Empiric Antibiotics for HAP VAP: When and How to Cover MRSA, Pseudomonas, and MDR Pathogens Incriminated Gram negative bacteria in HAP and VAP. Download Scientific Diagram VAP #HAP #pneumonia The diagnosis of VAP is difficult as clinical signs suggestive of pneumonia, such as fever, tachycardia, and leukocytosis, are nonspecific in critically ill patients. Moreover, particularly in A 58 year old male presents to the ER with a 4 day history of high fever, a dry hacking cough, and severe shortness of breath. He also complains of profuse watery diarrhea and confusion.