Pseudomonas aeruginosa was the most common organism to be isolated from the forty episodes of VAP.This finding is in agreement with other studies, which have stated the incidence of Pseudomonas VAP to be the highest among all pathogens. (14, 27, 28). A systematic analysis reported that gram negative bacteria represented 58% of the recovered organisms (1). Of these, most of the episodes were caused predominantly by Pseudomonas aeruginosa (24.4%), Enterobacteriaceae (14.1%), Acinetobacter (7.9%) while Staphylococcus aureus was reported in 20.4% and Candida sps for 0.9% of the episodes of VAP.