genomic characterization of multidrug-resistant carbapenemase-producing enterobacter cloacae ecl189, co-producing kpc-2, ndm-1, tem-1, tem-95, and shv-66

Background: carbapenem-resistant enterobacteriaceae (cre) has become a public health threat due to resistance to multiple antibiotics. the production of β-lactamase is the most important resistance mechanism of enterobacteriaceae. although isolates producing kpc-2 or ndm-1 enzymes have been reported widely, isolates co-producing kpc-2, ndm-1, tem-1, tem-95, shv-66, and other β-lactamases have rarely been detected in the same strain, especially in enterobacter cloacae. objectives: in this study, we identified and sequenced the genome of carbapenem-resistant e. cloacae ecl189 to in-depth analyze the resistance and transmission mechanisms of e. cloacae. methods: we investigated the antimicrobial susceptibility of ecl189 by a vitek 2 system, e-test gradient strips, and k-b method. whole-genome sequencing was used by the pacbio rs ii platform and illumina hiseq 4000 platform. antimicrobial resistance genes, virulence genes, non-coding rna, and repeat sequences were predicted by biological information databases. a pcr was used to further confirm that the blakpc-2, blandm-1, blatem-1, blatem-95, and blashv-66 genes existed in ecl189. a conjugation experiment was performed to determine the transferability of resistance. molecular typing of ecl189 was done by multilocus sequence typing (mlst). results: enterobacter cloacae ecl189 was resistant to 21 out of 23 tested antibiotics, but its transconjugant was resistant to 10 out of 18 tested antibiotics. the genome of ecl189 consisted of a 5,026,406 bp chromosome and four circular plasmids. in total, 26 resistance genes and 58 resistance proteins were identified. in addition, 77 determinants associated with bacterial virulence were identified. a large number of resistance and virulence genes were located in the plasmids. the results of whole-genome sequencing were consistent with the β-lactamase genes. the mlst analysis revealed that this strain belonged to st74. conclusions: this study further revealed the resistance, virulence, and transmission mechanisms of carbapenem-resistant e. cloacae. resistance and virulence genes spread in bacteria by the horizontal transfer of plasmids, which should attract more attention in relevant departments.