Presence and quantification of pathogenic Arcobacter and Campylobacter species in retail meats available in Japan

Contamination of Japanese Retail Foods With Enterotoxigenic Clostridium Perfringens Spores

The contamination of Japanese retail foods and the intestinal contents of animals with the spores of enterotoxigenic Clostridium perfringens were investigated by analyzing clostridial toxin genes (cpa and cpe) using a culture method and PCR. Enterotoxigenic C. perfringens was detected in 12.3% (8/65 samples) of shellfishes, 8.4% (7/83 samples) of dried seafoods, 7.4% (15/204 samples) of curry mixes and spices, 2.6% (1/39 samples) of dried seaweeds, 2.5% (2/79 samples) of fishes and shrimp, 1.9% (2/105 samples) of chicken, and 0.8% (1/121 samples) of root vegetables. Enterotoxigenic C. perfringens was not detected in beef (95 samples) and pork (110 samples). The ratio of enterotoxigenic C. perfringens-positive to all C. perfringens-positive samples was high for fish and shrimp (40.0%), curry mixes and spices (19.0%), shellfish (18.1%), dried seafood (16.7%), and dried seaweed (16.7%). Although C. perfringens was investigated in the intestinal contents of cattle (212 samples), pigs (207 samples), and chicken (159 samples), enterotoxigenic C. perfringens was not detected. These results indicate that beef and pork sold in Japan are unlikely to be contaminated with enterotoxigenic C. perfringens, and that other foods such as curry powder, shellfish, and dried seafoods are more important as the sources of contamination in Japan. Dried seafoods are frequently used to make soup stock in Japanese and other Asian dishes. In cases of food-borne illness linked to C. perfringens contamination of Japanese and Asian dishes, dried seafood should be investigated, in addition to other ingredients such as meat.

Genomic Characterization of Antibiotic-Resistant Campylobacterales Isolated from Chilean Poultry Meat

Due to the lack of knowledge about Campylobacterales in the Chilean poultry industry, the objective of this research was to know the prevalence, resistance, and genotypes of Campylobacter, Arcobacter and Helicobacter in 382 samples of chicken meat purchased in Valdivia, Chile. The samples were analyzed using three isolation protocols. Resistance to four antibiotics was evaluated by phenotypic methods. Genomic analyses were performed on selected resistant strains to detect resistance determinants and their genotypes. A total of 59.2% of the samples were positive. Arcobacter butzleri (37.4%) was the most prevalent species, followed by Campylobacter jejuni (19.6%), C. coli (11.3%), A. cryaerophilus (3.7%) and A. skirrowii (1.3%). Helicobacter pullorum (14%) was detected by PCR in a subset of samples. Campylobacter jejuni was resistant to ciprofloxacin (37.3%) and tetracycline (20%), while C. coli and A. butzleri were resistant to ciprofloxacin (55.8% and 2.8%), erythromycin (16.3% and 0.7%) and tetracycline (4.7% and 2.8%), respectively. Molecular determinants were consistent with phenotypic resistance. The genotypes of C. jejuni (CC-21, CC-48, CC-49, CC-257, CC-353, CC-443, CC-446 and CC-658) and C. coli (CC-828) coincided with genotypes of Chilean clinical strains. These findings suggest that besides C. jejuni and C. coli, chicken meat could play a role in the transmission of other pathogenic and antibiotic-resistant Campylobacterales.

Two-Round Treatment With Propidium Monoazide Completely Inhibits the Detection of Dead Campylobacter spp. Cells by Quantitative PCR

Campylobacter spp. are known as important foodborne gastroenteric pathogens worldwide. Campylobacter spp. can exist in a viable but non-culturable (VBNC) state under unsuitable environmental conditions, which is undetectable by conventional culture methods. Quantitative polymerase chain reaction (qPCR) can be used to detect VBNC Campylobacter spp.; however, both viable and dead bacteria are detected during qPCR and are indistinguishable. Propidium monoazide (PMA), which can only enter dead bacterial cells through a damaged cell wall/cell membrane, binds to DNA and inhibits qPCR. PMA treatment has been performed along with qPCR (PMA-qPCR) to detect viable bacteria. However, the efficacy of detection inhibition differed among studies, and PMA can potentially enter living cells after changes in cell membrane permeability. In this study, we optimized the PMA treatment method by conducting it before qPCR. Two-round PMA treatment completely inhibited the qPCR signals from dead cells, whereas single-round PMA treatment failed to facilitate this. An optimized PMA-qPCR method was developed using commercial chicken meat, and VBNC Campylobacter spp., which are undetectable using conventional culture-based methods, were successfully detected. In conclusion, this study presents a novel, efficient PMA treatment method for the detection of viable Campylobacter spp., including VBNC Campylobacter spp., in chicken meat. We believe that this method will aid the reliable risk assessment of commercial chicken meat.