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: The risk of clinically important idiopathic liver disease was similar for persons prescribed TMP - SMZ ( 5 . 2 / 100 , 000 ) and those prescribed trimethoprim alone ( 3 . 8 / 100 , 000 ) .
### Output Text:
The risk of clinically important idiopathic liver disease was similar for persons prescribed <span class="chemical">TMP - SMZ</span> ( 5 . 2 / 100 , 000 ) and those prescribed <span class="chemical">trimethoprim</span> alone ( 3 . 8 / 100 , 000 ) . 