科研之友
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摘要
Background: Carbapenem-resistant Gram-negative bacilli (GNB) have become an important cause of nosocomial infections of hospitalized patients. @@@ Methods: To investigate the microbial infection patterns and molecular epidemiology characteristics of the carbapenem-resistant GNB isolates from a long-term hospitalized patient, antimicrobial susceptibility testing, phenotypic screening test for carbapenemase production, PCR screening and DNA sequencing of carbapenemase genes, repetitive extragenic palindromic sequence-based PCR (REP-PCR), multilocus sequencing typing (MLST) and genetic environment analysis were performed. @@@ Results: Twelve strains with carbapenemase genes were detected from 63 carbapenem-resistant isolates, including two bla(IMP-25)-carrying Pseudomonas aeruginosa, one bla(NDM-1)-carrying Citrobacter freundii, three bla(NDM-1)-carrying Klebsiella pneumoniae and six bla(KPC-2)-carrying K. pneumoniae. Only the bla(NDM-1) genes were successfully transferred from three K. pneumoniae strains to Escherichia coli C600 by conjugation. Genetic environment of bla(IMP-25), bla(NDM-1) and bla(KPC-2) genes in our study were consistent with previous reports. Molecular typing of K. pneumoniae performed by MLST revealed that most of the isolates belonged to ST11. bla(NDM-1)-carrying K. pneumoniae sequencing type 1416 was first reported in our study. @@@ Conclusions: Carbapenem-resistant GNB are common pathogens during long-term hospitalization, and ST11 bla(KPC-2)-carrying K. pneumoniae is the dominant bacterium in our study. Colonization and horizontal transmission of resistance by plasmids of carbapenem-resistant GNB have increased the risks of persistent infection and mortality of long-term hospitalized patients.
