Legionnaires' disease in transplant recipients: A 15‐year retrospective study in a tertiary referral center

Legionnaires' disease ( LD ) can be fatal among high‐risk transplant recipients. To understand the epidemiology of LD , we reviewed 15‐year longitudinal data from a center in Seattle, Washington that cares for both solid organ transplant ( SOT ) and hematopoietic cell transplant ( HCT ) recipients. We identified all laboratory‐confirmed LD and extracted data on species, diagnostic modalities, clinical presentation, management, and outcomes from medical records. Among 32 patients with LD , transplant recipients made up the majority of diagnoses (22, 69%; SOT 10, HCT 12). Approximately 0.8% of transplant recipients who underwent L egionella‐ specific testing were positive. Non‐ pneumophila L egionella species ( LNLP ), which are not detected by urinary antigen test, accounted for half the cases, led by L egionella micdadei (32%). The severity and outcome between L egionella pneumophila and LNLP infections were similar (attributed mortality, 36% vs 27%); all LNLP deaths occurred in transplant recipients with L . micdadei . The clinical and radiological features mimicked other opportunistic pathogens; 32% (n=7) were not on empiric treatment at the time of diagnosis. These data add to the emerging literature describing the importance of LD and highlight the need for both routine L egionella testing on transplant recipients with pulmonary findings and empiric L egionella ‐active antibiotic therapy.