Welcome to the post-antibiotic world. Doctors say that a 49-year-old woman in Pennsylvania was infected with a “truly pan-drug resistant bacteria,” in other words, a bacteria that will not respond to any known antibiotics.

Earlier this year, reports indicated that bacteria containing a gene (MCR-1) that makes them resistant to colistin—an antibiotic of last resort that had largely gone unused because of its potential for collateral damage to the patient—had spread to 19 countries on four different continents, but that it hadn’t been identified here in the U.S.

That was until, according to a report published today in the journal Antimicrobial Agents and Chemotherapy, on April 26 a woman who believed she had a urinary tract infection provided a urine sample at a Pennsylvania clinic.

It was subsequently passed on to researchers at Walter Reed National Military Medical Center, which—in response to concern over MCR-1—now looks at all E. coli samples that meet certain red-flag criteria for antibiotic resistance.




The E. coli cultured from this patient’s urine sample—genetically linked to a strain first found in the UK in 2008—was found to be carrying the MCR-1 gene, plus an additional 14 different antibiotic resistance genes.

“To the best of our knowledge, this is the first report of mcr-1 in the USA,” reads the report, which notes that the patient had not done any traveling in the five months leading up to providing the sample.

The researchers at Walter Reed have now tested 21 E. coli samples. All the others have tested negative for MCR-1 and are sensitive to treatment with colistin. But as they note, this testing program has only been up and running at Walter Reed for three weeks, so “it remains unclear what the true prevalence of mcr-1 is in the population… Continued surveillance to determine the true frequency for this gene in the USA is critical.”

In a statement to the Washington Post, CDC Director Tom Frieden says that the discovery of MCR-1 in a human patient “basically shows us that the end of the road isn’t very far away for antibiotics—that we may be in a situation where we have patients in our intensive-care units, or patients getting urinary tract infections for which we do not have antibiotics.”

Frieden says this is already a problem for some strains of tuberculosis: “I’ve cared for patients for whom there are no drugs left. It is a feeling of such horror and helplessness.”