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: Chlorhexidine phosphanilate ( CHP ) , a new broad - spectrum antimicrobial agent , has been evaluated as a topical burn wound dressing in cream form , but preliminary clinical trials reported that it was painful upon application .
### Output Text:
<span class="chemical">Chlorhexidine phosphanilate</span> ( <span class="chemical">CHP</span> ) , a new broad - spectrum antimicrobial agent , has been evaluated as a topical burn wound dressing in cream form , but preliminary clinical trials reported that it was painful upon application . 