Microbiology 2002, 148:3385–3394.PubMed Authors’ contributions AYo participated in the study design, wrote the manuscript, and was responsible for the overall coordination of the

study. AYa and SN performed the microbiological analysis, DNA manipulation, and PMA-qPCR analysis. KMo and KMa performed clinical examinations and sampling of oral specimens. IS and SA conducted statistical analyses. TA supervised this study.”
“Background Pseudomonas aeruginosa is a Gram-negative bacterium which is ubiquitous in water and soil. It is able to produce and secrete several hydrolases which are important for nutrition of the bacterium, for biofilm structure [1] and, moreover, as virulence factors [2]. As an opportunistic human pathogen, P. aeruginosa can #Belnacasan manufacturer randurls[1|1|,|CHEM1|]# cause severe acute and chronic infections, especially in immuno-compromized patients. In addition to infections of the urinary tract, wounds, middle ear and eyes, P. aeruginosa is well known as the causative agent of chronic lung infections of cystic fibrosis (CF) patients [3]. Most of these infections are biofilm-associated [4, 5]. Biofilms represent a bacterial state of life in which the cells are attached to biotic or abiotic surfaces or to each other. Thereby, they are embedded

in a matrix of self-produced Selumetinib mouse extracellular polymeric substances (EPS). Different amounts of polysaccharides, lipids, nucleic acids and proteins can be detected in the EPS matrix of biofilms formed by P. aeruginosa. Part of the proteins show enzyme activities in vitro and in vivo. The expression of several exoenzyme encoding genes was detected in the sputum of infected CF-patients by transcriptome analysis [6] and the presence of significant levels of extracellular enzyme specific antibodies

in sera of infected CF patients is an indirect evidence for the production of extracellular enzymes during infection processes [7, 8]. Therefore, the biofilm matrix of P. aeruginosa was described as a reservoir of enzymes [9]. The main extracellular enzymes produced by P. aeruginosa are type I and II-secreted hydrolases, including alkaline protease [10], elastase A (LasA) and B (LasB) [11], phospholipase C [12] and lipases [13, 14]. These enzymes alone or synergistically with others are causing cell death, severe tissue click here damage and necrosis in the human host [2, 15, 16]. The simultaneous production of these exoenzymes and polysaccharides were described for P. aeruginosa[17, 18]. During persistent CF-lung infections the conversion to a mucoid, i.e. an alginate overproducing phenotype is commonly observed [19]. Alginate is a high-molecular weight extracellular copolymer consisting the uronic acid monomers β-D-mannuronate and its C-5 epimer α-L-guluronate, which are linked by 1,4-glycosidic bonds [20, 21]. These components are arranged in homopolymeric blocks of poly-β-D-mannuronate and heteropolymeric sequences with random distribution of mannuronate and guluronate residues [22].