Salmonella contamination in a network of 10 pig farms interconnected within the same cooperative.

OBJECTIVE: To evaluate whether pig farms interconnected within the same cooperative share similar Salmonella contamination patterns. SETTING: Ten finishing pig farms within a 100 km radius of a common slaughterhouse were selected. Their inclusion was based on their association to the same cooperative and the sharing of common resources: piglets, feed, swine transporters, slaughterhouse, technicians and veterinarians. PROCEDURE: Each farm was visited three times over a 10-month period. Pig faeces, the barn front door handle, the feed pipeline, mobile objects (shovel, balance and pig board), the landing stage, the concrete slab of the feed bins, the tire tracks left on the pathways by the animal feed truck, the pig delivery truck and the carcase knacker truck and the mudguards and cabin carpets of the veterinarian and technician vehicles on their arrival at the farm were all analysed for the presence of Salmonella. RESULTS: All farms were not equally contaminated with Salmonella. Whereas some farms yielded up to 12 Salmonella isolates, other farms were Salmonella free. Some locations, most notably the landing stage, were more contaminated than others. Salmonella contamination was dynamic in time. Some contaminations seen on farms, on specific locations on the first visit, had disappeared on the second and third visits, but new contaminations were detected on different locations. CONCLUSIONS: Contamination with Salmonella was not disseminated through the network of the 10 pig farms interconnected within the same cooperative but was rather most often restricted in time to specific locations on specific farms.

Kobuvirus shedding dynamics in a swine production system and their association with diarrhea.

Porcine kobuviruses are widely distributed in swine, but the clinical significance of these viruses remains unclear, since they have been associated with both diarrheic and healthy pigs. In addition, there is a paucity of data on Kobuvirus prevalence in Canadian pig herds. In this study, a total of 181 diarrheic and healthy piglets were monitored and sampled on four occasions, intended to represent the different stages of production. The piglets were sampled at the nursing farms (birth to weaning stage), at the nursery farms (post-weaning stage), and at finishing farms (at the beginning and the end of the fattening stage). Fecal and environmental samples were collected during each life stage. Following viral extraction, Kobuvirus detection by RT-PCR was conducted, and positive samples were sequenced. During the late-nursing stage (6-21 days old), piglets with diarrhea shed more Kobuvirus than healthy individuals. Piglets shed more Kobuvirus during the post-weaning stage (nursery farms) than during any of the other life stages. This was evidenced in individual samples as well as in environmental samples. Over 97% of the sampled piglets shed Kobuvirus at least once in their lifetime. All piglets shedding a Kobuvirus strain or mix of strains at the nursing stage did not appear to shed another porcine kobuvirus strain at a later life stage. Overall, our findings throw light on Kobuvirus shedding dynamics and their potential role in neonatal diarrhea at the nursing stage, which appears to be the point of entry for kobuviruses into swine production systems.

Correction: In vitro efficacy of potentiated egg yolk powder against Campylobacter jejuni does not correlate with in vitro efficacy.

[This corrects the article DOI: 10.1371/journal.pone.0212946.].

In vitro efficacy of potentiated egg yolk powder against Campylobacter jejuni does not correlate with in vitro efficacy.

Campylobacter jejuni is a zoonotic agent responsible for the foodborne gastroenteritis campylobacteriosis. Control of C. jejuni load in the poultry primary production is recognized as an avenue to reduce human exposure to the pathogen. As for now, no commercially applicable control methods exist at the farm. Several studies tested egg yolk powders, potentiated or not against C. jejuni, as feed additives for chicken and suggested that the quantity and quality of the antibodies presence in the yolk are determinant factors for the full success of this approach. Unfortunately, data from these studies inconsistently showed a reduction of cecal C. jejuni carriage. Our first goal wwas to characterize (quantification by ELISA, agglutination test, bacterial antigen recognition profiles by Western blot, bactericidal effect by serum killing assays and C. jejuni mobility by soft agar migation) the antibodies extracted from egg yolk powders originating from different egg production protocols. Secondly, these powders were microencapsulated and recharacterized. Finally the protected powders were tested as a feed additive to destabilize C. jejuni colonization in an in vivo assay. Despite the in vitro results indicating the ability of the egg yolk powders to recognize Campylobacter and potentially alter its colonization of the chicken caecum, these results were not confirmed in the in vivo trial despite that specific caecal IgY directed toward Campylobacter were detected in the groups receiving the protected powders. More research is needed on Campylobacter in order to effectively control this pathogen at the farm.

Overlooked sources of Salmonella contamination in the pig production network: Slaughterhouse yard pathways and mudguards and carpets from transport trucks.

This report describes various Salmonella serovars which were found on often overlooked locations in a pig farm/slaughterhouse interface. These include slaughterhouse yard pathways and mudguards and carpets of transport trucks arriving at and departing from production sites.

Sources négligées de contamination par Salmonella dans un réseau de production de porcs: les voies de circulation de l'abattoir et les garde-boues et les tapis de cabine des camions de transport. Nous montrons ici que Salmonella, l'agent causal de la salmonellose, peut être trouvé sur des sites très inhabituels et négligés dans l'interface ferme porcine/abattoir: les voies de circulation de la cour d'abattoir, et les garde-boues et tapis des camions de transport qui arrivent et partent vers les sites de production.(Traduit par les auteurs).

Distribution of Virulence Genes among Salmonella Serotypes Isolated from Pigs in Southern Vietnam.

This study was carried out to evaluate the prevalence of Salmonella serogroups and serotypes and their virulence gene carriage in pig fecal samples from farms and slaughterhouses in some southern provinces of Vietnam. The presence of Salmonella was assessed based on culture enrichment of the collected samples and biochemical and serological analyses; 27.7% (51) of 184 samples were posititve for Salmonella. Based on the availability of antisera, serogroups were determined for 61% (31) of 51 isolates. Twenty isolates belonging to Salmonella serotypes Typhimurium (10 isolates), Anatum (8 isolates), Senftenberg (7 isolates), Paratyphi B (3 isolates), Paratyphi A (1 isolate), Montevideo (1 isolate), and Saintpaul (1 isolate) were further characterized by a multiplex PCR protocol targeting Salmonella invasion A and virulence plasmid C genes ( invA and spvC, respectively). Individual PCR assays were developed to detect genes for Salmonella enterotoxin ( stn) , Salmonella outer protein B ( sopB), and Salmonella fimbriae ( pef). Various carriage patterns were identified among tested isolates. The invA and sopB genes were found in all isolates, and the stn gene was found in 95% of the isolates. The spvC gene was found in only 5% of the Salmonella Typhimurium isolates. None of the isolates were positive for the pef gene. Among all isolates, the predominant genotypic virulence profile (virulotype) was characterized by the concomitant presence of invA, sopB, and stn in carrier strains. In contrast, two virulotypes comprising either invA, sopB, spvC, and stn or invA and sopB were identified for the Salmonella Typhimurium isolates. Virulotypes made up of multiple virulence genes were predominant in most Salmonella strains tested in this study, indicating that pigs might act as a reservoir for these virulent strains.

Selection of risk factors to be included in the Canadian Food Inspection Agency risk assessment inspection model for food establishments.

The Canadian Food Inspection Agency (CFIA) is developing a risk assessment model for food establishments. Previous research on the significance of food safety risk factors determined by literature review and expert advice served as the bases for the current study, to further refine, discriminate and select the most important criteria to be included in the model. This process considered the availability of data sources, the clarity and measurability of the selected factors, undertook the elimination of lower-rated risk factors and grouped those with similar focus of attention, enabling the selection of a final list of risk factors for the model. A method of assessment for the remaining factors was then proposed to allow the quantification of individual risk factors within the model. From the 155 risk factors initially identified, 17 consolidated factors were kept and will be considered for the development of the risk assessment model.

Broiler chicken carcasses and their associated abattoirs as a source of enterotoxigenic Clostridium perfringens: Prevalence and critical steps for contamination.

Clostridium perfringens ranks among the three most frequent bacterial pathogens causing human foodborne diseases in Canada, and poultry meat products are identified as a source of infection for humans. The objective of the current study was to estimate the proportion of broiler chicken flocks, carcasses and various environmental samples from critical locations of the slaughter plant positive for the presence of C. perfringens enterotoxin encoding gene (cpe). From the 16 visits conducted, 25% of the 79 flocks sampled, 10% of the 379 carcasses sampled and 5% of the 217 environmental samples collected were found positive for cpe. The proportion of cpe-positive carcasses was statistically different between surveyed plants, with 17.0% for one abattoir and 2.2% for the other. For the most contaminated plant, cpe-positive carcasses were identified at each step of the processing line, with prevalence varying between 10.0% and 25.0%, whereas this prevalence varied between 0% and 25.0% for the environmental surfaces sampled. Based on the results obtained, enterotoxigenic C. perfringens strains could potentially represent a risk for the consumer.

Reduction of Salmonella Shedding by Sows during Gestation in Relation to Its Fecal Microbiome.

Pork meat is estimated to be responsible for 10-20% of human salmonellosis cases in Europe. Control strategies at the farm could reduce contamination at the slaughterhouse. One of the targeted sectors of production is maternity, where sows could be Salmonella reservoirs. The aim of this study was to assess the dynamics of shedding of Salmonella in terms of variation in both shedding prevalence and strains excreted during gestation in Quebec's maternity sector. The evolution of the fecal microbiota of these sows during gestation was also assessed to detect bacterial populations associated with these variations. A total of 73 sows both at the beginning and the end of the gestation were randomly selected and their fecal matter was analyzed. Salmonella detection was conducted using a method that includes two selective enrichment media (MSRV and TBG). Nine isolates per positive samples were collected. Among the 73 sows tested, 27 were shedding Salmonella. Sows in the first third of their gestation shed Salmonella significantly more frequently (21/27) than those in the last third (6/46) (χ2P < 0.05). The shedding status of 19 of the sows that were previously sampled in the first third of their gestation was followed, this time in the last third of their gestation, which confirmed reduction of shedding. Using 16S rRNA gene sequencing and qPCR, significant differences between the fecal flora of sows at the beginning and the end of the gestation, shedding Salmonella or not and with different parity number were detected. Using MaAsLin, multiple OTUs were found to be associated with the time of gestation, the status of Salmonella excretion and parity number. Some of the identified taxa could be linked to the reduction of the shedding of Salmonella at the end of gestation. In this study, we showed that the level of Salmonella shedding was variable during gestation with significantly higher shedding at the beginning rather than at the end of gestation. We also observed for the first time a significant change in the microbiota during sow gestation and identified interesting taxa which could be linked to a reduced Salmonella shedding.

Production and characterization of anti-Campylobacter jejuni IgY derived from egg yolks.

BACKGROUND: Campylobacter jejuni is a major cause of foodborne disease having chickens as an important reservoir. Its control at the farm would lower the contamination of the final products and therefore also lower the risk of transmission to humans. At the farm, C. jejuni is rarely found in chickens before they reach 2 weeks of age. Past studies have shown that maternal antibodies could hamper C. jejuni gut colonization. The objective of this study was to compare protocols to use in order to produce anti-C. jejuni antibodies derived from egg yolks in the perspective to be used as feed additives for the control of chicken C. jejuni colonization. Laying hens were naturally contaminated with four well-characterized strains or injected with either outer membrane proteins or formalin-killed whole bacteria derived from these same strains. Eggs were collected and IgYs present in the yolks were extracted. The amount and the specificity of the recovered antibodies were characterized. RESULTS: It was observed that injection yielded eggs with superior concentrations of both total and anti-C. jejuni antibodies. Equivalent performances for antibodies recovered from all protocols were observed for the ability of the antibodies to agglutinate the live C. jejuni homologous strains, to hinder their motility or to lyse the bacteria. Western blot analyses showed that proteins from all strains could be recognized by all IgY extracts. All these characteristics were strain specific. The characterization assays were also made for heterologous strains and weaker results were observed when compared to the homologous strains. CONCLUSIONS: Based on these results, only an IgY quantitative based selection can be made in regards to which protocol would give the best anti-C. jejuni IgY enriched egg-yolks as all tested protocols were equivalent in terms of the recovered antibody ability to recognized the tested C. jejuni strains.

Phenotypic and Transcriptomic Responses of Campylobacter jejuni Suspended in an Artificial Freshwater Medium.

Campylobacter jejuni is the leading cause of campylobacteriosis in the developed world. Although most cases are caused by consumption of contaminated meat, a significant proportion is linked to ingestion of contaminated water. The differences between C. jejuni strains originating from food products and those isolated from water are poorly understood. Working under the hypothesis that water-borne C. jejuni strains are better equipped at surviving the nutrient-poor aquatic environment than food-borne strains, the present study aims to characterize these differences using outbreak strains 81116 and 81-176. Strain 81116 caused a campylobacteriosis outbreak linked to consumption of water, while strain 81-176 was linked to consumption of raw milk. CFU counts and viability assays showed that 81116 survives better than 81-176 at 4°C in a defined freshwater medium (Fraquil). Moreover, 81116 was significantly more resistant to oxidative stress and bile salt than strain 81-176 in Fraquil. To better understand the genetic response of 81116 to water, a transcriptomic profiling study was undertaken using microarrays. Compared to rich broth, strain 81116 represses genes involved in amino acid uptake and metabolism, as well as genes involved in costly biosynthetic processes such as replication, translation, flagellum synthesis and virulence in response to Fraquil. In accordance with the observed increase in stress resistance in Fraquil, 81116 induces genes involved in resistance to oxidative stress and bile salt. Interestingly, genes responsible for cell wall synthesis were also induced upon Fraquil exposure. Finally, twelve unique genes were expressed in Fraquil; however, analysis of their distribution in animal and water isolates showed that they are not uniquely and ubiquitously present in water isolates, and thus, unlikely to play a major role in adaptation to water. Our results show that some C. jejuni strains are more resilient than others, thereby challenging current water management practices. The response of 81116 to Fraquil serves as a starting point to understand the adaptation of C. jejuni to water and its subsequent transmission.

Characterisation of InlA truncation in Listeria monocytogenes isolates from farm animals and human cases in the province of Quebec.

The introduction of Listeria monocytogenes into the food production chain is a concern, with numerous grouped cases of listeriosis associated with milk-derived or pork-derived products have been documented. Management of this zoonotic pathogen considers all strains as an equal risk. Recently, a new perspective for characterisation of strain virulence was introduced with the discovery of the unaltered sequence of InlA as a determinant of strain virulence; this has also been reported as an infrequent finding among so-called environmental strains, that is, strains isolated from food or from surfaces in food industries. The aim of this study was to differentiate L monocytogenes strains isolated from animal cases versus those from human cases and to differentiate clinical strains from environmental ones using a Caenorhabditis elegans virulence testing model. In Quebec in 2013/2014, the surveillance of L monocytogenes clinical isolates registered a total of 20 strains of animal origin and 16 pulsed-field gel electrophoresis types isolated from human cases. The mixed PCR multiplex agglutination protocol used for geno-serotyping clearly discriminated genogroup IVB strains from bovine and human origins. The presence of a premature stop codon single nucleotide polymorphism in the inlA gene sequence in clinical strains and the identical behaviour of particular strains in the C elegans model are discussed in this paper from the perspective of industrial management of L monocytogenes risk.

Recurring Necrotic Enteritis Outbreaks in Commercial Broiler Chicken Flocks Strongly Influence Toxin Gene Carriage and Species Richness in the Resident Clostridium perfringens Population.

Extensive use of antibiotic growth promoters (AGPs) in food animals has been questioned due to the globally increasing problem of antibiotic resistance. For the poultry industry, digestive health management following AGP withdrawal in Europe has been a challenge, especially the control of necrotic enteritis. Much research work has focused on gut health in commercial broiler chicken husbandry. Understanding the behavior of Clostridium perfringens in its ecological niche, the poultry barn, is key to a sustainable and cost-effective production in the absence of AGPs. Using polymerase chain reaction and pulsed-field gel electrophoresis, we evaluated how the C. perfringens population evolved in drug-free commercial broiler chicken farms, either healthy or affected with recurring clinical necrotic enteritis outbreaks, over a 14-month period. We show that a high genotypic richness was associated with an increased risk of clinical necrotic enteritis. Also, necrotic enteritis-affected farms had a significant reduction of C. perfringens genotypic richness over time, an increase in the proportion of C. perfringens strains harboring the cpb2 gene, the netB gene, or both. Thus, necrotic enteritis occurrence is correlated with the presence of an initial highly diverse C. perfringens population, increasing the opportunity for the selective sweep of particularly virulent genotypes. Disease outbreaks also appear to largely influence the evolution of this bacterial species in poultry farms over time.

Post weaning diarrhea in pigs: risk factors and non-colistin-based control strategies.

Post-weaning diarrhea (PWD) is one of the most serious threats for the swine industry worldwide. It is commonly associated with the proliferation of enterotoxigenic Escherichia coli in the pig intestine. Colistin, a cationic antibiotic, is widely used in swine for the oral treatment of intestinal infections caused by E. coli, and particularly of PWD. However, despite the effectiveness of this antibiotic in the treatment of PWD, several studies have reported high rates of colistin resistant E. coli in swine. Furthermore, this antibiotic is considered of very high importance in humans, being used for the treatment of infections due to multidrug-resistant (MDR) Gram-negative bacteria (GNB). Moreover, the recent discovery of the mcr-1 gene encoding for colistin resistance in Enterobacteriaceae on a conjugative stable plasmid has raised great concern about the possible loss of colistin effectiveness for the treatment of MDR-GNB in humans. Consequently, it has been proposed that the use of colistin in animal production should be considered as a last resort treatment only. Thus, to overcome the economic losses, which would result from the restriction of use of colistin, especially for prophylactic purposes in PWD control, we believe that an understanding of the factors contributing to the development of this disease and the putting in place of practical alternative strategies for the control of PWD in swine is crucial. Such alternatives should improve animal gut health and reduce economic losses in pigs without promoting bacterial resistance. The present review begins with an overview of risk factors of PWD and an update of colistin use in PWD control worldwide in terms of quantities and microbiological outcomes. Subsequently, alternative strategies to the use of colistin for the control of this disease are described and discussed. Finally, a practical approach for the control of PWD in its various phases is proposed.

Lack of Evidence That Selenium-Yeast Improves Chicken Health and Modulates the Caecal Microbiota in the Context of Colonization by Campylobacter jejuni.

Faced with ever-increasing demand, the industrial production of food animals is under pressure to increase its production. In order to keep productivity, quality, and safety standards up while reducing the use of antibiotics, farmers are seeking new feed additives. In chicken production, one of these additives is selenium. This element is expected to confer some advantages in terms of animal health and productivity, but its impact on chicken intestinal microbiota as well as on the carriage of foodborne pathogens is unknown. In this study, chickens raised in a level 2 animal facility were fed or not 0.3 ppm of in-feed selenium-yeast until 35 days of age and were inoculated or not with the foodborne pathogen Campylobacter jejuni at the age of 14 days. At the end of the study, body weight, seric IgY, intestinal IgA, seric gluthatione peroxydase activity, the caecal microbiota (analyzed by MiSeq 16S rRNA gene sequencing), and C. jejuni caecal levels were analyzed. The experiment was completely replicated twice, with two independent batches of chickens. This study revealed that, for healthy chickens raised in very good hygienic conditions, selenium-yeast does not influence the bird's body weight and lowers their seric gluthatione peroxidase activity as well as their intestinal IgA concentrations. Furthermore, selenium-yeast did not modify the caecal microbiota or the colonization of C. jejuni. The results also showed that C. jejuni colonization does not impact any of the measured chicken health parameters and only slightly impacts the caecal microbiota. This study also clearly illustrated the need for true biological replication (independent animal trials) when assessing the microbiota shifts associated with treatments as the chickens microbiotas clearly clustered according to study replicate.

Extended-spectrum ß-lactamases, carbapenemases and the mcr-1 gene: is there a historical link?

The plasmid mediated mcr-1 gene encoding for Enterobacteriaceae colistin resistance has been recently identified across five continents. The objective of the present study was to trace historical events concerning the discovery and emergence of the mcr-1 gene along with ESBL and carbapenemase genes since several studies have reported identifying mcr-1 genes among Extended-Spectrum ß-Lactamases (ESBL) and/or carbapenemase producing Escherichia coli. A retrospective study reported the identification of the mcr-1 gene in E. coli strains isolated in the 1980s, and this seems to correspond to the first identification of ESBL enzymes. The first discovery of the New Delhi metallo-beta-lactamase-1 (NDM-1) in 2009 was associated with a significant increase in mcr-1 gene prevalence in E. coli strains obtained from food producing animals. We noticed that a historical link has existed between mcr-1, ESBL and carbapenemase genes since the 1980s, and we believe that the re-evaluation of colistin use in livestock needs an overall approach that includes not only colistin use reduction but also the reduction of all antibiotic use.

The fecal presence of enterotoxin and F4 genes as an indicator of efficacy of treatment with colistin sulfate in pigs.

BACKGROUND: Enterotoxigenic Escherichia coli (ETEC) strains producing multiple enterotoxins are important causes of post-weaning diarrhea (PWD) in pigs. The aim of the present study was to investigate the fecal presence of ETEC enterotoxin as well as F4 and F18 genes as an indicator of colistin sulfate (CS) efficacy for treatment of PWD in pigs. Forty-eight piglets were weaned at the age of 21 days, and were divided into four groups: challenged treated, challenged untreated, unchallenged treated, and unchallenged untreated. Challenge was performed using 109 CFU of an ETEC: F4 strain, and treatment was conducted using oral CS at the dose of 50,000 IU/kg. The fecal presence of genes encoding for STa, STb, LT, F4 and F18 was detected using PCR. RESULTS: The PCR amplification of ETEC virulence genes showed that nearly 100% of pigs excreted genes encoding for STa and STb toxins in the feces before the challenge. These genes, in the absence of the gene encoding F4, were considered as a marker for F4-negative ETEC. One day after ETEC: F4 oral challenge pigs in the two challenged groups excreted the genes encoding LT and F4 in the feces. These genes were considered as a marker for F4-positive ETEC. However, the gene encoding F18 was not detected in any fecal samples of the 4 groups throughout the experiment. After only 3 days of successive oral treatment with CS, a significant reduction in both the F4-positive and negative ETEC populations was observed in the challenged treated group compared to the challenged untreated group (p < 0.0001). CONCLUSIONS: Our study is among the first to report that under controlled farming conditions, oral CS treatment had a significant effect on both fecal F4-positive and F4-negative ETEC in pigs. However, CS clinical efficiency was correlated with non-detection of F4-positive ETEC in the feces. Furthermore the fecal presence of F4-negative ETEC was not associated with clinical symptoms of post-weaning diarrhea in pigs.

Dynamics of Virus Distribution in a Defined Swine Production Network Using Enteric Viruses as Molecular Markers.

Modern swine production systems represent complex and dynamic networks involving numerous stakeholders. For instance, livestock transporters carry live animals between fattening sites, abattoirs, and other premises on a daily basis. This interconnected system may increase the risk of microbial spread within and between networks, although little information is available in that regard. In the present study, a swine network composed of 10 finishing farms, one abattoir, and three types of stakeholders (veterinarians, livestock transporters, and nutritional technicians) in Quebec, Canada, was selected to investigate specific vectors and reservoirs of enteric viruses. Environmental samples were collected from the premises over a 12-month period. Samples were screened using targeted reverse transcription-PCR and sequencing of two selected viral markers, group A rotaviruses (RVA) and porcine astroviruses (PoAstV), both prevalent and genetically heterogeneous swine enteric viruses. The results revealed frequent contamination of farm sites (21.4 to 100%), livestock transporter vehicles (30.6 to 68.8%) and, most importantly, the abattoir yard (46.7 to 94.1%), depending on the sample types. Although high levels of strain diversity for both viruses were found, identical PoAstV and RVA strains were detected in specific samples from farms, the abattoir yard, and the livestock transporter vehicle, suggesting interconnections between these premises and transporters. Overall, the results from this study underscore the potential role of abattoirs and livestock transport as a reservoir and transmission route for enteric viruses within and between animal production networks, respectively. IMPORTANCE: Using rotaviruses and astroviruses as markers of enteric contamination in a swine network has revealed the potential role of abattoirs and livestock transporters as a reservoir and vectors of enteric pathogens. The results from this study highlight the importance of tightening biosecurity measures. For instance, implementing sanitary vacancy between animal batches and emphasizing washing, disinfection, and drying procedures on farms and for transportation vehicles, as well as giving limited access and circulation of vehicles throughout the production premises, are some examples of measures that should be applied properly. The results also emphasize the need to closely monitor the dynamics of enteric contamination in the swine industry in order to better understand and potentially prevent the spread of infectious diseases. This is especially relevant when a virulent and economically damaging agent is involved, as seen with the recent introduction of the porcine epidemic diarrhea virus in the country.

Colistin in Pig Production: Chemistry, Mechanism of Antibacterial Action, Microbial Resistance Emergence, and One Health Perspectives.

Colistin (Polymyxin E) is one of the few cationic antimicrobial peptides commercialized in both human and veterinary medicine. For several years now, colistin has been considered the last line of defense against infections caused by multidrug-resistant Gram-negative such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Colistin has been extensively used orally since the 1960s in food animals and particularly in swine for the control of Enterobacteriaceae infections. However, with the recent discovery of plasmid-mediated colistin resistance encoded by the mcr-1 gene and the higher prevalence of samples harboring this gene in animal isolates compared to other origins, livestock has been singled out as the principal reservoir for colistin resistance amplification and spread. Co-localization of the mcr-1 gene and Extended-Spectrum-ß-Lactamase genes on a unique plasmid has been also identified in many isolates from animal origin. The use of colistin in pigs as a growth promoter and for prophylaxis purposes should be banned, and the implantation of sustainable measures in pig farms for microbial infection prevention should be actively encouraged and financed. The scientific research should be encouraged in swine medicine to generate data helping to reduce the exacerbation of colistin resistance in pigs and in manure. The establishment of guidelines ensuring a judicious therapeutic use of colistin in pigs, in countries where this drug is approved, is of crucial importance. The implementation of a microbiological withdrawal period that could reduce the potential contamination of consumers with colistin resistant bacteria of porcine origin should be encouraged. Moreover, the management of colistin resistance at the human-pig-environment interface requires the urgent use of the One Health approach for effective control and prevention. This approach needs the collaborative effort of multiple disciplines and close cooperation between physicians, veterinarians, and other scientific health and environmental professionals. This review is an update on the chemistry of colistin, its applications and antibacterial mechanism of action, and on Enterobacteriaceae resistance to colistin in pigs. We also detail and discuss the One Health approach and propose guidelines for colistin resistance management.

Detection and Phylogenetic Analysis of the Hepatitis E Virus in a Canadian Swine Production Network.

Viral contamination along the production chain is a significant concern in both food safety and livestock health. Pigs have been reported to act as a reservoir for zoonotic viruses, sometimes emerging ones, and epidemiological studies have shown direct links between the consumption of uncooked pork offal and cases of hepatitis caused by the hepatitis E virus (HEV) genotype 3 in humans. The presence of HEV in swine herds has been reported, but its dissemination in pork production environments is still unknown. To investigate viral contamination sources in the swine industry, 452 environment and fecal samples, including samples from livestock transportation vehicles, were collected over a period of 11 months from ten farms and one slaughterhouse that together represent a single production network. Hepatitis E virus RNA was detected by nested RT-PCR in 32 samples from both inside and outside farm buildings, on trucks, and, mostly, from fomites collected in the slaughterhouse yard, such as on a utility vehicle. Phylogenetic analysis showed a wide diversity of HEV genotype 3 strains, similar to human and swine strains previously found. According to the results of this study, the movements of trucks and utility vehicles might play an important role in HEV dissemination on a slaughterhouse site and throughout an entire network.