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: The prophylactic lamivudin group consisted of 37 patients who received prophylactic lamivudine treatment .
### Output Text:
The prophylactic <span class="chemical">lamivudin</span> group consisted of 37 patients who received prophylactic <span class="chemical">lamivudine</span> treatment . 