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
The most common pathogens responsible for nosocomial pneumonias in the ICU are: 
Select and explain. 
A. Gram positive organisms, B. Gram negative organisms, C. Mycoplasma, D. Virus infections
B: Gram negative organisms
Answer: B: Gram negative organisms 
Explanation: None