Molecular characterisation and diversity in Enterobacter cloacae from Edinburgh and Egypt carrying blaCTX-M-14 and blaVIM-4 β-lactamase genes

The purpose of this study was to compare the carbapenemases and extended-spectrum β-lactamases (ESBLs) associated with resistance, the genetic environment of these genes, and their location on plasmids among Enterobacter cloacae isolates from Edinburgh (UK) and Egypt. Nine E. cloacae isolates were obtained from Egypt (n = 3) and Edinburgh (n = 6). Antimicrobial susceptibility testing was performed by agar dilution. Molecular detection of carbapenemase genes, blaCTX-M-14 and the presence of integron structures was done by PCR and sequencing. Genotyping of the strains was performed by pulsed-field gel electrophoresis (PFGE) with XbaI restriction. Plasmids were extracted to determine the location of the resistance genes. PCR sequencing revealed that all of the isolates carried the blaCTX-M-14 ESBL gene, whilst two isolates also carried the blaVIM-4 metallo-β-lactamase gene. The blaCTX-M-14 genes in two isolates were associated with the ISEcp1 transposase. Analysis of the integrons found an intI1 integron associated with the complex ISCR1. The blaVIM-4 gene was identified in the form of a gene cassette within the class 1 integron, followed downstream by the resistance genes aacA7, dfrA1 and aadA2. PFGE revealed genetic relatedness among six isolates, whereas the others were diverse although related. Plasmid analysis revealed a single plasmid carrying both blaVIM-4 and blaCTX-M-14. In conclusion, the presence of insertion sequence ISEcp1 upstream of blaCTX-M-14 suggests its involvement in the expression and mobilisation of this gene. Linked carriage of blaVIM-4 and blaCTX-M-14 on the same plasmid in E. cloacae results in resistance to all β-lactams and limits antibiotic treatment options.