Systematic review on microbiome-related nutritional interventions interfering with the colonization of foodborne pathogens in broiler gut to prevent contamination of poultry meat.

This systematic review aimed to compile the available body of knowledge about microbiome-related nutritional interventions contributing to improve the chicken health and having an impact on the reduction of colonization by foodborne pathogens in the gut. Original research articles published between 2012 and 2022 were systematically searched in Scopus and PubMed. A total of 1,948 articles were retrieved and 140 fulfilled the inclusion criteria. Overall, 73 papers described 99 interventions against colonization by Escherichia coli and related organisms; 10 papers described 15 interventions against Campylobacter spp.; 36 papers described 54 interventions against Salmonella; 40 papers described 54 interventions against Clostridium perfringens. A total of 197 microbiome-related interventions were identified as effective against one or more of the listed pathogens and included probiotics (n = 80), prebiotics (n = 23), phytobiotics (n = 25), synbiotics (n = 12), organic acids (n = 12), enzymes (n = 4), essential oils (n = 14) and combination of these (n = 27). The identified interventions were mostly administered in the feed (173/197) or through oral gavage (11/197), in the drinking water (7/197), in ovo (2/197), intra amniotic (2/197), in fresh or reused litter (1/197) or both in the feed and water (1/197). The interventions enhanced the beneficial microbial communities in the broiler gut as Lactic acid bacteria, mostly Lactobacillus spp., or modulated multiple microbial populations. The mechanisms promoting the fighting against colonization by foodborne pathogens included competitive exclusion, production of short chain fatty acids, decrease of gut pH, restoration of the microbiome after dysbiosis events, promotion of a more stable microbial ecology, expression of genes improving the integrity of intestinal mucosa, enhancing of mucin production and improvement of host immune response. All the studies extracted from the literature described in vivo trials but performed on a limited number of animals under experimental settings. Moreover, they detailed the effect of the intervention on the chicken gut without details on further impact on poultry meat safety.

Microbiological safety of dry-cured fish from the raw material to the end of processing.

The commercialization of processed fish products is rising in restaurants and small to medium enterprises. However, there is a lack of data related to the microbiological safety of such products. In this study total aerobic colony count and Enterobacteriaceae, as proxy of process hygiene criteria, and detection of Listeria monocytogenes and concentration of histamine, as food safety criteria, were investigated in Salmo salar (salmon), Xiphias gladius (swordfish) and Thunnus albacares (yellowfin tuna), before, during, and at the end of a dry-curing process, performed in a dedicated cabinet, at controlled temperature, relative humidity and ventilation, up to 240 h. The microbiological parameters were investigated in the tested fish products by culture methods and shotgun metagenomic, while the presence of histamine, and other biogenic amines, was quantified by High Performance Liquid Chromatography. In the raw material, and up to the end of the dry curing process, the concentration of Enterobacteriaceae was always lower than 10 CFU/g, while total aerobic colony counts ranged between 3.9 and 5.4 Log CFU/g in salmon; 5.5 and 5.9 Log CFU/g in swordfish; 4.4 and 4.8 Log CFU/g in tuna. The pH values were significantly different between fish species, in the raw materials and during processing except for T4, occurring 70 h after the start of the process for salmon and after 114 h for swordfish and tuna. Water activity was different at specific sampling points and at the end of processing. Overall, 79 % of the sequences identified in the tested fish samples were assigned to y bacteria. The most abundant phyla were Pseudomonadota, Bacillota and Mycoplasmatota. The microbial populations identified by shotgun metagenomic in the tested fish species clustered well separated one from the other. Moreover, the microbial richness was significantly higher in salmon and tuna in comparison to swordfish. Listeria monocytogenes was not detected in the raw material by using the reference cultural method and very few reads (relative abundance <0.007) were detected in swordfish and tuna by shotgun metagenomic. Histamine producing bacteria, belonging to the genera Vibrio, Morganella, Photobacterium and Klebsiella, were identified primarily in swordfish. However, histamine and other biogenic amines were not detected in any sample. To the best of our knowledge this is the first paper reporting time point determinations of microbiological quality and safety parameters in salmon, swordfish and tuna, before, during and at the end of a dry-curing process. The data collected in this paper can help to predict the risk profile of ready to eat dry-cured fish products during storage before consumption.

Routes of dispersion of antibiotic resistance genes from the poultry farm system.

Poultry farms are hotspots for the development and spread of antibiotic resistance genes (ARGs), due to high stocking densities and extensive use of antibiotics, posing a threat of spread and contagion to workers and the external environment. Here, we applied shotgun metagenome sequencing to characterize the gut microbiome and resistome of poultry, workers and their households - also including microbiomes from the internal and external farm environment - in three different farms in Italy during a complete rearing cycle. Our results highlighted a relevant overlap among the microbiomes of poultry, workers, and their families (gut and skin), with clinically relevant ARGs and associated mobile elements shared in both poultry and human samples. On a finer scale, the reconstruction of species-level genome bins (SGBs) allowed us to delineate the dynamics of microorganism and ARGs dispersion from farm systems. We found the associations with worker microbiomes representing the main route of ARGs dispersion from poultry to human populations. Collectively, our findings clearly demonstrate the urgent need to implement more effective procedures to counteract ARGs dispersion from poultry food systems and the relevance of metagenomics-based metacommunity approaches to monitor the ARGs dispersion process for the safety of the working environment on farms.

Reduction of the microbial load in meat maturation rooms with and without alkaline electrolyzed water fumigation.

Dry aging is a process during which meat is stored within maturation chambers at low temperatures and low relative humidity, resulting in improved tenderness and flavor development. The cuts are exposed to the atmosphere by hanging them or setting them on racks in the maturation chamber without any protective packaging. Animals and humans are usually the major sources of bacterial food contamination in the meat industry, but other routes might be involved. Therefore, procedures to reduce or eliminate pathogens from surfaces are crucial for an effective hazard analysis critical control point program in the food industry and other environments. This study aimed to assess the survival of Listeria monocytogenes, Escherichia coli, Salmonella spp., and Staphylococcus aureus on the inner surface of dry aging chambers. Moreover, we tested the efficacy of alkaline electrolyzed water (REW) for its application within a procedure aimed at reducing foodborne pathogens during meat storage. Environmental conditions inside the dry aging cabinet determine a reduction of circa 3 log CFU/cm2 of the considered microorganisms on the inner surface in 24 hours. Additionally, the nebulization of REW with the smoking system increased the count reduction in 24 hours due to environmental conditions for L. monocytogenes (~1 log CFU/cm2) and for S. aureus (~2 log CFU/cm2). In this context, the use of REW can be justified for routine cleaning procedures of the surfaces, with the added value of being safe to handle, not containing environmental pollutants, and making it unnecessary to rinse surfaces due to its instability.