Lung Involvement in Patients with Leptospirosis in Tropical Australia; Associations, Clinical Course and Implications for Management

Lung involvement in patients with leptospirosis is associated with a more complicated disease course. However, the demographic and clinical associations of lung involvement are incompletely defined, and its optimal management is uncertain. This retrospective study examined consecutive patients admitted to a referral hospital in tropical Australia, with laboratory-confirmed leptospirosis between January 2015, and June 2024. Lung involvement was defined as new lung parenchymal changes on chest imaging at any point during the patients' hospitalisation. The demographics, clinical findings and clinical course of the patients with and without lung involvement were compared. The median (interquartile range (IQR)) age of the 109 patients was 39 (24-56) years; 93/109 (85%) were male. Lung involvement was present in 62/109 (57%), 55 (89%) of whom had no documented comorbidities. Patients with lung involvement received antibiotics later in their disease course than those without lung involvement (after a median (IQR) of 5 (4-6) versus 3 (2-5) days of symptoms, <i>p</i> = 0.001). Lung involvement was frequently associated with multi-organ failure: patients with lung involvement were more likely to require intensive care unit admission than patients without lung involvement (41/62 (66%) versus 15/47 (32%), <i>p</i> < 0.001). Overall, 30/109 (28%) satisfied criteria for acute respiratory distress syndrome (ARDS) and 26/109 (24%) developed pulmonary haemorrhage. Patients with lung involvement received cautious fluid resuscitation, vasopressor support and prompt initiation of additional supportive care-including mechanical ventilation, renal replacement therapy and extracorporeal membranous oxygenation-guided by the patients' physiological parameters and clinical trajectory. All 109 patients in the cohort were alive 90 days after discharge. Life-threatening lung involvement was identified in the majority of individuals in this cohort and occurred in young and otherwise well individuals. However, in Australia's well-resourced health system excellent outcomes can be achieved using a standard contemporary approach to the management of a patient with undifferentiated infection while a confirmed diagnosis of leptospirosis is awaited.