This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology (Gram Positive Bacilli, Gram Negative Bacilli), Subject name: Microbiology
Organism most likely associated with VAP? 
Select and explain. 
A. Pseudomonas, B. Klebsiella, C. Clostridium, D. Mycobacterium TB
A: Pseudomonas
Answer: A: Pseudomonas 
Explanation: Gram negative bacilli are mostly responsible for ventilator associated pneumonia. Acinetobacter is most likely to cause ventilator associated pneumonia (VAP) since it is most commonly isolated during ICU sittings.