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: RESULTS : The cumulative incidence of persistent sterile leukocyturia ( > or = 75 cells / micro L in at least 2 consecutive visits ) after 96 weeks was 53 % .
### Output Text:
RESULTS : The cumulative incidence of persistent sterile leukocyturia ( > or = 75 cells / micro L in at least 2 consecutive visits ) after 96 weeks was 53 % . 