CDC via Associated Press, Janice Carr
This 2006 colorized scanning electron micrograph image made available by the Centers for Disease Control and Prevention shows the O157:H7 strain of the E. coli bacteria. Bacteria with a special type of resistance to antibiotics have been found for a second time in the U.S., increasing worries that the country will soon see a superbug that cannot be treated with known medications. This case, first reported in a medical journal Monday, July 11, 2016, occurred a year earlier in New York.

NEW YORK — A New York City patient was found to have been infected with bacteria last year that had a special type of resistance to antibiotics, the earliest known case in the U.S. of bacteria that could lead to a superbug impervious to medications.

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.

Researchers found bacteria that were resistant to colistin, an old, powerful antibiotic that is now seen as a drug of last resort.

A similar infection was reported in a Pennsylvania woman earlier this year and initially reported as the first known U.S. case, but the New York case happened almost a year before.