Melioidosis on Phu Quoc Island, Vietnam: a retrospective case series from a remote tropical setting
Melioidosis, caused by Burkholderia pseudomallei , is an important but frequently under-recognized cause of severe infection in tropical regions, including Vietnam. Although cases have been reported from several parts of the country, published clinical data from remote island settings remain scarce. To our knowledge, no clinical case series of melioidosis from Phu Quoc Island has been previously reported. This study describes the clinical presentations, underlying comorbidities, management, and outcomes of patients diagnosed with melioidosis at a tertiary hospital on Phu Quoc Island, Vietnam. We retrospectively reviewed all patients with culture-confirmed melioidosis admitted to Vinmec Phu Quoc General Hospital between July 2022 and February 2026. Archived isolates underwent molecular confirmation using a TTS1-targeted quantitative polymerase chain reaction (qPCR) assay, followed by recA gene sequencing. Nine patients were included. Clinical, laboratory, microbiological, radiological, treatment, and outcome data were extracted from medical records. Pneumonia was the predominant manifestation, occurring in seven patients, and eight patients presented with bacteremic disease. Diabetes mellitus was the most common underlying condition (7/9), followed by chronic liver disease and previous tuberculosis. Most patients were admitted with sepsis, including four cases complicated by septic shock. Two patients developed rapidly progressive pulmonary melioidosis with acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS) and died despite intensive antimicrobial and supportive therapy, including one previously healthy individual. The remaining seven patients survived. TTS1 qPCR confirmed all available isolates, while recA sequencing demonstrated the presence of at least two closely related sequence variants among circulating isolates. Antimicrobial susceptibility testing by broth microdilution showed preserved susceptibility to amoxicillin/clavulanic acid, ceftazidime, imipenem, and trimethoprim/sulfamethoxazole in all tested isolates. This report represents, to our knowledge, the first published clinical case series of melioidosis from Phu Quoc Island. The findings highlight the broad clinical spectrum of melioidosis and its potential for rapid progression to life-threatening pneumonia, septic shock, and multiorgan failure. Clinicians should maintain a high index of suspicion in patients presenting with severe pneumonia or sepsis, particularly during the rainy season and among individuals with diabetes mellitus or chronic liver disease. Strengthening conventional microbiological capacity, including timely blood culture, accurate organism identification, and standardized antimicrobial susceptibility testing, remains essential for improving diagnosis and patient outcomes in geographically isolated settings.