To keep sickness at bay, many of us constantly wash hands and disinfect surfaces. But a new lab study shows one pesky bacterium eats cleansers for breakfast: When disinfectant was applied to lab cultures of the bacteria, they adapted to survive not only the disinfectant but also a common antibiotic.

The research team focused on Pseudomonas aeruginosa, a bacterium responsible for a range of infections in people with weakened immune systems. When the scientists added increasing amounts of disinfectant to P. aeruginosa cultures, the bacteria adapted to survive not only the disinfectant but also the antibiotic called ciprofloxacin.

Here's how: The bacteria were able to more efficiently pump out antimicrobial agents. The adapted bacteria also had a genetic mutation that allowed them to resist ciprofloxacin-type antibiotics specifically.

"In principle this means that residue from incorrectly diluted disinfectants left on hospital surfaces could promote the growth of antibiotic-resistant bacteria," said lead researcher Gerard Fleming of the National University of Ireland in Galway. "What is more worrying is that bacteria seem to be able to adapt to resist antibiotics without even being exposed to them."

The results, published in the January issue of the journal Microbiology, show just how savvy some bugs are, adding to research on superbugs - drug-resistant microbes that modern medicine struggles to combat.

MRSA, or methicillin-resistant Staphylococcus aureus, has become a deadly and growing problem in hospitals in recent years. And news out this week suggests the country's first case of a highly drug-resistant form of tuberculosis.

A major factor in the emergence of these antibiotic-resistant bacteria is the overuse and misuse of antibiotics, according to the Centers for Disease Control and Prevention. The new study suggests disinfectants may be part of the problem, though more research is needed to firm up the link.

"We need to investigate the effects of using more than one type of disinfectant on promoting antibiotic-resistant strains," Fleming said. "This will increase the effectiveness of both our first and second lines of defense against hospital-acquired infections."

Fleming also stressed the importance of studying the environmental factors that might promote antibiotic resistance.

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• Original Story: Disinfectants Cause Some Bacteria to Adapt, Thrive