In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: CONCLUSIONS : Clinicians should be aware that fluconazole , even at low doses , may cause prolongation of the QT interval , leading to TDP .
### Output Text:
CONCLUSIONS : Clinicians should be aware that <span class="chemical">fluconazole</span> , even at low doses , may cause prolongation of the QT interval , leading to TDP . 