How do you decide when to test for Legionella in patients with pneumonia, given periodic outbreaks and risk for delayed diagnosis?

Legionella testing is really a question of pretest probability, not a reflex order on every CAP admission, and that distinction matters practically, since the ATS/IDSA 2019 CAP guideline explicitly moves away from routine testing toward a targeted strategy.

The clearest indication is severity. Any pa...