Olivier Tenaillon at Denis Diderot University, Paris, and colleagues were studying bacterial evolution by exposing Escherichia coli to high temperatures and little food. Unexpectedly, some bacteria spontaneously became resistant to the antibiotic rifampicin, even though they had never encountered it. The mutation that helped them deal with environmental stress just happened to confer resistance to the drug, used to treat TB and meningitis.
"Our work suggests that selective pressure other than antibiotics may drive resistance," says Tenaillon.
Moreover, bacteria with the mutation grew 20 per cent faster than otherwise-identical bacteria – a first for a resistance mutation.
Primary source: BMC Evolutionary Biology