Performance of various testing methodologies for detection of heteroresistant vancomycin-intermediate Staphylococcus aureus in bloodstream isolates

van Hal, Sebastian J., Wehrhahn, Michael C., Barbagiannakos, Thelma, Mercer, Joanne, Chen, Dehua, Paterson, David L. and Gosbell, Iain B. (2011) Performance of various testing methodologies for detection of heteroresistant vancomycin-intermediate Staphylococcus aureus in bloodstream isolates. Journal of Clinical Microbiology, 49 4: 1489-1494. doi:10.1128/JCM.02302-10

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Author van Hal, Sebastian J.
Wehrhahn, Michael C.
Barbagiannakos, Thelma
Mercer, Joanne
Chen, Dehua
Paterson, David L.
Gosbell, Iain B.
Title Performance of various testing methodologies for detection of heteroresistant vancomycin-intermediate Staphylococcus aureus in bloodstream isolates
Formatted title
Performance of various testing methodologies for detection of heteroresistant vancomycin-intermediate Staphylococcus aureus in bloodstream isolates
Journal name Journal of Clinical Microbiology   Check publisher's open access policy
ISSN 0095-1137
1070-633X
1098-660X
Publication date 2011-04-01
Sub-type Article (original research)
DOI 10.1128/JCM.02302-10
Open Access Status File (Publisher version)
Volume 49
Issue 4
Start page 1489
End page 1494
Total pages 6
Place of publication Washington, DC, United States
Publisher American Society for Microbiology
Language eng
Formatted abstract
The best screening method for detecting heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) remains unclear. Using population analysis profiling utilizing the area under the concentration-time curve (PAP-AUC) as the gold standard, we screened 458 consecutive methicillin-resistant S. aureus (MRSA) bloodstream isolates to determine the most accurate and cost-effective testing strategy to detect the presence of heteroresistance. All isolates were also tested using the macromethod Etest (MET) and glycopeptide resistance detection (GRD) Etest. The MIC was determined by several methods, including standard vancomycin Etest, vancomycin broth microdilution (BMD), and Vitek2 testing. Fifty-five (12%) hVISA and 4 (1%) VISA isolates were detected by PAP-AUC. Compared to PAP-AUC, the sensitivities and specificities of MET, GRD Etest, BMD (using a MIC cutoff of ≥2 mg/liter), and standard vancomycin Etest (using a MIC cutoff of ≥2 mg/liter) were 89 and 55%, 71 and 94%, 82 and 97%, and 71 and 94%, respectively. Combination testing increased the overall testing accuracy by reducing the number of false-positive results. Cost was determined predominately by the number of PAP-AUC runs required following a screening assay. The most cost-effective strategy was BMD (using a MIC cutoff of ≥2 μg/ml) as a standalone assay or in combination with PAP-AUC, provided that BMD testing was batched. GRD Etest remained an alternative, with 71% of hVISA isolates detected. Prevalence influenced both cost and test accuracy, with results remaining unchanged for hVISA prevalences of up to 25%. Implementation of any testing strategy would therefore be dependent on balancing cost with accuracy in a given population and clinical context.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: UQ Centre for Clinical Research Publications
Official 2012 Collection
School of Medicine Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 37 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 43 times in Scopus Article | Citations
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Created: Wed, 19 Oct 2011, 22:50:50 EST by Laurie Beechey on behalf of UQ Centre for Clinical Research