Hospital acquired pneumonia is infection occurring after how many days of hospital admission?

Ans b (2 days) Ref: Harrison 's, 16th ed, p. 1538, 17th ed, p. 1619Nosocomial pneumonia is defined as pneumonia occurring at least 48 hrs after hospital admission and not incubating at the time of admission.Cause of nosocomial infection- Gram negative bacilli- Staph aureusThough Gram negative bacilli are the most common cause of nosocomial pneumonia. Staph aureus is the single most common individual agent causing nosocomial pneumonia.Note:Pneumatocoeles are seen inUpper lobe predilectionPneumonia in alcoholics- Staph aureus and Klebsiella- Klebsiella- KlebsiellaMost common nosocomial infection is UTI