• It is necessary to find the most appropriate antimicrobial agent for therapy as soon as possible, but there are an increasing number of questions concerning direct sensitivity testing
  
• Current methods are not tolerant of variability in inoculum or the methodology may not be modified specific to organisms needs (e.g. media), and as such may not always give reliable results
  
• Etest is a flexible method and can be used in a macro format handling these shortcomings
  
• Direct specimen testing with Etest may provide faster information for therapy guidance and / or correction of empiric therapy in urgent clinical situations
  

Time lapse images of a Gram negative organism inoculated directly onto a plate from a positive blood culture bottle, tested against Ertapenem and Cefotaxime ESBL Etest, incubated at 37oC. Etest's unique predefined concentration gradient provides increased tolerance to inoculum variance.

MIC value remains constant despite increasing inoculum size

References

1. "The direct Etest correlated within one dilution factor with pure culture Etest." - Gallagher et al (2000), ICF Poster

2. "This data indicates that Etest is useful to obtain MIC data on gram positive cocci directly from blood cultures." - Hong et al (1996), DMI. 25:21-25

3. "The 'non-standardised' Etest method performed exceedingly well when compared to NCCLS disc testing and VITEK" - Costello (1993), ASM 93rd Poster C-206

4. "Performing Etest sensitivity analysis in respiratory or blood samples before microorganism identification provides important information the following pneumonia onset, with a substantial reduction in the period of inadequate therapy" - Vidaur (2005), Respiratory care 150(7):965-974

5. "The Etest method was feasible for direct susceptibility testing of blood cultures positive for yeast" - Chang et al (2001), JCM, 39(4):1328-1333

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