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The use of antimicrobials in agricultural, veterinary and medical practice exerts selective pressure on environmental microbiota, promoting the emergence and spread of antimicrobial resistance (AMR), a global concern for the One Health Initiative Task Force (OHITF). Honeybees have been studied as bioindicators of AMR in the environment, but little is known about beehive products like honey and pollen. The aim of this study was to assess the prevalence of AMR genes (ARGs) in beehive products and investigated their origins. Specifically, possible associations between ARGs, microbiota and other characteristics of different honey and pollen samples, including country of origin, flower type, type of commercial distribution and environmental factors, such as land use, weather and composition of the environment surrounding the beehives were investigated. We found that beehive products harboured ARGs conferring resistance to β-lactams, macrolides, (fluoro)quinolones and polymyxins. Most samples possessed resistance to multiple antimicrobial classes, with honey and pollen showing similar ARG profiles. Even if Lactobacillus and Acinetobacter genera were common in the microbial communities of both honey and pollen, Bacillus, Clostridium, and Bombella defined honey microbiota, while Pseudomonas and Vibrio were enriched in pollen. ErmB and blaTEM-1 co-occurred with Lactobacillus and Fructobacillus, while positive associations between β-lactams and macrolides and anthropogenic environments (i.e. industrial and commercial areas and non-irrigated arable lands) were found. Altogether, our findings suggest that ARGs in honey and pollen might originate from the honeybee foraging environment, and that the beehive products can be used as bioindicators of the AMR environmental contamination.

A conference abstract from NIRItalia online 2021 in English and Italian., This research was financially supported by Padova University (Project CPTA158894/15).

Pyrrolizidine alkaloids (PAs) are natural toxins, supposed to be converted to hepatotoxic metabolites in the liver of mammalians, and preventing the uptake of PAs is the only way to reduce the attendant health risks. A liquid chromatography coupled to mass spectrometry (LC-MS/MS) method was developed according to the Decision 2002/657/EC, to evaluate the contamination of Veneto honey by the following pyrrolizidine alkaloids: echimidine, heliotrine, lycopsamine, retrorsine, senecionine, and seneciphylline, as well as their N-oxides (pyrrolizidine alkaloid N-oxides (PANOs)). Before the solid-phase extraction, a reduction step with zinc dust in the presence of sulfuric acid was carried out for the reduction of PANOs to PAs in honey samples. For all of the analytes, the mean recovery ranged between 82.70 and 104.16 % and the limit of quantification (LOQ) was 0.25 μg kg−1, fully satisfying the LOQ of 1 μg kg−1 as requested by EFSA (2012). The validated method was applied for the analysis of 60 Veneto samples produced from local beekeepers. Among the samples, 17 % were positive for the PAs monitored, and their total PA contents ranged from 0.6 to 17.6 μg kg−1. In all of the samples, the contribution from the PANOs appeared to be negligible. The total PA contents found in the Veneto honey samples never exceeded the limit of 0.42 μg per day for an individual weighing 60 kg, established by the German Federal Institute of Risk Assessment (BfR) in 2011. These preliminary results provide useful advice to beekeepers for finding the most suitable location for beehives to achieve a substantial reduction of the PAs in honey.