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: We report the case of a patient in whom troleandomycin - induced hepatitis was followed by prolonged anicteric cholestasis .
### Output Text:
We report the case of a patient in whom <span class="chemical">troleandomycin</span> - induced hepatitis was followed by prolonged anicteric cholestasis . 