Molecular epidemiology of carbapenem-resistant Klebsiella pneumoniae in intensive care unit

Abstract:

Objective To analyze the molecular characteristics and prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolated from the intensive care unit (ICU), and provide laboratory data for infection control and antimicrobial treatment. Methods 51 CRKP strains isolated from ICU of a hospital from July 2018 to July 2020 were collected, minimum inhibitory concentration (MIC) was determined by broth microdilution method, homology of strains was analyzed by multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE), resis-tance and virulence genes of strains were detected, transferability of plasmid was verified with conjugation testing. Results Antimicrobial susceptibility testing showed that CRKP strains were all susceptible to ceftazidime/avibactam, resistance rate to tegacyclin was the lowest (3.9%), followed by amikacin (49.0%) and polymyxin (64.7%), while strains were all highly resistant to imipenem (96.1%), meropenem (98.0%), levofloxacin (98.0%) and ceftazidime (100.0%). Among 51 CRKP strains, 49 strains (96.1%) were positive in mCIM testing, 1 strain (2.0%) was positive in eCIM testing. Carbapenemase gene bla_KPC-2 positive strains accounted for 96.1%. Among all isolates, 4 strains (7.8%) exhibited the hypermucoviscous phenotype, positive rates of virulence genes were uge (100.00%), mrkD (94.1%), kpn (94.1%), fim-H (72.5%), aero (2.0%), and rmpA (2.0%). ST11 and ST1373 CRKP accounted for 98.0% (50/51) and 2.0% (1/50) respectively among ICU strains. One highly virulent Klebsiella pneumoniae strain ST1373 was isolated. The success rate of conjugation testing of bla_KPC-2-harboring strains was 12.2%. Conclusion There is a monoclonal transmission of ST11 CRKP that produces KPC-2 in ICU, and it carries certain virulence genes. The plasmid of bla_KPC-2-harboring gene can be transmitted horizontally through conjugation. Ceftazidime/avibactam has high susceptibility to CRKP and can be used in clinical treatment.

Key words:carbapenem-resistant Klebsiella pneumoniae;molecular epidemiology;multi-locus sequence typing;intensive care unit;plasmid conjugation