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: A 47 - year - old man who had been taking minocycline for palmoplantar pustulosis developed fever , myalgias , polyneuropathy , and testicular pain , with elevated C - reactive protein ( CRP ) .
### Output Text:
A 47 - year - old man who had been taking <span class="chemical">minocycline</span> for palmoplantar pustulosis developed fever , myalgias , polyneuropathy , and testicular pain , with elevated C - reactive protein ( CRP ) . 