Older antibiotics -- polymyxin drugs derived from Bacillus polymyxa -- that were developed almost a half-century ago have begun to show the first signs of bacterial resistance, according to a recent study presented during the 47th annual meeting of the Infectious Diseases Society of America (ISDA).

Although the polymyxin class of drugs had lost some of their past appeal over the past 20 years due to kidney toxicity, these antibiotics have been making a recent comeback as a weapon to treat infections patients acquired in hospital settings that had been resistant to other antibiotics.

After comparing samples of bacteria taken from 1,041 patients in a New York hospital from 2005-08, 6 percent were resistant to polymyxin B and E drugs. And, the prevalence of resistance to polymyxin, according to the study, had exploded by some 50 percent over a two-year period.

Even more alarming, more than 30 percent of samples taken from patients were resistant to five classes of antibiotics, says lead author Dr. Jason Kessler, meaning that polymyxin may be the only treatment alternative.

The greatest fear, according to UCLA professor and ISDA expert Dr. Brad Spellberg, is fast becoming a reality. "Antibiotic development is dying, and we are running out of drugs. We have organisms that are already resistant to every antibiotic we can throw at them."

U.S. News and World Report/Science News October 30, 2009

healthfinder.gov October 30, 2009