Soil Nutrient Depletion Is Associated with the Presence of Burkholderia pseudomallei
Hantrakun V., Rongkard P., Oyuchua M., Amornchai P., Lim C., Wuthiekanun V., Day NPJ., Peacock SJ., Limmathurotsakul D.
<jats:title>ABSTRACT</jats:title><jats:p><jats:named-content content-type="genus-species">Burkholderia pseudomallei</jats:named-content>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 to the bacterium. Little is known about the soil physicochemical properties associated with the presence or absence of the organism. Here, we evaluated the soil physicochemical properties and presence of<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>in 6,100 soil samples collected from 61 rice fields in Thailand. The presence of<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>was negatively associated with the proportion of clay, proportion of moisture, level of salinity, percentage of organic matter, presence of cadmium, and nutrient levels (phosphorus, potassium, calcium, magnesium, and iron). The presence of<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>was not associated with the level of soil acidity (<jats:italic>P</jats:italic>= 0.54). In a multivariable logistic regression model, the presence of<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>was negatively associated with the percentage of organic matter (odds ratio [OR], 0.06; 95% confidence interval [CI], 0.01 to 0.47;<jats:italic>P</jats:italic>= 0.007), level of salinity (OR, 0.06; 95% CI, 0.01 to 0.74;<jats:italic>P</jats:italic>= 0.03), and percentage of soil moisture (OR, 0.81; 95% CI, 0.66 to 1.00;<jats:italic>P</jats:italic>= 0.05). Our study suggests that<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>thrives in rice fields that are nutrient depleted. Some agricultural practices result in a decline in soil nutrients, which may impact the presence and amount of<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>bacteria in affected areas.</jats:p><jats:p><jats:bold>IMPORTANCE</jats:bold><jats:named-content content-type="genus-species">Burkholderia pseudomallei</jats:named-content>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<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>in soil defines geographic regions where humans and livestock are at risk of melioidosis, yet little is known about the soil properties associated with the presence of the organism. We evaluated the soil properties and presence of<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>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 the presence and amount of<jats:named-content content-type="genus-species">B. pseudomallei</jats:named-content>bacteria in affected areas.</jats:p>