A new study shows that the genes that make germs immune to antibiotics can spread among many more types of bacteria than previously thought. Bacteria pass around collections of antibiotic resistance genes on pieces of genetic material called integrons.

Scientists previously believed that only one particular category of bacteria could harbor integrons, but the new research found them in bacteria that are up to 500 times more common than those known to carry the clusters of drug resistance genes. Microbiologist Anne Summers at the University of Georgia led the study.

"So this is really not just about antibiotic resistance, it's about multiple antibiotic resistance. And it looks like there are a lot more players out there that can toss these things around than we ever expected," she said.

The study appears in the journal "Proceedings of the National Academy of Sciences."