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: Forty patients with a diagnosis consistent with a hematologic / oncologic disorder that required treatment with an aminoglycoside were randomized to either conventional or extended - interval amikacin .
### Output Text:
Forty patients with a diagnosis consistent with a hematologic / oncologic disorder that required treatment with an <span class="chemical">aminoglycoside</span> were randomized to either conventional or extended - interval <span class="chemical">amikacin</span> . 