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: Severe thrombocytopenia and haemolytic anaemia associated with ciprofloxacin : a case report with fatal outcome .
### Output Text:
Severe thrombocytopenia and haemolytic anaemia associated with <span class="chemical">ciprofloxacin</span> : a case report with fatal outcome . 