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: CASE SUMMARY : A 46 - year - old African - American man experienced recurrent grand mal seizures during intravenous infusion of amphotericin B , then petit mal seizures as the infusion was stopped and the drug concentrations decreased with time .
### Output Text:
CASE SUMMARY : A 46 - year - old African - American man experienced recurrent grand mal seizures during intravenous infusion of <span class="chemical">amphotericin B</span> , then petit mal seizures as the infusion was stopped and the drug concentrations decreased with time . 