LASA, ALKALINE PROTEASE AND ELASTASE IN CLINICAL STRAINS OF PSEUDOMONAS-AERUGINOSA - QUANTIFICATION BY IMMUNOCHEMICAL METHODS

Thirty Pseudomonas aeruginosa strains were isolated from the sputa of cystic fibrosis patients. In each culture supernatant, the amount of t hree exoproteases (LasA, alkaline protease and elastase) was determine d using immunochemical procedures. These assays used selected peptide- MAP (multiple antigen peptide) strategy as antigen for animal immunisa tion. The method appeared to be reproducible, simple, sensitive and sp ecific without cross-reactivity between the antisera. The resulting va lues differed from one strain to another mostly for elastase productio n. Despite the fact that four genes (lasA, lasB, lasR and rhlR) were s hown to be necessary for full elastolytic activity, it was obvious tha t if LasA was not secreted in a naturally non-elastase-producing strai n, in return in an elastase-producing strain, there were no apparent r elationships between LasA and elastase production and between LasA and alkaline protease secretion. Furthermore, in vitro, the secretion of the three exoproteases seemed to be independent of the mucoid or non-m ucoid phenotype of the bacteria.