1887

Abstract

The aim of this study was to evaluate Etest for detectability of linezolid-resistant meticillin-resistant (MRSA). The MIC of linezolid obtained by the Etest method in 18 linezolid-resistant strains of MRSA was compared with that obtained using standard agar and broth dilution methods according to Clinical and Laboratory Standards Institute guidelines. The mean linezolid MIC obtained by Etest in 18 linezolid-resistant strains of MRSA using Mueller–Hinton (MH) agar was 12.6-fold lower than that obtained by the agar dilution method, with the result that 78 % of the linezolid-resistant strains were incorrectly classified as linezolid-susceptible. The MIC of linezolid by Etest on brain–heart infusion (BHI) agar had a mean value 2.5-fold lower than that obtained by the agar dilution method, suggesting that replacing MH agar with BHI agar considerably improved the detectability of linezolid-resistant MRSA. Use of blood agar (MH agar supplemented with 5 % sheep blood) and 48 h of incubation resulted in 100 % agreement with the agar and broth dilution methods. Thus, this study revealed that the Etest on MH agar and BHI agar yielded false-negative results in a significant fraction of the linezolid-resistant MRSA. Hence, the use of blood agar and prolonged incubation is highly recommended for the accurate detection of linezolid-resistant MRSA using Etest.

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2012-07-01
2019-10-14
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References

  1. Arias C. A., Vallejo M., Reyes J., Panesso D., Moreno J., Castañeda E., Villegas M. V., Murray B. E., Quinn J. P.. ( 2008;). Clinical and microbiological aspects of linezolid resistance mediated by the cfr gene encoding a 23S rRNA methyltransferase. . J Clin Microbiol 46:, 892–896. [CrossRef][PubMed]
    [Google Scholar]
  2. Bozdogan B., Appelbaum P. C.. ( 2004;). Oxazolidinones: activity, mode of action, and mechanism of resistance. . Int J Antimicrob Agents 23:, 113–119. [CrossRef][PubMed]
    [Google Scholar]
  3. CLSI ( 2007;). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically; Approved Standard. M7-A7. . Wayne, PA:: Clinical and Laboratory Standards Institute;.
  4. Gómez-Garcés J. L., López-Fabal F., Burillo A., Gil Y.. ( 2010;). [Comparative study of the susceptibility to daptomycin and other antimicrobials against Staphylococcus spp. resistant to methicillin and Enterococcus spp. using Wider, E-test, and microdilution methods]. . Rev Esp Quimioter 23:, 87–92 (in Spanish).[PubMed]
    [Google Scholar]
  5. Ikeda-Dantsuji Y., Hanaki H., Nakae T., Takesue Y., Tomono K., Honda J., Yanagihara K., Mikamo H., Fukuchi K.. & other authors ( 2011a;). Emergence of linezolid-resistant mutants in a susceptible-cell population of methicillin-resistant Staphylococcus aureus. . Antimicrob Agents Chemother 55:, 2466–2468. [CrossRef][PubMed]
    [Google Scholar]
  6. Ikeda-Dantsuji Y., Hanaki H., Sakai F., Tomono K., Takesue Y., Honda J., Nonomiya Y., Suwabe A., Nagura O.. & other authors ( 2011b;). Linezolid-resistant Staphylococcus aureus isolated from 2006 through 2008 at six hospitals in Japan. . J Infect Chemother 17:, 45–51. [CrossRef][PubMed]
    [Google Scholar]
  7. Locke J. B., Hilgers M., Shaw K. J.. ( 2009;). Novel ribosomal mutations in Staphylococcus aureus strains identified through selection with the oxazolidinones linezolid and torezolid (TR-700). . Antimicrob Agents Chemother 53:, 5265–5274. [CrossRef][PubMed]
    [Google Scholar]
  8. Meka V. G., Gold H. S.. ( 2004;). Antimicrobial resistance to linezolid. . Clin Infect Dis 39:, 1010–1015. [CrossRef][PubMed]
    [Google Scholar]
  9. Meka V. G., Pillai S. K., Sakoulas G., Wennersten C., Venkataraman L., DeGirolami P. C., Eliopoulos G. M., Moellering R. C. Jr, Gold H. S.. ( 2004;). Linezolid resistance in sequential Staphylococcus aureus isolates associated with a T2500A mutation in the 23S rRNA gene and loss of a single copy of rRNA. . J Infect Dis 190:, 311–317. [CrossRef][PubMed]
    [Google Scholar]
  10. Shinabarger D.. ( 1999;). Mechanism of action of the oxazolidinone antibacterial agents. . Expert Opin Investig Drugs 8:, 1195–1202. [CrossRef][PubMed]
    [Google Scholar]
  11. Tenover F. C., Williams P. P., Stocker S., Thompson A., Clark L. A., Limbago B., Carey R. B., Poppe S. M., Shinabarger D., McGowan J. E. Jr. ( 2007;). Accuracy of six antimicrobial susceptibility methods for testing linezolid against staphylococci and enterococci. . J Clin Microbiol 45:, 2917–2922. [CrossRef][PubMed]
    [Google Scholar]
  12. Tsiodras S., Gold H. S., Sakoulas G., Eliopoulos G. M., Wennersten C., Venkataraman L., Moellering R. C. Jr, Ferraro M. J.. ( 2001;). Linezolid resistance in a clinical isolate of Staphylococcus aureus. . Lancet 358:, 207–208. [CrossRef][PubMed]
    [Google Scholar]
  13. Tubau F., Fernández-Roblas R., Liñares J., Martín R., Soriano F.. ( 2001;). In vitro activity of linezolid and 11 other antimicrobials against 566 clinical isolates and comparison between NCCLS microdilution and Etest methods. . J Antimicrob Chemother 47:, 675–680. [CrossRef][PubMed]
    [Google Scholar]
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