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A symbiotic or mixed animal husbandry (e.g., pigs and chickens) is considered to have a positive effect for animal welfare and sustainable agriculture. On the other hand, a risk of infection and transmission of microorganisms, especially of zoonotic pathogens, between animal species may potentially occur and thus might increase the risk of foodborne illnesses for consumers. To prove these assumptions, two groups of animals and their environmental (soil) samples were investigated in this study. Animals were kept in a free-range system. In the first group, pigs and chickens were reared together (pasture 1), while the other group contained only pigs (pasture 2). During a one-year study, fecal swab samples of 240 pigs and 120 chickens, as well as 120 ground samples, were investigated for the presence of Campylobacter spp., Salmonella spp. and E. coli. Altogether, 438 E. coli and 201 Campylobacter spp. strains were isolated and identified by MALDI-TOF MS. Salmonella spp. was not isolated from any of the sample types. The prevalences of Campylobacter coli and C. jejuni in pigs were 26.7% and 3.3% in pasture 1 and 30.0% and 6.7% in pasture 2, while the prevalences of C. coli and C. jejuni in chickens from pasture 1 were 9.2% and 78.3%, respectively. No correlation between the rearing type (mixed vs. pigs alone) and the prevalence of Campylobacter spp. was observed. All swab samples were positive for E. coli, while the average prevalences in soil samples were 78.3% and 51.7% in pasture 1 and 2, respectively. Results of similarity analysis of the MALDI-TOF MS spectra (for C. coli, C. jejuni and E. coli) and FT-IR spectra (for E. coli) of the same bacterial species showed no recognizable correlations, no matter if strains were isolated from chickens, pig or soil samples or isolated at different sampling periods. The results of the study indicate that the symbiotic husbandry of pigs and chickens neither results in an increased risk of a transmission of Campylobacter spp. or E. coli, nor in a risk of bacterial alteration, as shown by MALDI-TOF MS and FT-IR spectra. In conclusion, the benefits of keeping pigs and chickens together are not diminished by the possible transmission of pathogens.

Listeria monocytogenes (Lm) is a ubiquitous bacterium that causes listeriosis, a serious foodborne illness. In the nature-to-human transmission route, Lm can prosper in various ecological niches. Soil and decaying organic matter are its primary reservoirs. Certain clonal complexes (CCs) are over-represented in food production and represent a challenge to food safety. To gain new understanding of Lm adaptation mechanisms in food, the genetic background of strains found in animals and environment should be investigated in comparison to that of food strains. Twenty-one partners, including food, environment, veterinary and public health laboratories, constructed a dataset of 1484 genomes originating from Lm strains collected in 19 European countries. This dataset encompasses a large number of CCs occurring worldwide, covers many diverse habitats and is balanced between ecological compartments and geographic regions. The dataset presented here will contribute to improve our understanding of Lm ecology and should aid in the surveillance of Lm. This dataset provides a basis for the discovery of the genetic traits underlying Lm adaptation to different ecological niches.

In this contribution, the antimicrobial susceptibility toward 11 antibiotics and four biocides of a panel of 205 Listeria monocytogenes (Lm) strains isolated from different ecological niches (i.e., food, animals and natural environment) was evaluated. The impact of exposure to biocides on the antibiotic susceptibilities of Lm was also investigated. Lm strains isolated from food exhib-ited overall a lower susceptibility (higher minimal inhibitory concentrations, MIC) for ammonium quaternary compounds (QACs) and peracetic acid (PAC) than strains isolated from animals and natural environments. Conversely, the ecological origins of Lm strains did not significantly affect their susceptibilities towards antibiotics. Interestingly, repeated exposure to QACs recurrently led to a decrease in susceptibility toward ciprofloxacin (CIP), a fluoroquinolone antibiotic, largely used in human medicine. Moreover, these lower levels of susceptibility to CIP remained stable in most Lm strains even after subcultures without biocide selection pressure, suggesting an adaptation involving modifications at the genetic level. Results underlined the ability of Lm to adapt to biocides, especially QACs, and the potential link between this adaptation and the selection of resistance toward critical antibiotics such as ciprofloxacin. These data support a potential role of the extensive use of QACs from “farm to fork” in the selection of biocide and antibiotic resistance in pathogenic bacteria such as Lm.

International audience

Pyrrolizidine alkaloids (PA) and their N‑oxides (PANO) are a group of toxic secondary plant metabolites occurring predominantly as contaminants in (herbal) teas, honeys and food supplements, as well as in spices and culinary herbs. Depending on the botanical origin of the contaminating plant, the pattern of PA/PANO can strongly vary within a sample. The current study aimed to broaden the existing data on the occurrence of PA/PANO in spices and culinary herbs. For this, 305 authentic samples covering 15 different matrices mainly harvested in 2016 or 2017 and originating from 36 countries were investigated for the presence of 44 PA/PANO. Fifty-eight percent of the samples contained at least one PA/PANO. The average sum content over all samples was 323 &micro, g/kg (median of 0.9 &micro, g/kg, 95% percentile of 665 &micro, g/kg). The highest amount of 24.6 mg/kg was detected in an oregano sample. Additionally, conspicuous analyte patterns were discovered in samples from similar cultivation regions, indicating related botanical sources of PA/PANO contaminations. Particularly, oregano and cumin from Turkey often contained high amounts of PA/PANO. The results were used to assess the acute and chronic health risks related to PA/PANO intake via spices and culinary herbs, indicating a potential health risk in particular for adults and children with high consumption or when considering worst‑case contamination scenarios of a sum content of 5500 &micro, g/kg.

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