12639
Compounds ( 1 - 6 ) were screened for in vitro antibacterial activity against a representative panel of Gram - positive and Gram - negative bacteria using levofloxacin as the reference drug .
 Chemical: levofloxacin
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: levofloxacin