title: Prevalence of Klebsiella pneumoniae strains producing carbapenemases and increase of resistance to colistin in an Italian teaching hospital from January 2012 To December 2014.
abstract: BACKGROUND
  The aim of this study was to characterize the spread of carbapenemase-producing Klebsiella pneumoniae (CPKP) in a tertiary level hospital using ongoing active surveillance with rectal swab cultures. Furthermore, this study analyzed the presence of CPKP in the clinical samples (CS) of a single patient as well as the evolution of Colistin-sensitive strains (CoS) to Colistin-resistant strains (CoR).
  
  
  METHODS
  This study was performed from January 1, 2012 to December 31, 2014. In 2012, a survey was conducted in the Intensive Care Department. In autumn 2013, active monitoring was extended to the Surgery Department, and since mid-2014, the surveillance has included the Medical Department as well. Only the first isolated strain from each patient was included. Antimicrobial susceptibility testing was performed on CPKP isolates: Klebsiella pneumoniae carbapenemase, oxacillinase-48, Verona integron-encoded metallo-β-lactamase and New Delhi metallo-β-lactamase were detected using a validated in-house PCR method, and multilocus sequence typing (MLST) was used to investigate the clonal transmission of strains.
  
  
  RESULTS
  A total of 15,104 patients were included in the study, and 496 consecutive non-replicated strains of CPKP were collected: 149 strains were collected in 2012 (39 [26.2 %] from surveillance rectal swabs [SRS]), 133 strains were collected in 2013 (70 [52.6 %] from SRS) and 214 strains were collected in 2014 (164 [76.6 %] from SRS). We observed a significant increase in the percentage of positive SRS cases in 2014 relative to 2013 and 2012 (p = 0.0001 and p = 0.0172, respectively) and in the proportion of CPKP first isolated by SRS relative to those identified by CS (p < 0.0001). Among all available samples, the number of CoR isolated from SRS was higher in 2013 and 2014 compared with 2012 (p = 0.0019 and p = 0.008, respectively). ST-258 and ST-512 were more prevalent in the tested specimens, and a new single locus variant (SLV) of ST-512 (ST-745) was isolated.
  
  
  CONCLUSIONS
  The results of this 3-year study of 15,104 patients highlight the clinical relevance of antimicrobial resistance as well as the drug-selection pressure of colistin therapy. The active surveillance in the three different departments increased the level of CPKP cases isolated by SRS.
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. saverio.parisi@unipd.it.
authors.forename: Saverio Giuseppe
authors.initials: SG
authors.lastname: Parisi
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. andbarto@libero.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bartolini
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. erica.esse@hotmail.it.
authors.forename: Erica
authors.initials: E
authors.lastname: Santacatterina
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. castellanielena2606@gmail.com.
authors.forename: Elena
authors.initials: E
authors.lastname: Castellani
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. roberto.ghirardo@gmail.com.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ghirardo
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. alessandro.berto@studenti.unipd.it.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Berto
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. elisa.franchin@unipd.it.
authors.forename: Elisa
authors.initials: E
authors.lastname: Franchin
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. nicola.menegotto@hotmail.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Menegotto
authors.affiliation: Microbiology and Virology Unit, Padova Hospital, Padova, Italy. ettore.decanale@sanita.padova.it.
authors.forename: Ettore
authors.initials: E
authors.lastname: De Canale
authors.affiliation: Microbiology and Virology Unit, Padova Hospital, Padova, Italy. tiziana.tommasini@sanita.padova.it.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Tommasini
authors.affiliation: Infectious Diseases Unit, Padova Hospital, Padova, Italy. rinaldipd@gmail.com.
authors.forename: Roberto
authors.initials: R
authors.lastname: Rinaldi
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. monica.basso@unipd.it.
authors.forename: Monica
authors.initials: M
authors.lastname: Basso
authors.affiliation: Department of Biomedical and Biotecnological Sciences, University of Catania, Catania, Italy. stefanis@unict.it.
authors.forename: Stefania
authors.initials: S
authors.lastname: Stefani
authors.affiliation: Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35100, Padova, Italy. giorgio.palu@unipd.it.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Palù
mesh_terms: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins / Q000378:metabolism*; D005075:Biological Evolution; D003091:Colistin; D024881:Drug Resistance, Bacterial; D006784:Hospitals, Teaching; D006801:Humans; D007362:Intensive Care Units; D007558:Italy / Q000453:epidemiology; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D016133:Polymerase Chain Reaction; D015995:Prevalence; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1; C063912:carbapenemase; C108449:oxacillinase; D003091:Colistin