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: Gastrointestinal bleed , seizures , infection , and acute renal failure were documented in seven ( 10 % ) , five ( 7 . 1 % ) , 26 ( 37 . 1 % ) , and seven ( 10 % ) patients , respectively .
### Output Text:
Gastrointestinal bleed , seizures , infection , and acute renal failure were documented in seven ( 10 % ) , five ( 7 . 1 % ) , 26 ( 37 . 1 % ) , and seven ( 10 % ) patients , respectively . 