A mechanically ventilated patient has developed VAP from an endogenous source. How could such bacteria have invaded this patient's lungs? I. growth from condensate in the ventilator breathing circuit II. an HME not changed in a timely fashion III. gastroesophageal reflux IV. colonization of bacteria on the patient's skin

A. I, II only
B. III, IV only
C. I, II, IV only
D. II, III, IV only

ANS: B
A. Incorrect response: See explanation B.
B. Correct response: Colonization of the oropharynx and trachea with the causative pathogen has been shown to be important in the pathogenesis of VAP. Endogenous bacteria (stomach and intestines) can reach the oropharynx after colonizing the skin or via a vector, such as hands of the ICU team, or by gastroesophageal reflux.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B