title: Heat resistance mediated by a new plasmid encoded Clp ATPase, ClpK, as a possible novel mechanism for nosocomial persistence of Klebsiella pneumoniae.
abstract: Klebsiella pneumoniae is an important opportunistic pathogen and a frequent cause of nosocomial infections. We have characterized a K. pneumoniae strain responsible for a series of critical infections in an intensive care unit over a two-year period. The strain was found to be remarkably thermotolerant providing a conceivable explanation of its persistence in the hospital environment. This marked phenotype is mediated by a novel type of Clp ATPase, designated ClpK. The clpK gene is encoded by a conjugative plasmid and we find that the clpK gene alone renders an otherwise sensitive E. coli strain resistant to lethal heat shock. Furthermore, one third of a collection of nosocomial K. pneumoniae isolates carry clpK and exhibit a heat resistant phenotype. The discovery of ClpK as a plasmid encoded factor and its profound impact on thermal stress survival sheds new light on the biological relevance of Clp ATPases in acquired environmental fitness and highlights the challenges of mobile genetic elements in fighting nosocomial infections.
authors.affiliation: Department of Microbiological Surveillance and Research, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Martin Saxtorph
authors.initials: MS
authors.lastname: Bojer
authors.forename: Carsten
authors.initials: C
authors.lastname: Struve
authors.forename: Hanne
authors.initials: H
authors.lastname: Ingmer
authors.forename: Dennis Schrøder
authors.initials: DS
authors.lastname: Hansen
authors.forename: Karen Angeliki
authors.initials: KA
authors.lastname: Krogfelt
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003428:Cross Infection / Q000201:enzymology / Q000235:genetics / Q000382:microbiology; D006358:Hot Temperature; D006801:Humans; D007710:Klebsiella Infections / Q000201:enzymology / Q000235:genetics; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics; D009154:Mutation; D010957:Plasmids / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D000251:Adenosine Triphosphatases