3081
Of those evaluated with posttherapy audiograms , three of four netilmicin and piperacillin - treated patients had auditory thresholds return to baseline compared with one of nine tobramycin and piperacillin - treated patients .
 Chemical: netilmicin; Chemical: piperacillin; Chemical: tobramycin; Chemical: piperacillin
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: netilmicin; Chemical: piperacillin; Chemical: tobramycin; Chemical: piperacillin