Tuesday, December 29, 2009

Disinfectants boost bacteria resistance - study

This study illuminates the importance of aseptic practices ("cleanliness", for short) -- now largely abandoned in British government (NHS) hospitals. No wonder so many people die of "superbugs" acquired in NHS hospitals

DISINFECTANTS commonly used in homes and medical facilities can boost the resistance of some bacteria to life-saving antibiotics, according to a study.

The findings shed light on how at least one pathogen - Pseudomonas aeruginosa - spreads and could apply to other hospital superbugs as well, the authors said. P. aeruginosa, responsible for one-in-10 hospital-acquired infections, is a so-called "opportunistic" bacteria that attacks people with weakened immune systems. It typically infects the pulmonary and urinary tracts, as well as burns and puncture wounds.

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. Safe for humans, BSK is widely-used in cleaning and disinfecting products to kill bacteria, fungi and algae. The DNA-altered bacteria were able withstand concentrations of BSK up to 400 times greater than the non-mutated strain.

More critically, they also developed a resistance to an antibiotic, ciprofloxacin, even though they had never been exposed to the drug. 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.

"This is very, very worrying," Gerard Fleming, a professor at the National University of Ireland in Galway, said. "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 tyre with a huge hole in it."

The disinfectant-resistant strain of P. aeruginosa built up immunity against ciprofloxacin up to 10 times more effectively than did the baseline bacteria, the study reported.

In further experiments, the two strains were put together in an environment containing a diluted dose of disinfectant, such as might be found in a hospital or home. The mutated bugs were "highly competitive" with the non-mutated ones, Mr Fleming said. "They outgrew the so-called 'sensitive' strains so rapidly it was hard to believe. "That means that we have a problem - disinfectant may proliferate antibiotic resistance."

Mr Fleming hastened to add that this did not mean that disinfectants should not be used at all. "They are quite important as a first-line defence," he said. "The message is to use them properly - don't water them down to concentrations where they are no longer effective."


Blame your genes for debt binge

SO how's the credit card looking right now? Or are you still in denial for the moment? The orgy of Christmas spending is over, but for many the post-Christmas sales still beckon, and the annual "Jesus Christ" moment can arrive not so much on December 25, but early next month when mail from the likes of Visa and Mastercard starts to lob.

Relax though, for in this brave new era of blame-shifting and absence of personal responsibility, a propensity to overspend may not be your fault, but rather the result of a genetic condition. According to recent research from the London School of Economics and the University of California, some of us may actually have a debt gene which makes us predisposed to over-extending on the credit front.

OK, it's not quite a debt gene as such, but according to co-author Jan-Emmanuel De Neve of the LSE (and quoted on smartmoney.com), humans have "a set of genes whose expression, in combination with environmental factors, influences financial decision-making". This little bit of DNA is called the MAOA gene, which apparently can degrade neurotransmitters in the brain that regulate such things as impulsive behaviour.

A study involving some 2500 US young adults (18-26) found that those with a "low efficiency" MAOA gene were more likely to be saddled with credit card debt. In other words, they were more likely to seek immediate gratification rather than weighing up the consequences first.

Apparently, if you carry the wrong variants of this gene (which is also linked to addictive behaviour), the chance you have unpaid bills on the plastic can increase by up to 16 per cent. Whether this means banks in years to come will demand a DNA sample before giving you a credit limit is doubtful, but based on this study it appears some of us may be hard-wired for profligacy. As with most genetic conditions, there is no easy cure. Happy New Year bill paying.


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