Severe rhabdomyolysis and acute kidney injury associated with probable Legionella pneumophila infection: a case report

Background Legionella pneumophila infection is an uncommon but recognised association with severe rhabdomyolysis and acute kidney injury. We describe an atypical, predominantly extrapulmonary presentation complicated by several plausible causes of rhabdomyolysis and update the literature since the 2020 systematic review. Case presentation A 78-year-old Caucasian male presented with three weeks of progressive lower-limb weakness, anorexia, weight loss, dark urine, oliguria, and a preceding flu-like illness. Examination demonstrated volume depletion and proximal lower-limb weakness with preserved upper-limb strength. Initial investigations revealed severe acute kidney injury, with creatinine 989 µmol/L, estimated glomerular filtration rate 4 mL/min/1.73 m², urea 40.2 mmol/L, and creatine kinase 33,400 U/L. Despite supportive treatment, progressive oliguria, metabolic acidosis, and hyperkalaemia necessitated haemodialysis. Investigations did not support autoimmune, obstructive or haematological causes; medication-related myotoxicity and metal-ion exposure remained possible. Legionella urinary antigen testing was negative. However, serology demonstrated L. pneumophila serogroup 1 IgM and total antibody titres ≥ 1:512. Without respiratory culture, PCR or paired serology, the findings supported probable recent infection rather than microbiologically proven Legionnaires’ disease. Conclusions This case demonstrates the diagnostic complexity of severe rhabdomyolysis-associated acute kidney injury when several plausible causes coexist. Probable recent Legionella infection was considered a potential precipitating factor. A negative urinary antigen result does not exclude Legionella infection when clinical and epidemiological suspicion persists, although single-titre serology should be interpreted cautiously.