@cholash I asked AI your question and AI defines an exacerbation as a “sudden worsening of symptoms” that can be attributed to many causes including NTM: “A practical way doctors frame it is: Is this exacerbation mainly mucus/bronchiectasis mechanics, a superimposed bacterial/viral infection, or evidence that NTM disease is becoming more active? They determine that with repeat cultures (including AFB), additional infection testing, and imaging comparisons.”