One of the major transmission routes for the foodborne bacterial pathogen Campylobacter is undercooked poultry meat, contaminated from intestinal contents during processing. In broilers, Campylobacter can grow to very high densities in the caeca, and is often considered to be a commensal or an opportunistic pathogen in poultry. Reduction of caecal loads of Campylobacter may assist in lowering incidence rates of Campylobacter food poisoning. To achieve this, there needs to be a better understanding of the dynamics of Campylobacter colonization in its natural niche, and the effect of the local microbiome on colonization. Previous studies have shown that the microbiome differed between Campylobacter colonized and non-colonized chicken intestinal samples. To characterize the microbiome of Campylobacter-colonized broilers, caecal samples of 100 randomly selected birds from four farms were analyzed using amplified 16S rRNA gene sequences. Bacterial taxonomic analysis indicated that inter-farm variation was greater than intra-farm variation. The two most common bacterial groups were Bacteroidetes and Firmicutes which were present in all samples and constituted 29.7–63.5 and 30.2–59.8% of the bacteria present, respectively. Campylobacter was cultured from all samples, ranging from 2 to 9 log₁₀ CFU g^-1. There was no clear link between Campylobacter counts and Firmicutes, Bacteroidetes, or Tenericutes levels in the 16S rRNA operational taxonomic unit (OTU)-based analysis of the caecal microbiome, but samples with high Campylobacter counts (>9 log CFU g^-1) contained increased levels of Enterobacteriaceae. A decrease in Lactobacillus abundance in chicken caeca was also associated with high Campylobacter loads. The reported associations with Lactobacillus and Enterobacteriaceae match changes in the intestinal microbiome of chickens and mice previously reported for Campylobacter infection, and raises the question about temporality and causation; as to whether increases in Campylobacter loads create conditions adverse to Lactobacilli and/or beneficial to Enterobacteriaceae, or that changes in Lactobacilli and Enterobacteriaceae levels created conditions beneficial for Campylobacter colonization. If these changes can be controlled, this may open opportunities for modulation of chicken microbiota to reduce Campylobacter levels for improved food safety.

This study was conducted to determine the prevalence and antimicrobial resistance of Listeria monocytogenes recovered from chicken carcasses in slaughterhouses in Northern Greece. A total of 100 poultry samples (300 carcasses) were examined for Listeria spp. The samples were neck skin taken from four different slaughterhouses in Northern Greece. Forty samples were also taken from the environment of the slaughterhouses. Identification of L. monocytogenes was carried out by PCR and fingerprinting of the isolates by random amplified polymorphic DNA. L. monocytogenes strains isolated from chicken carcasses and from the environment of the slaughterhouses were also examined for antibiotic resistance. Fifty-five isolates of L. monocytogenes were tested for susceptibility to 20 antibiotics using the disk diffusion method. Listeria spp. were present in 99 of the poultry samples tested (99%), and 38 yielded L monocytogenes (38%). L. monocytogenes was also isolated in 80% of samples from the environment of a certain slaughterhouse, while the other slaughterhouses were found to be contaminated only with Listeria spp. All isolates were resistant to nalidixic acid and oxolinic acid, the majority of them to clindamycin, and only a few to tetracycline and oxytetracycline, whereas they were found to be susceptible to all other antimicrobials. The results of this study demonstrate a high prevalence of L. monocytogenes contamination in chicken carcasses, and all isolates were found to be sensitive to the antimicrobials most commonly used to treat human listeriosis.

The highly toxic Aflatoxin M1 (AFM1) is most often detected in milk using an Enzyme-Linked-Immunosorbent Assay (ELISA) for screening purposes, while High-Performance Liquid Chromatography with Fluorescence Detector (HPLC-FL) is the reference method used for confirmation. The aim of the present study was the comparison between three commercially available ELISA kits and a newly developed HPLC-FL method for the determination of the AFM1 in milk samples. The developed HPLC-FL method was validated for the AFM1 and Aflatoxin M2 (AFM2), determining the accuracy, precision, linearity, decision limit, and detection capability with fairly good results. All three ELISA kits were also validated and showed equally good performance with high recovery rates. Moreover, the Limit Of Detection (LOD) and Limit Of Quantification (LOQ) values were found to be significantly lower than the Maximum Residue Limit (MRL) (50 ng kg⁻¹). After the evaluation of all three commercial kits, the ELISA kit with the optimum performance along with the HPLC method was used for the determination of AFM1 in raw cow’s, goat’s, and sheep’s milk samples (396) obtained from producers in different regions of Greece. The evaluation of both methods showed that this ELISA kit could be considered as a faster and equally reliable alternative method to HPLC in routine analysis for the determination of AFM1 in milk.