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: CONCLUSION : Low adherence to SOPs for potentially nephrotoxic antibiotics was associated with a higher occurrence of AKI .
### Output Text:
CONCLUSION : Low adherence to SOPs for potentially nephrotoxic antibiotics was associated with a higher occurrence of AKI . 