title: Detection of ESBL among AmpC producing enterobacteriaceae using inhibitor-based method.
abstract: BACKGROUND
  The occurrence of multiple β-lactamases among bacteria only limits the therapeutic options but also poses a challenge. A study using boronic acid (BA), an AmpC enzyme inhibitor, was designed to detect the combined expression of AmpC β-lactamases and extended-spectrum β-lactamases (ESBLs) in bacterial isolates further different phenotypic methods are compared to detect ESBL and AmpC.
  
  
  METHODS
  A total of 259 clinical isolates of Enterobacteriaceae were isolated and screened for ESBL production by (i) CLSI double-disk diffusion method (ii) cefepime- clavulanic acid method (iii) boronic disk potentiation method. AmpC production was detected using cefoxitin alone and in combination with boronic acid and confirmation was done by three dimensional disk methods. Isolates were also subjected to detailed antibiotic susceptibility test.
  
  
  RESULTS
  Among 259 isolates, 20.46% were coproducers of ESBL and AmpC, 26.45% were ESBL and 5.40% were AmpC. All of the 53 AmpC and ESBL coproducers were accurately detected by boronic acid disk potentiation method.
  
  
  CONCLUSIONS
  The BA disk test using Clinical and Laboratory Standards Institute methodology is simple and very efficient method that accurately detects the isolates that harbor both AmpCs and ESBLs.
authors.affiliation: Department of Microbiology, Centre for Post Graduate Studies, Jain University, Bangalore, Karnataka--560 011, India.
authors.forename: Sasirekha
authors.initials: S
authors.lastname: Bakthavatchalu
authors.forename: Uma
authors.initials: U
authors.lastname: Shakthivel
authors.forename: Tannu
authors.initials: T
authors.lastname: Mishra
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D001826:Body Fluids / Q000382:microbiology; D001897:Boronic Acids / Q000494:pharmacology*; D000077723:Cefepime; D002440:Cefoxitin / Q000378:metabolism / Q000494:pharmacology; D018550:Cephalosporin Resistance; D002511:Cephalosporins / Q000378:metabolism / Q000494:pharmacology; D019818:Clavulanic Acid / Q000494:pharmacology; D052978:Disk Diffusion Antimicrobial Tests; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D004790:Enzyme Induction / Q000187:drug effects; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006801:Humans; D013379:Substrate Specificity; D018440:beta-Lactam Resistance / Q000235:genetics; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001897:Boronic Acids; D002511:Cephalosporins; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D002440:Cefoxitin; D000077723:Cefepime; C048795:AmpC beta-lactamases; D001618:beta-Lactamases
keywords: ESBL; ampc beta-lactamases; boronic acid; cefepime; enterobacteriaceae