chickens-eating-antibiotics-700.jpgPoultry farms that transition to organic and stop giving their birds antibiotics have significantly lower levels of drug-resistant bacteria, according to new research out of the University of Maryland’s School of Public Health.

The authors of the study, published in Environmental Health Perspectives this week, say it’s the first to demonstrate lower levels of drug-resistant bacteria on newly organic farms in the United States, adding credence to what environmental and public health advocates have been saying for years: antibiotic usage needs to be curtailed in American agriculture to combat growing antibiotic resistance.

Most experts agree that overusing antibiotics in both human medicine and animal agriculture is contributing to the problem — more than 100,000 people in the U.S. die from bacterial infections, 70 percent of which are resistant to antibiotics. Recent U.S. Food and Drug Administration data indicate approximately 80 percent of all antibiotics sold in the U.S. are given to food animals. 

This research, which comes just days after the largest Class I recall of a USDA-regulated product for multi-drug resistant Salmonella Heidelberg, suggests that removing antibiotics from large-scale poultry farms can have an immediate impact lowering antibiotic resistance for some enterococci bacteria, a genus of bacteria that can cause infections in humans.

“We initially thought we would see some differences in on-farm levels of antibiotic-resistant enterococci when poultry farms transitioned to organic practices. But we were surprised to see that the differences were so significant across several different classes of antibiotics even in the very first flock of birds that was produced after the transition to organic standards,” said Amy Sapkota, an assistant professor with the Maryland Institute for Applied Environmental Health. “It is very encouraging.”

Sapkota and her team, which included researchers from Pennsylvania State University and Johns Hopkins Bloomberg School of Public Health, measured the impact of removing antibiotics from poultry farms by looking at 10 conventional and 10 newly organic large-scale poultry houses in the mid-Atlantic region. They tested for the presence of enterococci bacteria in poultry litter, feed, and water, and tested its resistance to 17 common antimicrobials.

“We chose to study enterococci because these microorganisms are found in all poultry, including poultry on both organic and conventional farms. The enterococci also cause infections in human patients staying in hospitals. In addition, many of the antibiotics given in feed to farm animals are used to fight Gram-positive bacteria such as the enterococci. These features, along with their reputation of easily exchanging resistance genes with other bacteria, make enterococci a good model for studying the impact of changes in antibiotic use on farms,” explained Sapkota.

As expected, Enterococci bacteria were present in the poultry litter, feed and water at all farms, conventional and organic, but the newly organic farms had a markedly lower percentage of bacteria resistant to commonly used antibiotics.

According to researchers, 67 percent of Enterococcus faecalis recovered from conventional poultry farms were resistant to erythromycin, a drug widely used to treat infection in humans. At the recently transitioned organic farms, 18 percent of Enterococcus faecalis were resistant to the same antibiotic.

“Dramatic” changes were also observed in other multi-drug resistant bacteria — organisms resistant to three or more antimicrobial classes — on the organic farms.

“Multi-drug resistant bacteria are of particular public health concern because they can be resistant to all available antibiotics, and are, therefore, very difficult to treat if contracted by an animal or human. Forty-two percent of Enterococcus faecalis from conventional farms were multi-drug resistant, compared to only 10 percent from newly organic farms, and 84 percent of Enterococcus faecium from conventional farms were multi-drug resistant compared to 17 percent of those from newly organic farms,” the researchers said.

“While we know that the dynamics of antibiotic resistance differ by bacterium and antibiotic, these findings show that, at least in the case of enterococci, we begin to reverse resistance on farms even among the first group of animals that are grown without antibiotics, added Sapkota. “Now we need to look forward and see what happens over five years, 10 years in time.” 

  • Doc Mudd

    Interesting study with important results that are poorly interpreted and widely reported in the media. No surprise, considering the funder of the study.
    Perusing table 4 of the report…available at: of Print (AOP)
    …reveals (not surprisingly) if feed is contaminated with various enterococci, comparable enterococci will be cultured from the litter. “Conventional” systems with positive findings for resistant enterococci had, in every instance, similarly resistant enterococci introduced via the feed.
    Now, here’s the more interesting finding: Resistant enterococci existed in all “organic” systems, but in the absence of comparable enterococci being introduced via feed.
    Obviously this study is seriously flawed by uncontrolled variables, but this should suggest directions for further research that might be truly productive in understanding the phenomenon of antimicrobial resistance in food systems.
    An important red flag in this study is its professional release to the media — a characteristic maneuver of the FUNDER of this study: Center for a Livable Future, Johns
    Hopkins (an anti-agriculture activist group whom we hear from at regular intervals here at FSN).
    Antibiotics could and should be utilized more effectively in animals and in humans. Poor quality science and amateur interpretation, staged and hyped by professional anti-agriculture organizations will not further progress on that front, only embarrass and hinder it.

  • federal microbiologist

    Good science, by a capable group of investigators, published in the top journal in the field of environmental health, a journal that requires all authors to disclose conflict of interests (i.e., Ag Industry and / or Chem Industry ties) in order for their article or letter to be published.
    Needless to say, this study is going to provoke rancorous denunciations from our Favorite Comments Troll…. !

  • Doc Mudd

    You’re way behind the 8-ball with your name-calling this morning, “fed”.
    Since you probably won’t trouble yourself to read the actual study, I’ll pass along another choice piece of information Ralph Loglisci conveniently left out of his press release — turns out the organic chickens experienced about twice the death rate of the conventional birds. Not that anti-agriculture cults like Helene Lerner’s “Center for a Livable Future” understand or care about practical things like that.

  • pappa luigi

    Also, this just in: A 7 year, multimillion dollar study in which many prestegious universities participated, has conclusively proven that 1 plus 2 equals 3! Many are shocked by the results, and say the jury is still out calling into question the financial ties to the underwriters of the landmark study and a possible political agenda pushed by some faculty members. We still may never know the true answer to the age old problem of 1 plus 2.

  • LoraJ

    @ doc mudd – you say
    Since you probably won’t trouble yourself to read the actual study, I’ll pass along another choice piece of information Ralph Loglisci conveniently left out of his press release — turns out the organic chickens experienced about twice the death rate of the conventional birds. Not that anti-agriculture cults like Helene Lerner’s “Center for a Livable Future” understand or care about practical things like that
    well i READ THE ENTIRE ARTICLE and never saw ANYTHING about the death rate – please tell me the page and paragraph you are quoting. thanks!

  • Doc Mudd

    see Table 1:
    Cumulative Mortality Rate (%)
    Conventional = 2.51
    Organic = 4.72
    Also from Table 1 we can learn that the organic birds were much less crowded than the conventional birds (nearly half) but still more organic birds perished! [to see that you will have to use your math skills and your reading skills, Lora. Can you figure it out??]
    Anything else I can read to you, while I have the paper out?