Detection of the site of contamination by Staphylococcus aureus within the defeathering machinery of a poultry processing plant

Microbiological baseline study of broiler chickens at Swedish slaughterhouses

This 1-year study was conducted to estimate the prevalence and concentrations of pathogenic and indicator bacteria on Swedish broiler chickens. A total of 636 chilled carcasses were collected from 10 slaughterhouses and sent to the National Food Administration for analyses of carcass rinses. No carcasses were positive for Salmonella. Campylobacter, predominantly Campylobacter jejuni, were detected on 15% (by enrichment) or 14% (by direct plating) of the carcasses. With one exception, all samples from late December through April were Campylobacter negative. The 10th and 90th percentiles of Campylobacter numbers per carcasses were 3.0 and 5.0 log CFU, respectively, and the maximum was 7.1 log CFU. Coagulase-positive staphylococci were detected on 68% of the carcasses, with a maximum of 3.5 log CFU/cm2. The 10th and 90th percentiles were 3.4 and 4.4 log CFU/cm2 for total aerobic microorganisms, 1.8 and 3.3 log CFU/cm2 for Enterobacteriaceae, and 2.0 and 3.6 log CFU/cm2 for Escherichia coli. No correlation was found between numbers of any indicator bacteria and numbers of pathogenic bacteria. Subsets of the samples were analyzed for Listeria monocytogenes, Clostridium perfringens, pathogenic Yersinia enterocolitica, and Enterococcus, resulting in prevalence estimates of 29, 18, 9 (as determined by a PCR assay), and 97%, respectively. L. monocytogenes was most common at slaughterhouses with a low prevalence of coagulase-positive staphylococci, and vice versa. These results will improve the ability of researchers to assess the importance of chicken as a source of foodborne pathogens and can serve as a basis for risk management actions.

Comparison of poultry processing equipment surfaces for susceptibility to bacterial attachment and biofilm formation

During processing of poultry meat products, broiler carcasses come in contact with many solid surfaces. Bacteria from the carcasses can attach to wet equipment surfaces, form biofilms, and provide a source of cross-contamination for subsequent carcasses. In this study an array of common equipment surface materials was compared for susceptibility to bacterial attachment and biofilms. To model mixed microbial populations relevant to poultry processing, samples were taken directly from the processing line and exposed to the surface materials. Whole carcasses were rinsed with phosphate-buffered saline (100 mL), and the rinse was diluted in nutrient broth. Absorbance values (412 nm) of the suspensions at varying dilutions containing test surfaces were compared hourly with controls without test surfaces. The kinetics of bacterial attachment and biofilm formation on test surfaces were determined under the influence of pH, time, and bacterial cell density, and the elemental composition of the surface materials was determined by energy-dispersive X-ray analysis. Our results showed that surfaces vary in affinity for bacterial attachment and biofilm formation. Analysis by spectrophotometry and scanning electron microscopy confirmed that attachment to stainless steel, polyethylene, and belting was not significantly different from controls. Attachment to picker-finger rubber was significantly less than attachment to stainless steel and the other surfaces. In fact, picker-finger rubber inhibits bacterial contamination. An increased understanding of bacterial attachment and biofilm formation will assist in the development of interventions to counteract these processes and, thereby, enhance plant sanitation and pathogen control.

Microbiological survey of a South African poultry processing plant

Bacterial populations associated with poultry processing were determined on neck skin samples, equipment surfaces and environmental samples by replicate surveys. Aerobic plate counts, Enterobacteriaceae counts, Enterobacteriaceae counts and Pseudomonas counts were performed by standard procedures and the prevalence of Listeria, presumptive Salmonella and Staphylococcus aureus determined. Statistically significant (P < 0.05) increases in counts of all types of bacteria were obtained on product samples as a result of processing. Although bacterial counts on neck skin samples decreased by 0.3 to 0.4 log CFU g-1 after spray washing of carcasses, subsequent spinchilling and packaging of whole carcasses resulted in 0.7 to 1.2 log CFU g-1 increases. Bacterial numbers on equipment surfaces, however, decreased significantly from the "dirty" to the "clean" areas of the abattoir. Transport cages, "rubber fingers", defeathering curtains, shackles and conveyor belts repeatedly showed aerobic plate counts in excess of 5.0 log CFU 25 cm-2. Aerobic plate counts of scald tank and spinchiller water were 2 log CFU ml-1 higher than those of potable water samples. Bacterial numbers of the air in the "dirty" area were higher than those of the "clean" area. Listeria, presumptive Salmonella and Staphylococcus aureus were isolated from 27.6, 51.7 and 24.1% of all product samples, respectively, and Listeria and Staphylococcus aureus were also isolated from selected equipment surfaces.