Pneumonia is a very common illness. Hospital-acquired pneumonia (HAP) tends to be more serious than community acquired pneumonia as the patient’s defense mechanisms against infection often are impaired during a hospital stay. HAP is the second most common nosocomial infection in the United States. It is one of the most common diagnoses made in ICUs and is very common in patients undergoing mechanical ventilation (VAP). The most common pathogens isolated include aerobic Gram-negative bacilli such as Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii species and less commonly Eschericia coli and Stenotrophomonas maltophilia as well as Gram-positive organisms such as methicillin resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae. The Gram positive bacteria accounts for approximately 20-30 % of all cases of HAP.