Vu Thi Ngoc Anh, Tran Thi Le Quyen, Bui Nguyen Hai Linh, Trinh Trung Thanh
VNU-Institute of Microbiology and Biotechnology, Vietnam National University, Hanoi, Vietnam.
PLoS Negl Trop Dis. 2025 Jul 30;19(7):e0013322. doi: 10.1371/journal.pntd.0013322. eCollection 2025 Jul.
Melioidosis, a fatal infectious disease caused by the environmental bacterium Burkholderia pseudomallei, is known to be associated with the rainy season. Although several attempts have been made to explain this phenomenon, data on the association between the presence of B. pseudomallei in environmental reservoirs and weather variables remain limited. This study focused on water samples collected from a paddy field in north-central Vietnam to investigate this association. A total of 800 samples were collected over eight different time points in 2018. Using a two-step enrichment method, 349 samples (43.6%) were positive by a B. pseudomallei-specific real-time PCR assay targeting the TTSS1 gene and by B. pseudomallei isolation on Ashdown agar. The positive culture rate of B. pseudomallei ranged from 5% in the winter to 82% in the summer. Quantitative culture method directly detected B. pseudomallei colonies only from samples collected in the summer, with an overall mean count of 93.1 CFU/ml (n = 13; range from 5 to 750). The positive culture rate of B. pseudomallei showed a strong positive correlation with the average ambient temperature when binned from three days up to a month before the sampling dates, with the strongest correlation observed at the 19-day bin data (rs = 0.905; p = 0.002). Two clusters of melioidosis cases were identified in the summer, one after tropical depressions and another after rice harvesting activities. Diverse B. pseudomallei genotypes were found within this small-scale paddy field, with a novel sequence type (ST) 1994 persisting throughout the year. In conclusion, our study demonstrated that increased ambient temperature significantly contributed to the higher occurrence and bacterial load of B. pseudomallei in surface water, leading to more melioidosis cases if combined with severe rainfalls or occupational agricultural exposure. These findings should be considered in the context of global warming and climate change.
类鼻疽病是一种由环境细菌伯克霍尔德菌引起的致命传染病，已知与雨季有关。尽管已经多次尝试解释这一现象，但关于环境蓄水池中伯克霍尔德菌的存在与天气变量之间关联的数据仍然有限。本研究聚焦于从越南北部中心地区的一个稻田采集的水样，以调查这种关联。2018年在八个不同时间点共采集了800个样本。采用两步富集法，通过针对TTSS1基因的伯克霍尔德菌特异性实时PCR检测以及在阿什当琼脂上进行伯克霍尔德菌分离，349个样本（43.6%）呈阳性。伯克霍尔德菌的阳性培养率从冬季的5%到夏季的82%不等。定量培养法仅从夏季采集的样本中直接检测到伯克霍尔德菌菌落，总体平均计数为93.1 CFU/ml（n = 13；范围为5至750）。当对采样日期前三天至一个月的数据进行分组时，伯克霍尔德菌的阳性培养率与平均环境温度呈现出强正相关，在19天分组数据时观察到最强的相关性（rs = 0.905；p = 0.002）。在夏季确定了两集群类鼻疽病病例，一组在热带低气压过后，另一组在水稻收割活动之后。在这个小规模稻田中发现了多种伯克霍尔德菌基因型，一种新的序列类型（ST）1994全年持续存在。总之，我们的研究表明，环境温度升高显著导致了地表水伯克霍尔德菌的更高发生率和细菌载量，如果再加上暴雨或职业性农业暴露，会导致更多类鼻疽病病例。在全球变暖和气候变化的背景下，应考虑这些发现。
