3947
All the patients were skin test negative to BPO ; 49 of 51 ( 96 % ) were also negative to MDM , and 44 of 46 ( 96 % ) to PG .
 BPO, MDM, PG
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 BPO, MDM, PG