OBJECTIVE To investigate the horizontal transfer mechanisms and genetic evolutionary characteristics of virulence genes in hypervirulent Klebsiella pneumoniae(HvKP)and resistance genes in carbapenem-resistant K.pneumoniae(CRKP).METHODS The donor strain was a CRKP strain harboring both VIM and KPC resist-ance genes.The positive control was a CRKP strain containing blaIMP-4.The recipient strain was Escherichia coli J53.The horizontal transfer capability of the resistance genes was verified by plasmid conjugation assay.Fifty HvKP strains were collected from the First Affiliated Hospital of Jinan University from 2017 to 2021 and conjuga-ted with the plasmids of five CRKP strains which could mediate the transmission of drug resistance genes.The conjugants were screened by selective medium containing meropenem,and polymerase chain reaction(PCR)was used to detect the resistance and virulence genes in the conjugation-successful strains.The lethality of conjugants was verified by Galleria mellonella larval assays.RESULTS The donor CRKP strain had the ability to mediate re-sistance gene transmission.Its blaKPC gene was successfully transferred to E.coli J53,but the transference of the VIM gene failed.Five CRKP strains with the ability to mediate resistance gene transmission were screened,of which one strain carried both VIM and KPC resistance genes,and the other four strains carried the IMP-4 resist-ance gene.Only one CRKP strain with the blaIMP-4 resistance gene was successfully conjugated with HvKP,carry-ing both virulence genes(aerobactin and RmpA)and the blaIMP-4 resistance gene,with positive wire drawing test result.The Galleria mellonella larvae test showed that the conjugation-successful strain caused the death of all lar-vae within 24 hours.CONCLUSIONS In the hospital environment,CRKP and HvKP can form"superbugs"with both drug resistance and high virulence through plasmid conjugation,posing a severe challenge to clinical an-ti-infection treatment.It is necessary to strengthen the prevention and control of hospital-acquired infections.

OBJECTIVE To investigate the horizontal transfer mechanisms and genetic evolutionary characteristics of virulence genes in hypervirulent Klebsiella pneumoniae(HvKP)and resistance genes in carbapenem-resistant K.pneumoniae(CRKP).METHODS The donor strain was a CRKP strain harboring both VIM and KPC resist-ance genes.The positive control was a CRKP strain containing blaIMP-4.The recipient strain was Escherichia coli J53.The horizontal transfer capability of the resistance genes was verified by plasmid conjugation assay.Fifty HvKP strains were collected from the First Affiliated Hospital of Jinan University from 2017 to 2021 and conjuga-ted with the plasmids of five CRKP strains which could mediate the transmission of drug resistance genes.The conjugants were screened by selective medium containing meropenem,and polymerase chain reaction(PCR)was used to detect the resistance and virulence genes in the conjugation-successful strains.The lethality of conjugants was verified by Galleria mellonella larval assays.RESULTS The donor CRKP strain had the ability to mediate re-sistance gene transmission.Its blaKPC gene was successfully transferred to E.coli J53,but the transference of the VIM gene failed.Five CRKP strains with the ability to mediate resistance gene transmission were screened,of which one strain carried both VIM and KPC resistance genes,and the other four strains carried the IMP-4 resist-ance gene.Only one CRKP strain with the blaIMP-4 resistance gene was successfully conjugated with HvKP,carry-ing both virulence genes(aerobactin and RmpA)and the blaIMP-4 resistance gene,with positive wire drawing test result.The Galleria mellonella larvae test showed that the conjugation-successful strain caused the death of all lar-vae within 24 hours.CONCLUSIONS In the hospital environment,CRKP and HvKP can form"superbugs"with both drug resistance and high virulence through plasmid conjugation,posing a severe challenge to clinical an-ti-infection treatment.It is necessary to strengthen the prevention and control of hospital-acquired infections.