Pneumonia is the second most common nosocomial infection and is associated with substantial morbidity and mortality. 

Most patients who have nosocomial pneumonia are infants, young children, and persons >65 years of age. (7)

 

Nosocomial pneumonia consists of an hospital-acquired infection of the pulmonary parenchyma occurring in patients who were admitted to the hospital for more than 48 hours. Nosocomial pneumonia can be classified into Hospital-Acquired Pneumonia (HAP), Ventilator-Acquired Pneumonia (VAP), and Health Care Associated Pneumonia (HCAP).

 

Bacteria can invade the lower respiratory tract by aspiration of oropharyngeal organisms, inhalation of aerosols containing bacteria, or, less frequently, by hematogenous spread from a distant body site. In addition, bacterial translocation from the gastrointestinal tract has been hypothesized recently as a mechanism for infection. (7)

 

Currently, therapy often involves monotherapy or combination therapy with antimicrobial agents against Gram negative and positive bacteria.