60% of VAP is due to which group of organisms?

• A. Aerobic Gram-positive Cocci
• B. Aerobic Gram-Negative Bacilli
• C. Anaerobes
• D. Fungi

Answer: (B)

In ventilator-associated pneumonia, the majority of infections come from aerobic gram-negative bacilli, such as Pseudomonas and members of the Enterobacteriaceae (Klebsiella, E. coli, etc.). These organisms readily colonize intubated airways, form biofilms on the endotracheal tube, and are often aspirated from the oropharynx, making them the most frequent culprits in this setting. That real-world pattern is why about 60% of VAP cases are due to this group.

Anaerobes and fungi are less common causes of VAP, and while Gram-positive cocci (like Staphylococcus aureus) do occur, they do not account for the majority in most cohorts. This distribution explains why aerobic gram-negative bacilli are the best answer.