More cases of superbug precursor reported, but no spread

Researchers are reporting that a fourth U.S. person has been diagnosed with bacteria resistant to a last resort antibiotic, but they are expressing some relief that 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 Friday.

She and three other Americans have been found to have E. coli bacteria that were resistant to a last-resort medicine called colistin, and health experts worry that the trait could be passed to germs that already resist other antibiotics. Researchers last week reported a worrisome infection in a New Jersey man that could resist colistin and another important antibiotic.

The cases were treatable, however, and the infections did not appear to spread.