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

Abstract

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 2nd to 4th cephalosporins, β-lactamase/β-lactamase inhibitors, carbapenems, fluoroquinolones are empirical choices. Hv-CRKP may confer an urgent challenge in the future.

Higher Virulence Renders K2 Klebsiella pneumoniae a Stable Share Among Those from Pyogenic Liver Abscess

“…The tested strains H2, H4, and H8 were from different lineages as pulse-field confirmed by gel electrophoresis. 8 …”

“…Therefore, K2 K. pneumoniae also plays an indispensable role in PLA. It is noted that the proportion of K1 K. pneumoniae declined, while that of K2, accounting for around 20.0%, was retained, as indicated by the 3 reports, 8 , 12 , 20 which included K. pneumoniae strains from PLA during different years and regions. It is intriguing as to why K2 maintained the share over the past several years.…”

“… 5 With the use of antibiotics and percutaneous catheter drainage, the mortality rate of PLA decreased from over 31.0% 60 years ago 6 to around 10.0% in recent years. 7 , 8 The agents of PLA include various bacteria, of which Klebsiella pneumoniae and Escherichia coli are the most documented, particularly in Asia. 9 , 10 In the past 3 to 4 decades, K. pneumoniae has replaced E. coli as the foremost agent of PLA, 11 the share of which exceeded 80.0%.…”

“… 18 For K. pneumoniae strains causing PLA, although a couple of serotypes are involved, e.g. K1, K2, K5, K16, K20, K54, K57, and K64, K1 and K2 are usually the predominant 2 types, which accounted for nearly 70.0% in sum; 8 , 19 the ratio of K1 versus K2 is about 2:1. Therefore, K2 K. pneumoniae also plays an indispensable role in PLA.…”