Molecular Epidemiological Characteristics of Klebsiella pneumoniae Associated with Bacteremia among Patients with Pneumonia
Methods: From April 2004 through April 2012, a total of 68 K. pneumoniae isolates from patients with pneumonia (23 from BP and 45 from non-bacteremic pneumonia [NBP]) were collected from ten medical institutions in Japan. Additionally, ten K2-positive strains which were isolated more than 30 years ago were included in this study. These isolates were characterized using multilocus sequence typing (MLST), and characteristics of their virulence factors such as hypermucoviscosity phenotype, RmpA, and aerobactin production between BP and NBP were examined.
Results: MLST analysis was performed with the 68 isolates from patients with pneumonia, and some sequence type (ST) groups were defined as genetic lineages (GLs), which were groups of STs in which allele profiles had at least 5 loci in common on the basis of the profile of primary founders or subgroup founders in a population snapshot determined by eBURST. GL65s were significantly more prevalent among patients with BP (21.7%) than those with NBP (4.4%). K2-positive strains were classified into GL14 and GL65, depending on the virulence factors. The rmpA and gene for aerobactin were all positive among the GL65-K2 strains and all negative among the GL14-K2 strains. In multivariate analysis, the independent risk factors for bacteremia included GL65 (adjusted odds ratio [AOR], 15.96; 95% confidence interval [CI], 2.03–125.47) as well as neoplastic disease (AOR, 7.83; 95% CI, 1.86–33.00) and hypoalbuminemia (AOR, 4.25; 95% CI, 1.03–17.47).
Conclusion: GL65 was more prevalent among patients with BP, and was associated with the virulence factors of K. pneumoniae.
D. Kobayashi, None
W. Jin, None
J. I. Wachino, None
K. Yamada, None
K. Kimura, None
T. Yagi, None
Y. Hasegawa, None
Y. Arakawa, None