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Evaluation of three techniques for detection of low-level methicillin-resistant Staphylococcus aureus (MRSA): a disk diffusion method with cefoxitin and moxalactam, the Vitek 2 system, and the MRSA-screen latex agglutination test.
J Clin Microbiol. 2002 Aug; 40(8):2766-71.JC

Abstract

Very-low-level methicillin-resistant Staphylococcus aureus (MRSA), or class 1 MRSA, is often misdiagnosed as methicillin-susceptible S. aureus (MSSA). We evaluated the performances of three methods for detection of low-level methicillin resistance: the disk diffusion method using the cephamycin antibiotics cefoxitin and moxalactam, the Vitek 2 system (bioMérieux), and the MRSA-screen test (Denka). Detection of the mecA gene by PCR was considered to be the "gold standard." We also determined the sensitivity of the oxacillin disk diffusion method with 5- and 1-microg disks and that of the Oxascreen agar assay with 6 mg of oxacillin liter(-1) for detection of MRSA. We compared the distributions of MICs of oxacillin and cefoxitin by the E-test (AB Biodisk), and those of moxalactam by dilutions in agar, for MRSA and MSSA isolates. The 152 clinical isolates of S. aureus studied were divided into 69 MSSA (mecA-negative) and 83 MRSA (mecA-positive) isolates, including 63 heterogeneous isolates and 26 class 1 isolates (low-level resistance). The cefoxitin and moxalactam disk diffusion tests detected 100% of all the MRSA classes: cefoxitin inhibition zone diameters were <27 mm, and moxalactam inhibition zone diameters were <24 mm. The Vitek 2 system and the MRSA-screen test detected 94 and 97.6% of all MRSA isolates, respectively. The sensitivities of the 5- and 1-microg oxacillin disks were 95.2 and 96.4%, respectively, whereas that of the Oxascreen agar screen assay was 94%. All of the tests except the 1-microg oxacillin disk test were 100% specific. For the class 1 MRSA isolates, the sensitivity of the Vitek 2 test was 92.3%, whereas those of the MRSA-screen test and the disk diffusion method with cefoxitin and moxalactam were 100%. Therefore, the cefoxitin and moxalactam disk diffusion methods were the best-performing tests for routine detection of all classes of MRSA.

Authors+Show Affiliations

Service de Bactériologie-Virologie-Hygiène, Hôpital Saint-Louis, 75475 Paris Cedex 10, France. annie.felten@sls.ap-hop-paris.frNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Evaluation Study
Journal Article

Language

eng

PubMed ID

12149327

Citation

Felten, Annie, et al. "Evaluation of Three Techniques for Detection of Low-level Methicillin-resistant Staphylococcus Aureus (MRSA): a Disk Diffusion Method With Cefoxitin and Moxalactam, the Vitek 2 System, and the MRSA-screen Latex Agglutination Test." Journal of Clinical Microbiology, vol. 40, no. 8, 2002, pp. 2766-71.
Felten A, Grandry B, Lagrange PH, et al. Evaluation of three techniques for detection of low-level methicillin-resistant Staphylococcus aureus (MRSA): a disk diffusion method with cefoxitin and moxalactam, the Vitek 2 system, and the MRSA-screen latex agglutination test. J Clin Microbiol. 2002;40(8):2766-71.
Felten, A., Grandry, B., Lagrange, P. H., & Casin, I. (2002). Evaluation of three techniques for detection of low-level methicillin-resistant Staphylococcus aureus (MRSA): a disk diffusion method with cefoxitin and moxalactam, the Vitek 2 system, and the MRSA-screen latex agglutination test. Journal of Clinical Microbiology, 40(8), 2766-71.
Felten A, et al. Evaluation of Three Techniques for Detection of Low-level Methicillin-resistant Staphylococcus Aureus (MRSA): a Disk Diffusion Method With Cefoxitin and Moxalactam, the Vitek 2 System, and the MRSA-screen Latex Agglutination Test. J Clin Microbiol. 2002;40(8):2766-71. PubMed PMID: 12149327.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evaluation of three techniques for detection of low-level methicillin-resistant Staphylococcus aureus (MRSA): a disk diffusion method with cefoxitin and moxalactam, the Vitek 2 system, and the MRSA-screen latex agglutination test. AU - Felten,Annie, AU - Grandry,Bernadette, AU - Lagrange,Philippe Henri, AU - Casin,Isabelle, PY - 2002/8/1/pubmed PY - 2002/11/1/medline PY - 2002/8/1/entrez SP - 2766 EP - 71 JF - Journal of clinical microbiology JO - J. Clin. Microbiol. VL - 40 IS - 8 N2 - Very-low-level methicillin-resistant Staphylococcus aureus (MRSA), or class 1 MRSA, is often misdiagnosed as methicillin-susceptible S. aureus (MSSA). We evaluated the performances of three methods for detection of low-level methicillin resistance: the disk diffusion method using the cephamycin antibiotics cefoxitin and moxalactam, the Vitek 2 system (bioMérieux), and the MRSA-screen test (Denka). Detection of the mecA gene by PCR was considered to be the "gold standard." We also determined the sensitivity of the oxacillin disk diffusion method with 5- and 1-microg disks and that of the Oxascreen agar assay with 6 mg of oxacillin liter(-1) for detection of MRSA. We compared the distributions of MICs of oxacillin and cefoxitin by the E-test (AB Biodisk), and those of moxalactam by dilutions in agar, for MRSA and MSSA isolates. The 152 clinical isolates of S. aureus studied were divided into 69 MSSA (mecA-negative) and 83 MRSA (mecA-positive) isolates, including 63 heterogeneous isolates and 26 class 1 isolates (low-level resistance). The cefoxitin and moxalactam disk diffusion tests detected 100% of all the MRSA classes: cefoxitin inhibition zone diameters were <27 mm, and moxalactam inhibition zone diameters were <24 mm. The Vitek 2 system and the MRSA-screen test detected 94 and 97.6% of all MRSA isolates, respectively. The sensitivities of the 5- and 1-microg oxacillin disks were 95.2 and 96.4%, respectively, whereas that of the Oxascreen agar screen assay was 94%. All of the tests except the 1-microg oxacillin disk test were 100% specific. For the class 1 MRSA isolates, the sensitivity of the Vitek 2 test was 92.3%, whereas those of the MRSA-screen test and the disk diffusion method with cefoxitin and moxalactam were 100%. Therefore, the cefoxitin and moxalactam disk diffusion methods were the best-performing tests for routine detection of all classes of MRSA. SN - 0095-1137 UR - https://www.unboundmedicine.com/medline/citation/12149327/Evaluation_of_three_techniques_for_detection_of_low_level_methicillin_resistant_Staphylococcus_aureus__MRSA_:_a_disk_diffusion_method_with_cefoxitin_and_moxalactam_the_Vitek_2_system_and_the_MRSA_screen_latex_agglutination_test_ L2 - http://jcm.asm.org/cgi/pmidlookup?view=long&amp;pmid=12149327 DB - PRIME DP - Unbound Medicine ER -