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Staying alive

Staying alive  it is not only humans that have understood the importance of sticking together for success. For long we have known that animals also keep together for survival. But few expected that tiny microbes also adopt this strategy to ward off the efforts of drugs and doctors to finish them. Now scientists are increasingly recognising this new weaponry in the hands of the bugs. That the bacteria have learnt to counter the might of both the immune system and antibiotics thrown at them to combat infections by this new strategy has just been reported.

Such treatment has generally proved ineffective if bacteria cluster in colonies called biofilms. Biofilms are organised groups of bacteria that work together to defend against attack from antibiotics and the body's immune system. Biofilms can grow from a bacterium that attaches to a surface, such as a cell lining a blood vessel. The bacterium may then begin to multiply and spread across the surface. When the cells reach a certain density, they build a complex biofilm structure. The all pervasive nature of this slimy conglomerate can be understood by the fact that they cause problems in a host of varied infections and organs. Biofilms foul tubules and implants, such as heart valves and artificial hips and they attack body tissues like teeth and gums, the lungs, the ears, and the urogenital tract.

According to the best known disease sleuths at the Centres for Disease Prevention and Control, Atlanta, usa , an estimated 65 per cent of all human bacterial infections involve biofilms ( Science , Vol 283, No 5409). Bacteria sequestered in biofilms are shielded from attack by the hosts' immune system and are often much harder to kill with antibiotics than their free floating cousins, says William Coserton, director of the Centre for Biofilm Engineering at Montana State University in Bozeman. This is why it is hard to rid the body permanently of some infections, such as those of the ear or the urinary tract.

Take for example the largest kind of infection suffered by humans

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