Updated: Superbug found in Illinois and South Carolina

U.S. officials have found bacteria resistant to the antibiotic of last resort in a sample from a second pig, increasing concerns about the spread of a newly discovered superbug that initially surfaced in this country in March.

The latest report involves an antibiotic-resistant strain of E. coli from a pig intestine, which was detected by scientists at the U.S. Department of Agriculture, a spokeswoman said Monday evening. The E. coli bacteria carried a gene making it resistant to the antibiotic colistin, the drug used against particularly dangerous types of superbugs that can already withstand many other antibiotics.