## 3 Biological Mechanisms in Bacterial Adhesion as Potential Subjects of Label-Free Monitoring
### Role of Bacteria's Glycocalyx in Their Adhesion
Pathogens in the urinary tract have well-developed glycolayxes that protect the cells from being washed out with the urine. The specificity of some bacteria that invade only a certain host tissue is in correlation with the specificity of the glycoloxy for the host-tissue cells [18]. In contrast, pathogenic bacteria adhere to tissues and induce acute disease by the production of enzymes/toxins or adhere to a tissue and multiply until they inhibit organ function and cause a cryptic disease [19]. Animal pathogens within infected tissues have thick glycolayves [19; 329]. Most importantly, the glycoloxyx prevents desiccation of the bacteria and also plays a role in retaining digestive enzymes produced by the bacterial cell and directing them against the host cell. Similarly nutrient molecules and ions in the immediate environment can be bound in the glycoloxy. In some illnesses, the production of bacterial glycolayxes and thereby the virulence of bacteria seems to be increased by increased concentrations of particular nutrients. Attachment to a surface protects the bacterial cells from particular protozoans, furthermore, the glycoloxyx is a physical margin against bacterial viruses and predatory bacteria [18]. The glycoloxyx prevents host antibodies binding to bacterial antigens, for example, in case of _P. aeruginosa_ in the urinary tract [18; 319]. In many chronic illnesses, bacteria form biofilms, which are communities of bacteria encased in their glycoloxy on different surfaces [18; 330; 331; 332; 333]. The general stages of biofilm development are the adhesion of planktonic bacteria to the surface (reversible-irreversible attachment, influenced by hydrodynamic forces, gravitational forces, nutrient levels, chemotaxis, ionic strength, pH, temperature, and adhesive molecules), microcolony formation, biofilm maturation (gene expression alterations, upregulating factors favoring sessility, increase of cDNA amounts, regulation of DNA release by Atn autolysin) and dispersal (escape from the matrix) [334]. Bacteria in biofilms are very resistant; they can be 1000 times more resistant to antimicrobial treatments than planktonic bacteria of the same species [330; 331]. Biofilm formation is the serious clinical problem--65% of all human bacterial infections involve biofilms [330; 333]. Due to their high resistance to antibiotic treatments, the best treatment for foreign body-associated biofilm infections is to remove the infected device, but the removal is difficult in some cases such as prostheses, cardiac implants, and pacemakers [334; 335]. Therefore, numerous studies have focused on ablating bacterial adherence as the first step of biofilm formation with mannosides, pilicides, and curlicides [334]. Other agents inhibit the enzymes involved in the synthesis or modification of matrix components destabilize biofilm architecture by interfering with bacterial membrane stability or alter signaling cascades [334]. We would like to point out that the term \"glyocolxyx\" was abandoned in favor of \"extracellular polymeric substances\" (EPS) [336]. In 1978, the matrix material was considered to be polysaccharides [18; 336]. Later, it turned out that lipids, nucleic acids, and proteins are its other major constituents [336]. The role of the EPS matrix turns out to be fundamental for maturing biofilms [336].