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Fungal Molecular Diagnostics


Slide 17

February 2011

This slide highlights the PNA FISH Yeast Traffic Light Probe method. The probes are single stranded peptide nucleic acids labeled with a fluorophore such as fluorescein or rhodamine. When a blood culture bottle signals as positive in the laboratory on an automated blood culture instrument, the technologist performs a Gram stain. If the Gram stain indicates that yeast are present, a small amount of the blood is then fixed to a fresh slide and the PNA FISH probes targeting unique rRNA sequences are added to the blood smear. The smear and probe combination is allowed to hybridize at 55°C for a specified amount of time and the slide is then washed to removed unincorporated probes. Finally the smears are mounted with a mounting medium and are examined by fluorescence microscopy.



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