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Biofilms are omnipresent.In mountain lakes, they may serve as indicators of environmental influences [12]. Biofilms are found in water drinking distributors [13] and in water hydraulic systems [14]. Biofilms might be a reservoir for pathogens, water systems may distribute Chlamydiales, Legionella sp. [15], and drains are a source of Pseudomonas aeruginosa [16].

After being neglected for several decades, biofilms are gaining more and more interest in medicine. There are infections associated with biofilm formation on incorporated materials or medical devices used for treatment. Furthermore, other infections are clearly associated with biofilms, such as chronic wound infections and lung infections in cystic fibrosis. The diagnostic criteria for identifying a biofilm-associated infection are a localized chronic or foreign infection, or a medical history of predisposing factors for biofilm formation, such as cystic fibrosis, a recurrent infection, and antibiotic failure, among others [3].

Chronic wound infections, such as diabetic food ulcera, develop slowly and are difficult to eradicate. The majority of these infections are biofilm associated, the healing time is prolonged as microorganisms in biofilms are protected against host response, and furthermore, the biofilm may act as a barrier against re-epithelialization [17]. Cystic fibrosis is a congenital disorder and affects many organs, clinically characteristic is the production of mucous and repeated respiratory infections. Often the lower respiratory tract is infected with P. aeruginosa as a biofilm-growing species, which means the host response is unable to clear the chronic infection [18]. The gastrointestinal tract is highly colonized by different microorganisms. Within the mucous layer, the close contact enables biofilm formation. Also, the ability of Clostridium difficile to form biofilms hinders treatment with antibiotics [19].

Modern medicine incorporates biomaterial into the human body, either temporary as central venous catheters or permanently as a joint arthroplasty. These artificial surfaces are immediately coated by conditioning layers and predestined to be colonized by microbial biofilms. Gram-negative rods such as Pseudomonas sp. and Acinetobacter sp., and also oral bacteria such as streptococci and Neisseria sp. are frequently found in biofilms formed in endotracheal tubes [20]. Prosthetic joint infections are the main reason for periprosthetic joint infection; they are the most common reason for revision of total knee arthroplasties and the third most common reason for revision of total hip arthroplasties [21]. The infections occur up to 24 months after surgery as a possible contamination during surgery and thereafter as a hematogenous spreading of microorganisms from other parts of the body. Most identified microorganisms are Staphylococcus aureus and gram-negative bacilli [22].