Multisystemic Legionellosis presenting with encephalopathy: A Case Report

Legionella infection may be associated with numerous extra-pulmonary features including encephalopathy. The mechanism of this is unclear but may be related to molecular mimicry, immune-mediated mechanisms of toxins, intracellular inflammasome pathways or vascular pathologies. Case: We present the case of a 61-year-old gentleman with pyrexia and multi-organ failure after returning from Thailand. He was confused with slurred speech and an unsteady gait with left-sided hemiparesis. His neurological status deteriorated requiring intubation and admission to the Intensive Care Unit. Inflammatory markers were raised and he had a new acute kidney injury and raised troponin. Brain magnetic resonance showed bilateral watershed infarcts, multiple corpus callosum hyper-intensities on T2-weighting and caudate and pontine signal changes suggestive of encephalitis or possible pontine/extra-pontine myelinolysis. Cerebrospinal fluid investigations were normal. Subsequent urine antigen and broncho-alveolar lavage Polymerase chain reaction was positive for Legionella pneumophila . Given all the findings, a diagnosis of Legionella-associated metabolic encephalopathy was made. Neurosequelae are a rare and under-reported complication of Legionellosis. Imaging and cerebrospinal fluid are typically normal and diagnosis is by exclusion. Clinical teams should be aware of the neurological manifestations of Legionellosis as impairment can be significant and recovery prolonged.