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: His echocardiographic abnormalities and heart failure resolved after posaconazole was substituted for AmB .
### Output Text:
His echocardiographic abnormalities and heart failure resolved after <span class="chemical">posaconazole</span> was substituted for <span class="chemical">AmB</span> . 