Genetic and biochemical characterisation of CTX-M-37 extended-spectrum β-lactamase from an Enterobacter cloacae clinical isolate from Mongolia

The CTX-M-37-producing E. cloacae isolate showed relatively low-level resistance to cefotaxime and the purified enzyme had lower kinetic parameters as the result of Asn114Asp substitution. Presence of an ISEcp1 element and putative promoters upstream of the blaCTX-M-37 gene in E. cloacae, but not in the K. cryocrescens isolate, indicated their roles in mobilisation and expression of the gene.