Clinical and Molecular Analysis of Klebsiella pneumoniae Causing Liver Abscess in China.

OBJECTIVE: Hypervirulent Klebsiella pneumoniae (hvKP) has been characterized as the major pathogen associated with the development of liver abscesses. Although the prevalence of K. pneumoniae in liver abscesses in Chinese patients is on the rise, methods for the early laboratory identification and recognition of hvKP are lacking, and hvKP detection and surveillance are thus limited.

METHODS: A retrospective study was conducted in 240 patients with cultures that were positive for K. pneumoniae, who were hospitalized in the Hospital of Beijing area from May 2013 to August 2014. The clinical and molecular characteristics of K. pneumoniae strains that cause liver abscesses were studied. Thirty-eight (16.7%) of 240 patients positive for K. pneumoniae cultures had liver abscesses.

RESULTS: Among these K. pneumoniae isolates, 92.1% (35/38) and 84.2% (32/38) were rmpA and aerobactin (abc) positive, respectively, as indicated by multiplex PCR, while 81.6% (31/38) were string test positive. Intriguingly, K. pneumoniae isolates that were positive for rmpA, abc, or string test accounted for almost all isolates (97.3%; n = 37/38) and thus were defined as hvKP in this study. Based on the new criteria for hvKP, none of these hvKP strains were positive for extended spectrum β-lactamases.

CONCLUSIONS: Compared to the string test alone, integrating rmpA and abc detection with the string test is robuster and more extensive in the identification of liver abscess-causing hvKP strains. Multiplex PCR assays may therefore accelerate the early laboratory detection of hvKP.