Bacteria code is discovered

Researchers have cracked the codes that bacteria use to set upcolonies, offering a possible new tool against bacterial resistanceto disinfectants and antibiotics.

A study published today in the journal Science describes thechemical molecules that a microbe called Pseudomonas aeruginosa usesto tell its fellows to start forming up in sheets called biofilms.These are organized groups of single-celled animals that arrangethemselves to allow nutrients and waste to pass in and out of theirstructures.

While the research has no immediate practical application, itoffers hope of better control against the microbe, which is a leadingcause of hospital-acquired infections.Most bacteria live in such clusters, whether on a scummy rock ina creek or within a blood vessel or on a hospital instrument.Researchers have determined that microbes organized as biofilms aremuch harder to destroy, either with detergents or antibiotics."Bacteria love to stick, and once they settle down and make abiofilm, it's notoriously difficult to get rid of them," said BarbaraIglewski, professor of microbiology and immunology at the Universityof Rochester, N.Y., and a co-author of the study.Iglewski and colleagues from Rochester, the University of Iowaand Montana State University report having pinpointed the chemicalswitch that tells bacteria to start forming biofilm when it hits asuitable surface and begins congregating.The researchers found that by removing a gene that regulates thechemical signals, the Pseudomas bacteria are left with only a vagueidea how to colonize. Rather than forming elaborate pillars andmushroom domes, the genetically impaired bacteria simply clumptogether on top of one another and are much more susceptible toattack.When the scientists hit such a pile of germs with a detergent,the bacteria started falling apart in just 30 seconds and the scumwas gone in minutes.The rod-shaped germs target people whose immune defenses alreadyare weakened, such as post-surgical patients, burn victims, cancerpatients getting chemotherapy or patients hooked up to ventilators orcatheters, making it the No. 1 cause of hospital-acquired infections.