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: Another 15 ( 1 . 2 % ) had ATT and simultaneous hepatitis virus infection .
### Output Text:
Another 15 ( 1 . 2 % ) had ATT and simultaneous hepatitis virus infection . 