Resistance mechanism found against new antibiotics

ANN ARBOR — Bacteria naturally adapt to protect themselves from the antibiotics developed to fight them. This has created a race to develop new antibiotics that will continue to be effective against dangerous infections.

This week a team of researchers from the University of Michigan Life Sciences Institute, University of Illinois, Chicago, and University of Southern Denmark has identified a resistance mechanism against ketolides, a new type of antibiotic just entering widespread use.

Ketolides — like many antibiotics — are themselves produced by certain common soil bacteria as a self-defense mechanism.

In a study published online Oct. 5 in the Proceedings of the National Academy of Sciences, the researchers identified two genes within the ketolide-producing bacteria responsible for protecting it from the antibiotic.

They also found that resistance mechanism remains functional when the genes are transferred to other species of bacteria — a type of exchange that commonly happens inside of host organisms through a process called “horizontal gene transfer.”

“This group of antibiotics is just entering clinical use, but we can already predict that resistance is going to be a problem,” says co-author David H. Sherman, Ph.D., a faculty member of the U-M Life Sciences Institute, where his lab is located. “Our findings emphasize a need for vigilance to detect and limit resistance in the clinical setting, and the preemptive development of new drugs that can remain effective in the face of this resistance mechanism.”