What is the reason for conflicting results for vancomycin minimum inhibitory concentration values of methicillin-resistant Staphylococcus aureus?

References

• Edwards B, Milne K, Lawes T, Cook I, Robb A, Gould IM. Is vancomycin MIC “creep” method dependent? Analysis of methicillin-resistant Staphylococcus aureus susceptibility trends in blood isolates from North East Scotland from 2006 to 2010. J Clin Microbiol 2012;50:318–25.
   PubMed Web of Science ®Google Scholar
• Steinkraus G, White R, Friedrich L. Vancomycin MIC creep in non-vancomycin-intermediate Staphylococcus aureus (VISA), vancomycin-susceptible clinical methicillin-resistant S. aureus (MRSA) blood isolates from 2001–05. J Antimicrob Chemother 2007;60:788–94.
   PubMed Web of Science ®Google Scholar
• Lodise TP, Graves J, Evans A, Graffunder E, Helmecke M, Lomaestro BM, et al. Relationship between vancomycin MIC and failure among patients with methicillin-resistant Staphylococcus aureus bacteremia treated with vancomycin. Antimicrob Agents Chemother 2008;52:3315–20.
   PubMed Web of Science ®Google Scholar
• Wang G, Hindler JF, Ward KW, Bruckner DA. Increased vancomycin MICs for Staphylococcus aureus clinical isolates from a university hospital during a 5-year period. J Clin Microbiol 2006;44:3883–6.
   PubMed Web of Science ®Google Scholar
• Reynolds R, Hope R, Warner M, Macgowan AP, Livermore DM, Ellington MJ, et al. Lack of upward creep of glycopeptide MICs for methicillin-resistant Staphylococcus aureus (MRSA) isolated in the UK and Ireland 2001–07. J Antimicrob Chemother 2012;67:2912–8.
   PubMedGoogle Scholar
• Sader HS, Fey PD, Limaye AP, Madinger N, Pankey G, Rahal J, et al. Evaluation of vancomycin and daptomycin potency trends (MIC creep) against methicillin-resistant Staphylococcus aureus isolates collected in nine U.S. medical centers from 2002 to 2006. Antimicrob Agents Chemother 2009;53:4127–32.
   PubMed Web of Science ®Google Scholar
• Hsu DI, Hidayat LK, Quist R, Hindler J, Karlsson A, Yusof A, et al. Comparison of method-specific vancomycin minimum inhibitory concentration values and their predictability for treatment outcome of meticillin-resistant Staphylococcus aureus (MRSA) infections. Int J Antimicrob Agents 2008;32:378–85.
   PubMed Web of Science ®Google Scholar
• Prakash V, Lewis JS 2nd, Jorgensen JH. Vancomycin MICs for methicillin-resistant Staphylococcus aureus isolates differ based upon the susceptibility test method used. Antimicrob Agents Chemother 2008;52:4528.
   PubMed Web of Science ®Google Scholar
• Sader HS, Rhomberg PR, Jones RN. Nine-hospital study comparing broth microdilution and Etest method results for vancomycin and daptomycin against methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2009;53:3162–5.
   PubMed Web of Science ®Google Scholar
• Picazo JJ, Betriu C, Rodriguez-Avial I, Culebras E, Lopez-Fabal F, Gomez M, et al. Comparative activities of daptomycin and several agents against staphylococcal blood isolates. Glycopeptide tolerance. Diagn Microbiol Infect Dis 2011;70:373–9.
   PubMed Web of Science ®Google Scholar
• Sancak B, Yagci S, Mirza HC, Hasçelik G. Evaluation of vancomycin and daptomycin MIC trends for methicillin- resistant Staphylococcus aureus blood isolates over an 11 year period. J Antimicrob Chemother 2013;68:2689–91.
   PubMedGoogle Scholar
• van Hal SJ, Barbagiannakos T, Jones M, Wehrhahn MC, Mercer J, Chen D, et al. Methicillin-resistant Staphylococcus aureus vancomycin susceptibility testing: methodology correlations, temporal trends and clonal patterns. J Antimicrob Chemother 2011;66:2284–7.
   PubMed Web of Science ®Google Scholar
• Keel RA, Sutherland CA, Aslanzadeh J, Nicolau DP, Kuti JL. Correlation between vancomycin and daptomycin MIC values for methicillin-susceptible and methicillin- resistant Staphylococcus aureus by 3 testing methodologies. Diagn Microbiol Infect Dis 2010;68:326–9.
   PubMed Web of Science ®Google Scholar
• Kehrmann J, Kaase M, Szabados F, Gatermann SG, Buer J, Rath PM, et al. Vancomycin MIC creep in MRSA blood culture isolates from Germany: a regional problem?. Eur J Clin Microbiol Infect Dis 2011;30:677–83.
   PubMed Web of Science ®Google Scholar
• Ludwig F, Edwards B, Lawes T, Gould IM. Effects of storage on vancomycin and daptomycin MIC in susceptible blood isolates of methicillin-resistant Staphylococcus aureus. J Clin Microbiol 2012;50:3383–7.
   PubMedGoogle Scholar
• Kelley PG, Gao W, Ward PB, Howden BP. Daptomycin non-susceptibility in vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous-VISA (hVISA): implications for therapy after vancomycin treatment failure. J Antimicrob Chemother 2011;66:1057–60.
   PubMed Web of Science ®Google Scholar