Colistin-resistant bacteria found in United States

Colistin-resistant bacteria found in United States

Department of Defense, USDA and Department of Health and Human Services continue to study antibiotic resistance.

The Department of Defense, Department of Agriculture and Department of Health and Human Services are co-chairing a Presidential Advisory Council on Combating Antibiotic-Resistant Bacteria.

The first colistin-resistant mcr-1 E. coli was identified in a person in the United States last week. (Photo: Manjurul/Thinkstock)

The three agencies have made discoveries regarding antibiotic resistance in the United States. Last week, the Department of Defense notified stakeholders that its Multidrug-resistant Organism Repository and Surveillance Network (MRSN) at the Walter Reed Institute of Research had identified the first colistin-resistant mcr-1 E. coli in a person in the United States. A USDA and HHS search for colistin-resistant bacteria in food animals, retail meats and people also has found colistin-resistant E. coli in a single sample from a pig intestine. Scientists also determined that the mcr-1 carrying colistin-resistant E. coli is resistant to other antibiotics including ampicillin, streptomycin, sulfisoxazole, and tetracycline.

These discoveries are of concern because colistin is used as a last-resort drug to treat patients with multi-drug resistant infections. Finding colistin-resistant bacteria in the United States is important, as it was only last November that scientists in China first reported that the mcr-1 gene in bacteria confers colistin resistance. Following the revelation in China, scientists across the globe began searching for other bacteria containing the mcr-1 gene, and the bacteria have since been discovered in Europe and Canada. The mcr-1 gene exists on a plasmid, a small piece of DNA that is not a part of a bacterium’s chromosome. Plasmids are capable of moving from one bacterium to another, spreading antibiotic resistance between bacterial species.

The patient with colistin-resistant E. coli was treated in an outpatient military treatment facility in Pennsylvania.  Biologic samples were sent to the Walter Reed National Military Medical Center for initial testing and then to MRSN for genetic sequencing to identify the mcr-1 gene.

The National Antimicrobial Resistance Monitoring System (NARMS) is continuing its search for evidence of colistin-resistant bacteria in the United States. For the past 20 years, NARMS has detected emerging resistance to clinically important antibiotics. NARMS is a partnership between HHS and USDA, as well as state and local public health departments, dedicated to tracking changes in the antimicrobial susceptibility of intestinal bacteria found in ill people, in retail meats, and in food animals.

Sources: David J. Smith, M.D., Deputy Assistant Secretary of Defense for Health Readiness Policy and Oversight; Cathie Woteki, Ph. D., USDA Under Secretary for Research, Education & Economics; Beth P. Bell, MD MPH, Director of CDC’s National Center for Emerging and Zoonotic Infectious Diseases,

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