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Evaluation of Sensititre® Yeastone® for direct antifungal susceptibility testing from blood cultures

Abstract number: P877

Camporese A., Grosso S., Bruschetta G., De Rosa R., Avolio M.

Objectives: The aim of this study was to evaluate Sensititre YeastOne (TREK Diagnostic Systems, Cleveland, USA), already used in our routine diagnostics for performing in-vitro antifungal susceptibility testing, starting directly from the bottle of blood culture positive for yeasts, with the explicit aim of intervening to reduce the TAT for antifungal susceptibility testing.

Methods: In our laboratory, blood culture bottles are normally incubated using the system BacT/ALERT 3D (bioMerieux, Marcy l'Etoile, France). Sensititre YeastOne was used by direct inoculation from positive blood culture bottles in 40 cases of candidaemia. All the results obtained directly from a positive bottle were compared with those obtained using standard laboratory procedures, after sub-culturing from a positive bottle onto solid media. The strain of Candida parapsilosis ATCC 22019 was used for quality control. The direct susceptibility test was performed as follows: the positive blood culture bottle was shaken and used to prepare a Gram stain to confirm the presence of yeast monomicrobism. Five to six ml of the sample were aspirated with a vacutainer test tube (Sarstedt, Nümbrecht, Germany) and centrifuged at 3200 revs for 15 minutes; the microbial pellet was gradually suspended in a small aliquot of physiological solution then diluted with physiological solution in order to obtain turbidity of 0.5 McFarland. This final suspension was used to perform the susceptibility test according to the manufacturer's instructions. Incubation at 35°C was continued for 24 hours.

Results: The table summarises the in vitro susceptibilities (MIC's range, MIC 50 and MIC 90) of the 40 isolates of Candida spp., compared with the results obtained in accordance with the standard procedures. Considered as a whole, out of a total of 40 strains tested, no very major errors or major errors were revealed and only five minor errors (98% agreement rate out of a total of 240 drug/bug combinations tested).

Conclusion: The results obtained from direct inoculation of Sensititre YeastOne demonstrated excellent performance and compared very well with tests performed using standard procedures. In addition, results were easy to interpret and available on average 3 days earlier than conventional results, allowing a potentially very significant reduction in the TAT and providing tangible information, about the current management of antifungal therapy or, if necessary, its modification.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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