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: Few cases of drug - induced hiccups have been reported related to macrolide antimicrobials .
### Output Text:
Few cases of drug - induced hiccups have been reported related to <span class="chemical">macrolide</span> antimicrobials . 