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Survey of Seattle Chickens finds Bacterial Contamination

chickenmarler-featured.jpgWe 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.)

See full story at Food Safety News and Full Survey in PDF and as Spreadsheet.

  • Carl Custer

    STEC have been reported to occur on poultry and pork for several years. One finding (don’t have it handy) claimes the O157:H7 in pork didn’t have the attachment tools and thus wasn’t a problem. But see the last ref below. tick, tick, tick
    Griffin PM and Tauxe RV 1991. The epidemiology of infections caused by Escherichia coli O157:H7, other enterohemorrhagic E. coli, and associated hemolytic uremic syndrome. Epidemiologic Reviews. 13:60-98. Non-O157 serotypes have been found in ground pork, chicken, cheese, and ground beef [
    Pilipcinec E, Tkáciková L, Naas HT, Cabadaj R, Mikula I. Isolation of verotoxigenic Escherichia coli O157 from poultry. Folia Microbiol (Praha). 1999;44(4):455-6.
    Results obtained by examination of cloacal swabs from poultry for the presence of verotoxigenic strains of E. coli O157:H7 are presented. Twenty samples (9.2%) of 216 samples examined were positive for E. coli O157. Out of 20 E. coli O157, 19 strains were positive for the production of both verotoxins (VT1 and VT2). However, none of them was positive for the presence of H7 antigen.
    Conedera G, Mattiazzi E, Russo F, Chiesa E, Scorzato I, Grandesso S, Bessegato A, Fioravanti A, Caprioli A. A family outbreak of Escherichia coli O157 haemorrhagic colitis caused by pork meat salami. Epidemiol Infect. 2007 Feb;135(2):311-4.

  • doc raymond

    Can you further break this down comparing whole carcasses to chicken parts? I think that would be enlightening to the consumer.

  • http://www.marlerclark.com/wmarler.htm Bill Marler

    if you download the study it lists all the “parts”

  • Sam

    That’s why we don’t eat raw meat. Maybe your money would be better spent elsewhere.
    Sam

  • http://www.marlerclark.com/wmarler.htm Bill Marler

    Sam, I realize that you are trying to be cute, but I think the money was well spent. I think giving consumers more knowledge about the extent of fecal contamination on the chickens that are brought into restaurants and homes is a good thing. It may also put more pressure on chicken producers to do a better job and prompt regulators to do their jobs.

  • Donna Byrne

    If I ate chicken, I would NEVER put the raw chicken on a cutting board (like it is in the picture you posted) after reading this.
    I do put eggs on the counter, though, and wonder whether I should be more careful with them.
    Thanks for doing this, Bill.

  • http://www.marlerblog.com Bill Marler

    Walid Q. Alali, Siddhartha Thakur, Roy D. Berghaus, Michael P. Martin, Wondwossen A. Gebreyes. Foodborne Pathogens and Disease. November 2010, 7(11): 1363-1371. doi:10.1089/fpd.2010.0566.
    In the study, 300 samples from an organic farm and 400 samples from a conventional farm were tested for the presence of Salmonella. The samples were taken from the poultry’s feed samples, water supply, and floor droppings. The results showed that the organic farm had Salmonella in 4.3% of the samples compared to 28.8% at the conventional farm. Another troubling result that was discovered, was 36% of the positive conventional samples were resistant to streptomycin, while only 25% of the organic samples were. Also, none of the positive organic samples had multidrug resistance to ampicillin, streptomycin, amoxicillin/clavulanic acid, cephalothin, ceftiofur, and cefoxitin, while 39.7% of the conventional samples did. The study’s results were initially released in November 2010 and was conducted with the assistance of Ohio State University and North Carolina State University.

  • http://klopt.wordpress.com Mike W

    Bill,
    I downloaded the survey but could not figure out what the findings are. It appears that they obtain samples, coded the samples, then gave results using the codes. Is there any breakdown that would help a consumer follow your advice to seek out the best producers? Who are they?

  • http://www.marlerclark.com/wmarler.htm Bill Marler

    Mike, I added a link to both as a PDF and Spreadsheet. Hope that helps.

  • Bill Anderson

    I hate to sound like a broken record here, but this confirms what I have been saying — sunshine and green grass do matter for overall food safety when raising any kind of food animal. It is not something which can be reduced to a single variable in a scientific experiment. It is a wholistic system.
    Sunshine and green grass are not a 100% guarentee of food safety, but they are a good starting point.

  • http://www.marlerclark.com/wmarler.htm Bill Marler

    I have not yet tested sunshine and green grass chickens yet.

  • Bill Anderson

    One would hope that “sunshine and green grass” is an implication of “certified organic.”
    Obviously, there are some huge corporate CAFOs that have figured out how to twist the organic rules, but more often than not, organic = sunshine and green grass.

  • Minkpuppy

    IMO, the infection rates on the organic chickens are still disturbingly high even though they are less than conventionally raised chickens. 54% is nothing to cheer about.
    I’d be interested in finding out if any of the conventionally raised chickens came from flocks that are vaccinated for Salmonella. I know of one company that was trying that in an attempt to bring down their Salmonella counts and they did have some encouraging results. I don’t think anyone has developed a Campy vaccine yet.

  • Cathy C

    It is interesting that the recent baseline survey of young chickens in US shows only 46.7% of samples are positive for Campylobacter and 7.5% are positive for Salmonella. Your sample size is somewhat more limited, but shows there may be increased positives at retail. Since Campylobacter is not likely to be able to grow under the conditions it is exposed to after slaughter, could it be that you are using more sensitive methods than the USDA? Could you tell us what methods were used for the survey?
    Cathy