ULTRASTRUCTURAL AND GENETIC ANALYSIS OF MUCOGENICITY IN KLEBSIELLA PNEUMONIAE

Abstract

A mucoviscous clinical respiratory isolate of K. pneumoniae was found toproduce 414 ng/106 CFU of polysaccharide. Transmission Electron Microscopy(TEM) revealed that the isolate has a dense thick capsule with a diameter of 190nm. The isolate was harboring a single large plasmid encoding multipleresistance to antibiotics.The isolate was subjected to successive subculturing for 480 generation onM9 medium with and without 150 μg/ml salicylic acid at 37 ºC. Six mucoidvariants were obtained, five (A, B, C, D and E variants) after salicylic acidtreatment. The six derivatives varied in the quantity of polysaccharidesproduced, genetic and physical behavior and their fine structures as indicatedby TEM photography.One of the variants (variant A) has a small capsule and its colonies lost themucoviscous phenotype. Another (variant B) a non-capsulated as indicated byfluorescent antibody staining with antigen serum of wild type.Plasmid DNA was extracted from each of the six Klebsiella variants andtransformed into E.coli MM294 competent cells. The transformed E.coli showedvariable mucoid traits and resistant profile with temperature dependent geneexpression of mucogenicity; one of the variants derived plasmid (pKP10)induced mucoid phenotype in E.coli at 37ºC, altered cell division at 37ºC andlead to its inability to ferment lactose on MacConkey medium at both 30 and 37ºC.