Drug-resistant microbes are gaining ground and the few "last resort" antibiotics used to treat infections with such bacteria are being used more frequently, new research shows.

The study findings, published in the journal Public Library of Science ONE, were based on an analysis of two antibiotics -- polymyxins and tigecycline – used in 127 Veterans Affairs medical centers between 2005 and 2010.
Researchers, led by Makoto Jones of the Veterans Affairs Salt Lake City Health Care System, found that the overall use of the drugs was quite low, but increased over the 5-year course of the study.
They also found eight facilities accounted for three-quarters of all polymyxin use, and 26 facilities accounted for three-quarters of all tigecycline use.
"The use of polymyxins, a class of relatively toxic antibiotics, has been increasing over time and appears to be a marker of very resistant bacteria,” said Jones. “To address this potential harbinger of a growing epidemic, a clear strategy of infection control, antibiotic development, and antibiotic stewardship will be necessary."
Researchers noted that although the study involved the use of the antibiotics in VA facilities, “the trend is almost certainly not limited to the VA.”
The work was funded, in part, by the Pew Charitable Trusts, the Department of Veterans Affairs and the Centers for Disease Control and Prevention.