Anti-superbug clues in deep isolated cave

A deep, isolated cave in New Mexico harbors strains of antibiotic-resistant bacteria that might hold clues for fighting modern-day superbugs. The hope is the discovery means there are previously unknown antibiotics occurring naturally, that could be used to treat infections. Researchers from McMaster University, in Hamilton, Ontario, Canada, and the University of Akron, in Akron, Ohio, USA, write about their findings in the 11 April online issue of PLoS ONE. Resistance to antibiotics among bacteria is giving rise to superbugs like methicillin-resistant Staphylococcus aureus (MRSA), and a growing concern for human health. In extreme cases the bacteria are resistant to all drugs and the only option left to deal with the infection is surgery. An important question for research is where and how these organisms acquire their resistance. Study co-author Gerry Wright, scientific director of the Michael G. DeGroote Institute for Infectious Disease Research at McMaster, told the media that much of the resistance originates in harmless bacteria in the environment. "Our study shows that antibiotic resistance is hard-wired into bacteria. It could be billions of years old, but we have only been trying to understand it for the last 70 years," added Wright. The scientists say none of the bacteria collected from the Lechuguilla Cave in New Mexico, a place only recently touched by man, causes disease in humans. And while none has ever been exposed to the sources of antibiotics used in medicine today, they found nearly all the strains were resistant to at least one drug, and some to as many as 14. Between them, the strains of bacteria in the caves appear to be resistant to nearly every type of antimicrobial drug used today. Wright said this has important clinical implications: "It suggests that there are far more antibiotics in the environment that could be found and used to treat currently untreatable infections." There is even a suggestion that the bacteria in the cave are resistant in a way that is yet to emerge clinically. One example is a resistant bacteria that is related to a strain that causes anthrax: such resistance is as yet unknown in medicine. Hazel Barton, associate professor of biology at the University of Akron, who with Wright, collected samples of the "microbiome" from deep recesses in the Lechuguilla Cave, said the message for doctors that comes out of this is: "While this isn't a problem right now, it could be in the future, so you need be aware of this pre-existing resistance and be prepared if it emerges in the clinic, or you are going to have a problem." The microbiome in Lechuguilla Cave is a perfect resource for this type of research because it contains a pre-existing reservoir of naturally occurring antibiotic resistance. The cave, which was discovered in 1986, contains an environment uncontaminated by the run-off from today's agricultural practices, which is laden with man-made antibiotics. Enclosed in impermeable rock means water takes 10,000 years to reach the cave's deepest recesses. And only a few expert cavers and researchers have access to it every year. Wright and colleagues took bacteria from this pristine, foreign environment, grew them in the lab, and then showed they contain genes that help them fight antibiotics, said microbiologist Julian Davies of the University of British Columbia. Davies, who wasn't involved with the study, commented to National Geographic News, that the study tells us antibiotic resistance genes are very old: "... but what it doesn't tell us is how they find their way into the hospital."