Burkholderia pseudomallei (B. pseudomallei), the causative agent of melioidosis, is endemic to tropical and subtropical regions, particularly in Mainland Southeast Asia (MSEA). Despite its significant impact on human and animal health, the ecological distribution and public health burden of this environmental pathogen are still poorly documented. In MSEA, the bacterium is widespread, especially in rice-paddy irrigation water, canals, rivers, waterfalls, drinking-water sources, and even in ornamental fish tanks. It has been detected at various soil depths, up to 3 m, and is commonly associated with specific soil types. Environmental factors, including the physicochemical properties of soil and water, strongly influence the distribution of B. pseudomallei. Natural disasters and extreme weather events such as flooding, tsunamis, and heavy rainfall can significantly increase the incidence of melioidosis in MSEA. Animal infections have been reported, including outbreaks in zoos and domestic animals across MSEA. Despite its public health impact, melioidosis remains a non-notifiable disease in several MSEA countries, including Cambodia, Lao PDR, Myanmar, Peninsular Malaysia, and Vietnam. Treatment guidelines have been developed in several MSEA countries, although national guidance is absent or incomplete in Myanmar and is available only at the state level in Peninsular Malaysia. B. pseudomallei is widely distributed throughout the environment in MSEA, highlighting the need for integrated surveillance of environment, animal, and human infection. This narrative review aims to provide a comprehensive overview of the current knowledge on the ecology, epidemiology, and public health aspects of B. pseudomallei and melioidosis in MSEA, highlighting key knowledge gaps and priorities for surveillance, laboratory capacity, and cross-border collaboration. Understanding the environmental distribution of B. pseudomallei and its links to climate and ecological factors is essential for anticipating changes in disease risk and implementing effective One Health strategies across MSEA.
Melioidosis is a neglected tropical disease caused by Burkholderia pseudomallei, endemic to Southeast Asia and Northern Australia. Despite its increasing global public health and clinical significance, the molecular epidemiology of melioidosis and genetic diversity of B. pseudomallei in Cambodia remains poorly understood. This study aims to elucidate the genetic diversity and antibiotic susceptibility profiles of B. pseudomallei isolates responsible for melioidosis in humans. For this purpose, 14 clinical isolates cryopreserved at the Medical Biology Laboratory at Institut Pasteur du Cambodge from 2016 to 2020 were subjected to antimicrobial susceptibility testing and Multilocus Sequence Typing (MLST). Phenotypic testing revealed that 92.86% (13/14) of the isolates were sensitive to all tested antibiotics, while one isolate exhibited resistance to trimethoprim-sulfamethoxazole. MLST analysis resolved our isolates into 14 unique Sequence Types (STs), including 10 previously documented in Southeast Asia. Notably, ST1858, ST2064, ST2065, and ST2066 were identified as novel STs, while ST54, ST99, ST211, and ST1359 were reported in Cambodia for the first time in this study. Comparing our MLST data with available sequences on PubMLST (n = 165), our study unveiled a high genetic diversity of B. pseudomallei in Cambodia. The identified STs were closely associated with isolates from other Southeast Asian countries, particularly Thailand, Vietnam, and Malaysia. In conclusion, this study provided insight into the genetic diversity among B. pseudomallei clinical isolates in Cambodia and their close genetic association with Southeast Asian isolates. To further our understanding, a One Health approach, incorporating human, environmental (mainly soil), and animal compartments, is essential to decipher the epidemiology of B. pseudomallei in Cambodia.