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Abstract: Biofilms are clusters of one or more microbes such as bacteria or fungi attached to a surface embedded in a self-produced matrix. From a medical perspective, biofilms have significant effects on human health and medicine. This article talks about Biofilms and their impact on human health.
It is a general misconception that bacteria exist as individual organisms in a planktonic state. Although ecologists observed as early as the 1940s that more microbes in aquatic environments were found attached to surfaces (sessile) than were free-floating (planktonic). Microorganisms have been shown to naturally accumulate on a wide variety of surfaces, where they form sessile, sedentary communities. Those surfaces include household and industrial pipes, biomaterials such as contact lenses, medical devices, and plant and animal tissues. These accumulations of microorganisms of mono- or poly-microbial aggregates are commonly referred to as biofilm and can consist of diverse communities of bacteria and fungi. Biofilm formation is apparently an ancient ability among the microbes, as evidence for biofilms can be found in the fossil record from about 3.4 billion years ago.
In microbiology, Biofilms are defined as communities of microorganisms that grow together encased in the extracellular matrix they secrete themselves. This extracellular matrix is composed of proteins, extracellular deoxyribonucleic acid (DNA) and exopolysaccharides (EPS). Biofilms are ubiquitous in nature, where they are most often seen as layers of slime on rocks or other objects in the water.
Biofilms can form on virtually any surface once it has been conditioned by proteins and other molecules present in the environment. Initially, microbes attach to the conditioned surface but can readily detach. Eventually, they begin releasing polysaccharides, proteins, and DNA and these polymers allow the microbes to stick more stably to the surface. The microbes reproduce and secrete additional polymers as the biofilm thickens and matures. The result is a complex, dynamic community of microorganisms. The microbes interact in a variety of ways. For instance, the waste products of one microbe may be the energy source for another microbe. The close proximity of the microorganisms enables substrate exchange, distribution of metabolic products and removal of toxic end products so that the different species can support each other. Members of the biofilm community can take up the DNA present in the extracellular slime. Thus, genes can be transferred from one cell (or species) to another.
Biofilms can be found almost anywhere and may impact human health both positively and negatively. One example of a positive effect includes the biofilms of commensal bacteria such as Staphylococcus epidermidis, which disrupts the colonization of potentially pathogenic bacteria through the stimulation of host-cell immune defences and the prevention of adhesion. However, biofilms are more often associated with many pathogenic forms of human diseases and plant infections. Biofilm disease includes device-related infections, chronic infections in the absence of a foreign body, and even malfunction of medical devices.
It has been found that chronic infections and biofilms are closely related. The colonization of P. aeruginosa growing as biofilms in the lungs of patients with cystic fibrosis was one of the first infections associated with this microbiological characteristic. Biofilms are also found to facilitate the development of chronic infections such as chronic otitis media, osteomyelitis, wounds, kidney stones, endocarditis, gingivitis, among others. Of significant concern is the formation of biofilms on medical devices such as hip and knee implants, contact lenses, intravascular catheters, joint prostheses and urinary catheters. These biofilms often cause severe illness and failure of medical devices.
It is currently known that biofilm pathogenesis lies mainly in their capability to generate persistent chronic infections, which are challenging to eradicate. This is due to the fact that microorganisms that grow inside biofilms increase their tolerance to antimicrobial molecules (antibiotics and antiseptics) and develop mechanisms of resistance to antibiotics. Also, the EPS of the extracellular matrix help to evade the host immune response. While in the biofilm, microbes are protected from numerous harmful agents such as UV light, antibiotics, and other antimicrobial agents. This is partly due to the extracellular matrix in which they are embedded, but it is also due to physiological changes. Indeed, numerous proteins synthesized or activated in biofilm cells are not observed in planktonic cells and vice versa. A small percentage of microorganisms developing within the biofilm is known to be highly tolerant to antibiotics and has typically been involved in causing a relapse of infections.
The resistance of biofilm cells to antimicrobial agents has serious consequences. Infections caused by biofilm formation are challenging to treat. When biofilms form on a medical device such as a hip implant, they are difficult to kill and can cause serious illness. Often the only way to treat patients in this situation is by removing the implant generating higher costs for both patients and the health care system.
Due to the widespread distribution of biofilms in diseases and their resilience to numerous antimicrobial treatments, biofilm research is receiving more attention. Owing to increasing antimicrobial resistance, the focus of current research is shifting from targeting bacterial growth/division that causes cell death or dormancy toward novel approaches. By this means, health systems could save the high economic costs generated by infections associated with biofilms caused by hospitalization costs and prolonged antimicrobial treatments. Moreover, the use of these treatments would avoid the consequences that these types of infections can generate for patients.
References
Willey, J.M.S.L.M.W.C.J., Biofilms Are Common in Nature, in Prescott’s Microbiology 2017, McGraw-Hill Education, 2 Penn Plaza, New York, NY 10121. p. 151.
Biofilms and their role in pathogenesis | British Society for Immunology. Immunology.org. (2022). Retrieved 15 March 2022, from https://www.immunology.org/public-information/bitesized-immunology/pathogens-and-disease/biofilms-and-their-role-in.
Ortega-Peña, S., & Hernández-Zamora, E. (2019). Microbial biofilms and their impact on medical areas: physiopathology, diagnosis and treatment. Boletín Médico Del Hospital Infantil De México (English Edition), 75(2). https://doi.org/10.24875/bmhime.m18000026
About the Author
Author: Sanyami Jain
About the author: Sanyami is a recent graduate from Daulat Ram College, Delhi University majoring in botany along with Zoology and chemistry as minors. Her research interests lie in Cancer biology, Immunology and Metagenomics. She is fascinated by the molecular mechanisms of cancer cells and how the same mechanisms can be used to treat cancer. Sanyami is extremely passionate about having a career as a researcher. She aims to pursue higher studies in the domain of cancer biology. She aspires to become a cancer biologist and someday have her own research laboratory.
Editor: Shubhi Agrawal
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