title: Comparison of M.I.C.E. and Etest with CLSI agar dilution for antimicrobial susceptibility testing against oxacillin-resistant Staphylococcus spp.
abstract: OBJECTIVE
  The main objective of this study was to comparatively evaluate the performance of M.I.C.E. and Etest methodologies to that of agar dilution for determining the antimicrobial susceptibility profile of oxacillin-resistant Staphylococcus spp.
  
  
  METHODS
  A total of 100 oxacillin-resistant Staphylococcus spp. isolates were collected from hospitalized patients at a teaching hospital. Antimicrobial susceptibility testing for vancomycin, teicoplanin and linezolid was performed using the reference CLSI agar dilution method (2009), Etest and M.I.C.E. methodologies. The MIC values were interpreted according to CLSI susceptibility breakpoints and compared by regression analysis.
  
  
  RESULTS
  In general, the essential agreement (±1-log2) between M.I.C.E. and CLSI agar dilution was 93.0%, 84.0% and 77.0% for linezolid, teicoplanin and vancomycin, respectively. Essential agreement rates between M.I.C.E. and Etest were excellent (>90.0%) for all antibiotics tested. Both strips (M.I.C.E. and Etest) yielded two very major errors for linezolid. Unacceptable minor rates were observed for teicoplanin against CoNS and for vancomycin against S. aureus.
  
  
  CONCLUSIONS
  According to our results, linezolid and teicoplanin MICs against all staphylococci and S. aureus, respectively, were more accurately predicted by M.I.C.E. strips. However, the Etest showed better performance than M.I.C.E. for predicting vancomycin MICs against all staphylococci. Thus, microbiologists must be aware of the different performance of commercially available gradient strips against staphylococci.
authors.affiliation: Laboratório Alerta, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo - SP, Brazil.
authors.forename: Eloiza H
authors.initials: EH
authors.lastname: Campana
authors.affiliation: Laboratório Alerta, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo - SP, Brazil.
authors.forename: Cecilia G
authors.initials: CG
authors.lastname: Carvalhaes
authors.affiliation: Laboratório Alerta, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo - SP, Brazil.
authors.forename: Bruna
authors.initials: B
authors.lastname: Nonato
authors.affiliation: Laboratório Central do Hospital São Paulo, Universidade Federal de São Paulo, São Paulo - SP, Brazil.
authors.forename: Antonia M de O
authors.initials: AM
authors.lastname: Machado
authors.affiliation: Laboratório Alerta, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo - SP, Brazil.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Gales
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000362:Agar / Q000737:chemistry; D000890:Anti-Infective Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006801:Humans; D000069349:Linezolid; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology*; D023303:Oxazolidinones / Q000494:pharmacology; D012044:Regression Analysis; D015203:Reproducibility of Results; D013210:Staphylococcus / Q000187:drug effects*; D017334:Teicoplanin / Q000494:pharmacology; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000081:Acetamides; D000890:Anti-Infective Agents; D023303:Oxazolidinones; D017334:Teicoplanin; D014640:Vancomycin; D000362:Agar; D000069349:Linezolid; D010068:Oxacillin
references.citation: J Clin Microbiol. 2004 Jun;42(6):2398-402
references.pmid: 15184410
references.citation: J Antimicrob Chemother. 2010 Aug;65(8):1702-11
references.pmid: 20562429
references.citation: J Antimicrob Chemother. 2011 May;66(5):1192-3
references.pmid: 21393161
references.citation: J Antimicrob Chemother. 2008 Dec;62(6):1464-6
references.pmid: 18772157
references.citation: J Clin Microbiol. 2012 Apr;50(4):1153-7
references.pmid: 22238439
references.citation: J Clin Microbiol. 2012 Apr;50(4):1147-52
references.pmid: 22238441
references.citation: J Clin Microbiol. 1998 Apr;36(4):1020-7
references.pmid: 9542929