title: Impact of minimal inhibitory concentration breakpoints on local cumulative bacterial susceptibility data and antibiotic consumption.
abstract: BACKGROUND
  The phenotypic antimicrobial susceptibility testing (AST) of bacteria depends on minimal inhibitory concentration breakpoints issued by national and international breakpoint committees. The current study was performed in order to test the influence of different AST standards on local cumulative AST data and on antibiotic consumption.
  
  
  METHODS
  Automated AST was performed with clinical isolates of Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus faecalis, and E. faecium. From each species 100 prospectively collected non-duplicate clinical isolates were tested and MIC data were interpreted according to the interpretation standards issued by DIN and EUCAST, respectively. In addition cumulative AST data from clinical isolates and antibiotic consumption were monitored before and after implementation of new EUCAST MIC breakpoints.
  
  
  RESULTS
  The susceptibility rate of P. aeruginosa against piperacillin and gentamicin, and of C. freundii against piperacillin/tazobactam increased significantly, whereas the susceptibility rates of E. cloacae, S. marcescens, and M. morganii against ciprofloxacin decreased significantly after switching from DIN to EUCAST MIC breakpoints. These changes in the cumulative antibiotic resistance pattern were reflected by enhanced consumption of piperacillin/tazobactam after implementation of EUCAST MIC breakpoints.
  
  
  CONCLUSIONS
  These data show that changes of AST breakpoints have a significant influence on local cumulative AST data and on antibiotic consumption.
authors.forename: Sofia
authors.initials: S
authors.lastname: Stokkou
authors.forename: Ina
authors.initials: I
authors.lastname: Tammer
authors.forename: Stefanie
authors.initials: S
authors.lastname: Zibolka
authors.forename: Christina
authors.initials: C
authors.lastname: Grabau
authors.affiliation: Institut für Medizinische Mikrobiologie und Krankenhaushygiene, Universitätsklinikum Magdeburg, Leipziger Str, 44, 39120 Magdeburg, Germany. gernot.geginat@med.ovgu.de.
authors.forename: Gernot
authors.initials: G
authors.lastname: Geginat
mesh_terms: D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D001419:Bacteria / Q000145:classification / Q000187:drug effects* / Q000378:metabolism; D008826:Microbial Sensitivity Tests
chemical_list: D000900:Anti-Bacterial Agents