title: beta-Lactamase bioassay: a simplified method to determine extended-spectrum beta-lactamases (ESBL) in enterobacteria.
abstract: With the simultaneous use of an isoelectric focusing gel (IEF) and a nitrocefin/cefotaxime bioassay, it is possible to identify the Extended-Spectrum beta-lactamases (ESBL) with precision. A mixture of soft agar and susceptible bacterial cells are layered over the gel following overnight incubation and areas of cell growth are detected where the antibiotic has been hydrolyzed by specific enzymes. This innovative method improves sensitivity and specificity for the identification of ESBLs in those enterobacteria strains producing more than one beta-lactamase and are resistant to third generation cephalosporines.
authors.affiliation: Instituto Nacional de Salud Pública, Centro de Investigaciones Sobre Enfermedades, Infecciosas, Cuernavaca, Morelos, Mexico. jsilva@insp3.insp.mx
authors.forename: J
authors.initials: J
authors.lastname: Silva-Sánchez
authors.forename: C
authors.initials: C
authors.lastname: Aguilar-Zacarías
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis* / Q000378:metabolism; D001681:Biological Assay; D002439:Cefotaxime / Q000378:metabolism; D002511:Cephalosporins / Q000378:metabolism; D004755:Enterobacteriaceae / Q000201:enzymology*; D004926:Escherichia coli / Q000201:enzymology; D007525:Isoelectric Focusing; D007711:Klebsiella pneumoniae / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D012680:Sensitivity and Specificity; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000032:analysis* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002511:Cephalosporins; D001618:beta-Lactamases; C021720:nitrocefin; D002439:Cefotaxime