ULTRASTRUCTURAL AND GENETIC ANALYSIS OF MUCOGENICITY IN KLEBSIELLA PNEUMONIAE

A mucoviscous clinical respiratory isolate of K. pneumoniae was found to produce 414 ng/106 CFU of polysaccharide. Transmission Electron Microscopy (TEM) revealed that the isolate has a dense thick capsule with a diameter of 190 nm. The isolate was harboring a single large plasmid encoding multiple resistance to antibiotics. The isolate was subjected to successive subculturing for 480 generation on M9 medium with and without 150 μg/ml salicylic acid at 37 ºC. Six mucoid variants were obtained, five (A, B, C, D and E variants) after salicylic acid treatment. The six derivatives varied in the quantity of polysaccharides produced, genetic and physical behavior and their fine structures as indicated by TEM photography. One of the variants (variant A) has a small capsule and its colonies lost the mucoviscous phenotype. Another (variant B) a non-capsulated as indicated by fluorescent antibody staining with antigen serum of wild type. Plasmid DNA was extracted from each of the six Klebsiella variants and transformed into E.coli MM294 competent cells. The transformed E.coli showed variable mucoid traits and resistant profile with temperature dependent gene expression of mucogenicity; one of the variants derived plasmid (pKP10) induced mucoid phenotype in E.coli at 37ºC, altered cell division at 37ºC and lead to its inability to ferment lactose on MacConkey medium at both 30 and 37 ºC.