A person's chances of acquiring a drug-resistant infection may be higher if she lives in a warmer area.

A study appearing today in Nature Climate Change from researchers at the University of Toronto (U.T.) and Children's Hospital Boston links the emergence of drug-resistant bacteria to a hotter climate. Researchers found a 10-degree Celsius increase in daily minimum temperature was associated with a small increase in resistance in common pathogens, including those that develop into methicillin-resistant Staphylococcus aureus (MRSA), the root of many persistent and sometimes deadly hospital infections. "This is a very important and timely study stemming from meticulously collected and arranged records of antibiotic resistance," says Elena Naumova, an epidemiologist at Tufts University who was not involved in the work. "What's great about this study is that they really broaden the concept of antibiotic-resistance patterns."

Scientists have long observed bacteria in the laboratory grow and reproduce more quickly at warmer temperatures. And increased growth can cause a hike in resistant strains when DNA mutations crop up during reproduction. Bacteria can also swap DNA with one another and spread resistance via a process called horizontal gene transfer, which also increases at higher temperatures. Now scientists are asking if this phenomenon also occurs outside the laboratory.

The research was enabled by a large-scale data collection effort to create a free and open Web-based application that gives the geographical locations of drug-resistant bacteria. The site, called Resistance Open, allows anyone in the world to punch in their postal code and see which drug-resistant infections are present in their hometown. "For a physician, they can have a better understanding of what is happening in the community rather than just in their hospital," says John Brownstein, a professor of medicine at Harvard Medical School and co-senior author of the study. And the tool allows scientists to see new patterns in drug resistance, such as how it may be affected by climate.