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Bacterial Biofilms: a Confrontation to Medical Science

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Bacterial Biofilms: a Confrontation to Medical Science International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391 Bacterial Biofilms: A Confrontation to Medical Science Sorabh Singh Sambyal1, Preeti Sharma2, Divya Srivastava3 1Ph.D Scholar, Jaipur National University 2Ph.D Scholar, Jaipur National University 3Joint Director, Life Sciences, Jaipur National University Abstract: Biofilms is a consortia of microorganisms in which microorganism adhere to a substratum in an irreversible manner and are enclosed in self – produced matrix of extracellular polymeric substance. Common example of biofilm are dental plaque, device associated infection. Mostly biofilms are infective in nature and can be a source of Nosocomial infection. According to a report published by national institute of Health about 65% of all microbial infections and 80% of all chronic infections are associated with biofilms. The structural anatomy of biofilms protects microbial cells from antimicrobial agents, UV rays. These biofilms act as a barrier; antibiotics cannot reach to these microbes hindering the killing of the microbes thus posing a serious threat to public health. Management of these bacterial biofilms requires an early detection method and development of novel and efficient control measures for treating patients improving patient care and timely management. Keywords: Biofilm, Biofilm-matrix Antimicrobial resistance, Polymeric Substances, Tissue-culture plate 1. Introduction London[9] In year 1933, Henrici presented his recorded observations concerning biofilms in which he observed that In nature, microorganism subsist primarily by adhering to water bacteria were not free floating, but they submerged and growing upon biotic and inanimate surfaces. These surface[8]. In year 1940, H. Heukelekian and A. Heller substrates can be of distinct forms, including those found in wrote about the development of bacterial slime and colonial aquatic system, soil and those on spectrum of indwelling growth attached to surfaces. In year 1943, Zobell described medical devices and those of on living tissue such as heart about seawater and described many of the fundamental valves or the lungs or the middle ear or dental enamel. No characteristics of attached microbial communities. In year bacterium is alone i.e. nearly all bacteria live with; depend 1973, Characklis examined microbial slimes in industrial on other microorganism for carbon, energy and other water systems and was able to demonstrate that they were nutrients. Thus, most of the bacteria in the world live in not only pertinacious, but also extremely resistant to micro ecosystem filled with hundreds of other disinfectants such as chlorine [10]. In 1978, Chesterton was microorganism. Researchers have recently realized that in instrumental in alerting the world about the importance of the natural world more than 99% of all bacteria exist as biofilms and coined the term biofilm. He also articulated a biofilm [1]. A biofilm is a well organized consortium of theory of biofilm that elucidated the mechanism by which microorganism. Biofilm associated cell is differentiated Microorganism cohere to living and non living materials and from suspended counterparts by reduced growth rate, up and the benefits accumulated by this ecological niche. Micro- down regulation of gene and generation of extra polymeric organism constitutes the most successful form of life on matrix (EPSs). Primarily comprised of complex mixture of earth and effect human existence directly or indirectly by polymers comprising polysaccharides, as well as proteins, carrying out processes in nature and manmade nucleic acids, lipids and humid substances [2,3]. These environments. [9] Mechanism of biofilm formation Biofilm polysaccharides are major components of EPS and they also may be formed on broad motley of substratum including mediate most of the cell-to- cell and cell-to-surface living tissues, indwelling medical devices, Indus or portable interaction required for biofilm formation and water system piping or natural water system piping. The stabilization.[4] It manifests an altered growth rate and biofilm on the medical devices composed of a single coccid transcribes gene that free floating counterparts do not organism and the associated extracellular polymeric transcribe.[5] Microbial adhesion to hydrophilic and substance's matrix [8]. The formation process of biofilm is hydrophobic surfaces is influenced by the EPS to some extremely complex, in which Microorganism cells transform extent. It has also been showed that the formation of EPS from plank tonic to sessile mode of growth. It has also been leads to irreversible attachment with different surfaces. It insinuated that the formation of biofilm depends upon the also helps the microorganisms to escape their killing by expression of specific genes that directs the constitution of antibiotics.[6,7,8] biofilm[11,12]. A fully developed biofilm is composed of many layers comprising a matrix of exopolysaccharide with 2. A Brief History and Development vertical structures, and a conditioning film. Vertical structures of Microorganisms sometimes they took the form In year 1684, a Dutch named Antonie Van Leeuwenhoek of towers or mushrooms, and are set-apart by interstitial displayed animalcule (bacteria) found in the plaque of teeth spaces. that he reported in his report submitted to Royal society of Volume 6 Issue 1, January 2017 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Paper ID: ART20164426 1608 International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391 3. Formation of a biofilm occurs Step by Step worker reveals that Staphylococcus aureus biofilms required 110 times the MBC of vancomycin to provide a 3-log 1) Repositioning of the conditioning film which affects reduction [21]. The effect on susceptibility may be built-in the surface properties of the substratum and introit or acquired. Antimicrobial agents must diffuse through the microorganism to conglutinate to the surface. EPS matrix to contact and inactivate the organisms within 2) Attachment of the Microorganism (Planktonic) with the the biofilm. Extra Polymeric substances retard diffusion conditioning film. either by limiting the transport rate or by chemically reacting 3) Bacterial colonization and Growth. The bacteria begin with the antimicrobial molecules. Hoyle and his co- workers to multiply while effusing chemical signals that were able to demonstrate that the EPSs of Pseudomonas „intercommunicate‟ among the bacterial cells. Once the aeruginosa was capable of binding tobramycin where as signal intensity exceeds, the genetic mechanism dispersed cells were 15 times more susceptible to this underlying exopolysaccharide production is activated antibiotic than were cells in intact biofilms. Also, biofilm- where production of polysaccharides helps to anchor the associated organisms have reduced growth rates, minimizing bacteria to the surface allowing it to multiply within the the rate that antimicrobial agents are taken into the cell and embedded exopolysaccharide matrix, thus giving rise to thus affecting inactivation kinetics [22]. Du Guid and his co- the formation of micro colonies. [2, 13,14,15]. worker discovered that an explosive growth rate resulted in 4) Biofilm formation, whereas an amply matured biofilm an increase in susceptibility of Staphylococcus epidermidis will include an EPS matrix and vertical structures biofilms. They also demonstrated that ciprofloxacin activity isolated by interstitial surfaces. It has been suggested that was influenced by the cell cycle; newly formed daughter these interstitial spaces channels constitute primitive cells were more susceptible than other populations in the circulatory system, delivering nutrients to and removing biofilm. The surrounding environment of the cells within a waste products from the communities of cells in the biofilm may provide conditions that further guards the micro colonies. Some cells are taken up to the surface for organism.[23,24].Research had showed that plasmids can be only a limited time, before being de adsorbed, in a exchanged in biofilms under a number of conditions. process called “reversible adsorption”. The initial Plasmids are extra chromosomal circles of DNA that may connection is based on electrostatic attraction and encode resistance to a large number of antimicrobial agents, physical forces, but not due to any chemical attachments. including b-lactams, erythromycin, amino glycosides, Some of these reversible adsorbed cells begin to make trimethoprim, tetracycline, glycopeptides, and sulfonamides preparations for a lengthy stay by forming structures [25]. A large number of bacterial species showed transfer of which may then permanently hold-fast them to the plasmids to other bacterial species [26]. Ehlers and Bower surfaces within the next few hours, the trailblazer cells demonstrated transfer of plasmid via conjugation between proceed to reproduce and the daughter cells, from micro different gram-negative bacteria growing in biofilms [27]. colonies on the surface and begin to produce a polymer The rates of horizontal plasmid transfer were several orders matrix around the micro colonies, in an irreversible higher in biofilms than in liquid cultures of the same step.[16] organisms. Other investigators were also able to demonstrate 5) Detachment:-After biofilm formation, some bacteria are similar phenomenon [28–30]. Both
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