Monday, 21 November 2011

Bacteria that don’t know they are hungry are thousands of times eaier to kill.

Dr Nguyen
Microbiologists have long known that bacteria whose food supply is running low issue a chemical alarm telling them to prepare for starvation. They also noticed that bacteria often run out of food during an infection or when clumped in biofilms that only allow the outside ones to feed easily. These clumps and biofilms are very hard to kill, even when attacked by antibiotics to which they have no known resistance.  What if the alarm turns on the resistance?
To their amazement, bacteria engineered so they didn’t sense starvation were thousands of times more sensitive to killing than those that could.
"That experiment was a turning point," Singh said. "It told us that the resistance of starved bacteria was an active response that could be blocked. It also indicated that starvation-induced protection only occurred if bacteria were aware that nutrients were running low."
Further research showed that the starvation shutdown response protected them from the toxic form of oxygen,  chemically hyperactive free radicals.  Free radicals are also what antiobiotics generate when killing bacteria.  Elegant.
Bacterial clusters living in the lungs of a cystic 
fibrosis patient are highly resistant to 
killing by antibiotics

The good news goes beyond understanding the problem.  Existing antibiotics that may seem ineffective today may get a power boost of up to a thousand fold on certain resistant bacteria.

Edited from Science Daily News reporting on work by lead author Dr. Dao Nguyen (McGill), Dr. Singh and others.

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