title: Broth microdilution method to detect extended-spectrum beta-lactamases and AmpC beta-lactamases in enterobacteriaceae isolates by use of clavulanic acid and boronic acid as inhibitors.
abstract: This study was designed to evaluate the performance of the broth microdilution (BMD) method to detect production of extended-spectrum beta-lactamases (ESBLs) and AmpC beta-lactamases in Enterobacteriaceae by using clavulanic acid (CA) and boronic acid (BA) as ESBL and AmpC beta-lactamase inhibitors, respectively. A total of 100 clinical isolates of Enterobacteriaceae were analyzed. Mueller-Hinton broth containing serial twofold dilutions of cefotaxime (CTX), ceftazidime (CAZ), aztreonam (ATM), or cefepime (FEP) with or without either or both CA and BA was prepared. An eightfold or greater decrease in the MIC of CTX, CAZ, ATM, or FEP in the presence of CA and BA was considered a positive result for ESBL and plasmid-mediated AmpC beta-lactamase (PABL), respectively. In tests with CA, expanded-spectrum beta-lactams containing BA (CTX-BA, CAZ-BA, ATM-BA, and FEP-BA) showed higher positive rates in detecting ESBL producers than those without BA. The combination of CTX- and CAZ-based BMD tests with CA and BA showed sensitivity and specificity of 100% for the detection of ESBLs and PABLs. The BMD testing could be applicable for routine use in commercially available semiautomated systems for the detection of ESBLs and PABLs in Enterobacteriaceae.
authors.affiliation: Department of Laboratory Medicine, Hallym University College of Medicine, 948-1 Daerim 1-Dong, Youngdeungpo-Gu, Seoul 150-950, Republic of Korea.
authors.forename: Seok Hoon
authors.initials: SH
authors.lastname: Jeong
authors.forename: Wonkeun
authors.initials: W
authors.lastname: Song
authors.forename: Jae-Seok
authors.initials: JS
authors.lastname: Kim
authors.forename: Han-Sung
authors.initials: HS
authors.lastname: Kim
authors.forename: Kyu Man
authors.initials: KM
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001897:Boronic Acids / Q000494:pharmacology*; D019818:Clavulanic Acid / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000201:enzymology* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*; D012680:Sensitivity and Specificity; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D000900:Anti-Bacterial Agents; D001897:Boronic Acids; D003470:Culture Media; D004791:Enzyme Inhibitors; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D001618:beta-Lactamases