A fourth U.S. person has been diagnosed with bacteria resistant to a last resort antibiotic, but researchers are expressing relief that so far these superbug precursors have not spread to others.
The latest case is a 2-year-old Connecticut girl who was diagnosed earlier this year, the Centers for Disease Control and Prevention reported.
She and three other Americans have been found to have E. coli bacteria that were resistant to an important medicine called colistin. Colistin is an old, powerful drug with significant side effects that is reserved for germs that already resist other important antibiotics.
Health officials have worried that the colistinresistant bacteria will spread their special trait to bacteria already resistant to other medicines, setting the stage for true superbug infections that are impervious to all known antibiotics.
For example, researchers reported recently a worrisome case of a 76-yearold man treated in 2014 at a New Jersey hospital. In follow-up testing this year, he was found to have been infected by a germ that was resistant to both colistin and another class of antibiotics called carbapenems that are also reserved to treat especially tough bugs.
It was the first time this kind of double-resistance was reported in the U.S., though several other cases have been reported elsewhere in the world.
All the U.S. cases have been treatable by other antibiotics.
And, importantly, researchers report that the bacteria do not seem to have infected other people. When bacteria spread, they encounter other bacteria and can exchange genetic traits, creating more opportunity for a superbug to emerge.