title: A Klebsiella pneumoniae strain that shares a type-specific antigen with Shigella flexneri serotype 6. Characterization of the strain and strain and structural studies of the O-antigenic polysaccharide.
abstract: A strain of Klebsiella pneumoniae was found as the only isolate with pathogenic potential from the stool of a two-year old patient with diarrhoea. A strong serological cross-reactivity with Shigella flexneri serotype 6 was demonstrated. The cross-reacting antigens were shown to reside in the cell wall lipopoly-saccharide. Studies of the pathogenic potential of the Klebsiella strain showed low level of invasion of HEp-2 cells. However, tests for adherence to HEp-2 cells as well as tests for toxin production were negative. The strain had several small plasmids and was multidrug resistant. These data do not form a sufficient basis for estimating the pathogenic potential of the organism. No K antigen was detected. The structure of the O-antigenic polysaccharide from the K. pneumoniae strain was investigated using methylation analysis, NMR spectroscopy, and Smith degradation as the principal methods. The O-antigenic polysaccharide has the following pentasaccharide repeating unit: -->3)- alpha -L-Rhap-(1-->3)- alpha -L-Rhap-(1-->2)- alpha-L-Rhap- (1-->2)- alpha-L-Rhap-(1-->2)- alpha-L-Rhap-(1-->. This structure is not identical to any of the previously described O-antigens of K. pneumoniae. The strong serological cross-reactivity with the Shigella flexneri serotype 6 O-antigen can most likely be attributed to the structural element alpha-L-Rhap-(1-->2)- alpha -L-Rhap present in the O-polysaccharide repeating unit of this serotype. Antiserum raised against the K. pneumoniae strain also agglutinated S. dysenteriae serotype 1 and strains of all different serotypes of S. flexneri. The Shigella strains contain the structural element alpha-L-Rhap-(1-->3)- alpha-L-Rhap in their O-antigen polysaccharides which may be responsible for the observed cross-reactivity.
authors.affiliation: International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh.
authors.forename: M
authors.initials: M
authors.lastname: Ansaruzzaman
authors.forename: M J
authors.initials: MJ
authors.lastname: Albert
authors.forename: T
authors.initials: T
authors.lastname: Holme
authors.forename: P E
authors.initials: PE
authors.lastname: Jansson
authors.forename: M M
authors.initials: MM
authors.lastname: Rahman
authors.forename: G
authors.initials: G
authors.lastname: Widmalm
mesh_terms: D001422:Bacterial Adhesion; D002240:Carbohydrate Sequence; D002460:Cell Line; D002675:Child, Preschool; D003429:Cross Reactions; D005260:Female; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000276:immunology* / Q000302:isolation & purification / Q000472:pathogenicity; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D019081:O Antigens / Q000737:chemistry*; D012703:Serotyping; D012763:Shigella flexneri / Q000145:classification / Q000276:immunology*; D014774:Virulence / Q000276:immunology
chemical_list: D019081:O Antigens