Prevalence of the main food-borne pathogens in retail food under the national food surveillance system in Japan

The National Food Surveillance System in Japan was formed in 1998 to monitor the contamination of retail foods with bacterial pathogens. Approximately 2000–3000 samples were tested annually, and the data from food categories that had more than 400 samples collected during 1998–2008 were analysed. With regard to meat, the frequency of positive samples for Salmonella in chicken for raw consumption and ground chicken was 12.7% and 33.5%, respectively. Moreover, Shiga toxin-producing Escherichia coli (STEC) O157 was found in ground meat, organ meat and processed meat, although at a low frequency (0.1%). The prevalence of Campylobacter jejuni/coli was 13.3% and 20.9% in chicken for raw consumption and ground chicken, respectively. In vegetables and fruit, Salmonella was detected in cucumber, lettuce, sprout and tomato samples at a frequency of around 0.1–0.2%. With regard to seafood, Salmonella was found in 0.5% of oysters for raw consumption. Seafood was not contaminated with STEC O157 or Shigella. Serotype Infantis was the most frequently detected serotype of Salmonella in seafood, followed by the serotypes Typhimurium, Schwarzengrund and Manhattan. In ground chicken, 72.2% of the strains were identified as the serotype Infantis. E. coli, as an indicator of food hygiene, was detected in all food categories. The results show the prevalence of the above-mentioned pathogens in the retail food supplied in Japan; further, they indicate that consumption of raw food carries the risk of contracting food-borne infections.     

Towards the production of reliable quantitative microbiological data for risk assessment: Direct quantification of Campylobacter in naturally infected chicken fecal samples using selective culture and real-time PCR

Poultry has been identified as a significant source for human campylobacteriosis which constitutes an important zoonosis and public health problem in many areas of the world. Rapid, direct and accurate quantification of Campylobacter in poultry is essential for the assessment of public health risks and for the evaluation of control strategies implemented in poultry production. The aim of this study was to compare estimates of the numbers of Campylobacter spp. in naturally infected chicken fecal samples obtained using direct quantification by selective culture and by real-time PCR. Absolute quantification of Campylobacter by real-time PCR was performed using standard curves designed for two different DNA extraction methods: Easy-DNA™ Kit from Invitrogen (Easy-DNA) and NucliSENS^® MiniMAG^® from bioMérieux (MiniMAG). Results indicated that the estimation of the numbers of Campylobacter present in chicken fecal samples was partly dependent on the methodologies used. In general, the numbers of Campylobacter obtained by real-time PCR when extracting DNA using the MiniMAG method were in most cases higher than the numbers of Campylobacter obtained by selective culture and by real-time PCR when using the Easy-DNA method. Although there were differences in terms of estimates of Campylobacter numbers between the methods and samples, the differences between culture and real-time PCR were not statistically significant for most of the samples used in this study.     

Occurrence of Yersinia enterocolitica and Campylobacter spp. in slaughter pigs and consequences for meat inspection,slaughtering, and dressing procedures

The purpose of the present investigation was to assess the occurrence of Yersinia enterocolitica and Campylobacter spp. in the lymphoid tissues and intestinal tract in pigs and the risk for contamination during the compulsory meat inspection procedures and the procedures during slaughtering and dressing. Another objective of the investigation was to compare traditional isolation methods, the use of a polymerase chain reaction (PCR) method (BUGS'n BEADS™ bacterial DNA isolation kit) and an ELISA method (VIDAS CAM) as tools in risk management in the slaughterhouse.

The results indicate that the compulsory procedure for the incision of the submaxillary lymph nodes represents a cross-contamination risk for virulent Yersinia. In the screening of 97 animals in 1999, 5.2% of the samples were positive, and by the sampling of 24 samples in 2000–2001, 12.5% of the samples were positive. In the last case, Y. enterocolitica O:3 was found in the kidney region in one of the subsequent carcasses that was only touched by the meat inspection personnel before sampling. In addition, incision of the mesenteric lymph nodes might represent a cross-contamination risk since 8.3% of the samples were positive.

The association between antibody titres and the occurrence of virulent yersiniae in the tonsils (21–18) was striking, with virulent yersiniae found in the tonsils in most pigs with high titres.

The contents of the stomach, ileum, caecum, and colon also represent contamination risks for Y. enterocolitica O:3 if the slaughterhouse personnel cuts into the viscera with their knives by accident; the frequency of virulent Yersinia varied from 4.2% to 16.7% within these sections.

Campylobacter was detected in the gastrointestinal tract of all pigs, and the high contamination of tonsils (66.7%) and intestinal tract (100%) might represent an occupational health hazard.

There was no statistical difference between the traditional method for isolation of Y. enterocolitica [International Organization for Standardization, 1994. Microbiology—General Guidance for the Detection of Presumptive Pathogenic Yersinia enterocolitica (ISO 10273). International Organization for Standardization, Genève, Switzerland (16 pp.)] and the BUGS'n BEADS™ detection method for virulent Y. enterocolitica. Likewise, there was no statistical difference between the traditional method for isolation of Campylobacter spp. [Nordic Committee on Food Analysis, 1990. Campylobacter jejuni/coli. Detection in Food. Method No. 119, 2nd ed. Nordic Committee on Food Analysis, Esbo (7 pp.)] and the BUGS'n BEADS™ detection method or the VIDAS CAM method for detection of Campylobacter spp.     

Citrus Extracts as Inhibitors of Quorum Sensing,Biofilm Formation and Motility of Campylobacter jejuni

Quorum Sensing (QS), a signaling system present in bacteria, influences the expression of a variety of virulence factors. This study investigated the ability of citrus extracts to inhibit the activity of AI-2 molecules that mediate QS in Campylobacter jejuni and the effects of these extracts on motility, biofilm formation and expression of flaA-B. Cultures of C. jejuni were exposed to extracts of Citrus limon, Citrus medica and Citrus aurantium peels at various concentrations. Swarm motility tests were performed in Muller Hinton agar; biofilm formation was determined colorimetrically in microtiter plates; AI-2 activity was measured with a bioluminescence assay using V. harveyi; and flaA-B expression was determined by qRT-PCR. Treatment with C. limon or C. medica peel extract reduced swarm motility 44–59%, whereas treatment with C. aurantium extract reduced swarm motility 35–40%. Biofilm formation was reduced 60–75 % by these extracts, depending on extract concentration and /or strain tested. All three citrus extracts decreased AI-2 activity by about 90 %, and at 75 % of MBC, significantly (P ≤ 0.05) reduced expression of flaA-B. These findings provide preliminary metabolic and molecular insights into the effects of edible antimicrobials on QS and virulence factors of C. jejuni.     

Campylobacter jejuni: A Review of its Characteristics, Pathogenicity, Ecology, Distribution, Subspecies Characterization and Molecular Methods of Detection

Campylobacter jejuni is considered to be the leading cause of enteric illness in the United States and other industrialized nations, causing mild to severe symptoms including serious infections of the extremities and permanent neurological symptoms. The organism is a cytochrome oxidase positive, microaerophilic, curved Gram-negative rod exhibiting corkscrew motility and is carried in the intestine of many wild and domestic animals, particularly avian species including poultry, where the intestine is colonized resulting in healthy animals as carriers. Wildlife have long been considered an infectious reservoir for campylobacters because of their close association with and contamination of surface waters. This review deals with the areas of: phenotypic characteristics of C. jejuni and related human pathogenic species of Campylobacter, their ecological distribution, virulence factors, isolation of C. jejuni from foods, serotyping of Campylobacter isolates, bacteriophage typing, molecular methods of detecting and typing campylobacters, the viable but nonculturable state of campylobacters, the coccoid form of C. jejuni and immunomagnetic capture of C. jejuni.     

Evaluation of Potassium‐Clavulanate‐Supplemented Modified Charcoal‐Cefoperazone‐Deoxycholate Agar for Enumeration of Campylobacter in Chicken Carcass Rinse

Potassium‐clavulanate‐supplemented modified charcoal‐cefoperazone‐deoxycholate agar (C‐mCCDA) that was described in our previous study was compared with original mCCDA for the enumeration of Campylobacter in pure culture and chicken carcass rinse. The quantitative detection of viable Campylobacter cells from a pure culture, plated on C‐mCCDA, is statistically similar (P > 0.05) to mCCDA. In total, 120 chickens were rinsed using 400 mL buffered peptone water. The rinses were inoculated onto C‐mCCDA and mCCDA followed by incubation at 42 °C for 48 h. There was no statistical difference between C‐mCCDA (45 of 120 plates; mean count, 145.5 CFU/mL) and normal mCCDA (46 of 120 plates; mean count, 160.8 CFU/mL) in the isolation rate and recovery of Campylobacter (P > 0.05) from chicken carcass rinse. The Pearson correlation coefficient value for the number of Campylobacter cells recovered in the 2 media was 0.942. However, the selectivity was much better on C‐mCCDA than on mCCDA plates (P < 0.05). Significantly fewer C‐mCCDA plates (33 out of 120 plates; mean count, 1.9 CFU/mL) were contaminated with non‐Campylobacter cells than the normal mCCDA plates (67 out of 120 plates; mean count, 27.1 CFU/mL). The C‐mCCDA may provide improved results for enumeration of Campylobacter in chicken meat alternative to mCCDA with its increased selectivity the modified agar possess.