Mycotic aneurysms due to Burkholderia pseudomallei in Far North Queensland, tropical Australia: a case series and review of the literature

Since 2019, Burkholderia pseudomallei has been the most common cause of mycotic aneurysm at Cairns Hospital in tropical Australia; a mycotic aneurysm has been diagnosed in 8/233 (3.4%) culture-confirmed cases of melioidosis. All 8 patients had at least 1 risk factor for melioidosis, all 8 had either established vascular disease (or risk factors for it) and all 8 presented during the local wet season or shortly thereafter. Although the patients were managed in a well-resourced, high-volume melioidosis centre, the diagnosis of mycotic aneurysm was frequently delayed. The patients had a turbulent course: 6/8 (75%) required intensive care unit admission and 7/8 (88%) required surgical intervention. While all 8 patients survived to hospital discharge, 2 (25%) ultimately died as a result of their B. pseudomallei infection, a high case-fatality rate by contemporary Australian standards. Adverse drug reactions were documented in 4/7 (57%) who commenced oral trimethoprim-sulfamethoxazole (TMP-SMX) eradication therapy; an additional 2 patients were unable to adhere to their prescribed TMP-SMX, one of whom died from relapsed melioidosis. Mycotic aneurysm is an infrequent manifestation of B. pseudomallei infection, is challenging to diagnose and has a high attributable mortality. The diagnosis should be considered in older patients who reside in, or who have travelled to, endemic areas and who present with fever and abdominal or back pain and who have risk factors for melioidosis and vascular disease. Early, comprehensive imaging, thorough microbiological evaluation, prompt vascular surgery review, targeted antimicrobial therapy, close longitudinal follow-up and strategies to ensure patients' retention in care are crucial to achieve optimal outcomes.