title: Molecular identification of aminoglycoside-modifying enzymes in clinical isolates of Escherichia coli resistant to amoxicillin/clavulanic acid isolated in Spain.
abstract: The activity of eight aminoglycosides (amikacin, apramycin, arbekacin, gentamicin, kanamycin, neomycin, netilmicin and tobramycin) against a collection of 257 amoxicillin/clavulanic acid (AMC)-resistant Escherichia coli isolates was determined by microdilution. Aminoglycoside resistance rates, the prevalence of aminoglycoside-modifying enzyme (AME) genes, the relationship between AME gene detection and resistance phenotype to aminoglycosides, and the association of AME genes with mechanisms of AMC resistance in E. coli isolates in Spain were investigated. Aminoglycoside-resistant isolates were screened for the presence of genes encoding common AMEs [aac(3)-Ia, aac(3)-IIa, aac(3)-IVa, aac(6')-Ib, ant(2″)-Ia, ant(4')-IIa and aph(3')-Ia] or 16S rRNA methylases (armA, rmtB, rmtC and npmA). In total, 105 isolates (40.9%) were resistant to at least one of the aminoglycosides tested. Amikacin, apramycin and arbekacin showed better activity, with MIC90 values of 2mg/L (arbekacin) and 8mg/L (amikacin and apramycin). Kanamycin presented the highest MIC90 (128mg/L). The most common AME gene was aac(6')-Ib (36 strains; 34.3%), followed by aph(3')-Ia (31 strains; 29.5%), ant(2″)-Ia (29 strains; 27.6%) and aac(3)-IIa (23 strains; 21.9%). aac(3)-Ia, aac(3)-IVa, ant(4')-IIa and the four methylases were not detected. The ant(2″)-Ia gene was usually associated with OXA-1 [21/30; 70%], whilst 23/25 (92%) strains producing CTX-M-15 had the aac(6')-Ib gene. The most prevalent AME gene was aac(6')-Ib (18/41; 44%) in nosocomial isolates, whilst ant(2″)-Ia and aph(3')-Ia genes (20/64; 31%) were more frequent in strains of community origin. In 64.6% isolates the phenotypic profile correlated with the presence of commonly encountered AMEs.
authors.affiliation: Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla (IDIVAL), 39008 Santander, Spain. Electronic address: mfmtorrelavega@yahoo.es.
authors.forename: Marta
authors.initials: M
authors.lastname: Fernández-Martínez
authors.affiliation: Servei de Microbiologia, Hospital de la Santa Creu i Sant Pau, Institut d'Investigació Biomèdica Sant Pau, Barcelona, Spain.
authors.forename: Elisenda
authors.initials: E
authors.lastname: Miró
authors.affiliation: Laboratorio de Antibióticos, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
authors.forename: Adriana
authors.initials: A
authors.lastname: Ortega
authors.affiliation: Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña-INIBIC, A Coruña, Spain.
authors.forename: Germán
authors.initials: G
authors.lastname: Bou
authors.affiliation: Servei de Microbiología, Hospital Universitari Vall d'Hebrón, Barcelona, Spain.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: González-López
authors.affiliation: Servicio de Microbiología, Hospital Son Espases, Instituto de Investigación Sanitaria de Palma (IdISPa), Palma de Mallorca, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Oliver
authors.affiliation: Unidad de Enfermedades Infecciosas y Microbiología Clínica, Hospital Universitario Virgen Macarena, Departamento de Microbiología, Facultad de Medicina, Universidad de Sevilla, Seville, Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual
authors.affiliation: Servicio de Microbiología, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Emilia
authors.initials: E
authors.lastname: Cercenado
authors.affiliation: Laboratorio de Antibióticos, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Oteo
authors.affiliation: Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla (IDIVAL), 39008 Santander, Spain; Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Martínez
authors.affiliation: Servei de Microbiologia, Hospital de la Santa Creu i Sant Pau, Institut d'Investigació Biomèdica Sant Pau, Barcelona, Spain; Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Ferran
authors.initials: F
authors.lastname: Navarro
mesh_terms: D000123:Acetyltransferases / Q000235:genetics; D000617:Aminoglycosides / Q000378:metabolism*; D000658:Amoxicillin / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D019818:Clavulanic Acid / Q000378:metabolism; D016000:Cluster Analysis; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D008658:Inactivation, Metabolic; D019868:Kanamycin Kinase / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000378:metabolism; D013030:Spain; D012359:tRNA Methyltransferases / Q000235:genetics
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D012336:RNA, Ribosomal, 16S; D019818:Clavulanic Acid; D000658:Amoxicillin; D012359:tRNA Methyltransferases; D000123:Acetyltransferases; C019681:aminoglycoside acetyltransferase; D019868:Kanamycin Kinase; D009713:Nucleotidyltransferases; C020565:gentamicin 2''-nucleotidyltransferase
keywords: Aminoglycoside; Aminoglycoside-modifying enzyme; Amoxicillin/clavulanic acid; Escherichia coli; Resistance