Once the clinical decision has been made to initiate therapy, antibiotic selection for each patient should be based on the risk factors for MDR pathogens. Appropriate antibiotics for the initial management of HAP, VAP, and HCAP should be decided based on time of onset of disease and risk for MDR pathogens. If patients develop HAP during or shortly after antibiotic treatment for a different infection, the empiric therapy should probably involve an agent from a different antibiotic class. Recent exposure to a class of antibiotics can predict subsequent resistance to a variety of agents, usually to the same class but occasionally other classes of agents as well (75). Additionally, risk factors for pneumonia due to MDR pathogens would require initiating treatment with broader spectrum antibiotics as shown in the algorithm (45).Broad-spectrum empiric antibiotic therapy should be accompanied by a commitment to de-escalate antibiotics, based on serial clinical and microbiologic data, to limit the emergence of resistance in the hospital.