Biofilms are syntrophic communities of microorganisms where the cells are embedded in a sticky matrix attached to surfaces or as suspended aggregates.

The sticky matrix produced by the microorganisms is composed of extracellular polymeric substances (EPSs). The EPS provides structure and protection for the microbial communities and creates chemical microenvironments.

In medicine, pathogenic biofilms have become recognized as a serious threat. The National Institutes of Health (NIH) estimates that over 80% of infections are biofilm related. Examples include, cystic fibrosis (CF), urinary tract infections (UTIs), bacterial endocarditis, otitis media, Legionnaire’s disease, skin and soft tissue infections, and indwelling medical device infections.

Biofilms that form on surfaces and water systems in health care facilities are also an important health concern as potential vectors of transmission of hospital acquired infections (HAIs).

Biofilms are 10 to 1,000 times more difficult to treat with antimicrobials because of a combination of factors: incomplete antibiotic penetration; altered chemical microenvironments; a subpopulation of persister cells that are dormant non-dividing cells with antimicrobial resistance (AMR); and the uptake of resistance genes by horizonal gene transfer.