title: Concurrent emergence of multidrug resistance and heat resistance by CTX-M-15-encoding conjugative plasmids in Klebsiella pneumoniae.
abstract: A plasmid-encoded ClpK protein was recently identified as a predictor of a heat-resistant phenotype in the opportunistic pathogen Klebsiella pneumoniae. This study was undertaken to evaluate the presence of the clpK gene in extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae and to assess the probable co-transfer of multi-resistance with the heat resistance phenotype. A Danish collection of 80 ESBL-producing K. pneumoniae bloodstream infection isolates was screened for clpK by colony hybridization. Nineteen isolates (24%) were positive for clpK; some of them representing major clones identified in Denmark. Among these, nine isolates belonged to a single K. pneumoniae CTX-M-15 clone with sequence type (ST)16 exhibiting a heat-resistant phenotype. This clone has a multi-hospital occurrence and has also been detected outside Denmark. Horizontal co-transfer of multiple antibiotic resistances, including the CTX-M-15 resistance determinant, and the heat resistance phenotype was observed. Thus, the clpK gene is harbored by different ESBL-producing K. pneumoniae isolates including a clone of ST16 internationally spread. The co-localization of clpK on transferable ESBL-encoding plasmids allowing co-dissemination of multiple drug resistance with bacterial heat resistance is a highly interesting phenomenon that may further complicate the prevention of spreading of certain successful clones of multi-resistant K. pneumoniae.
authors.affiliation: Department of Microbiological Surveillance and Research, Statens Serum Institut, Copenhagen S, Denmark.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Bojer
authors.forename: Anette M
authors.initials: AM
authors.lastname: Hammerum
authors.forename: Steffen L
authors.initials: SL
authors.lastname: Jørgensen
authors.forename: Frank
authors.initials: F
authors.lastname: Hansen
authors.forename: Stefan S
authors.initials: SS
authors.lastname: Olsen
authors.forename: Karen A
authors.initials: KA
authors.lastname: Krogfelt
authors.forename: Carsten
authors.initials: C
authors.lastname: Struve
mesh_terms: D003227:Conjugation, Genetic; D003718:Denmark / Q000453:epidemiology; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology / Q000378:metabolism / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D009693:Nucleic Acid Hybridization; D010957:Plasmids / Q000235:genetics; D012189:Retrospective Studies; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases