title: The need to assay the real MIC when making the decision to eradicate Staphylococcus aureus with vancomycin.
abstract: OBJECTIVE
  The aim of the study was a comparison of the MIC (minimal inhibitory concentration) evaluated in the automatic system Vitek 2 and the real MIC of vancomycin by the Etest method for S. aureus strains isolated from clinical materials.
  
  
  METHODS
  Over a twelve-month study period we compared the results obtained with two commercial methods - the automatic system VITEK 2 and the real MIC by Etest - for 359 strains of S. aureus isolated from clinical materials.
  
  
  RESULTS
  Most of the strains of S. aureus were cultured from wounds (84), the ear (60) and nose (42). MSSA (methicillin-sensitive Staphylococcus aureus) was isolated in 342 cases and MRSA (methicillin-resistant Staphylococcus aureus) in 17 cases. The test with the Vitek automatic method showed that vancomycin had MIC values of ≤1.0 μg/ml in more than 96% and 2.0 μg/ml in over 3% of cases. Using the Etest technique MIC ≤ 1.0 μg/ml was obtained in only 16.4% of cases and values of >1.0 μg/ml in 83.6% of cases.
  
  
  CONCLUSIONS
  In view of such big differences between the MIC values obtained with the two methods the authors suggest that the Etest method of assaying the real MIC is more useful than the automatic method.
authors.affiliation: Central Laboratory of Microbiology, University Hospital, Poznań, Poland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Tomczak
authors.forename: Edyta
authors.initials: E
authors.lastname: Szałek
authors.forename: Wioleta
authors.initials: W
authors.lastname: Błażejewska
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Myczko
authors.forename: Anna
authors.initials: A
authors.lastname: Horla
authors.forename: Edmund
authors.initials: E
authors.lastname: Grześkowiak
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009666:Nose / Q000382:microbiology; D015203:Reproducibility of Results; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology* / Q000627:therapeutic use; D014947:Wounds and Injuries / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin