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: Clinical examination and continued vigilance for neurologic deterioration after epidural steroid injections is important .
### Output Text:
Clinical examination and continued vigilance for neurologic deterioration after epidural <span class="chemical">steroid</span> injections is important . 