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Evaluation of new Vitek 2 card and disk diffusion method for determining susceptibility of Staphylococcus aureus to oxacillin.
J Clin Microbiol. 2008 Aug; 46(8):2525-8.JC

Abstract

Detection of methicillin resistance in Staphylococcus aureus is a challenge, especially low-level resistance, which is often misdiagnosed. The aim of this study was to compare the diagnostic accuracies of the automated Vitek 2 system and disk diffusion tests, using cefoxitin and moxalactam, for the detection of methicillin resistance in S. aureus strains. Four sets of genotypically diverse isolates were selected from a national reference collection, including mecA-negative S. aureus isolates (n = 56), hospital-acquired (n = 88) and community-acquired (n = 40) S. aureus isolates, and heterogeneous methicillin-resistant S. aureus isolates (n = 29). Oxacillin susceptibility was tested by the Vitek 2 system with the AST P549 card and by disk diffusion methods using 10, 30, and 60 microg cefoxitin and 30 microg moxalactam. Oxacillin resistance was confirmed by PCR for the mecA gene. The overall sensitivities for oxacillin resistance detection were 97.5% for the Vitek 2 automated system, 98.7% for 60-microg cefoxitin and moxalactam disk diffusion, and 99.6% for 10- and 30-microg cefoxitin disks, respectively. Methicillin-susceptible S. aureus isolates were correctly reported as susceptible by all methods. The median times for methicillin testing were 7 h for the Vitek 2 system versus 24 h for disk diffusion methods. In conclusion, the cefoxitin and moxalactam disk diffusion methods and the Vitek 2 automated system are highly accurate methods for methicillin resistance detection, including a range of representative Belgian methicillin-resistant S. aureus strains and unusual strains exhibiting cryptic or low-level oxacillin resistance.

Authors+Show Affiliations

Laboratoire de Référence MRSA-Staphylocoques, Department of Microbiology, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium. sroisin@ulb.ac.be [corrected]No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Evaluation Study
Journal Article

Language

eng

PubMed ID

18550733

Citation

Roisin, Sandrine, et al. "Evaluation of New Vitek 2 Card and Disk Diffusion Method for Determining Susceptibility of Staphylococcus Aureus to Oxacillin." Journal of Clinical Microbiology, vol. 46, no. 8, 2008, pp. 2525-8.
Roisin S, Nonhoff C, Denis O, et al. Evaluation of new Vitek 2 card and disk diffusion method for determining susceptibility of Staphylococcus aureus to oxacillin. J Clin Microbiol. 2008;46(8):2525-8.
Roisin, S., Nonhoff, C., Denis, O., & Struelens, M. J. (2008). Evaluation of new Vitek 2 card and disk diffusion method for determining susceptibility of Staphylococcus aureus to oxacillin. Journal of Clinical Microbiology, 46(8), 2525-8. https://doi.org/10.1128/JCM.00291-08
Roisin S, et al. Evaluation of New Vitek 2 Card and Disk Diffusion Method for Determining Susceptibility of Staphylococcus Aureus to Oxacillin. J Clin Microbiol. 2008;46(8):2525-8. PubMed PMID: 18550733.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evaluation of new Vitek 2 card and disk diffusion method for determining susceptibility of Staphylococcus aureus to oxacillin. AU - Roisin,Sandrine, AU - Nonhoff,Claire, AU - Denis,Olivier, AU - Struelens,Marc J, Y1 - 2008/06/11/ PY - 2008/6/14/pubmed PY - 2008/10/7/medline PY - 2008/6/14/entrez SP - 2525 EP - 8 JF - Journal of clinical microbiology JO - J. Clin. Microbiol. VL - 46 IS - 8 N2 - Detection of methicillin resistance in Staphylococcus aureus is a challenge, especially low-level resistance, which is often misdiagnosed. The aim of this study was to compare the diagnostic accuracies of the automated Vitek 2 system and disk diffusion tests, using cefoxitin and moxalactam, for the detection of methicillin resistance in S. aureus strains. Four sets of genotypically diverse isolates were selected from a national reference collection, including mecA-negative S. aureus isolates (n = 56), hospital-acquired (n = 88) and community-acquired (n = 40) S. aureus isolates, and heterogeneous methicillin-resistant S. aureus isolates (n = 29). Oxacillin susceptibility was tested by the Vitek 2 system with the AST P549 card and by disk diffusion methods using 10, 30, and 60 microg cefoxitin and 30 microg moxalactam. Oxacillin resistance was confirmed by PCR for the mecA gene. The overall sensitivities for oxacillin resistance detection were 97.5% for the Vitek 2 automated system, 98.7% for 60-microg cefoxitin and moxalactam disk diffusion, and 99.6% for 10- and 30-microg cefoxitin disks, respectively. Methicillin-susceptible S. aureus isolates were correctly reported as susceptible by all methods. The median times for methicillin testing were 7 h for the Vitek 2 system versus 24 h for disk diffusion methods. In conclusion, the cefoxitin and moxalactam disk diffusion methods and the Vitek 2 automated system are highly accurate methods for methicillin resistance detection, including a range of representative Belgian methicillin-resistant S. aureus strains and unusual strains exhibiting cryptic or low-level oxacillin resistance. SN - 1098-660X UR - https://www.unboundmedicine.com/medline/citation/18550733/Evaluation_of_new_Vitek_2_card_and_disk_diffusion_method_for_determining_susceptibility_of_Staphylococcus_aureus_to_oxacillin_ L2 - http://jcm.asm.org/cgi/pmidlookup?view=long&pmid=18550733 DB - PRIME DP - Unbound Medicine ER -