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: Although tacrolimus was suspected to be the cause of late post - transplant renal acidosis and was replaced by sirolimus , acidosis , and electrolyte imbalance got worse .
### Output Text:
Although <span class="chemical">tacrolimus</span> was suspected to be the cause of late post - transplant renal acidosis and was replaced by <span class="chemical">sirolimus</span> , acidosis , and electrolyte imbalance got worse . 