Antibiotic-Resistant Bacteria Contaminating Retail Poultry Products
On December 9, 2002, the Sierra Club together with the Minneapolis-based Institute for Agriculture and Trade Policy (IATP) released a report entitled Poultry on Antibiotics: Hazards to Human Health (pdf), which examined the prevalence of antibiotic-resistant bacteria contaminating retail chicken and turkey products. The Sierra Club and IATP conducted the study as part of their participation in Keep Antibiotics Working, a coalition of medical, scientific, environmental, and animal welfare groups dedicated to preserving the effectiveness of antibiotics for the treatment of human infections. The North Star Chapter was selected by the national Sierra Club to participate in this pilot project. The Chapter effort was directed by staffer Kendra Kimbirauskas and a committee chaired by volunteer Jon Rosenblatt.
In recent years, increasing resistance of bacteria to commonly used antibiotics has become a serious problem. The spread of antibiotic resistance is directly related to the widespread and often indiscriminate use of the agents; i.e. the more antibiotics are used, the more resistance will develop. The healthcare community has responded, belatedly, with a number of strategies to promote only the most prudent use of antibiotics by physicians and patients. The fact is, however, that over 70% of all the antibiotics used in the United States are not used to treat human infections at all, but are used in industrialized animal agriculture. The great bulk of this use is for sub-therapeutic ("low dose, not to treat infections") routine administration in animal feed for growth promotion and other non-specific effects or for metaphylaxis (wholesale preventative dosing of entire herds or flocks when sickness occurs in one or a few animals). This excessive use is necessary for survival of food animals raised in the crowded and unsanitary conditions of confined animal feedlot operations (CAFOs). Under these conditions, animals become colonized with antibiotic resistant bacteria which can cause infections in humans (Salmonella, Campylobacter, E. coli) or may simply become part of the normal human GI tract flora (Enterococcus, E. coli). In the first instance, these infections may be difficult to treat and in both instances the bacteria (or even fragments of killed bacteria) may transfer the genetic elements of resistance to other bacteria resident in the GI tract. These elements can then be readily transferred to other bacteria in an ever-widening circle of resistance. We do not know the extent to which antibiotic resistance in food animal bacteria contributes to the problem of antibiotic resistance in human infections, but it has been amply demonstrated that such a transfer of resistance does, in fact, take place. Sweden and Denmark have reacted in a precautionary mode by banning the use of antibiotics as growth promoters (without adversely affecting animal health) and the European Union intends to end all such use by 2006. However, the United States still allows such use for 19 different antibiotics, many of which are the same or similar to agents used to treat human infections.
Our study was undertaken to assess the current status of colonization of retail poultry products sold in Minneapolis and Des Moines with antibiotic resistant bacteria. Previous similar studies had shown that Campylobacter was isolated from 88% of retail chicken products and 23% were resistant to ciprofloxacin (Minnesota, 1997), that Salmonella were isolated from 20% of ground meats and 84% were resistant to at least one antibiotic (Washington D.C., 1998), and that Enterococcus was isolated from 86% of retail chickens and that as many as 93% were resistant to quinupristin-dalfopristin (Synercid), (Minnesota, Georgia, Maryland and Oregon, 1998-99). In the current study we purchased 200 fresh whole chickens and 200 packages of fresh ground turkey from large supermarket chains (Rainbow Foods and Cub Foods) in Des Moines (Country Pride chicken and Honeysuckle White turkey) and Minneapolis (GoldN Plump chicken and Jennie-O turkey). We contracted with a certified food-testing laboratory to test the products for the presence of three bacterial strains — Salmonella, Campylobacter and Enterococcus — and for resistance to a number of antibiotics.
Salmonella or Campylobacter contaminated a large proportion of the whole chickens and ground turkey we purchased. There was widespread resistance of bacteria in these poultry samples to one or multiple antibiotics. Ninety-five percent of the 100 whole chickens we tested were positive for Campylobacter, the top cause of bacterial foodborne illness, or food poisoning, in the U.S.; 62% of these were resistant to 1 or more antibiotics. More than 6% of Campylobacter were resistant to ciprofloxacin, the antibiotic of choice for presumptively treating severe bacterial gastroenteritis. Nearly 18 percent of whole chickens purchased were contaminated with Salmonella and 6 percent were resistant to 4 or more antibiotics. Both Salmonella and Campylobacter contaminated 22% of the chickens that we tested for both. Ground turkey was more contaminated with Salmonella than was whole chicken, with an overall rate of 45%;. 62% of these were resistant to 1 or more antibiotics and a third were resistant to 4 or more antibiotics. Enterococcus was found on 100% of tested chicken and turkey products and more than 90 percent were resistant to Synercid. Strains of resistant Enterococcus are a growing cause of serious infections in hospitals, and Synercid is one of a few antibiotics still effective against them.
The human health implications of this report are clear. Poultry and other retail meat products are frequently contaminated with bacteria and these bacteria are frequently resistant to multiple antibiotics-the same antibiotics which are used to treat infections in humans. These bacteria can cause infections when the meat products are ingested by humans and these infections may be difficult to treat because of antibiotic resistance. Moreover, the genetic elements which control antibiotic resistance may be transferred from these bacteria to other bacteria in the human GI tract. Although we lack information on the extent to which this resistance from animal bacteria contributes to the whole problem in humans, we would be wise to follow the Precautionary Principle; that is, in the face of a potentially major health problem which would affect a large segment of the population, we should be conservative and limit the use of antibiotics in animals to only the most prudent treatment situations. We should eliminate the routine use of antibiotics in food animals.
Many medical and scientific organizations have endorsed these principles, the FDA is considering rule changes, and bills have been introduced in Congress. However, these are slow processes with uncertain outcomes. Consumers themselves can effect change by requesting meat products from animals raised without the routine use of antibiotics. Alternative sources are available in the form or independent sustainable farmers who do not use routine antibiotics and some markets and restaurant chains have already made strides in the right direction. Ultimately, it will be consumers concerned about the health of their families who will be the driving force to preserve the effectiveness of antibiotics in human health.