title: Modulation of surface antigen expression by Klebsiella pneumoniae in response to growth environment.
abstract: Growth in pooled human body fluids [urine, serum and peritoneal dialysate (HPD)] modulated the expression of cell envelope antigens in virulent (serotype O1:K1) and avirulent (serotype O1:K66) Klebsiella pneumoniae strains. Marked variations in the outer membrane protein (OMP) and lipopolysaccharide (LPS) profiles were noted when broth-grown cells were compared with those of bacteria cultured in body fluids. In particular, for the O1:K1 serotype strain, growth in the latter resulted in: (a) the expression of at least five iron-regulated OMPs in the 74-87 kDa range, the pattern of which was medium dependent; (b) alterations in the migration of the LPS core polysaccharide; and (c) the reversion of isogenic O-:K+ and O-:K- mutants to the O+ phenotype after growth in fresh serum but not in heat-inactivated serum, urine or HPD. Similar results were obtained for the O1:K66 serotype, although no variation in the migration of the LPS core was noted. For both O1:K1 and O1:K66 serotypes, neither the surface exposure of O1 serotype LPS nor the production of K-antigen (capsular polysaccharide) was affected by growth in body fluids. No reversion of K- mutants to the K+ phenotype was observed. These data illustrate the phenotype flexibility of this opportunistic pathogen and emphasise the crucial role of the O- rather than the K-antigen in protecting K. pneumoniae from complement-mediated serum killing.
authors.affiliation: Department of Microbiology, Faculty of Biology, University of Barcelona, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Camprubi
authors.forename: M A
authors.initials: MA
authors.lastname: Smith
authors.forename: J M
authors.initials: JM
authors.lastname: Tomas
authors.forename: P
authors.initials: P
authors.lastname: Williams
mesh_terms: D000942:Antigens, Bacterial / Q000378:metabolism*; D000954:Antigens, Surface / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001826:Body Fluids / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007711:Klebsiella pneumoniae / Q000145:classification / Q000254:growth & development / Q000276:immunology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D012703:Serotyping; D017262:Siderophores / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; D008070:Lipopolysaccharides; D017262:Siderophores