Bacteria Resistant to Last-Resort Antibiotic Discovered in the US

US health officials have reported the first case of a patient with an infection resistant to colistin, a “last resort” antibiotic held in reserve for use against bacteria unaffected by other antibiotics.

The infection was observed in a 49-year-old woman from Pennsylvania with a urinary tract infection who reported no travel within the last 5 years.
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The infection was reported in Antimicrobial Agents and Chemotherapy. The authors concluded that the colistin resistance observed in the bacteria was the result of the bacteria themselves having been infected with a plasmid containing a gene called mcr-1.

Bacteria resistant to colistin were first observed in China in November 2015 within a small number of people.

The Centers for Disease Control and Prevention now plans to screen the patient and individuals she has been in contact with in the hopes of identifying any others that may carry the organism.

The discovery “heralds the emergence of truly pan-drug resistant bacteria,” according to the authors of the report.

“Continued surveillance to determine the true frequency for this gene in the United States is critical.”

—Michael Potts

Reference:
McGann P, Snesrud E, Maybank R, et al. Escherichia coli Harboring mcr-1 and bla_CTX-M on a novel IncF plasmid: first report of mcr-1 in the United States [published online May 26, 2016]. Antimicrob Agents Chemother. doi:10.1128/AAC.01103-16.