Slaughterhouse effluent discharges into rivers not responsible for environmental occurrence of enteroaggregative Escherichia coli

Environmental contamination in a high-income country (France) by antibiotics, antibiotic-resistant bacteria, and antibiotic resistance genes: Status and possible causes

Antimicrobial resistance (AMR) is a major global public health concern, shared by a large number of human and animal health actors. Within the framework of a One Health approach, actions should be implemented in the environmental realm, as well as the human and animal realms. The Government of France commissioned a report to provide policy and decision makers with an evidential basis for recommending or taking future actions to mitigate AMR in the environment. We first examined the mechanisms that underlie the emergence and persistence of antimicrobial resistance in the environment. This report drew up an inventory of the contamination of aquatic and terrestrial environments by AMR and antibiotics, anticipating that the findings will be representative of some other high-income countries. Effluents of wastewater treatment plants were identified as the major source of contamination on French territory, with spreading of organic waste products as a more diffuse and incidental contamination of aquatic environments. A limitation of this review is the heterogeneity of available data in space and time, as well as the lack of data for certain sources. Comparing the French Measured Environmental Concentrations (MECs) with predicted no effect concentrations (PNECs), fluoroquinolones and trimethoprim were identified as representing high and medium risk of favoring the selection of resistant bacteria in treated wastewater and in the most contaminated rivers. All other antibiotic molecules analyzed (erythromycin, clarithromycin, azithromycin, tetracycline) were at low risk of resistance selection in those environments. However, the heterogeneity of the data available impairs their full exploitation. Consequently, we listed indicators to survey AMR and antibiotics in the environment and recommended the harmonization of sampling strategies and endpoints for analyses. Finally, the objectives and methods used for the present work could comprise a useful example for how national authorities of countries sharing common socio-geographic characteristics with France could seek to better understand and define the environmental dimension of AMR in their particular settings.

Phenotypic and Genetic Determination of Biofilm Formation in Heat Resistant Escherichia coli Possessing the Locus of Heat Resistance

Despite the effectiveness of thermal inactivation processes, Escherichiacoli biofilms continue to be a persistent source of contamination in food processing environments. E. coli strains possessing the locus of heat resistance are a novel food safety threat and raises the question of whether these strains can also form biofilms. The objectives of this study were to determine biofilm formation in heat resistant E. coli isolates from clinical and environmental origins using an in-house, two-component apparatus and to characterize biofilm formation-associated genes in the isolates using whole genome sequencing. Optimal conditions for biofilm formation in each of the heat resistant isolates were determined by manipulating inoculum size, nutrient concentration, and temperature conditions. Biofilm formation in the heat resistant isolates was detected at temperatures of 24 °C and 37 °C but not at 4 °C. Furthermore, biofilm formation was observed in all environmental isolates but only one clinical isolate despite shared profiles in biofilm formation-associated genes encoded by the isolates from both sources. The circulation of heat resistant E. coli isolates with multi-stress tolerance capabilities in environments related to food processing signify that such strains may be a serious food safety and public health risk.

Characterization of Diarrheagenic Escherichia coli Isolated in Organic Waste Products (Cattle Fecal Matter, Manure and, Slurry) from Cattle's Markets in Ouagadougou, Burkina Faso

Cattle farming can promote diarrheal disease transmission through waste, effluents or cattle fecal matter. The study aims to characterize the diarrheagenic Escherichia coli (DEC) isolated from cattle feces, manure in the composting process and slurry, collected from four cattle markets in Ouagadougou. A total of 585 samples (340 cattle feces, 200 slurries and 45 manures in the composting process) were collected from the four cattle markets between May 2015 and May 2016. A multiplex Polymerase Chain Reaction (PCR), namely 16-plex PCR, was used to screen simultaneously the virulence genes specific for shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC). DEC was detected in 10.76% of samples. ETEC was the most prevalent (9.91%). STEC and EAEC have been observed with the same rate (0.51%). ETEC were detected in 12.64% of cattle feces, in 6.66% of manure in the composting process and in 5% of slurry. STEC were detected in 0.58% of cattle feces and in 2.22% of manure in the composting process. EAEC was detected only in 1% of slurry and in 2.22% of manure in the composting process. ETEC strains were identified based on estIa gene and/or estIb gene and/or elt gene amplification. Of the 58 ETEC, 10.34% contained astA, 17.24% contained elt, 3.44% contained estIa and 79.31% contained estIb. The two positive EAEC strains contained only the aggR gene, and the third was positive only for the pic gene. The results show that effluent from cattle markets could contribute to the spreading of DEC in the environment in Burkina Faso.

Comparison of the incidence of pathogenic and antibiotic-resistant Escherichia coli strains in adult cattle and veal calf slaughterhouse effluents highlighted different risks for public health

The goal of this study was to investigate the involvement of bovine slaughterhouse effluents and biosolids in the risk of environmental dissemination of pathogenic and antibiotic-resistant Escherichia coli. Several samples were collected from one adult cattle and one veal calf slaughterhouse wastewater treatment plant (WWTP). The treatment process had no impact on the percentage of Shiga toxin-producing E. coli (STEC) and on the percentage of atypical enteropathogenic E. coli (aEPEC). A STEC O157:H7 was isolated from the thickened sludge of the adult cattle slaughterhouse. As thickened sludge is intended to be spread on agricultural lands, the detection of this pathogenic strain is a public health issue. The percentage of antibiotic-resistant E. coli was 5.0% and 87.5% in wastewater from the adult cattle and the veal calf slaughterhouse, respectively. These percentages were not significantly different after treatment. Integron-bearing E. coli isolates were only detected in the veal calf slaughterhouse WWTP with percentages above 50.0% for all sampling points whatever the step of the treatment process. Taken together, these findings highlighted the fact that different public health risks might be associated with adult cattle or veal calf slaughterhouses regarding the dissemination of pathogenic and antibiotic-resistant E. coli isolates into the environment.

Epidemiology and clinical manifestations of enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC) represents a heterogeneous group of E. coli strains. The pathogenicity and clinical relevance of these bacteria are still controversial. In this review, we describe the clinical significance of EAEC regarding patterns of infection in humans, transmission, reservoirs, and symptoms. Manifestations associated with EAEC infection include watery diarrhea, mucoid diarrhea, low-grade fever, nausea, tenesmus, and borborygmi. In early studies, EAEC was considered to be an opportunistic pathogen associated with diarrhea in HIV patients and in malnourished children in developing countries. In recent studies, associations with traveler's diarrhea, the occurrence of diarrhea cases in industrialized countries, and outbreaks of diarrhea in Europe and Asia have been reported. In the spring of 2011, a large outbreak of hemolytic-uremic syndrome (HUS) and hemorrhagic colitis occurred in Germany due to an EAEC O104:H4 strain, causing 54 deaths and 855 cases of HUS. This strain produces the potent Shiga toxin along with the aggregative fimbriae. An outbreak of urinary tract infection associated with EAEC in Copenhagen, Denmark, occurred in 1991; this involved extensive production of biofilm, an important characteristic of the pathogenicity of EAEC. However, the heterogeneity of EAEC continues to complicate diagnostics and also our understanding of pathogenicity.

Detection of pathogenic Escherichia coli in samples collected at an abattoir in Zaria, Nigeria and at different points in the surrounding environment

Pathogenic Escherichia coli can be released with the wastes coming from slaughterhouses into the environment, where they can persist. We investigated the presence of diarrheagenic E. coli in specimens taken at an abattoir located in the Zaria region, Nigeria, in samples of water from the river Koreye, where the effluent from the abattoir spills in, and vegetable specimens taken at a nearby farm. All the isolated E. coli were assayed for the production of Shiga toxins (Stx) by using the Ridascreen verotoxin Immunoassay and by PCR amplification of genes associated with the diarrheagenic E. coli. Three strains from the rectal content of two slaughtered animals and a cabbage were positive for the presence of the Stx-coding genes. Additionally we have isolated one Enteroaggregative E. coli (EAggEC) from the abattoir effluent and two Subtilase-producing E. coli from the slaughterhouse’s effluent and a sample of carrots. Our results provide evidence that pathogenic E. coli can contaminate the environment as a result of the discharge into the environment of untreated abattoir effluent, representing a reservoir for STEC and other diarrheagenic E. coli favouring their spread to crops.