Nutrient depleted soil is associated with the presence of Burkholderia pseudomallei

Burkholderia pseudomallei is a soil-dwelling bacterium and the cause of melioidosis, which kills an estimated 89,000 people per year worldwide. Agricultural workers are at high risk of infection due to repeated exposure. Little is known about soil physicochemical properties associated with presence or absence of the organism. Here, we evaluated the soil physicochemical properties and presence of B. pseudomallei in 6,100 soil samples collected from 61 rice fields in Thailand. The presence of B. pseudomallei was negatively associated with the proportion of clay, proportion of moisture, level of salinity, percentage of organic matter, presence of cadmium, and nutrient levels (phosphorous, potassium, calcium, magnesium and iron). The presence of B. pseudomallei was not associated with the level of soil acidity (p=0.54). In a multivariable logistic regression model, presence of B. pseudomallei was negatively associated with the percentage of organic matter (OR=0.06; 95%CI 0.01-0.47, p=0.007), level of salinity (OR=0.06; 95%CI 0.01-0.74, p=0.03), and percentage of soil moisture (OR=0.81; 95%CI 0.66-1.00, p=0.05). Our study suggests that in rice fields, B. pseudomallei thrives in those that are nutrient-depleted. Some agricultural practices result in a decline in soil nutrients, which may impact on the presence and amount of B. pseudomallei in affected areas. IMPORTANCE: Burkholderia pseudomallei is an environmental Gram-negative bacillus and the cause of melioidosis. Humans acquire the disease following skin inoculation, inhalation or ingestion of the bacterium in the environment. The presence of B. pseudomallei in soil defines geographic regions where humans and livestock are at risk of melioidosis, yet little is known about soil properties associated with presence of the organism. We evaluated the soil properties and presence of B. pseudomallei in 61 rice fields in East, Central and Northeast Thailand. We demonstrated that the organism was more commonly found in soils with lower levels of organic matter and nutrients including phosphorus, potassium, calcium, magnesium and iron. We also demonstrated that crop residue burning after harvest, which can reduce soil nutrients, was not uncommon. Some agricultural practices result in a decline in soil nutrients, which may impact on the presence and amount of B. pseudomallei in affected areas