New knowledge about the way communities of bacteria send out scout cells to swarm around and invade new locations could lead to new treatments to prevent infections from spreading, experts heard today.The presentation was made at the bi-annual meeting of the Society of General Microbiology at the University of East Anglia in the UK.
According to Professor Rasika Harshey of the University of Texas at Austin, "Swarming plays an important role in colonization by many species of bacteria, which grow in protective communities called biofilms.
"We've examined mutant strains of swarming bacteria and have found that they can't make a substance called lipopolysaccharide, which acts like a detergent. These mutants can stick better to plastic surfaces and make better biofilms.”
Biofilms can grow on any damp surface, such as the slime that forms down plugholes, or dental plaque. But they can also cause serious hospital acquired infections of surgical implants and catheters.
“Bacterial biofilms are formidable since they are resistant to antibiotics and the immune system. They provide a continuous supply of bacteria which can slough off and disseminate throughout the body, causing persistent infection,” Professor Harshey says.
He adds, “We know that both swarming and biofilm bacteria produce chemical signals which affect the behavior and appearance of their comrades. Biofilm bugs tell their mates to find a good spot and start building a biofilm, whereas swarming bacteria signal to others to head out and search for new territory.
“Now we have found that we can prevent biofilm formation by adding a surfactant (the active ingredient in detergents), which stops bacteria from sticking to surfaces.
"We have tested a number of chemical and biosurfactants, several of which inhibited biofilm development. For example, the naturally occurring surfactant ‘surfactin’ prevented Salmonella enterica from growing in urethral catheters.
"This research could soon lead to safer hospital stays and fewer infections of medical implants,” says Professor Harshey.
The Society for General Microbiology is the largest microbiology society in Europe, and has over 5,500 members worldwide. The Society provides a common meeting ground for scientists working in research and in fields with applications in microbiology, including medicine, veterinary medicine, pharmaceuticals, industry, agriculture, food, the environment and education.
(Editor's Note: A review of Professor Harshey's conference presentation, "Coming out on the surface: alternate life-styles of Salmonella typhimurium," is in press in the Journal of Bacteriology.)
[Contact: Professor Rasika M Harshey]
13-Sep-2001
