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: Antituberculosis therapy - induced acute liver failure : magnitude , profile , prognosis , and predictors of outcome .
### Output Text:
<span class="chemical">Antituberculosis</span> therapy - induced acute liver failure : magnitude , profile , prognosis , and predictors of outcome . 