Diagnosing fungaemia faster
Abstract number: P1341
Knudsen J.D., Arendrup M.C.
Objective: Rapid initiation of appropriate antifungal treatment is associated with a reduction in mortality. Unfortunately species identification and susceptibility testing is time consuming. Recently, a commercial susceptibility testing card to the VITEK system was developed, and we decided to evaluate this in a routine laboratory in comparison with the EUCAST reference method.
Methods: A strain collection of 20 yeast isolates from blood cultures (8 C. albicans, 6 C. glabrata, 2 C. tropicalis, 2 C. parapsilosis, 1 C. krusei and 1 Cryptococcus neoformans), were tested by VITEK® by the AST-YS01 card and the results were correlated to the MICs obtained by the EUCAST method performed at the reference laboratory. The VITEK resistance card includes amphotericin B, fluconazole, voriconazole and flucytosine. The EUCAST testing was performed as part of a surveillance scheme and included amphotericin B, fluconazole, voriconazole, itraconazole, posaconazole and caspofungin. Agreement was defined as identical classification in S, I/SDD/ and R.
Results: There were 100% agreement for amphotericin B susceptibilities, and all the strain's MICs were 1 mg/mL.
For 17:20 isolates the interpretations were in agreement for the azoles if S 2 mg/mL for fluconazole, S 1 mg/mL for voriconazole. Two strains showed minor disagreements for fluconazole, with MICs of 0.5 and 2 mg/mL by the EUCAST, and both 4 mg/mL by the VITEK method. One C. tropicalis showed high level resistance towards fluconazole and voriconazole by the EUCAST method, MICs >16 and >4 mg/mL, but by VITEK the MIC's were <1 and <0.12 mg/mL, respectively. This strain will be further examined. Flucytosine susceptibilities were tested by VITEK, and only the C. krusei were found resistant, MIC=16 mg/mL. The VITEK results were ready after median 18 h (range 1321).
Conclusion: The susceptibility profiles for the antifungals included in the card were reliably done overnight from colonies on agar plates. Including an resistance card when using identifications cards by VITEK, may be less time consuming, and is economical attractive compared to our routine methods. There is two disadvantages so far, no echinocandins are yet included in the card, and there is not yet any easy procedure for using samples directly from the blood culture bottles.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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