We decided to fund yet another bacterial test on retail meat – this time chicken. All the chicken in the 100 chicken IEH Labs survey, which included whole fryers and packages of chicken parts, was collected and tested from March 1 to April 4 from Seattle area grocery stores. The chicken was purchased from Fred Meyer, Safeway, QFC, Whole Foods, Costco, Sam’s Club, Albertsons, Thriftway, PCC Natural Markets and Ken’s Market stores.
IEH Labs found S. aurea, or staph, in 42 percent of the samples overall and Campylobacter in 65 percent. The supermarket chicken was contaminated with other pathogens as well: 19 percent of the samples tested positive for Salmonella, one tested positive for Listeria, and 10 percent showed the presence of the methicillin-resistant S. aureus (MRSA). In an unusual finding, one of the chicken samples tested positive for E. coli 026, Shiga-toxin producing E. coli (STEC) bacteria more likely to be a contaminant of beef than poultry. Organic Chicken proved to be slightly less contaminated than nonorganic with 7 of the 13 (54%) testing positive for harmful bacteria.
Some comparisons to other studies:
Campylobacter - Our study: 65%. Miller WG, Mandrell RE. 2005. Prevalence of Campylobacter in the food and water supply: incidence, outbreaks, isolation and detection, p. 101-163. In J. Ketley and ME Konkel (ed), Campylobacter: Molecular and Cellular Biology. Horizon Bioscience, Norfolk, United Kingdom. 33-53% average; (3-98% range)
Staphylococcus aureus (“Staph” or S. aureus) and MRSA (Methicillan resistant Staph Aureus) - Our finding of 42% contamination with Staph is similar to recent findings (41% in chicken) by Price et. al published in the journal Clinical Infectious Diseases. Price and colleagues found that (26% of the chicken samples with Staph) were resistant to at least 3 classes of antibiotics. In our study, 10 (24%) of the samples with S. aureus were Methicillan resistant. The importance of findings of S. aureus and MRSA in raw poultry needs to be evaluated. Extracellular toxin production by large cell numbers of S. aureus causes foodborne illness; ingestion of the bacteria themselves does not. MRSA typically causes nosocomial infection, not foodborne illness. Since there is no recognized increase in staphylococcal enterotoxin production by MRSA, while this pathogen is of great clinical significance its antibiotic resistance has no influence on staphylococcal food poisoning. While resistance may enable the pathogen to persist in the food processing environment, most cases of foodbonre illness related to S. aureus are related to post-processing contamination by human contact, making the industrial relevance of MRSA among S. aureus strains questionable.
Salmonella – Our study 19%. In 1996 the USDA FSIS published the “Final Rule on Pathogen Reduction and Hazard Analysis and Critical Control Point (HACCP) Systems in an effort to reduce the prevalence of salmonella in meat. This rule requires that meat and poultry industries have a HACCP plan. Prior to passage of the Final Rule, the contamination rate in broiler chickens was 24%. After the Final Rule, the rate dropped to 11%. The rate has been increasing though and in 2005 the rate was 16%. (REF: D’oust JY, Maurer J. 2007. Salmonella species. p.187-236. In MP Doyle and LR Beuchat (ed), Food Microbiology Fundamentals and Frontiers, 3rd ed., ASM Press, Washington, DC.)