Clinical Outcomes in Patients with Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Bloodstream Infection

Casapao, Anthony M.; Leonard, Steven N.; Davis, Susan L.; Lodise, Thomas P.; Patel, Nimish; Goff, Debra A.; LaPlante, Kerry L.; Potoski, Brian A.; Rybak, Michael J.

doi:10.1128/aac.00380-13

Cited by 68 publications

(74 citation statements)

References 39 publications

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“…Few studies have specifically examined exposure rates and differences in duration of prior vancomycin administration in VISA and MRSA patients, though what data are available suggest that about 25% of patients with MRSA infections have had prior vancomycin exposure (2,4,5,16,24), a rate about 10% lower than that determined for our cohort (35.3%). The higher prevalence of antecedent vancomycin exposure in our cohort may be a reflection of variations in local antibiograms or better availability of data on prior vancomycin exposure.…”

Section: Discussioncontrasting

confidence: 46%

“…Vancomycin has historically been the empirical therapy of choice for coverage of possible methicillin-resistant Staphylococcus aureus (MRSA) infection. The emergence of vancomycin-intermediate S. aureus (VISA) infections (vancomycin MIC of 4 or 8 g/ml) threatens the efficacy of vancomycin as empirical therapy in the management of critically ill patients (2)(3)(4)(5). Delays in appropriate antimicrobial treatment of greater than 24 h in patients with MRSA sterile-site infections are known to increase mortality (6).…”

mentioning

confidence: 99%

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Impact of Time to Appropriate Therapy on Mortality in Patients with Vancomycin-Intermediate Staphylococcus aureus Infection

Burnham

Warren

Kollef

2016

Antimicrob Agents Chemother

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Section: Discussioncontrasting

confidence: 46%

mentioning

confidence: 99%

Impact of Time to Appropriate Therapy on Mortality in Patients with Vancomycin-Intermediate Staphylococcus aureus Infection

Burnham

Warren

Kollef

2016

Antimicrob Agents Chemother

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“…hVISA is not associated with high mortality but with increased failure rates, suggesting that resistance may have a fitness cost [27][28][29][30]. According to this information, it would be interesting for the clinical management of severe S. aureus bacteraemia treated with vancomycin to know the presence of heteroresistance.…”

Section: Heteroresistancementioning

confidence: 99%

Treatment options for methicillin-resistant Staphylococcus aureus (MRSA) infection: Where are we now?

Edwards

Andini

Esposito

et al. 2014

Journal of Global Antimicrobial Resistance

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“…Because only a subpopulation of cells of hVISA strains (Յ10 Ϫ5 to 10 Ϫ6 ) have vancomycin MICs in the intermediate range, hVISA isolates frequently test susceptible to vancomycin (i.e., MICs of Յ2 g/ml) by broth microdilution methods, which typically test only approximately 10 4 cells. Consequently, patients with hVISA infections may never be identified, despite having higher vancomycin treatment failure rates than patients with VSSA bloodstream infections (12). Unlike methicillin resistance and frank vancomycin resistance, which arise through the acquisition of discrete genetic elements (mecA and vanA, respectively), the genetic changes that lead to manifestation of the VISA and hVISA phenotypes are varied and not easily detectible by a single gene assay (summarized in reference 13).…”

mentioning

confidence: 99%

Rapid Detection of Vancomycin-Intermediate Staphylococcus aureus by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

et al. 2016

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Vancomycin is the standard of care for the treatment of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections. Infections with vancomycin-nonsusceptible MRSA, including vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA), are clinically challenging and are associated with poor patient outcomes. The identification of VISA in the clinical laboratory depends on standard susceptibility testing, which takes at least 24 h to complete after isolate subculture, whereas hVISA is not routinely detected in clinical labs. We therefore sought to determine whether VISA and hVISA can be differentiated from vancomycin-susceptible S. aureus (VSSA) using the spectra produced by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Strains of MRSA were characterized for vancomycin susceptibility phenotype by broth microdilution and modified population analysis. We tested 21 VISA, 21 hVISA, and 38 VSSA isolates by MALDI-TOF MS. Susceptibility phenotypes were separated by using a support vector machine (SVM) machine learning algorithm. The resulting model was validated by leave-one-out cross validation. Models were developed and validated by using spectral profiles generated under various subculture conditions, as well as with and without hVISA strains. Using SVM, we correctly identified 100% of the VISA and 97% of the VSSA isolates with an overall classification accuracy of 98%. Addition of hVISA to the model resulted in 76% hVISA identification, 100% VISA identification, and 89% VSSA identification, for an overall classification accuracy of 89%. We conclude that VISA/hVISA and VSSA isolates are separable by MALDI-TOF MS with SVM analysis. Delayed initiation of appropriate antibiotic therapy results in increased mortality rates for patients with sepsis (1-6). Staphylococcus aureus is a pathogen frequently isolated from patients with sepsis, with worse clinical outcomes noted for patients with methicillin-resistant S. aureus (MRSA) (7). Vancomycin remains the standard of care for the treatment of invasive infections with MRSA (8, 9). Infections with vancomycin-nonsusceptible isolates are associated with prolonged bacteremia, longer hospital stays, and greater rates of clinical treatment failure than infections with vancomycin-susceptible S. aureus (VSSA) (10, 11).Vancomycin nonsusceptibility falls into two related phenotypes: vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA). The VISA phenotype is reliably detected by broth microdilution, and these strains are characterized by a vancomycin MIC of 4 or 8 g/ml. Reliance on susceptibility testing to identify the VISA phenotype therefore delays the identification of these strains and thus the initiation of appropriate antimicrobial therapy. Because only a subpopulation of cells of hVISA strains (Յ10 Ϫ5 to 10 Ϫ6 ) have vancomycin MICs in the intermediate range, hVISA isolates frequently test susceptible to vancomycin (i.e., MICs of Յ2 g/ml) by broth microdilution methods, which typically tes...

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Clinical Outcomes in Patients with Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Bloodstream Infection

Abstract: The prevalence of heterogeneous vancomycin-intermediate

Cited by 68 publications

References 39 publications

Impact of Time to Appropriate Therapy on Mortality in Patients with Vancomycin-Intermediate Staphylococcus aureus Infection

Impact of Time to Appropriate Therapy on Mortality in Patients with Vancomycin-Intermediate Staphylococcus aureus Infection

Treatment options for methicillin-resistant Staphylococcus aureus (MRSA) infection: Where are we now?

Rapid Detection of Vancomycin-Intermediate Staphylococcus aureus by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

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