Emergence of a multiresistant KPC-3 and VIM-1 carbapenemase-producing Escherichia coli strain in Spain

Resumen

Objectives: To characterize the mechanisms involved in carbapenem resistance, as well as the genetic elements supporting their mobilization, in a multidrug-resistant Escherichia coli isolate. Methods: The E. coli isolate was obtained from a patient with fatal urinary sepsis. Antimicrobial susceptibility testing was performed by the disc diffusion and agar dilution methods. The E. coli molecular type and phylogroup were determined using multilocus sequence typing and the triple PCR technique, respectively. PCR and sequencing were used for virulence and resistance genotype characterization. Plasmid content and gene location were analysed by S1-PFGE, I-Ceu1-PFGE and hybridization experiments. Transformation assays were performed. Results: The E. coli strain, typed as ST448 and phylogroup B1, was resistant to all tested antibiotics except fosfomycin, tigecycline and tetracycline. The following resistance and virulence genetic structures were obtained: ISKpn7 + blaKPC-3 + ISKpn6 linked to Tn4401; tnpR + aac(6')-Ib'-9 + aadA1 + blaOXA-9 + tnpR + blaTEM-1a + tnpB + strB + strA + sul2; intI1 + blaVIM-1 + aac(6')-Ib' + aphA15 + aadA1 + catB2 + qacEΔ1-sul1 + orf5; ISEcp1 + blaCMY-2; IS26 + blaSHV-12; aph(3')-I; aac(3)-IV; floR; catA; and fimA. Mutations in the ampC promoter (-18, -1 and +58) and substitutions in the GyrA (Ser-83→Leu and Asp-87→Asn) and ParC (Ser-80→Ile) proteins were observed. IncFII (ST2), IncA/C and ColETP plasmids of 145.5, 87 and <2 kb, respectively, were found. The blaVIM-1 gene was located in a non-typeable plasmid of >300 kb, and the blaKPC-3 gene in the 145.5 kb IncFII plasmid. Transformant strains carried the IncFII and ColETP plasmids, and the blaKPC-3, blaTEM-1a, blaOXA-9, aadA1, aac(6')-Ib'-9, aac(3)-IV and floR genes. Conclusions: This is the first report of the co-production of KPC-3, VIM-1, SHV-12, OXA-9 and CMY-2 in a unique clinical multiresistant E. coli isolate. The dissemination of these genes on mobile genetic elements is alarming and complicates antimicrobial therapies. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.