A biofilm is a community of microorganisms, such as bacteria, encased within a self-produced matrix that adheres to a surface. Biofilms are common inhabitants within the human body, forming in various locations.
Biofilms in Natural Body Environments
Biofilms form in several areas within the human body. The oral cavity is a prime example, with dental plaque being a well-known biofilm on teeth. These microbial communities also colonize the tongue and tonsils, thriving on moisture and food particles in saliva.
The respiratory tract also harbors biofilms, particularly in chronic sinusitis, where they are found in the sinuses. Biofilms can also colonize the lungs in individuals with cystic fibrosis or chronic obstructive pulmonary disease, benefiting from the moist environment and mucus. In the urinary tract, biofilms are present in the bladder and along the tract lining.
The gastrointestinal tract contains complex microbial communities that form biofilms along the gut lining. These biofilms contribute to overall gut health. On the skin, biofilms can develop, especially in moist areas or on wounds.
Biofilms on Medical Devices
Biofilms also establish themselves on artificial surfaces introduced into or onto the body. These medical devices provide stable environments ideal for microbial attachment and biofilm development. Catheters are common sites for biofilm formation, including urinary and intravenous (IV) catheters.
Prosthetic implants, such as joint replacements in hips and knees, as well as heart valves, are also susceptible to biofilm colonization. Dental devices, including dental implants, braces, and dentures, offer surfaces where microbes can adhere and form biofilms. Other devices like pacemakers, contact lenses, and endotracheal tubes can similarly become colonized by these microbial communities. The presence of these foreign materials provides a consistent substrate for microbial proliferation, distinct from the dynamic surfaces of natural tissues.
Factors Enabling Biofilm Persistence
The ability of biofilms to establish and persist across diverse bodily locations and on medical devices stems from several fundamental biological and environmental factors. Initial attachment of microbes to a surface is a necessary first step for biofilm formation. Once attached, the presence of available nutrients, derived from bodily fluids or consumed food, supports the growth and proliferation of microbial cells within the nascent biofilm.
A moist or fluid-rich environment is consistently required for biofilm development and its ongoing maintenance. A defining characteristic of biofilms is the production of an extracellular polymeric substance (EPS). This self-produced matrix provides structural integrity, encasing and protecting the microbial community, allowing it to persist. Microbes within the biofilm also engage in cell-to-cell communication, known as quorum sensing, which helps coordinate their collective behavior and enhances the community’s survival.