Molecular characteristics of global β-lactamase-producing Enterobacter cloacae by genomic analysis

Objective To analyze the characteristics of global β-lactamase-producing Enterobacter cloacae including the distribution of β-lactamase, sequence types (STs) as well as plasmid replicons. Methods All the genomes of the E. cloacae were downloaded from GenBank. The distribution of β-lactamase encoding genes were investigated by genome annotation after the genome quality was checked. The STs of these strains were analyzed by multi-locus sequence typing (MLST). The distribution of plasmid replicons was further explored by submitting these genomes to the genome epidemiology center. The isolation information of these strains was extracted by Per program from GenBank. Results A total of 272 out of 276 strains were found to carry β-lactamase encoding genes. Among them, 23 varieties of β-lactamase were identified, bla CMH ( n = 130, 47.8%) and bla ACT ( n = 126, 46.3%) were the most predominant ones, 9 genotypes of carbapenem-hydrolyzing β-lactamase (CHβLs) were identified with bla VIM ( n = 29, 10.7%) and bla KPC ( n = 24, 8.9%) being the most dominant ones. In addition, 115 distinct STs for the 272 ß-lactamase-carrying E. cloacae and 48 different STs for 106 CHβLs-producing E. cloacae were detected. ST873 ( n = 27, 9.9%) was the most common ST. Furthermore, 25 different plasmid replicons were identified, IncHI2 ( n = 65, 23.9%), IncHI2A ( n = 64, 23.5%) and IncFII ( n = 62, 22.8%) were the most common ones. Notably, the distribution of plasmid replicons IncHI2 and IncHI2A among CHβLs-producing strains were significantly higher than theat among non-CHβLs-producing strains ( p < 0.05). Conclusion Almost all the E. cloacae contained β-lactamase encoding gene. Among the global E. cloacae , bla CMH and bla ACT were main bla AmpC genes. Bla TEM and bla CTX-M were the predominant ESBLs. Bla KPC , bla VIM and bla NDM were the major CHβLs. Additionally, diversely distinct STs and different replicons were identified.