ABSTRACTSoils in household environments in low- and middle-income countries may play an important role in the persistence, proliferation, and transmission ofEscherichia coli. Our goal was to investigate the risk factors for detection, survival, and growth ofE. coliin soils collected from household plots.E. coliwas enumerated in soil and fecal samples from humans, chickens, and cattle from 52 households in rural Bangladesh. Associations betweenE. coliconcentrations in soil, household-level risk factors, and soil physicochemical characteristics were investigated. Susceptibility to 16 antibiotics and the presence of intestinal pathotypes were evaluated for 175E. coliisolates. The growth and survival ofE. coliin microcosms using soil collected from the households were also assessed.E. coliwas isolated from 44.2% of the soil samples, with an average of 1.95 log10CFU/g dry soil. Soil moisture and clay content were associated withE. coliconcentrations in soil, whereas no household-level risk factor was significantly correlated. Antibiotic resistance and pathogenicity were common amongE. coliisolates, with 42.3% resistant to at least one antibiotic, 12.6% multidrug resistant (≥3 classes), and 10% potentially pathogenic. Soil microcosms demonstrate growth and/or survival ofE. coli, including an enteropathogenic extended-spectrum beta-lactamase (ESBL)-producing isolate, in some, but not all, of the household soils tested. In rural Bangladesh, defined soil physicochemical characteristics appear more influential forE. colidetection in soils than household-level risk factors. Soils may act as reservoirs in the transmission of antibiotic-resistant and potentially pathogenicE. coliand therefore may impact the effectiveness of water, sanitation, and hygiene interventions.IMPORTANCESoil may represent a direct source or act as an intermediary for the transmission of antibiotic-resistant and pathogenicEscherichia colistrains, particularly in low-income and rural settings. Thus, determining risk factors associated with detection, growth, and long-term survival ofE. coliin soil environments is important for public health. Here, we demonstrate that household soils in rural Bangladesh are reservoirs for antibiotic-resistant and potentially pathogenicE. colistrains and can supportE. coligrowth and survival, and defined soil physicochemical characteristics are drivers ofE. colisurvival in this environment. In contrast, we found no evidence that household-level factors, including water, sanitation, and hygiene indicators, were associated withE. colicontamination of household soils.
The relation between yield indices of maize plant and soil physicochemical characteristics
