The study – published in Environmental Health Perspectives - highlights the risk for consumers to contract foodborne illness through contaminated animal products as well as the prevalence of multidrug-resistant organisms that, when they lead to illness, can complicate treatment, researchers at Johns Hopkins Bloomberg School of Public Health claimed.
The study revealed that USDA certified organic products were 56% less likely to be contaminated with multidrug-resistant bacteria compared to conventionally processed meats. The research was based on nationwide testing of meats from 2012 to 2017 as part of the US National Antimicrobial Resistance Monitoring System (NARMS).
The research team analysed NARMS data from randomly sampled chicken breast, ground beef, ground turkey, and pork for any contamination and for contamination by multidrug-resistant organisms. The analysis covers four types of bacteria: Salmonella, Campylobacter, Enterococcus, and Escherichia coli.
The study covered a total of 39,348 meat samples, of which 1,422 were found to be contaminated with at least one multidrug-resistant organism. The rate of contamination was 4 percent in the conventionally produced meat samples and just under 1 percent in those that were produced organically.
A longstanding concern about antibiotic use in livestock and livestock feed is the increased prevalence of antibiotic-resistant pathogens.
Globally, antibiotic resistant bacteria are linked to around 700,000 deaths a year. This figure could increase to 10m by 2050 if current trends continue, according to a report commissioned by the UK government.
The development of antimicrobial resistance (AMR) is closely linked to the over-use of antibiotics, particularly in livestock rearing. In order for meat to be certified organic by the USDA, animals can never have been administered antibiotics or hormones, and animal feed and forage such as grass and hay must be 100% organic.
"The presence of pathogenic bacteria is worrisome in and of itself, considering the possible increased risk of contracting foodborne illness," said senior author Meghan Davis, associate professor in the Department of Environmental Health and Engineering at the Bloomberg School. "If infections turn out to be multidrug resistant, they can be more deadly and more costly to treat."
Mixed processing facilities lower risk
The analysis also suggested that the type of processing facility may influence the likelihood of meat contamination.
Meat processors were split into three categories: exclusively organic, exclusively conventional, or those that handle both organic and conventional meats.
Looking at contamination rates in conventional meat, researchers found that those processed at facilities that exclusively handled conventional meats were contaminated with bacteria one-third of the time, while those handled at facilities that processed both conventional and organic meats were contaminated one-quarter of the time. The prevalence of multidrug-resistant bacteria was roughly the same in these two meat processor categories.
"The required disinfection of equipment between processing batches of organic and conventional meats may explain our findings of reduced bacterial contamination on products from facilities that process both types of meats," said Davis.
The paper’s lead author stressed that the way animals are reared and processed has important implications for both human and animal health. "As a veterinarian, I recognize that we sometimes need to use antibiotics to treat sick animals, but taking advantage of opportunities to reduce antibiotics use could benefit everyone. Consumer choice and regulatory oversight are two strategies to do this."
'Contamination of Retail Meat Samples with Multidrug-Resistant Organisms in Relation to Organic and Conventional Production and Processing: A Cross-Sectional Analysis of Data from the United States National Antimicrobial Resistance Monitoring System, 2012–2017'
Environmental Health Perspectives
Authors: Gabriel K. Innes, Keeve E. Nachman, Alison G. Abraham, Joan A. Casey, Andrew N. Patton, Lance B. Price, Sara Y. Tartof, and Meghan F. Davis