title: Molecular epidemiological characteristics of Klebsiella pneumoniae associated with bacteremia among patients with pneumonia.
abstract: Some important virulence factors have been elucidated in Klebsiella pneumoniae infections. We investigated the relationship between virulence factors and multilocus sequence types (STs) and assessed the risk factors for bacteremia in patients with pneumonia due to K. pneumoniae. From April 2004 through April 2012, a total of 120 K. pneumoniae isolates from patients with pneumonia (23 with bacteremia and 97 without bacteremia) were collected from 10 medical institutions in Japan. Additionally, 10 strains of K. pneumoniae serotype K2 that were isolated >30 years ago were included in this study. These isolates were characterized using multilocus sequence typing (MLST), and the characteristics of their virulence factors, such as hypermucoviscosity phenotype and RmpA and aerobactin production between patients with and without bacteremia, were examined. MLST analysis was performed on the 120 isolates from patients with pneumonia, and some sequence type groups were defined as genetic lineages (GLs). GL65 was more prevalent among patients with bacteremia (21.7%) than in those without bacteremia (7.2%). The majority of the strains with serotype K2 were classified into GL14 or GL65, and rmpA and the gene for aerobactin were present in all GL65-K2 strains but absent in all GL14-K2 strains. In a multivariate analysis, the independent risk factors for bacteremia included GL65 (adjusted odds ratio [AOR], 9.46; 95% confidence interval [CI], 1.81 to 49.31), as well as neoplastic disease (AOR, 9.94; 95% CI, 2.61 to 37.92), immunosuppression (AOR, 17.85; 95% CI, 1.49 to 214.17), and hypoalbuminemia (AOR, 4.76; 95% CI, 1.29 to 17.61). GL65 was more prevalent among patients with bacteremia and was associated with the virulence factors of K. pneumoniae.
authors.affiliation: Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Ito
authors.affiliation: Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan Institute for Advanced Research, Nagoya University, Nagoya, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Shindo
authors.affiliation: Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kobayashi
authors.affiliation: Center for Advanced Medicine and Clinical Research, Nagoya University Hospital, Nagoya, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ando
authors.affiliation: Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Wanchun
authors.initials: W
authors.lastname: Jin
authors.affiliation: Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Wachino
authors.affiliation: Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamada
authors.affiliation: Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Kimura
authors.affiliation: Department of Infectious Diseases, Nagoya University Hospital, Nagoya, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yagi
authors.affiliation: Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Hasegawa
authors.affiliation: Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Japan yarakawa@med.nagoya-u.ac.jp.
authors.forename: Yoshichika
authors.initials: Y
authors.lastname: Arakawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D005838:Genotype; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007711:Klebsiella pneumoniae / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D010641:Phenotype; D018410:Pneumonia, Bacterial / Q000150:complications* / Q000453:epidemiology / Q000382:microbiology*; D037521:Virulence Factors / Q000032:analysis* / Q000235:genetics
chemical_list: D037521:Virulence Factors