A team led by scientists from McMaster University in Ontario, Canada, descended 1,300 feet into the Lechuquilla Cave in New Mexico to collect samples of bacteria, Scientific American reported Wednesday.
Since surface water takes thousands of years to seep through overlying rock formations into the cave, it is a perfect location to study naturally occurring antibiotic resistance, researchers said, because it is unlikely the cave's bacteria could be exposed to modern-day antibiotics.
Of the 93 bacterial strains tested from the cave, most were resistant to at least some natural antimicrobials while others were resistant to antibiotics such as telithromycin, ampicillin and daptomycin, used by doctors to combat resistant infections.
"Our study shows that antibiotic resistance is hard-wired into bacteria," McMaster researcher Gerry Wright said. "It could be billions of years old."
"Most practitioners believe that bacteria acquire antibiotic resistance in the clinic.
"The actual source of much of this resistance are harmless bacteria that live in the environment," responding to naturally occurring antibacterials, he said.
"This has important clinical implications," Wright said. "It suggests that there are far more antibiotics in the environment that could be found and used to treat currently untreatable infections."