title: Detection of extended-spectrum beta-lactamases in members of the family Enterobacteriaceae: comparison of the double-disk and three-dimensional tests.
abstract: The three-dimensional and clavulanate double-disk potentiation tests were compared as procedures for the detection of extended-spectrum beta-lactamase production in 32 strains of Escherichia coli and Klebsiella pneumoniae, 31 of which produced TEM-1, TEM-2, TEM-3, TEM-4, TEM-5, TEM-7, TEM-8, TEM-9, TEM-10, TEM-12, TEM-101, SHV-1, SHV-2, SHV-3, SHV-4, SHV-5, CAZ-2, MIR-1, or an unidentified extended-spectrum beta-lactamase with a pI of 5.95, with some strains producing multiple beta-lactamases. The three-dimensional test, which was performed in conjunction with a routine disk diffusion test, detected extended-spectrum beta-lactamase production in 26 of 28 (93%) of the strains that produced extended-spectrum beta-lactamases. The clavulanate double-disk potentiation test detected extended-spectrum beta-lactamases in only 22 of the 28 strains (79%) when it was performed as currently recommended. The three-dimensional test, when performed in conjunction with the disk diffusion test, offered the advantages of providing simultaneous information about both antibiotic susceptibility and extended-spectrum beta-lactamase production, coupled with a greater sensitivity and earlier detection of extended-spectrum beta-lactamases.
authors.affiliation: Creighton University School of Medicine, Omaha, Nebraska 68178.
authors.forename: K S
authors.initials: KS
authors.lastname: Thomson
authors.forename: C C
authors.initials: CC
authors.lastname: Sanders
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology*; D004926:Escherichia coli / Q000201:enzymology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases