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: We present magnetic resonance imaging findings of a 5 - year - old girl who had a rapidly installing hemolytic anemia crisis induced by trimethoprim - sulfomethoxazole , resulting in cerebral anoxia leading to permanent damage .
### Output Text:
We present magnetic resonance imaging findings of a 5 - year - old girl who had a rapidly installing hemolytic anemia crisis induced by <span class="chemical">trimethoprim - sulfomethoxazole</span> , resulting in cerebral anoxia leading to permanent damage . 