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: Light chain proteinuria and cellular mediated immunity in rifampin treated patients with tuberculosis .
### Output Text:
Light chain proteinuria and cellular mediated immunity in <span class="chemical">rifampin</span> treated patients with tuberculosis . 