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17 April 2009

Running out of ammunition

Even the old killer germs – the ones we thought we’d beaten – have learnt to adapt to our fancy medicines.

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Do we have the ammunition to fight super bugs?
BY GREG CALLIGARO for YOU Pulse magazine

Even the old killer germs – the ones we thought we’d beaten – have learnt to adapt to our fancy medicines. This should come as no surprise: bacteria are after all the most successful organisms on the planet, having adapted over millions of years to every ecological niche from hot sulphuric springs to the deep ocean floor.

Only human arrogance could assume we could wipe them out with our array of chemical weapons in as little as 50 years.

Unfortunately, as Columbia University’s Dr Harold Neu observed in the journal Science, ‘‘Bacteria are cleverer than men.’’ For one thing, we’re hopelessly outnumbered – even our own bodies’ total number of cells are exceeded tenfold by the bacteria that colonise our skin and digestive tract.

Bacteria mutates
The key to their ability to develop resistance to antibiotics is that they can mutate (change their genetic structure). In a person with an active infection each bacterium may replicate as often as every 20 minutes.

With each division mutations develop spontaneously in their DNA and while most of these random reshufflings merely create useless or debilitating traits every now and again they may give a bacterium a survival advantage – such as the ability to pump out drugs from inside their cells or produce enzymes to chew them up.

Streptococcus pneumoniae, the bacterium most often responsible for pneumonia and meningitis (an infection of the membranes lining the brain), is now routinely resistant to penicillin. And the dreaded methicillin-resistant Staphylococcus aureus (MRSA), one of the so-called hospital superbugs, is becoming increasingly resilient to salvage therapy.

Even more alarmingly, these resistant bacteria are breaking out to infect healthy people outside hospital wards.

Antibiotics to blame
The rampant overuse of antibiotics and the prescribing habits of overzealous doctors are largely to blame. A study in the Journal of the American Medical Association found half of patients with a common cold were given antibiotics – even though antibiotics work only against bacteria and a cold is caused by a virus.

The situation is made worse by human behaviour. Patients often don’t follow the instructions when taking antibiotics or stop taking them when their symptoms improve but before the infection has completely cleared up.

And when faced with sub-lethal concentrations of antibiotics the hardier bacteria soon outnumber their more susceptible cousins, encouraging the development of resistant strains.

(This is an edited version of a story that originally appeared in YOU Pulse / Huisgenoot-POLS magazine, Autumn 2008. Buy the latest copy, on newsstands now, for more fascinating stories from the world of health and wellness.)

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Raiding the arsenal

 
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