Objective: This study investigated the epidemiology, virulence and drug resistance of invasive Klebsiella pneumoniae  (K. pneumoniae ) isolates at a children’s medical center in eastern China in order to obtain epidemiologic, virulence, and antimicrobial resistance data that can guide for the selection and development of anti-infection treatments.
Methods: A total of 94 invasive K. pneumoniae  strains were isolated from children between January 2016 and December 2020 at the Children’s Hospital of Soochow University. The strains were identified by mass spectrometry. The Kirby–Bauer method and VITEK 2 Compact system were used to analyze the antimicrobial susceptibility. Polymerase chain reaction (PCR) and sequencing was performed to detect the capsular serotypes, virulence-associated genes, β-lactam antibiotic resistance genes and multilocus sequence typing.
Results: The PCR results showed that 87 strains (92.55%) of invasive K. pneumoniae  were hypervirulent capsular serotypes, with K57 as the dominant capsular serotype (62.77%). All strains carried virulence-associated genes. Among them, 84 strains (89.36%) carried hypervirulence genes, with iroB  (86.17%) being the predominant; meanwhile, other virulence genes, including wabG  (100.00%), mrkD  (98.94%), ycfM  (96.81%), fimH  (95.74%) and Uge  (88.30%), were detected in most strains. All strains carried β-lactam antibiotic resistance genes; the main extended-spectrum β-lactamase gene was bla _SHV-11 (86.17%) and the major AmpC cephalosporinase genes were bla _FOX-1 (86.17%) and bla _ACT-1 (70.21%). Carbapenemase genes were detected in only a few isolates. Notably, 12 invasive K. pneumoniae  isolates were identified as carbapenem-resistant and hypervirulent K. pneumoniae  (CR-HVKP), and 14 other multidrug resistance (MDR) isolates were also detected.
Conclusion: The results of this study reveal the epidemiology, virulence and antimicrobial resistance of invasive K. pneumoniae  in pediatric patients. Both CR-HVKP and MDR strains were identified, which should be of great concern to clinicians.
Keywords: Klebsiella pneumoniae , invasive infection, children, virulence factors, resistance genes