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
Legionnaire disease is caused by? 
Select and explain. 
A. Motile gram positive, B. Motile gram negative, C. Non-motile gram positive, D. Non-motile gram negative
B: Motile gram negative
Answer: B: Motile gram negative 
Explanation: Ans. is 'b' i.e., Motile gram negative . Legionnaire disease is caused by legionella pneumophila, which is a gram-negative motile coccobacilli.