Pyogenic liver abscess-caused Klebsiella pneumoniae in a tertiary hospital in China in 2017: implication of hypervirulent carbapenem-resistant strains

Background To investigate the epidemiology of Klebsiella pneumoniae (K. pneumoniae) inducing pyogenic liver abscess (PLA) in east China and the role of hypervirulent carbapenem-resistant K. pneumoniae (Hv-CRKP). Methods Forty-three K. pneumoniae strains were collected from 43 patients with PLA at Hangzhou, China in 2017. Antimicrobial susceptibility tests, string test, multilocus sequence typing, pulsed-field gel electrophoresis, mobile genetic elements typing, regular PCR and sequencing, and Galleria mellonella (G. mellonella) lethality test were used to elucidate the epidemiology. Clinical data were collected. Results K. pneumoniae strains with serotypes K1 and K2 accounted for 69.8%, which shared 46.5% and 23.3% respectively. K. pneumoniae strains with clonal group 23 were predominant with a rate of 34.9%. Such antimicrobials showed susceptible rates over 80.0%: cefuroxime, cefotaxime, gentamycin, ticarcillin/clavulanate, ceftazidime, cefoperazone/tazobactam, cefepime, aztreonam, imipenem, meropenem, amikacin, tobramycin, ciprofloxacin, levofloxacin, doxycycline, minocycline, tigecycline, chloramphenicol, and trimethoprim-sulfamethoxazole. PFGE dendrogram showed 29 clusters for the 43 K. pneumoniae strains. Three Hv-CRKP strains were confirmed by G. mellonella lethality test, showing a constituent ratio of 7.0% (3/43). Totally three deaths were found, presenting a rate of 7.0% (3/43). The three died patients were all infected with Hv-CRKP. Conclusions K1 and K2 are the leading serotypes of K. pneumoniae causing PLA, which show highly divergent genetic backgrounds. Aminoglycosides, Generation 2(nd) to 4(th) cephalosporins, beta-lactamase/beta-lactamase inhibitors, carbapenems, fluoroquinolones are empirical choices. Hv-CRKP may confer an urgent challenge in the future.