effective against Salmonella Typhimurium definitive type 104 (DT 104) and two non-O157:H7 shiga-toxin producing Escherichia coli (STEC). Three separate experiments were conducted by inoculating pre-rigor beef surfaces with a fecal slurry containing S. Typhimurium and S. Typhimurium DT 104 (Experiment 1), E. coli O157:H7 and E. coli O111:H8 (Exp. 2), or E. coli O157:H7 and E. coli O26:H11 and spray washing with water, hot water, 2% acetic acid, 2% lactic acid, or 10% trisodium phosphate (15 s, 125 psi ? 5 psi, 35 deg C +/- 2 deg C). Remaining bacterial populations were determined immediately after treatments (day 0), after 2 days of storage at 4 deg C, and after 7, 21, and 35 days of vacuum packaged storage at 4 deg C. In addition to enumeration, confirmation of serotypes was performed for all treatments at all days. Of the interventions investigated, spray treatments with trisodium phosphate were the most effective, resulting in pathogen reductions of >3 log10 CFU/cm**2, followed by 2% lactic acid and 2% acetic acid (>2 log10 CFU/cm**2). Results also indicated that interventions used to reduce S. Typhimurium on beef surfaces were found to be equally effective against S. Typhimurium DT104. Similarly, E. coli O111:H8 and E. coli O26:H11 associated with beef surfaces were reduced by the interventions to the same extent as E. coli O157:H7. This study also indicated that isolation and detection of STEC should involve direct analysis of colonies on agar plates with antibodies. Based on these findings, interventions to reduce Salmonella spp. and E. coli O157:H7 appear to be effective against DT104 and other STEC.