Pathogenesis of Klebsiells airway infections
Principal Investigator: Steven Clegg
Affiliation: University of Iowa
Abstract: The opportunistic pathogen, Klebsiella pneumoniae, is responsible for a significant number of pulmonary infections in compromised individuals. The ubiquity of antibiotic resistant strains, particularly those producing extended-spectrum beta-lactamases, presents a serious clinical problem among groups such as hospitalized individuals and chronic alcoholics. The pathogenesis of Klebsiella airway infections has not been studied to any great extent and the investigation of the production of virulence determinants has essentially focused upon the role of capsules as antiphagocytic factors. The mouse has been extensively used as a model of airway infections due to K. pneumoniae primarily to investigate host cell responses. Also, epidemiologic observations suggest that specific capsular serotypes (e.g. K2) are most frequently associated with pulmonary infections. However, our preliminary data indicate that not all K2-positive isolates are virulent in the mouse model of infection. Therefore, although the capsule is most likely to be an antiphagocytic factor and prevent efficient killing of the bacteria in vivo, additional factors are necessary to establish airway infections with subsequent invasion of the bloodstream. We propose to identify and confirm the role of previously unknown virulence factors that mediate airway infections due to K. pneumoniae. Three techniques; signature-tagged mutagenesis, subtractive hybridization and in vivo gene expression technology will identify these determinants. The murine model of Klebsiella infection will be used to demonstrate the role of putative virulence factors during infection. The three approaches are complementary and have been used to investigate virulence in many different types of pathogens. Since very little is known about the virulence factors of K. pneumoniae, it is anticipated that these studies will provide information on new and novel virulence factors produced by these bacteria. Fundamental to devising new therapeutic approaches to opportunistic infections will be an understanding of the virulence factors produced by this group of organisms.
Funding Period: 2003-04-01 - 2009-03-31
more information: NIH RePORT
- Klebsiella pneumoniae type 3 fimbria-mediated immunity to infection in the murine model of respiratory diseaseHeather Lavender
College of Medicine, Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
Int J Med Microbiol 295:153-9. 2005..However, challenge with a high number of bacteria resulted in no protection against infection...
- Biofilm formation by Salmonella enterica serovar Typhimurium and Escherichia coli on epithelial cells following mixed inoculationsCristina L C Esteves
Department of Microbiology, University of Iowa College of Medicine, 51 Newton Road, 3334 -BSB, Iowa City, IA 52242, USA
Infect Immun 73:5198-203. 2005..enterica serovar Typhimurium. The results of this study indicate that S. enterica serovar Typhimurium can outgrow E. coli in heterologous infections and displace E. coli when it forms a biofilm on HEp-2 cells...
- Signature-tagged mutagenesis of Klebsiella pneumoniae to identify genes that influence biofilm formation on extracellular matrix materialJennifer D Boddicker
Department of Microbiology, College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
Infect Immun 74:4590-7. 2006..We identified mutations in the cps capsule gene cluster, previously unidentified transcriptional regulators, fimbrial, and sugar phosphotransferase homologues, as well as genetic loci of unknown function, that affect biofilm formation...
- A Dam methylation mutant of Klebsiella pneumoniae is partially attenuatedJoanna S Mehling
Department of Microbiology, The University of Iowa, Iowa City, IA 52242, USA
FEMS Microbiol Lett 268:187-93. 2007..In K. pneumoniae, a mutation-eliminating Dam function is shown here to result in only partial attenuation following intranasal and intraperitoneal infection of Balb/C mice...
- Identification of Klebsiella pneumoniae genes uniquely expressed in a strain virulent using a murine model of bacterial pneumoniaHelen Y Lau
Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109, USA
Microb Pathog 42:148-55. 2007....
- Utilization of an intracellular bacterial community pathway in Klebsiella pneumoniae urinary tract infection and the effects of FimK on type 1 pilus expressionDavid A Rosen
Department of Molecular Microbiology, Washington University School of Medicine, 660 S Euclid Ave, St Louis, MO 63110, USA
Infect Immun 76:3337-45. 2008..Thus, K. pneumoniae appears programmed for minimal expression of type 1 pili, which may explain, in part, why K. pneumoniae is a less prevalent etiologic agent of UTI than UPEC...
- A murine model of urinary tract infectionChia Suei Hung
Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, USA
Nat Protoc 4:1230-43. 2009..Nevertheless, one should expect 4 h of hands-on time, including inoculum preparation on the day of infection, transurethral inoculation, tissue harvest and post-harvest processing for a small group of mice (e.g., 5 mice)...