Editorial

      

Antibiotic Resistance Demonstrated on U.S. Swine Farm

Dec 16, 2016


    

Carbapenem resistance among potential pathogens was detected on U.S. swine farms by researchers at the Ohio State University.  Eighteen isolates of Enterobacteria have been shown to express imp-27, a gene coding for beta-lactamase production which confers resistance to carbapenem antibiotics. 

This plasmid gene is readily transmissible to other bacteria.  The isolates were obtained in the environment of a barn housing sows on a thorough-to-finish farm during 2015.  The resistance gene was identified in two isolates of E. coli and one of Proteus mirabilis a ubiquitous but nonpathogenic bacteria in a nursery room and from farrowing rooms.  Stock ready to harvest did not yield any bacteria carrying the imp-27 plasmid transmitted gene. 

  

Subsequent to the survey on the 1,500-sow operation, the OSU investigators recovered the gene from organisms in feces suggesting that some animals on the farm have been colonized with enterobacters carrying imp-27.  Dr. Thomas Wittum Chair of the Department of Veterinary Preventive Medicine at the OSU College of Veterinary Medicine speculates that “there is a clear relationship between carbepenem resistance and the use of ceftiofur antibiotic which is common to human therapy.  There is at this time no relationship between administration of cephalosporin antibiotic and the emergence of carbapenem resistance.”

Dr. Tim Johnson of the College of Veterinary Medicine at the University of Minnesota noted that the Ohio State University study “revealed the real and long thought inevitable threat of carbapenemase-producing Enterobacteriaceae making the way into animal production facilities with subsequent risks to the human food supply.”

While the finding is not a “smoking gun” the investigation together with a previous demonstration of the presence of mcr-1 plasmid mediated gene imparting resistance to colistin in Asia, the EU and most recently the U.S. justifies action taken by the FDA to restrict antibiotic use to veterinary supervision applying Prudent Use Principles.

Carbapenem resistance Enterobacteriaceae are taken seriously by the Centers for Disease Control and Prevention since it is estimated that there are 9,300 nosocomial (hospital-related) infections resulting in 600 deaths annually in the U.S.  Immunosuppressed patients and those on life support systems or receiving long-term intravenous therapy are especially at risk.

The National Pork Board placed a positive spin on the report noting that the antibiotic resistance gene was isolated in the environment of sows and weanlings and was not present in stock destined for slaughter and accordingly was not of any threat with respect to food safety.  This avoiding the issue.  The problem relates to transmissible drug resistance and not foodborne infection.

It is a matter of record that hog farmers participate in the Ohio State University Public Health Preparedness for Infectious Diseases Program.  Producers cooperate with research to understand the epidemiology of antibiotic resistance in foodborne disease.  The National Pork Board accepts that additional studies are necessary (to validate and attempt to replicate the findings).

Additional revelations will support contention of organizations opposed to intensive livestock production and will also result in congressional action with pressure on regulatory agencies including the FDA and the FSIS.

Any attempt to belittle the significance of the epidemiologic studies or to deprecate the activities of individuals at Ohio State University will boomerang to the detriment of the pork industry and indirectly all livestock production.