<prompt> A 60 year old male patient admitted in ICU develops fever and productive cough 48 hours after admission in the hospital. Which of the following is the most common causative organism?MycoplasmaPseudomonasStaphylococcusHemophhilus Influenza  <response>: Hospital acquired pneumonia is polymicrobial in origin and is most commonly caused by gram negative bacilli such as Pseudomonas, Klebsiella and E coli. Other causative organisms inlcudes anaerobic bacteria and Staphyloccoccus aureus. 