VISA/hVISA Confirmation

Confirmation of vancomycin intermediate Staphylococcus aureus (VISA) or heterogeneous vancomycin intermediate Staphylococcus aureus (hVISA) by Etest.

Pure culture.

N/A

Send cultures as growth on culture medium or in transport medium. Culture vessel should be leak-proof or sealed appropriately.

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

N/A

Completed Antimicrobial Resistance and Nosocomial Infections Requisition.

Since this combination of tests is not the gold standard for determining VISA status (as PAP-AUC is), it only suggests the organism may be hVISA/VISA if the vancomycin MIC measured by the standard Etest is ≤ 2 mg/L.

A combination of standard vancomycin Etest MIC determination and macro & GRD Etests are used to indicate if the organism is a probable hVISA or VISA or not. 

8 calendar days.

1. Walsh TR1, Bolmström A, Qwärnström A, Ho P, Wootton M, Howe RA, MacGowan AP, Diekema D. 2001. Evaluation of current methods for detection of staphylococci with reduced susceptibility to glycopeptides. J Clin Microbiol.  Jul;39(7):2439-44.
2. Yusof A, et al. 2008. Evaluation of a New Etest Vancomycin-Teicoplanin strip for detection of glycopeptide-intermediate Staphylococcus aureus (GISA), in particular heterogeneous GISA. J Clin Microbiol 46(9) 3042-3047.