Human influence and biotic homogenization drive the distribution of Escherichia coli virulence genes in natural habitats

Antimicrobial resistance, virulence genes, and ESBL (Extended Spectrum Beta-Lactamase) production analysis in E. coli strains from the Rio Grande/Rio Bravo River in Tamaulipas, Mexico

The Rio Grande/Rio Bravo River is used as a major water supply for diverse recreational, household, and industrial activities in Northeast Tamaulipas, Mexico, and South Texas. In this study, we sampled surface water from 38 sites along Rio Grande/Rio Bravo River (Díaz Ordaz, Reynosa and Matamoros). We isolated 105 E. coli strains that were molecularly and phenotypically characterized. The percentage of virulence genes detected in E. coli were: hlyA (15.23%), stx2 (11.42%), stx1 (9.52%), bfp (0.95%), and eae (0.0) and combinations of stx1/stx2 (2.85%), stx2/hlyA (1.90%), stx1/bfp (0.95%) and stx2/bfp (0.95%) were detected in these strains. Resistance to more than one antibiotic was detected in 85.71%, and 5.71% of strains were extended-spectrum β-lactamase-E. coli (ESBL-EC). These results indicate the presence of potentially pathogenic E. coli strains in the Rio Grande/Rio Bravo River; therefore, it can be considered a reservoir of pathogenic strains and represents a health risk for the population.

Co-exposure to pathogens in wild ungulates from Doñana National Park, South Spain

Multiple infections or co-exposure to pathogens should be considered systematically in wildlife to better understand the ecology and evolution of host-pathogen relationships, so as to better determine the potential use of multiple pathogens as indicators to guide health management. We describe the pattern of co-exposure to several pathogens (i.e. simultaneous positive diagnosis to pathogens in an individual considering Mycobacterium tuberculosis complex lesions, and the presence of antibodies against Toxoplasma gondii, bluetongue virus, and hepatitis E virus) and assessed their main drivers in the wild ungulate community from Doñana National Park (red deer, fallow deer, and wild boar) for a 13-years longitudinal study. The lower-than-expected frequency of co-exposure registered in all species was consistent with non-mutually exclusive hypotheses (e.g. antagonism or disease-related mortality), which requires further investigation. The habitat generalist species (red deer and wild boar) were exposed to a greater diversity of pathogens (frequency of co-exposure around 50%) and/or risk factors than fallow deer (25.0% ± CI95% 4.9). Positive relationships between pathogens were evidenced, which may be explained by common risk factors favouring exposure. The specific combination of pathogens in individuals was mainly driven by different groups of factors (individual, environmental, stochastic, and populational), as well as its interaction, defining a complex eco-epidemiological landscape. To deepen into the main determinants and consequences of co-infections in a complex assemblage of wild hosts, and at the interface with humans and livestock, there also is needed to expand the range of pathogens and compare diverse assemblages of hosts under different environmental and management circumstances.

Long-Term Determinants of the Seroprevalence of Toxoplasma gondii in a Wild Ungulate Community

Toxoplasma gondii is an obligate intracellular protozoan which infects warm-blooded vertebrates, including humans, worldwide. In the present study, the epidemiology of T. gondii was studied in the wild ungulate host community (wild boar, red deer, and fallow deer) of Doñana National Park (DNP, south-western Spain) for 13 years (2005-2018). We assessed several variables which potentially operate in the medium and long-term (environmental features, population, and stochastic factors). Overall, the wild ungulate host community of DNP had high seroprevalence values of T. gondii (STG; % ± confidence interval (CI) 95%; wild boar (Sus scrofa) 39 ± 3.3, n = 698; red deer (Cervus elaphus) 30.7 ± 4.4, n = 423; fallow deer (Dama dama) 29.7 ± 4.2, n = 452). The complex interplay of hosts and ecological/epidemiological niches, together with the optimal climatic conditions for the survival of oocysts that converge in this area may favor the spread of the parasite in its host community. The temporal evolution of STG oscillated considerably, mostly in deer species. The relationships shown by statistical models indicated that several factors determined species patterns. Concomitance of effects among species, indicated that relevant drivers of risk operated at the community level. Our focus, addressing factors operating at broad temporal scale, allows showing their impacts on the epidemiology of T. gondii and its trends. This approach is key to understanding the epidemiology and ecology to T. gondii infection in wild host communities in a context where the decline in seroprevalence leads to loss of immunity in humans.

Spatiotemporal Variability in Microbial Quality of Western US Agricultural Water Supplies: A Multistate Study

In 2011, the US Congress passed the Food Safety Modernization Act, which tasks the US Food and Drug Administration to establish microbiological standards for agricultural water. However, little data are available for the microbiological quality of surface water irrigation supplies. During the 2015 irrigation season, we conducted a baseline study on the microbial water quality of large irrigation districts in California ( = 2) and Washington ( 4). Monthly samples ( 517) were analyzed for bacterial indicators (fecal coliforms, enterococci, and ) and pathogens ( spp., O157, and non-O157 Shiga toxin-producing [STEC]). Although there was a high degree of variability (μ ± SD = 59.13 ± 106.0), only 11% of samples (56/517) exceeded 126 colony-forming units (CFU) 100 mL, and only six samples exceeded 410 CFU 100 mL. Two volumes of water were collected for pathogen analysis (1 L and 10 L); prevalence of in 10-L samples (68149) was nearly double of that found in 1-L samples (132/517). We found STEC during ∼9% of sampling events (58/517); serotypes O26 and O45 were the most common at 31 and 26%, respectively. Pathogens were not associated with exceedance of the regulatory threshold, yet the odds of detecting increased approximately threefold (odds ration [O.R.] = 3.14, 0.0001) for every log increase in turbidity. Microbiological outcomes were highly district-specific, suggesting drivers of water quality vary across spatiotemporal scales. The true risk of contamination of produce from irrigation water supplies remains unknown, along with the optimal monitoring strategy to improve food safety.

Human influence and biotic homogenization drive the distribution of Escherichia coli virulence genes in natural habitats

Cattle are the main reservoirs for Shiga-toxin-producing Escherichia coli (STEC), the only known zoonotic intestinal E. coli pathotype. However, there are other intestinal pathotypes that can cause disease in humans, whose presence has been seldom investigated. Thus, our aim was to identify the effects of anthropic pressure and of wild and domestic ungulate abundance on the distribution and diversity of the main human E. coli pathotypes and nine of their representative virulence genes (VGs). We used a quantitative real-time PCR (qPCR) for the direct detection and quantification of the genus-specific gene uidA, nine E. coli VGs (stx1, sxt2, eae, ehxA, aggR, est, elt, bfpA, invA), as well as four genes related to O157:H7 (rfb_O157 , fliC_H7 ) and O104:H4 (wzx_O104 , fliC_H4 ) serotypes in animals (feces from deer, cattle, and wild boar) and water samples collected in three areas of Doñana National Park (DNP), Spain. Eight of the nine VGs were detected, being invA, eae, and stx2 followed by stx1, aggR, and ehxA the most abundant ones. In quantitative terms (gene copies per mg of sample), stx1 and stx2 gave the highest values. Significant differences were seen regarding VGs in the three animal species in the three sampled areas. The serotype-related genes were found in all but one sample types. In general, VGs were more diverse and abundant in the northern part of the Park, where the surface waters are more contaminated by human waste and farms. In the current study, we demonstrated that human influence is more relevant than host species in shaping the E. coli VGs spatial pattern and diversity in DNP. In addition, wildlife could be potential reservoirs for other pathotypes different from STEC, however further isolation steps would be needed to completely characterize those E. coli.