Ortega, AdrianaOteo, JesúsAranzamendi-Zaldumbide, MaitaneBartolomé, Rosa MBou, GermánCercenado, EmiliaConejo, M CarmenGonzález-López, Juan JoséMarín, MercedesMartínez-Martínez, LuisMerino, MaríaNavarro, FerranOliver, AntonioPascual, AlvaroRivera, AlbaRodríguez-Baño, JesúsWeber, IreneAracil, BelénCampos, José2015-06-052015-06-052012-07Ortega A, Oteo J, Aranzamendi-Zaldumbide M, Bartolomé RM, Bou G, Cercenado E, et al. Spanish multicenter study of the epidemiology and mechanisms of amoxicillin-clavulanate resistance in Escherichia coli. Antimicrob. Agents Chemother.. 2012 ; 56(7):3576-810066-4804http://hdl.handle.net/10668/1901Journal Article; Multicenter Study; Research Support, Non-U.S. Gov't;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.enCombinación de amoxicilina clavulanato potásicoFarmacorresistencia bacterianaInfecciones por Escherichia coliEpidemiología molecularEstudios prospectivosEspañaMedical Subject Headings::Phenomena and Processes::Microbiological Phenomena::Bacterial Physiological Phenomena::Drug Resistance, BacterialMedical Subject Headings::Organisms::Bacteria::Gram-Negative Bacteria::Gram-Negative Facultatively Anaerobic Rods::Enterobacteriaceae::Escherichia::Escherichia coliMedical Subject Headings::Diseases::Bacterial Infections and Mycoses::Bacterial Infections::Gram-Negative Bacterial Infections::Enterobacteriaceae Infections::Escherichia coli InfectionsMedical Subject Headings::Analytical, Diagnostic and Therapeutic Techniques and Equipment::Investigative Techniques::Epidemiologic Methods::Molecular EpidemiologyMedical Subject Headings::Analytical, Diagnostic and Therapeutic Techniques and Equipment::Investigative Techniques::Epidemiologic Methods::Epidemiologic Study Characteristics as Topic::Epidemiologic Studies::Cohort Studies::Longitudinal Studies::Prospective StudiesMedical Subject Headings::Geographicals::Geographic Locations::Europe::SpainMedical Subject Headings::Chemicals and Drugs::Organic Chemicals::Amides::Lactams::beta-Lactams::Clavulanic Acids::Clavulanic Acid::Amoxicillin-Potassium Clavulanate Combinationresearch article22491692open access10.1128/AAC.06393-111098-6596PMC3393459