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: Therefore , certain limitations for malaria prophylaxis and treatment with mefloquine are recommended .
### Output Text:
Therefore , certain limitations for malaria prophylaxis and treatment with <span class="chemical">mefloquine</span> are recommended . 