Spanish multicenter study of the epidemiology and mechanisms of amoxicillin-clavulanate resistance in Escherichia coli

Adriana Ortega, Jesús Oteo, Maitane Aranzamendi-Zaldumbide, Rosa M. Bartolomé, Germán Bou, Emilia Cercenado, M. Carmen Conejo, Juan José González-López, Mercedes Marín, Luis Martínez-Martínez, María Merino, Ferran Navarro, Antonio Oliver, Álvaro Pascual, Alba Rivera, Jesús Rodríguez-Baño, Irene Weber, Belén Aracil, José Campos

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Abstract

We conducted a prospective multicenter study in Spain to characterize the mechanisms of resistance to amoxicillin-clavulanate (AMC) in Escherichia coli. Up to 44 AMC-resistant E. coli isolates (MIC ≥32/16 μg/ml) were collected at each of the seven participant hospitals. Resistance mechanisms were characterized by PCR and sequencing. Molecular epidemiology was studied by pulsed-field gel electrophoresis (PFGE) and by multilocus sequence typing. Overall AMC resistance was 9.3%. The resistance mechanisms detected in the 257 AMC-resistant isolates were OXA-1 production (26.1%), hyperproduction of penicillinase (22.6%), production of plasmidic AmpC (19.5%), hyperproduction of chromosomic AmpC (18.3%), and production of inhibitor-resistant TEM (IRT) (17.5%). The IRTs identified were TEM-40 (33.3%), TEM-30 (28.9%), TEM-33 (11.1%), TEM-32 (4.4%), TEM-34 (4.4%), TEM-35 (2.2%), TEM-54 (2.2%), TEM-76 (2.2%), TEM-79 (2.2%), and the new TEM-185 (8.8%). By PFGE, a high degree of genetic diversity was observed although two well-defined clusters were detected in the OXA-1-producing isolates: the C1 cluster consisting of 19 phylogroup A/sequence type 88 [ST88] isolates and the C2 cluster consisting of 19 phylogroup B2/ST131 isolates (16 of them producing CTX-M-15). Each of the clusters was detected in six different hospitals. In total, 21.8% of the isolates were serotype O25b/phylogroup B2 (O25b/B2). AMC resistance in E. coli is widespread in Spain at the hospital and community levels. A high prevalence of OXA-1 was found. Although resistant isolates were genetically diverse, clonality was linked to OXA-1-producing isolates of the STs 88 and 131. Dissemination of IRTs was frequent, and the epidemic O25b/B2/ST131 clone carried many different mechanisms of AMC resistance. Copyright © 2012, American Society for Microbiology. All Rights Reserved.
Original languageEnglish
Pages (from-to)3576-3581
JournalAntimicrobial Agents and Chemotherapy
Volume56
Issue number7
DOIs
Publication statusPublished - 1 Jul 2012

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    Ortega, A., Oteo, J., Aranzamendi-Zaldumbide, M., Bartolomé, R. M., Bou, G., Cercenado, E., Conejo, M. C., González-López, J. J., Marín, M., Martínez-Martínez, L., Merino, M., Navarro, F., Oliver, A., Pascual, Á., Rivera, A., Rodríguez-Baño, J., Weber, I., Aracil, B., & Campos, J. (2012). Spanish multicenter study of the epidemiology and mechanisms of amoxicillin-clavulanate resistance in Escherichia coli. Antimicrobial Agents and Chemotherapy, 56(7), 3576-3581. https://doi.org/10.1128/AAC.06393-11