Antimicrobial molecules become virulent

SEATTLE, Aug 18, 2005 (United Press International via COMTEX) -- A molecular mechanism allows bacteria to recognize antimicrobial peptide molecules and then respond by becoming virulent, say U.S. and Canadian researchers.

Many living things, from fruit flies to people, naturally produce disease-fighting chemicals, called antimicrobial peptides, to kill harmful bacteria. In a counter move, some disease-causing bacteria have evolved microbial detectors. The bacteria sense the presence of antimicrobial peptides as a warning signal. The alarm sets off a reaction inside the bacteria to avoid destruction, according to researchers at University of Washington in Seattle and McGill University in Montreal.

The findings, done on the bacterium Salmonella typhimurium, were published in the journal Cell.

Salmonella typhimurium can contaminate meats such as beef, pork and chicken, as well as cereals and other foods, and cause severe intestinal illness. Certain strains of the bacteria are difficult to treat, and are behind the increase of salmonellosis in people. Some food science institutes anticipate that virulent strains of salmonella will become more common throughout the food chain, according to Dr. Samuel Miller, of the University of Washington.