NEW YORK: After two confirmed US cases of a superbug that thwarts a last-resort antibiotic, infectious disease experts say they expect more cases in coming months because the bacterial gene behind it is likely far more widespread than previously believed.
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Italian researchers, meanwhile, said they detected a variant of the MCR-1 gene, which they called MCR-1.2, in Klebsiella pneumoniae.
The superbug has a gene that makes it resistant to treatment with colistin, an antibiotic often used by doctors as a last resort for antibiotic-resistant infections, the report states.
They found that 390 of them, or 1.9 percent, were resistant to colistin, and that 19 of them had the easily swapped MCR-1 gene. The Pennsylvania case was the first time this colistin-resistance gene had shown up in this country after it was first identified in China last fall.
Dr. Frank Esper, a pediatric infectious disease specialist at University Hospitals Case Medical Center, said the report was alarming but not surprising for infectious disease experts.
The new case involved a patient in NY, while the first reported case involved a woman from Pennsylvania. But the NY case happened nearly a year before, and scientists now believe these bacteria were likely in people in the USA even earlier.
The bacteria were found in a patient who was treated in May of 2015 and reported in a study published Monday in the American Society of Microbiology’s journal.
Alarms went out earlier this year when a team at the Walter Reed Army Institute of Research found the MCR-1 gene in a sample taken from a woman in Pennsylvania.
The mcr-1 superbug has been identified over the past six months in farm animals and people in about 20 countries, including China, Germany and Italy. “The prospect of a mobile gene encoding resistance to colistin spreading among isolates resistant to most antimicrobial agents clinically available is threatening for the therapy of serious infection caused by isolates”, said Mariana Castanheira of Iowa-based JMI Laboratories, which published the study. That’s how researchers found the most recent discovery in the NY patient. One sample was from a NY patient infected with E. coli, and whose name was not disclosed.
She said she and her colleagues are continuing their research. Following this discovery, scientists around the world began looking for other bacteria which are carriers of the MCR-1 gene, and have since discovered some in Europe and Canada. Researchers suspect the gene is on a plasmid, and are working with other labs to confirm that.
Researchers point out that in both cases, the carried a gene, known as mcr-1, that allows the organism to withstand colistin.
“It is the end of the road for antibiotics unless we act urgently”, Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, warned at the time.
The CDC is planning to establish seven regional laboratories this fall that will have the capacity to do better and faster testing for a broad range of antimicrobial resistance.
The 19 isolates originated in ten countries representing all of the above regions. Some strains in that family are already largely resistant to many kind of antibiotics in the U.S.
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In the current study, the authors, who coordinate the worldwide SENTRY Antimicrobial Surveillance Program, first tested 13,526nbsp;Escherichia coli and 7,480nbsp;Klebsiella pneumoniae clinical strains that had been collected systematically from hospitals in the Asia-Pacific region, Latin America, Europe, and North America in 2015.
