Prevention of Biofilm Formation Renders Bacteria Susceptible to Macrophage Attack

Microbiologists have used a recently patented antibiofilm enzyme to show that bacteria require both a leukotoxic agent and a surface polysaccharide to survive attack by immune system macrophages.

Biofilms are a major cause of a number of serious medical problems including chronic infections and medical device related infections. They develop on surfaces such as catheters, prosthetic implants, teeth, lungs, and the urogenital tract. Biofilms are pervasive, costly to deal with, and approximately 80% of all human bacterial infections involve biofilms.

Investigators from the University of Medicine and Dentistry (Newark, NJ, USA) worked with monolayer cultures of the human macrophage cell line THP-1. The cultures were infected with either wild type cultures of the bacterium Aggregatibacter actinomycetemcomitans (A.a) or with A.a mutants lacking either leukotoxin, a secreted lipoprotein that kills human polymorphonuclear leukocytes and macrophages, or poly-N-acetylglucosamine (PGA), a surface polysaccharide that mediates intercellular adhesion, biofilm formation, and detergent resistance.

In some experiments the bacteria were treated with Kane Biotech, Inc's (Winnipeg, MB, CA) patented antibiofilm enzyme Dispersin B, which is capable of both inhibiting and dispersing bacterial biofilms.

Results published in the June 5, 2008, online edition of the journal Microbial Pathogenesis revealed that pretreatment of wild-type A.a cells with the PGA-hydrolyzing enzyme dispersin B rendered them sensitive to killing by THP-1 cells leading to the conclusion that both leukotoxin and PGA were necessary for evasion of macrophage killing by A.a.

"Our studies showed that the pretreatment of biofilm-embedded A.a cells with DispersinB removes the biofilm and renders the cells sensitive to killing by the body's macrophages,” said senior author Dr. Jeffery Kaplan, professor of oral biology at the University of Medicine and Dentistry.

"The findings of Dr. Kaplan's group suggest that when DispersinB is used in products such as wound gels and device coatings, either in combination with an antimicrobial or alone, it makes biofilm-embedded bacterial pathogens susceptible to killing by both antimicrobials and macrophages or by our body's macrophages alone,” said Dr. Sri Madhyastha, CSO of Kane Biotech.


Related Links:
University of Medicine and Dentistry
Kane Biotech