High incidence of extended-spectrum β-lactamases among outpatient clinical isolates of Escherichia coli: a phenotypic assessment of NCCLS guidelines and a commercial method Sorlozano Puerto, Antonio Gutiérrez Fernández, José Palanca Giménez, Matilde María Soto, María José Piédrola Angulo, Gonzalo Escherichia coli Klebsiella spp. Extended-spectrum β-lactamases Urine The production of extended-spectrum beta-lactamases (ESBLs) among 357 clinical isolates of Escherichia coli and 175 of Klebsiella spp. was studied using both the National Committee for Clinical Laboratory Standards disk diffusion method and the semiautomated Wider system. We highlight the predominance of E. coli (50, 92.6%) among positive samples and the largely outpatient origin of these (40, 80%), including 39 samples of urine (97.5%) and one of urethral exudate. There were only four ESBL-producing isolates of Klebsiella spp. (7.4%), and three were in outpatient urine samples (75%, 2 K. oxytoca and 1 K. pneumoniae). The positive and negative predictive values for the Wider system were 81% and 98.5%, respectively. We stress the high incidence of ESBL in our setting, the predominance of cases in the outpatient setting, and the acceptable detection of ESBL by means of the Wider system in E. coli and Klebsiella spp. 2024-03-18T13:12:23Z 2024-03-18T13:12:23Z 2004-10 journal article Sorlózano A, Gutiérrez J, Palanca M, Soto MJ, Piédrola G. High incidence of extended-spectrum beta-lactamases among outpatient clinical isolates of Escherichia coli: a phenotypic assessment of NCCLS guidelines and a commercial method. Diagn Microbiol Infect Dis. 2004 Oct;50(2):131-4. https://doi.org/10.1016/j.diagmicrobio.2004.06.003 https://hdl.handle.net/10481/90085 10.1016/j.diagmicrobio.2004.06.003 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier