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: CONCLUSIONS : High - dose daptomycin may be an alternative option for MSSA bacteremia with or without a CNS source in patients who have failed or cannot tolerate standard therapy .
### Output Text:
CONCLUSIONS : High - dose <span class="chemical">daptomycin</span> may be an alternative option for MSSA bacteremia with or without a CNS source in patients who have failed or cannot tolerate standard therapy . 