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: Neutropenia grade greater than or equal to 3 was seen in 15 patients , infections with recovery in 3 , and grand mal seizures in 1 patient .
### Output Text:
Neutropenia grade greater than or equal to 3 was seen in 15 patients , infections with recovery in 3 , and grand mal seizures in 1 patient . 