Biofilms: Health implications and control in clinical settings

Biofilms are structured communities of microorganisms that adhere to biotic or abiotic surfaces and are enclosed within a self-produced matrix of extracellular polymeric substances. The transition of microbial cells from the free-living planktonic state to the sessile biofilm mode of growth is a major survival adaptation, conferring altered physiology, reduced antimicrobial susceptibility and heightened tolerance to host defences. In clinical settings, biofilms are recognised as a central cause of persistent, chronic and recurrent infections, and most human microbial infections are thought to involve a biofilm component. This narrative review examines the structure and developmental life cycle of biofilms, the clinically important biofilm-forming microorganisms, and the mechanisms by which biofilm-associated cells resist and tolerate antimicrobial therapy, including restricted drug penetration, altered microenvironments, slow growth and persister cells. The health implications of biofilms are discussed with reference to indwelling medical device infections, chronic wounds, cystic fibrosis, infective endocarditis, chronic otitis media, periodontitis and healthcare-associated infections. Laboratory approaches for detecting biofilm production are reviewed, including the tissue culture plate method, the tube method, Congo red agar, and microscopic and molecular techniques. Prevention and control strategies are considered, ranging from aseptic device management and antimicrobial-impregnated biomaterials to emerging approaches such as quorum sensing inhibition, matrix-degrading enzymes, bacteriophage therapy, antimicrobial peptides and nanotechnology. A sound understanding of biofilm biology is essential for the medical laboratory scientist, who plays a pivotal role in the detection, surveillance and control of biofilm-associated disease and in the containment of antimicrobial resistance.