Biofilms are usually defined as surface-associated microbial communities, surrounded by an extracellular polymeric substance matrix. There are three major steps that are observed in biofilm formation: initial attachment events, microcolony formation and construction of mushroom-like structure with secretion of extracelluar polymeric substances. These substances can be considered a mechanism to protect the bacterial community from external insults.Biofilms, significantly increase the ability of the pathogen to evade both host defenses and antibiotics and they are being implicated in the pathogenesis and also clinical manifestation of several infections. They cause a variety of persistent infections, such as native valve endocarditis, osteomyelitis, dental caries, middle ear infections, ocular implant infections, urinary tract infections and cystic fibrosis. Established biofilms can tolerate antimicrobial agents at concentrations of 10–1000-times that needed to kill genetically equivalent planktonic bacteria, and are also resistant to phagocytosis, making biofilms extremely difficult to eradicate from living hosts. Consequently, biofilm-related infections that appear to respond to a therapeutic course of antibiotics may relapse weeks or even months later, making surgical removal and replacement of the infected tissue or medical device a frequent and unfortunate necessity.Several pathogens associated with chronic infections, including Pseudomonas aeruginosa in cystic fibrosis pneumonia, Haemophilus influenzae and Streptococcus pneumoniae in chronic otitis media and Enteropathogenic Escherichia coli in recurrent urinary tract infections, are linked to biofilm formation.