3082
The number of greater than or equal to 15 - dB increases in auditory threshold as a proportion of total greater than or equal to 15 - dB changes ( increases and decreases ) was significantly lower in netilmicin and piperacillin - vs tobramycin and piperacillin - treated patients ( 18 of 78 vs 67 of 115 ) .
 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