Determining the prevalence, identity and possible origin of bacterial pathogens in soil

Abstract

Soil biomes are vast, exceptionally diverse and crucial to the health of ecosystems and societies. Soils also contain an appreciable, but understudied, diversity of opportunistic human pathogens. With climate change and other forms of environmental degradation potentially increasing exposure risks to soilborne pathogens, it is necessary to gain a better understanding of their ecological drivers. Here we use the Galleria mellonella insect virulence model to selectively isolate pathogenic bacteria from soils in Cornwall (UK). We find a high prevalence of pathogenic soil bacteria with two genera, Providencia and Serratia, being especially common. Providencia alcalifaciens, P. rustigianii, Serratia liquefaciens and S. plymuthica strains were studied in more detail using phenotypic virulence and antibiotic resistance assays and whole-genome sequencing. Both genera displayed low levels of antibiotic resistance and antibiotic resistance gene carriage. However, Serratia isolates were found to carry the recently characterized metallo-β-lactamase blaSPR-1 that, although not conferring high levels of resistance in these strains, poses a potential risk of horizontal transfer to other pathogens where it could be fully functional. The Galleria assay can be a useful approach to uncover the distribution and identity of pathogenic bacteria in the environment, as well as uncover resistance genes with an environmental origin.

Virulence assessment of enterohepaticHelicobacterspecies carried by dogs using the wax moth larvaeGalleria mellonellaas infection model

“…[25][26][27] Recently, this infection model was used to directly search the presence of pathogenic bacteria in environmental samples, water and soil, showing the usefulness and versatility to differentiate pathogenic from non-pathogenic bacteria. 28,29 The Helicobacter strains evaluated showed different larval survival suggesting that this model is useful in discriminating between virulent as well as avirulent EHH strains. Out of the species assessed in this study, H. canicola showed a significantly higher mortality (100%, 36 to 48 pi Figure 1A,B) than the other species tested.…”

“…and Yersinia spp 25‐27 . Recently, this infection model was used to directly search the presence of pathogenic bacteria in environmental samples, water and soil, showing the usefulness and versatility to differentiate pathogenic from non‐pathogenic bacteria 28,29 …”

Fast Synthesis of Graphene Oxide−β-Lactam as a Residue-Free Environmental Bacterial Inhibitor

“…These bacteria spread through soil, air, water, and human-to-human contact, increasing the susceptibility of environmental water and food ingredients to bacterial contaminations. 1 , 2 It is thus extremely important to enhance our quality of life with environmental bacterial inhibitors because of the ubiquity of pathogenic bacteria. 3 , 4 …”

Climate change‐triggered land degradation and planetary health: A review

“…A study of a surge in coccidioidomycosis (valley fever) caused by the Coccidioides immitis soil fungus found that exposure to the dust carrying the pathogen could be linked to occupational as well as environmental exposure, with a potential for the latter to increase with climate‐related events like drought and fire in endemic areas (Pearson et al, 2019). Opportunistic human pathogens have been detected in soil‐borne pathogenic bacteria, resulting in gastrointestinal diseases, respiratory infections, and skin and wound infections; these are made worse by antimicrobial resistance triggered by increased soil pollution that limits the treatability of infections (Ferraresso et al, 2020).…”