<div><p>Disinfectants commonly used in homes and medical facilities can boost the resistance of some bacteria to life-saving antibiotics, according to a study released Monday.</p><p>The findings shed light on how at least one pathogen -- Pseudomonas aeruginosa -- spreads, and could apply to other hospital superbugs as well, the authors say.</p><p>P. aeruginosa, responsible for one-in-10 hospital-acquired infections, is a so-called "opportunistic" bacteria that attacks people with weakened immune systems.</p><p>It typically infects the pulmonary and urinary tracts, as well as burns and puncture wounds.</p><p>In laboratory experiments, researchers showed that the bug can rapidly mutate, building resistance to progressively higher doses of a disinfectant known as BSK, or benzalkonium chloride.</p><p>Safe for humans, BSK is widely-used in cleaning and disinfecting products to kill bacteria, fungi and algae.</p><p>The DNA-altered bacteria were able withstand concentrations of BSK up to 400 times greater than the non-mutated strain.</p><p>More critically, they also developed a resistance to an antibiotic, ciprofloxacin, even though they had never been exposed to the drug.</p><p>Ciprofloxacin is a front-line medication in the fight against several bacterial infections, and is also the drug of last-resort against the deadly disease anthrax.</p><p>"This is very, very worrying," said Gerard Fleming, a professor at the National University of Ireland in Galway, and main architect of the study.</p><p>"We found that in both cases -- for the disinfectant and the antibiotic -- the [mutated] bacteria was taking them in, but expelling them just as quickly. It would be like trying to pump air into a bicycle tire with a huge hole in it," he told AFP by phone.</p><p>The disinfectant-resistant strain of P. aeruginosa built up immunity against ciprofloxacin up to ten times more effectively than did the baseline bacteria, the study reported.</p><p>In further experiments, Fleming and colleagues put the two strains together in an environment containing a diluted dose of disinfectant, such as might be found in a hospital or home.</p><p>The mutated bugs were "highly competitive" with the non-mutated ones, said Fleming: "They outgrew the so-called 'sensitive' strains so rapidly it was hard to believe."</p><p>"That means that we have a problem -- disinfectant may proliferate antibiotic resistance," he added.</p><p>Fleming hastened to add that this did not mean that disinfectants should not be used at all.</p><p>"They are quite important as a first-line defence. The message is to use them properly -- don't water them down to concentrations where they are no longer effective," he said.</p><p>The findings, to be published next month in the journal Microbiology, also point to the possibility that other drug-resistant hospital killers -- such as MRSA (methicillin-resistant Staphylococcus aureus) and C-diff (Clostridium difficile) -- could spread and build up immunity to antibiotics in the same way.</p><p>"We need to look at this very carefully. A lot more work needs to be done on this one," said Fleming.</p><img src="http://admatch-syndication.mochila.com/images/ad.gif?aid=66082652&bid=informcom" /></div><div id="copyright"><div>

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