Surrogate marker of intestinal permeability: serum concentrations of IgA and IgM against LPS of Gram (-) enterobacteria: Hafnia alvei, Pseudomonas aeruginosa, Morganella morganii, Proteus mirabilis, Pseudomonas putida, Citrobacter koseri, Klebsiella pneumonia. This evidence concerns the gene CD79A and Klebsiella pneumonia.