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Introduction: Melioidosis, a potentially life-threatening infection caused by Burkholderia pseudomallei, is endemic to Northern Australia with a peak during the ‘wet’ season, and infection predominantly presents in immunosuppressed individuals. Local guidelines recommend prophylactic use of trimetho- prim/sulfamethoxazole (TMP+SMX) in at-risk patients, such as those undergoing cytotoxic chemotherapy or on high dose steroids, administered once daily during the tropical ‘wet’ season, or year-round for those with positive melioidosis serology (titre ≥ 1:40). No previous research has assessed the extent to which at-risk solid- organ malignancy patients are receiving TMP+SMX, nor its effect on rates of melioidosis and associated toxicities. Methods: We retrospectively reviewed the extent of TMP+SMX usage among solid-organ malignancy patients in a Top End cancer centre over a single ‘wet’ season from November 2018 to April 2019. Pharmacy and medical records were accessed for data collection, including patient demographics, comorbidities, cancer diagnoses, treatment regimens, concurrent corticosteroid use and the number of patients who developed either melioidosis or TMP+SMX toxicity. Results: Four hundred fifty patients underwent systemic treatment for solid-organ malignancy during the study period. Of these, 97 patients (21.6%) received TMP+SMX prophylaxis. TMP+SMX was prescribed in 87 patients (89.7%) undergoing chemotherapy. Thirteen patients (13.4%) had prophylaxis due to high corticosteroid use (seven con- current with chemotherapy, four with immune checkpoint inhibitors). Eighty-eight patients (90.7%) had melioidosis serology pre-treatment, 16 were positive. One patient developed melioidosis on TMP+SMX, though adherence to this medication could not be confirmed. Four patients developed mild toxicity and one patient died due to toxic epi- dermal necrosis, a fatal complication of TMP+SMX use. Conclusions: TMP+SMX is used frequently in the Top End for prophy- laxis of melioidosis in solid-organ malignancy patients undergoing sys- temic therapy and/or while on high dose steroids. Rates of melioido- sis are low in this group, but this comes at a risk of TMP+SMX toxicity, which can be fatal. 1. Cheng AC, Currie BJ. Melioidosis: epidemiology, pathophysiol- ogy, and management. Clin Microbiol Rev. 2005;18(2):383–416. https://doi.org/10.1128/CMR.18.2.383-416.2005 2. Marshall, C. Opportunistic infections prevention in patients with immunosuppression TEHS guideline. Top End Health Service, Northern Territory Department of Health. Darwin: 2017. |
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