Ying He, Guangdong Medical College Futian Hospital, Shenzhen, China
Gongyi Shi, Bruker Daltonics Inc., Fremont, CA
Sam Fu, Bruker Daltonics Inc., Fremont, CA
Haijing Li, Vanderbilt University Medical Center, Nashville, TN
Markus Kostrzewa, Bruker Daltonik, GmbH, Bremen, Germany
Yi-Wei Tang, Vanderbilt University Medical Center, Nashville, TN |
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| Rapid and reliable identification of yeast-like pathogens recovered from blood is essential for antifungal treatment; however, currently phenotypic methods take several days for identification after the pathogens are observed in positive blood cultures. We explored the use of the MALDI BioTyper (Bruker Daltonics) for the rapid identification and speciation of yeast-like pathogens directly from postive blood culture broth specimens. The MALDI BioTyper incorporates matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI TOF MS) providing rapid microorganism identification. Specimen volumes arranging from 0.5 to 2.0 ml were mixed with equal volume of 0.1% triton in water, and pre-processed by one of following three methods to lyse and remove human blood cells: (1) ACK Lysis with amonium chloride (Invitrogen), (2) cell digestion with MolYsis (Molzym) and (3) filtration with Aerodisc Syringe and Glass Fiber Memberane (Life Sciences). The intact yeast cells were collected and further processed by a default extraction protocol recommended by the Bruker Daltonics. Each extract supernatent was then placed onto a MALDI target plate and analyzed by the MALDI BioTyper. All three pre-processing methods yield enough intact yeast cells for the subsequent MALDI TOF analysis. When one ml of orignal blood culture broth specimen was processed by the filtration method, satisfactory organism identification score values ranging from 1.861-2.012 were achieved. Two positive specimens were analyzed and species identification was matched with those by phenotypic methods. The whole MALDI TOF MS analysis procedure starting with specimen pre-processing by filtration can be completed within three hours, significantly shortening the time needed for phenotypic identification of yeast-like pathogens recovered from blood. |
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