Correlation between bacteriology of lymph nodes and serology for Salmonella diagnosis in slaughter pigs

Salmonella control programs in pigs are usually based on serological tests. The major objective of this cross-sectional study was to investigate the correlation between the serological results and the bacteriological results of Salmonella diagnosis in pigs at the herd level and at the animal level. From 60 farrow-to-finish herds, serum samples and mesenterial lymph nodes from 30 fattening pigs were taken in the slaughterhouse

Comparison of different enrichment media for the isolation of Salmonella from naturally infected slaughter pigs

The present study aimed to assess the impact of different enrichment media, Reppaport-vassiliadis (RV) broth, Rappaport-Vassiliadis Soya (RVS) broth, Diagnostic semi-solid Salmonella (DIA) agar, Simple Method Salmonella (SMS) agar, Modified Semisolid Rappaport Vassiliadis (MSRV) agar and Mueller Kauffmann Tetrathionate novobiocin (MKTTn) broth, on the detection of Salmonella as well as on the isolated serotype and genotype

Synergistic interactions within a multispecies biofilm enhance individual species protection against grazing by a pelagic protozoan

Biofilm formation has been shown to confer protection against grazing, but little information is available on the effect of grazing on biofilm formation and protection in multispecies consortia. With most biofilms in nature being composed of multiple bacterial species, the interactions and dynamics of a multispecies bacterial biofilm subject to grazing by a pelagic protozoan predator were investigated. To this end, a mono and multispecies biofilms of four bacterial soil isolates, namely Xanthomonas retroflexus, Stenotrophomonas rhizophila, Microbacterium oxydans and Paenibacillus amylolyticus, were constructed and subjected to grazing by the ciliate Tetrahymena pyriformis. In monocultures, grazing strongly reduced planktonic cell numbers in P. amylolyticus and S. rhizophila and also X. retroflexus. At the same time, cell numbers in the underlying biofilms increased in S. rhizophila and X. retroflexus, but not in P. amylolyticus. This may be due to the fact that while grazing enhanced biofilm formation in the former two species, no biofilm was formed by P. amylolyticus in monoculture, either with or without grazing. In four- species biofilms, biofilm formation was higher than in the best monoculture, a strong biodiversity effect that was even more pronounced in the presence of grazing. While cell numbers of X. retroflexus, S. rhizophila, and P. amylolyticus in the planktonic fraction were greatly reduced in the presence of grazers, cell numbers of all three species strongly increased in the biofilm. Our results show that synergistic interactions between the four-species were important to induce biofilm formation, and suggest that bacterial members that produce more biofilm when exposed to the grazer not only protect themselves but also supported other members which are sensitive to grazing, thereby providing a "shared grazing protection" within the four- species biofilm model. Hence, complex interactions shape the dynamics of the biofilm and enhance overall community fitness under stressful conditions such as grazing. These emerging inter-and intra-species interactions could play a vital role in biofilm dynamics in natural environments like soil or aquatic systems

Synergistic interactions in microbial biofilms facilitate the establishment of opportunistic pathogenic fungi in household dishwashers

Biofilms formed on rubber seals in dishwashers harbor diverse microbiota. In this study, we focussed on the microbial composition of bacteria and fungi, isolated from a defined area of one square centimeter of rubber from four domestic dishwashers and assessed their abilities to in vitro multispecies biofilm formation. A total of 80 isolates (64 bacterial and 16 fungal) were analyzed. Multiple combinations of bacterial isolates from each dishwasher were screened for synergistic interactions. 32 out of 140 tested (23%) four-species bacterial combinations displayed consistent synergism leading to an overall increase in biomass, in all experimental trails. Bacterial isolates from two of the four dishwashers generated a high number of synergistically interacting four-species consortia. Network based correlation analyses also showed higher co-occurrence patterns observed between bacterial members in the same two dishwasher samples, indicating cooperative effects. Furthermore, two synergistic fourspecies bacterial consortia were tested for their abilities to incorporate an opportunistic fungal pathogen, Exophiala dermatitidis and their establishment as biofilms on sterile ethylene propylene diene monomer M-class (EPDM) rubber and polypropylene (PP) surfaces. When the bacterial consortia included E. dermatitidis, the overall cell numbers of both bacteria and fungi increased and a substantial increase in biofilm biomass was observed. These results indicate a novel phenomenon of cross kingdom synergy in biofilm formation and these observations could have potential implications for human health

Effect of the use of organic acids in drinking water during the last two weeks prior to slaughter on salmonella shedding

In this study we investigated the effect of adding organic acids to the drinking water of finishing pigs two weeks prior to slaughter on the shedding and prevalence rate of Salmonella at slaughter. One hundred animals from 4 Belgian pig herds infected with Salmonella were included. Fifty of these ammals received drinking water supplemented with a mixture of different organic acids during 14 days prior to slaughter. Non-treated animals served as controls. Different samples were taken: contents of ileum and rectum, mesenteric lymph nodes and carcass swabs. All samples were submitted to Salmonella isolation using standard procedures. The results could not reveal a significant difference between both groups. This may be due to the limited power of the study (only 50 animals sampled in each group) or due to the fact that the treatment duration was insufficient to prove the benefit of the used organic acids

A qualitative risk assessment for human salmonellosis due to the consumption of fresh pork in Belgium

Although pigs contaminated with Salmonella rarely show clinical symptoms, control is important because of the public health concern. Both producers and consumers are interested in procedures for minimizing the risk of Salmonella infections. This study outlines the entire production path for fresh pork in Belgium, from farm to fork. Additionally, it describes the different critical points for Salmonella contamination, with emphasis on those steps that need extra attention and/or improvement. The data was collected by means of questionnaires at the different steps of the process. In total, 3658 questionnaires were collected, which made it possible to draw up a nationwide image of the pork production process. In the primary production phase, there are several points relating to biosecurity that can be improved in order to minimize the risk for Salmonella in fattening pigs that are sent to slaughter. In the slaughterhouse, there has been an increase in the number of pigs or carcasses that become infected with Salmonella. Attention should be paid to avoiding contact of the feces and tonsils of contaminated pigs with the carcass, and strict hygienic measures should be taken to avoid cross-contamination. During the transformation and distribution of the carcasses, there is a low risk of further spreading of Salmonella spp. Finally, during the consumer phase, the risk for Salmonella contamination increases because of inappropriate temperature conditions during storage, manipulation of the meat and possible cross-contamination with other food products, and the consumption of insufficiently heated and/or raw meat. The present study illustrates that the risk of Salmonella infection by consumption of fresh pork is relatively low under Belgian conditions. Nevertheless, it can be further decreased by implementing additional control measures, mainly in the slaughterhouse and in the domestic kitchen