 VAP was diagnosed when patient developed; new andor progressive infiltrates in chest radiograph plus two or more of the following; leucocytosis 12000mm3 or leucopenia 4000cmm3, fever 38oC or hypothermia 36oC, or mucopurulent secretion as evident by gross inspection. The clinically diagnosed VAP was confirmed by quantitative endotracheal aspirate at a cut off value 105 colony forming unit cfu ml. 