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: Although most cases of antibiotic induced acute interstitial nephritis are benign and self - limited , some patients are at risk for permanent renal injury .
### Output Text:
Although most cases of antibiotic induced acute interstitial nephritis are benign and self - limited , some patients are at risk for permanent renal injury . 