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: DISCUSSION : Daptomycin was initiated in our patient secondary to possible nafcillin - induced acute interstitial nephritis and relapsing bacteremia .
### Output Text:
DISCUSSION : <span class="chemical">Daptomycin</span> was initiated in our patient secondary to possible <span class="chemical">nafcillin</span> - induced acute interstitial nephritis and relapsing bacteremia . 