Los Angeles County public health officials announced Tuesday that they identified drug-resistant E. coli bacteria in a county resident, the first instance of the "superbug" in California.
The bacteria carries the mcr-1 gene -- which is resistant to the antibiotic colistin, one of a few antibiotics that are considered a last resort in treating highly-resistant bacteria.
Investigators believe the county resident probably acquired it while traveling internationally. Bacteria with the mcr-1 gene were first identified in the U.S. in April 2016 in a Pennsylvania woman.
Since then, the gene has been isolated from people in five more states and from animals in two states. The mcr-1 gene is of particular concern because it is carried on a piece of DNA that can be transmitted between bacteria, spreading resistance to more dangerous bacteria.
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In particular, colistin is used to treat a family of bacteria known as CRE, which the Centers for Disease Control and Prevention has cited as one of the country's most urgent drug-resistant threats.
CRE "superbugs" have been found resistant to a host of antibiotic options, leaving colistin as of the few options for treatment of this often fatal bacteria. Healthy people do not typically get CRE infections, which usually occur in patients in hospitals, nursing homes and other healthcare facilities.
Earlier this month, county health officials mandated that all acute care hospitals and skilled nursing facilities report on CRE cases.