For just the second time in the U.S., researchers have found evidence of E. coli bacteria that are genetically resistant to a last-resort antibiotic, according to a report published today in the medical journal Antimicrobial Agents and Chemotherapy.
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.
In this case, the bacteria were genetically resistant to colistin but not to other forms of antibiotics that could be used to kill the E. coli. However, researchers are concerned that these bacteria could transfer genes to other E. coli and different bacteria that are already resistant to all forms of antibiotics except colistin, leading to the chance of a fully antibiotic-resistant strain of bacterium. Researchers are especially concerned about the possibility that the gene could be transferred within the Enterobacteriaceae family of bacteria, which includes E. coli. Some strains in that family are already largely resistant to many kind of antibiotics in the U.S.
Researchers found the strain by testing 13,562 E. coli strains collected at hospitals across the globe. They found 19 strains had the gene mcr-1, which makes E.coli resistant to colistin. In one case, that strain was found in the U.S.
Researchers said the global findings are alarming because it means there may be an increasing likelihood of having outbreaks of E. coli bacteria that are totally resistant to antibiotics.
"The fact that the gene has been detected in food livestock and raw meat is also concerning," said report co-author Mariana Castanheira, the director of micro- and molecular biology at JMI Laboratories.
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.
"It's basically a wake-up call," he told ABC News. "It's only going to be a matter of time where the perfect storm happens ... Next thing you know, you throw your hands up and say we're out of ammunition" to fight certain infections.
Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, said health experts have been worried for years that there will be a rise in completely drug-resistant bacteria, especially since there have been few antibiotic breakthroughs in recent years.
He said there are several things that need to happen to minimize the chance of creating antibiotic-resistant bacteria.
"[No. 1], we prescribe antibiotics much more prudentially ... No. 2, we have to stop using antibiotics as freely as we do in our food industry," said Schaffner. "No. 3, we need to energize and create environments so pharmaceutical companies will once again start" developing antibiotics.
He said many pharmaceutical companies have little incentive to find and test new antibiotics, since they are usually used sparingly for a limited time and because the bacteria immediately start to become resistant to them, making them more likely to be rendered useless.
But Schaffner emphasized that more needs to be done to develop new antibiotics because there could be a spike of antibiotic-resistant bacteria outbreaks in the coming years.
"Developing new antibiotics is a long-term commitment, and we think in terms of five to 10 years," he said. "As that Chinese proverb states, the longest journey begins with first steps. We ought to make those steps now, because we're going to need those new antibiotics years from now."