Abstract:Objective To analyze the molecular characteristics and virulence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-HvKP), strengthen the clinical staff's understanding on this bacteria. Methods One strain of CR-HvKP isolated from respiratory tract specimen of a patient with severe pneumonia was performed antimicrobial susceptibility testing, resistance mechanism to carbapenems was studied. The molecular and virulence characteristics of the strain were analyzed through string test, virulence gene detection, virulence-related capsular antigen gene detection, multilocus sequence typing, Galleria mellonella infection model, and clinical manifestation of patient. Results CR-HvKP caused severe pneumonia in patient, patient received bronchoscopy, bronchoalveolar lavage fluid (BALF) specimen was taken for pathogenic culture and isolation, patient's condition was under control after adjusting antimicrobial use according antimicrobial susceptibility testing result. The strain was multidrug-resistant, expressed IMP-4 carbapenemase, negative for string test, ST2928 type, positive for prmpA2 virulence gene, positive for K54 capsular antigen gene, and in vitro high virulence in Galleria mellonella model test. Conclusion The isolated CR-HvKP strain with ST2928, positive K54 capsular antigen gene and producing IMP-4 carbapenemase is reported for the first time, CR-HvKP can cause more complicated and severe infection due to its combination of high drug resistance and high virulence, and its molecular characteristics are diverse.