A new study in PLoS One suggests that antibiotic resistance superbugs go a long way back, says Scientific American's Katherine Harmon at the Observations blog. While over-prescription of antibiotics in humans and livestock usually takes the blame for the development of these bacterial strains, "the capacity to fend off antibiotics might actually be lodged deep in bacteria's evolutionary history," Harmon says.
Researchers from McMaster University went to the 4 million-year old Lechuguilla Cave in New Mexico, a place few people have entered since it was discovered in 1986, and collected bacterial samples. Of the 93 bacterial cave strains tested, most were resistant to more than one of the 26 modern-day antibiotics the researchers tested on them. Some were resistant to more than a dozen common drugs. "The finding hardly exonerates humans for our role in creating conditions that exert a strong selective pressure on bacteria to become tolerant and resistant to antibiotics," Harmon adds. "But it does mean that pathogenic drug-resistant bacteria might deploy genetic traits that were already circulating in the environment and put them to use against our pharmaceutical armamentarium."