Empirical Therapy of Community-Acquired Pneumonia: Advancing Evidence or Just More Doubt?

Abstract

Pneumonia remains a significant cause ofmorbidity andmortality, whether community acquired (CAP) or hospital acquired. Althoughmanymicrobial pathogensmaycausepneumonia, themost commonlyencounteredarepneumococcus;atypicalorganisms,such as Mycoplasma pneumoniae or Legionella; and at times Staphylococcus aureus and certain gram-negative rods. As diagnostic tests have increased in availability and sophistication, identifying multiple pathogens in the same patient is increasingly common. Cliniciansrarelyknowtheetiologicpathogensatthetimeofchoosing antibiotic therapy. In the outpatient setting, not knowing the correct pathogen is usually not too important because most antimicrobialsprovidesufficientantibacterial coveragefor the likelypathogens andoverallmortality ratesaregenerally less than 1%.Forhospitalized patients,thestakesarehigherbecausethemortalityriskishigh(reports vary from 4%-23%),1 and a more diverse group of pathogens is encountered than in the outpatient setting. A number of evidencebased national guidelines have been prepared to assist physicians in selecting initial antibiotics, and adherence to a guideline appropriate for the local environment improves patient outcomes.2,3 Even though treatment options for pneumonia have improved, the best empirical therapy for CAP remains unclear. Two questions in particular have caused much debate in the past deJAMA INTERNALMEDICINE