Prevalence of methicillin-resistant Staphylococcus aureus in Canadian commercial pork processing plants.

AIMS: This study investigated the prevalence of Methicillin-resistant Staphylococcus aureus (MRSA), their spa-types, and antimicrobial resistance profiles at various steps during commercial pork production from three plants designated as A, B and C. METHODS AND RESULTS: Over a period of 1 year 2640 samples from three commercial pork plants were obtained on a rotating basis. Sample sources were: nasal swabs after bleeding (NSAB), nasal swab after scalding (NSASs, plant C) or skinning (NSASk, plants A, B), carcass swabs after pasteurization (CSAP, plant C) or washing (CSAW, plants A, B) and retail pork (RP). Overall MRSA prevalence at each sampling point in the pork plants after adjusting for clustering was: 61·93, 28·38 7·58 and 1·21% for NSAB, NSASc/Sk, CSAP/CSAW and RP respectively. The majority of MRSA isolates from the three pork plants belonged to livestock-associated MRSA spa-types t034 and t011 (3·8%; ST398). The mainly human spa-type t002 (15%) was also recovered. All MRSA isolates were resistant to ß-lactam and tetracycline antibiotics. Overall resistance to tigecycline was found in about 10% of MRSA isolates while <3% isolates were resistant to daptomycin, gentamicin, quinupristin/dalfopristin and trimethoprim/sulfamethoxazole. CONCLUSION: A higher prevalence of MRSA in the nasal cavity of incoming pigs was observed at all three plants, but a notable reduction in MRSA along the pork processing steps occurred. SIGNIFICANCE AND IMPACT OF THE STUDY: The highest prevalence of MRSA was found in the nasal cavity of incoming pigs in three commercial pig slaughter and pork processing plants. A reduction in MRSA prevalence occurred along the processing chain, and pork products from these plants showed significantly lower MRSA than the initial steps of slaughter and processing, suggesting a reduction in MRSA during the slaughter process with minimal cross-contamination.

Salmonella and Escherichia coli O157:H7 prevalence in cattle and on carcasses in a vertically integrated feedlot and harvest plant in Mexico.

To determine the prevalence of Salmonella and Escherichia coli O157:H7 in cattle feedlots and the impact of subsequent contamination on carcasses in a Mexican Federal Inspection Type Standards harvest facility, 250 animals were tagged and sampled in each step of the slaughter process. Samples were taken from hides and fecal grabs, and composite samples were taken from three anatomical carcass sites (hindshank, foreshank, and inside round) during the slaughter process, at preevisceration (PE), prior to entering the hot box (PHB), and after 24 h of dry chilling (DC). Additionally, 250 fecal samples were collected from the feedlot (FL), holding pens (HP), and intestinal feces (IF), and water samples were taken from the HP area. E. coli O157:H7 and Salmonella detection were carried out with the BAX System, immunomagnetic separation, and conventional methods. Overall Salmonella prevalence was 52.5%. The highest prevalence (92.4%) was found on hides, followed by feces from the HP (91.0%), FL (55.56%), PE (49.0%), IF (46.8%), and PHB (24.8%), for all sampling periods combined. The lowest prevalence of 6.0% was found after DC. The overall prevalence of E. coli O157:H7 was as follows: 11.7% for hides, 5.2% for IF, 2.7% for FL, 2.0% for HP, 0.8% for PE, 0.4% for PHB, and 0.4% for the cooler. High prevalence of Salmonella in IF and on hides present a significant risk factor for contamination by Salmonella at the different processing steps. These results serve as a warning as to the risks of contamination in meats for these pathogens and the importance of following good manufacturing practices during beef production processes.

Evaluation of the storage life of vacuum packaged Australian beef.

To establish the shelf-life of vacuum packaged Australian beef, 15 Strip-loins and 15 Cube-rolls for each Processor (A, B, and C) were evaluated at two week intervals (since wk 10 to 20). Steaks on the trays were placed in retail cabinets at 3 °C. Shelf-life evaluation was based on off-odor (only at week 10), microbial analysis, lipid oxidation, and color assessment by trained panelist and Hunter colorimeter. Panelists detected "slightly off-odor" in both primal cuts for Processors B and C (P<0.05). Processor A primal cut steaks displayed better color scores as well as CIE L*, a*, b*, Chroma and Hue values during storage and display period than steaks from the other processors. Also, primal cuts from Processor A showed lower microbial counts and TBARS values with respect to other processors during the trial. Processor A cuts showed improved shelf life attributes initially which helps to explain its slow shelf-life deterioration.