This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
True about montoux is - 
Select and explain. 
A. False negative in fulminant diseases, B. If once done, next time it is always positive, C. Results are given in terms of positive & negative, D. Indurations given in terms of length & breadth
A: False negative in fulminant diseases
Answer: A: False negative in fulminant diseases 
Explanation: Ans. is 'a' i.e., False negative in fulminant disease . A positive tuberculin test indicates hypersensitivity to tuberculoprotein, it may be due to : - Active infection - Subclinical infection - Past infection - BCG vaccination . In overwhelming tuberculosis (fulminant cases) due to depressed cellular immunity montoux test may be false negative.