High incidence of extended-spectrum beta-lactamases among outpatient clinical isolates of Escherichia coli: a phenotypic assessment of NCCLS guidelines and a commercial method.
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.
Department of Microbiology, School of Medicine, San Cecilio University Hospital, University of Granada, Granada, Spain.
Antonio
A
Sorlózano
José
J
Gutiérrez
Matilde
M
Palanca
María José
MJ
Soto
Gonzalo
G
Piédrola
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001431:Bacteriological Techniques; D004058:Diffusion; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000453:epidemiology; D017408:Guidelines as Topic; D006801:Humans; D007709:Klebsiella / Q000145:classification / Q000187:drug effects* / Q000201:enzymology*; D007710:Klebsiella Infections / Q000188:drug therapy / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013030:Spain; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001618:beta-Lactamases