Disinfectants boost bacteria resistance - Create Superbugs - study
Pastor Dale Morgan
Disinfectants boost bacteria resistance - Create Superbugs - study*
* From correspondents in Paris
* From: AFP
* December 29, 2009 8:34AM
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."