title: Phenotypic detection of broad-spectrum beta-lactamases in microbiological practice.
abstract: BACKGROUND
  Enterobacteriaceae producing ESBL and AmpC enzymes can be associated with failure of antibiotic therapy and related morbidity and mortality. Their routine detection in microbiology laboratories is still a problem. The aim of this study was to compare the sensitivity of selected phenotypic methods.
  
  
  METHODS
  A total of 106 strains of the Enterobacteriaceae family were tested, in which molecular biology methods confirmed the presence of genes encoding ESBL or AmpC. In ESBL-positive strains, the sensitivity of the ESBL Etest (AB Biodisk) and a modified double-disk synergy test (DDST) were evaluated. AmpC strains were tested by a modified AmpC disk method using 3-aminophenylboronic acid. For simultaneous detection of ESBL and AmpC, the microdilution method with a modified set of antimicrobial agents was used.
  
  
  RESULTS
  The sensitivity of the ESBL Etest was 95%; the modified DDST yielded 100% sensitivity for ESBL producers and the AmpC test correctly detected 95% of AmpC-positive strains. The sensitivity of the modified microdilution method was 87% and 95% for ESBL and AmpC beta lactamases, respectively.
  
  
  CONCLUSIONS
  The detection of ESBL and AmpC beta lactamases should be based on specific phenotypic methods such as the modified DDST, ESBL Etest, AmpC disk test and the modified microdilution method.
authors.affiliation: Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Czech Republic. miroslava.htoutou@seznam.cz
authors.forename: Miroslava
authors.initials: M
authors.lastname: Htoutou Sedlakova
authors.forename: Vojtech
authors.initials: V
authors.lastname: Hanulik
authors.forename: Magdalena
authors.initials: M
authors.lastname: Chroma
authors.forename: Kristyna
authors.initials: K
authors.lastname: Hricova
authors.forename: Milan
authors.initials: M
authors.lastname: Kolar
authors.forename: Tomas
authors.initials: T
authors.lastname: Latal
authors.forename: Reiner
authors.initials: R
authors.lastname: Schaumann
authors.forename: Arne C
authors.initials: AC
authors.lastname: Rodloff
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000032:analysis; D002511:Cephalosporins / Q000494:pharmacology; D004755:Enterobacteriaceae / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D007711:Klebsiella pneumoniae / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D010641:Phenotype; D012015:Reference Standards; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000032:analysis*
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases