High presence of extended-spectrum β-lactamases and resistance to quinolones in clinical isolates of Escherichia coli Sorlozano Puerto, Antonio Gutiérrez Fernández, José Luna Del Castillo, Juan De Dios Oteo, Jesús Liébana Ureña, José Soto, María José Piédrola Angulo, Gonzalo Escherichia coli CTX-M9 Quinolones PFGE A study was conducted to detect the presence of extended-spectrum beta-lactamases (ESBLs) in 706 isolates of Escherichia coli, largely from outpatients (75.2%). The Clinical and Laboratory Standards Institute (formerly NCCLS)-recommended disk diffusion procedure was used to detect ESBL presence; the VITEK 2 system (bioMérieux, Marcy L'Etoile, France) was used to determine the susceptibility to antibiotics of clinical interest, and the ESBLs were characterized by biochemical study, determining the isoelectric point, and by molecular study with PCR. Clonal distribution was studied in eight hospital isolates. There were 115 ESBL-producing isolates (16.3%), with a predominance of CTX-M9 type (58.3%). We draw attention to the high resistance to quinolones (>70%) in CTX-M9 and SHV enzyme producing isolates and the lower aminoglycoside activity in the latter. 2024-03-15T07:58:09Z 2024-03-15T07:58:09Z 2007-03 journal article Sorlózano A, Gutiérrez J, de Dios Luna J, Oteo J, Liébana J, Soto MJ, Piédrola G. High presence of extended-spectrum beta-lactamases and resistance to quinolones in clinical isolates of Escherichia coli. Microbiol Res. 2007;162(4):347-54. doi: 10.1016/j.micres.2006.02.003 https://hdl.handle.net/10481/89999 10.1016/j.micres.2006.02.003 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier