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: PURPOSE : We present a case of a patient who developed seizures shortly after initiating treatment with levofloxacin and to discuss the potential drug - drug interactions related to the inhibition of cytochrome P450 ( CYP ) 1A2 in this case , as well as in other cases , of levofloxacin - induced seizures .
### Output Text:
PURPOSE : We present a case of a patient who developed seizures shortly after initiating treatment with <span class="chemical">levofloxacin</span> and to discuss the potential drug - drug interactions related to the inhibition of cytochrome P450 ( CYP ) 1A2 in this case , as well as in other cases , of <span class="chemical">levofloxacin</span> - induced seizures . 