Bacterial biofilms are communities consist of single or multi-species bacteria that cooperate and interact with each other in different ways and with the surrounding environment, and perform complex processes, including the intercellular communication to affect the metabolic activities of each other by production of materials, trapping of nutrients, horizontal transmission of genetic material, in order to support each other biologically and physically to resist harsh environmental threats. The acquired characteristics by the bacteria after biofilm formation, including avoiding host immunity defenses, antibiotic therapies even with high doses, and biocides, make them a major health problem, as they are an important cause of medicaldevice related infection, like in case of prosthetic valves replacement, eye contact lenses and catheters. Recent studies are focusing on further discovering the mechanisms biofilms use to resist treatments to can find alternative effective ways to end their health risks.

biofilm structure; resisting antibiotics; nosocomial infections; water treatment; waste water