December 7, 2016

Fwd: Farm Animals Are Now Resistant to the Last-Resort Antibiotic

By chirosushi In Health, News



70 percent of antibiotics sold in the US are used for farm animals.
Researchers aren’t sure how the animals developed resistance to them.

new study just published by the American Society for Microbiology has found something potentially disturbing: Some of the strongest antibiotics, reserved only for severe, human infections, have somehow made their way to livestock. The research demonstrated, via direct collection of data from farm animals, livestock resistance to carbapenems, antibiotics used for infections that are caused by multidrug, drug-resistant bacterias. They are almost always reserved for people who are hospitalized -(source)

Drug resistance is a growing global health problem; experts estimate that in 2050, 10 million people will die from infections that are resistant to antibiotics each year. The use of antibiotics in livestock animals contributes to the problem, as does the inappropriate—but common—overprescribing of antibiotics. (source)


Carbapenemase-producing Enterobacteriaceaerecovered from the environment of a swine farrow-to-finish operation in the United States

  1. Dixie F. Mollenkopfa,
  2. Jason W. Stulla,
  3. Dimitria A. Mathysa,
  4. Andrew S. Bowmana,
  5. Sydnee M. Feichta,
  6. Susan V. Grootersa,
  7. Joshua B. Danielsb and
  8. Thomas E. Wittuma#

+Author Affiliations

  1. Department of Veterinary Preventive Medicine, The Ohio State University College of Veterinary Medicine, Columbus, Ohio, USAa

  2. Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, Ohio, USAb


Carbapenem-resistant Enterobacteriaceae (CRE) present an urgent threat to public health. While carbapenem antimicrobials are restricted in food-producing animals, other β-lactams, such as ceftiofur, are used in livestock. This use may provide selection pressure favoring the amplification of carbapenem resistance but this relationship has not been established. Previously unreported from US livestock, plasmid-mediated CREs have been reported from livestock in Europe and Asia.

Environmental and fecal samples were collected from a 1,500 sow, US farrow-to-finish operation during 4 visits over a 5 month period, 2015. Samples were screened using selective media for the presence of CRE, with resulting carbapenemase-producing isolates further characterized.

Of 30 environmental samples collected from a nursery room on our initial visit, 2 (7%) samples yielded 3 isolates: 2 ST 218 Escherichia coli and 1 Proteus mirabilis, carrying the metallo-β-lactamase gene blaIMP-27 on IncQ1 plasmids. We recovered 15 IMP-27-bearing isolates of multiple Enterobacteriaceae species from 11 of 24 (46%) environmental samples from 2 farrowing rooms collected on our third visit. These isolates each also carried blaIMP-27 on IncQ1 plasmids. No CRE isolates were recovered from fecal swabs or samples in this study.

As is common in US swine production, piglets on this farm receive ceftiofur at birth, with males receiving a second dose at castration (≈day 6). This selection pressure may favor the dissemination of blaIMP-27-bearing Enterobacteriaceae in this farrowing barn. The absence of this selection pressure in the nursery and finisher barns likely resulted in the loss of the ecological niche needed for maintenance of this carbapenem resistance gene.



Leave a Comment