Legionella longbeachae Pneumonia Detected by Microbial Cell-Free DNA Sequencing

We report a case of severe community-acquired pneumonia caused by Legionella longbeachae, a rare soil-associated organism undetected by conventional testing. The patient initially required intubation and extracorporeal membrane oxygenation. Subsequent microbial cell-free DNA sequencing identified L longbeachae and enabled precise therapy, contributing to clinical improvement. For clinicians, L longbeachae should be in the differential diagnosis as a rare cause for severe pneumonia, in patients with soil and compost exposure but negative standard testing. In patients with high suspicion, advanced testing such as microbial cell-free DNA sequencing can help solidify the diagnosis.