Bacterial Biofilm Formation by Clinical Isolates and their Clinical Impacts in Chronic Infections
Author(s): Taghreed Y Jamal, Magda M Aly* and Samyah Jastaniah
Abstract
Bacterial biofilm is a structured community of bacterial cells adherent to a surface and enclosed in a self-produced Exopolymeric substance (EPS) matrix which is mainly consists of polysaccharides and other biomolecules. Advantages for bacteria associated with biofilm formation include protection from the environment, nutrient availability, metabolic cooperation and acquisition of new genetic material. Many several pathogenic species have been reported to be able to form bio?lms such as Listeria monocytogenes, Streptococcus mutans, Staphylococcus aureus, Staphylococcus epidermidis, E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. The formation of biofilms depends on physical factors, such as composition of the nutrient media, pH, temperature and biological factors. Bacterial biofilms are extremely linked with and controlled by bacterial quorum sensing (QS) which is a cell-to-cell communication system that allows bacteria to monitor their population density and control the physiological processes by releasing and receiving small signal molecules called auto inducers (AIs). Biofilm formation is a significant virulence mechanism in the pathogenesis of many medically important bacterial pathogens causing serious life-threatening infections. The importance of biofilm-related infections arising from indwelling medical devices and implants such as catheters, artificial joints and contact lenses has been highlighted. Bacteria within the biofilm can persist, causing chronic and recurrent infections and developing antibacterial and immunological resistance. Several mechanisms contribute to biofilm resistance to antimicrobials, such as low penetration of the antimicrobial agent due to biofilm matrix barrier function, presence of persistent dormant cells, and small, highly resistant variant colonies. In spite of multiple mechanisms of biofilm resistance to antibacterial agents which vary with the bacteria present in the biofilm and the antibiotic being applied. Thus, new strategies for the prevention, dispersal and treatment of bacterial biofilms are urgently required.