A Review on Resistance Mechanisms in Bacterial Biofilm Formations

The purpose of this review is to present the mechanisms that cause the emergence of resistance to antimicrobial therapy in bacterial biofilms. Biofilm-producing bacteria cause chronic and persistent infections. They develop in joint prostheses, intravenous catheters and stents, endotracheal tubes and cardiovascular devices. The problem is enormous as it results in increased hospitalization costs, multiple surgeries and prolonged antibiotic intake. The mechanisms of resistance of bacterial biofilms differ from those of planktonic cells. They include as follows. Host defense bypass mechanisms, glycocalyx and extracellular polymeric substances (EPS), enzyme-mediated resistance to antibiotics, cell heterogeneity in metabolism and growth rate, Quorum Sensing (QS, Cell to cell signaling), persister cells, genetic adaptation and mutations, efflux pumps, adverse environmental conditions, outer membrane structure, bacteriophages, interactions between different types of bacteria in polymicrobial biofilms. Which mechanism or combinations of mechanisms are used, depends on the type of microorganism. Therefore, analysis and further elucidation of their function will assist in identifying ways in which to deal with the serious infections caused by biofilms.