A review of genes related to biofilm formation in Enterococcus faecium

Enterococcus faecium is of great importance among the species of this genus due to its antibioticresistance and biofilm formation. Several factors such as antibiotic resistance, expression of genesinvolved in pathogenesis, adhesion, and biofilm formation are involved in the stability of bacteria underdifferent conditions and also the spread of infection. Among these factors, the ability to form biofilm onliving surfaces can be an important factor in the occurrence of some diseases such as endocarditis, urinarytract infection, dental root infections, and eye infections.Studies show that biofilm formation in Enterococcus faecium depends on various factors such as multiplegenetic factors, and some signals and environmental conditions, many of which require furtheridentification and research. From a genetic point of view, attachment to surfaces, which is the first step inthe formation of a microbial biofilm, takes place in Enterococcus faecium through the esp gene. Then, inthe stages of biofilm formation, the bop gene and a series of important genes, especially the fsr locus, areinvolved in the production of surface proteins and polysaccharides. This locus, which encodes aregulatory system, is able to strongly affect virulence and biofilm formation. During the molecularinvestigations, it was found that the mentioned locus contains the fsrA, fsrB, and fsrC genes, and the fsrBgene itself can induce the production of two other genes, gelE and sprE. These genes, locatedimmediately downstream of the far regulon, encode two enzymes, gelatinase and serine protease,respectively. Polysaccharides that Enterococcus secretes in the form of capsules or exopolysaccharidescan be involved in the formation of its biofilm. Research shows that sal, atn, epa, dltA, ebpABC, and beegenes play an important role in the production of polysaccharides, and by increasing their expression, theamount of production and attachment to the extracellular matrix also increases. Therefore, a completeunderstanding of the role of genetic and environmental factors involved in the development of biofilmmay lead to the improvement and development of disease control strategies related to biofilm formationin Enterococcus species. Therefore, considering the special importance of Enterococcus faecium in theproduction of microbial biofilm, the purpose of this review is to investigate the role and mechanism of thegenes effective in the occurrence of biofilm of this species

Keywords:

Enterococcus faecium , Biofilm genes , pathogenesis mechanism