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: Daily excretion of total protein , endogenous lysozyme and NAG increased only after treatment with kanamycin and gentamicin .
### Output Text:
Daily excretion of total protein , endogenous lysozyme and NAG increased only after treatment with <span class="chemical">kanamycin</span> and <span class="chemical">gentamicin</span> . 