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: Transfusion and corticosteroid therapy resulted in a complete recovery of the patient .
### Output Text:
Transfusion and <span class="chemical">corticosteroid</span> therapy resulted in a complete recovery of the patient . 