Pork Production Chain Research Articles

Distribution, antimicrobial resistance and genomic characterization of Salmonella along the pork production chain in Jiangsu, China

Salmonella is an important foodborne pathogen that is widely distributed in foods of animal origin. Salmonella strains (n = 246) were identified from 1178 pork samples collected in Jiangsu, China. The most predominant Salmonella serovars in pork and slaughterhouse environment were S. London (49.13%, 85/173) and S. Rissen (53.42%, 39/73), respectively. A total of 13 STs were detected with ST469 dominant (33.33%, 82/246) in these isolates. Most strains were resistant to multiple drugs such as aminoglycosides (88.21%, 217/246), tetracycline (90.24%, 222/246) and florfenicol (91.87%, 226/246). Multiple antimicrobial resistance genes were identified, including that conferring resistance to aminoglycosides (strA, 64/246; strB, 60/246), β-lactam (blaTEM-1, 177/246), phenicols (floR, 115/246) and tetracyclines [tet(A), 216/246; tet(B), 13/246; tet(M), 51/246]. Notably, a novel IncFII(pCoo) blaNDM-1-positive plasmid was characterized. It is worth mentioning that this blaNDM-1-positive Salmonella could be successfully transferred into other Enterobacteriaceae. In addition, phylogenetic analysis indicated a high similarity between blaNDM-1-positive YT2-4-4 and blaNDM-1-positive Salmonella from human sources. To the best of our knowledge, blaNDM-1-carrying Salmonella of pig slaughterhouse origin was first detected. In the present study, we elaborated the distribution, drug resistance, as well as genomic characteristics of Salmonella in the pork production chain, providing valuable baseline data for food safety risk assessment.

Characterization of blaNDM-positive Enterobacteriaceae reveals the clonal dissemination of Enterobacter hormaechei coharboring blaNDM and tet(X4) along the pork production chain

The convergence of blaNDM and tet(X4) in a single strain has been sporadically detected in diverse pathogens from different sources, causing widespread concerns. However, the genomic characterization of blaNDM-positive or blaNDM- and tet(X4)-coharboring Enterobacteriaceae in the pork production chain, as well as how they emerged, remains mostly unclear. In this study, forty blaNDM-positive Enterobacteriaceae, including eleven tet(X4)- and blaNDM-coharboring isolates, were isolated from a pig slaughterhouse and a retail pork market in Yangzhou, China. This is the first report presenting the coexistence of blaNDM and tet(X4) in Enterobacter hormaechei, and it was demonstrated that they could spread clonally from the slaughterhouse to the retail market. Furthermore, we also discovered that the slaughterhouse served as a possible reservoir for blaNDM-positive ST48 E. coli strains. The blaNDM-bearing IncX3 plasmid was found in twenty blaNDM-positive strains as well as all blaNDM-5- and tet(X4)-coharboring strains, and most of them (30/31) were conjugative. In Klebsiella aerogenes NTT31XS, blaNDM was found on a nonconjugative ~17 kb IncX3 plasmid. When compared to the typical IncX3 plasmid, it deleted large-scale regions, which might imply a low fitness cost dissemination strategy for the IncX3 plasmid. Despite being from different species, tet(X4)-bearing plasmids carried by all blaNDM-5- and tet(X4)-coharboring strains were nonconjugative and had identical architectures. Phylogenetic analysis suggested that the formation of K. aerogenes NTT31XS may have been mediated by translocation of tet(X4)-positive circular intermediates and recombination events of regions in typical blaNDM-bearing IncX3 plasmids. Overall, this study expounded the prevalence and transmission characteristics of blaNDM-positive Enterobacteriaceae strains in the two links of pork production chain before they were exposed to humans, and expanded our knowledge of the molecular features and evolutionary history of tet(X4)- and blaNDM-5-coharboring strains. Strict control measures should be implemented to prevent the spread of such pathogens along food production chains.

86 Reaching Genetic Potential in Pigs: 10 Disruptive Digital Technologies

Abstract Consumer (‘prosumer’) concerns over animal welfare and the environmental footprint of pork production dominate the media. Indeed, the discussion of alternatives to pork, both from the continued global growth in chicken consumption and advances in cellular meat production and vegetable protein alternatives, represent real threats to pork’s future. Producers and processors continue to focus genetic improvement, nutrition, and management to improve meat production efficiency. Disease mitigation and animal health limit our ability to reach the pigs genetic potential, either in terms of pigs processed per sow, or breaching the 2:1 lifetime feed conversion. Can farmers continue to gain more pigs per sow, while keeping them healthy and alive? How do we maximize meat yield per carcass without losing flavor and the consumer experience? Are there limits to how low we can go in the conversion of nutrients into feed? Despite increased consumer demands and the continued need to improve production efficiency, the management of pigs has changed little in the last decades, often relying on decades old innovations and enhanced biosecurity. Innovations such as vertical hog farms in China, muti site production, and new feed technologies offer incremental but not disruptive improvements. The 10 digital technologies (PWC) is a useful framework to review the technologies with the potential to transform swine production. These are 3D Printing, Internet of Things, Artificial Intelligence, Data Analytics, Cloud Computing, Robotics, Drones, Blockchain, Virtual Reality and Augmented Reality (‘Metaverse’). Concepts such as precision nutrition, precision management recognize the need for better data, and data underpins advances such as nutrigenomics, microbiota and the environment of the pig. Digital technologies can disrupt pork production while offering the opportunity to respond to consumers, legislators, producer demands and other actors within the pork production chain.

Exploring the resistome, virulome, mobilome and microbiome along pork production chain using metagenomics

In order to understand and minimize microbial contaminants spread from animal to raw pork products, we explored the diversity of antibiotic resistance genes (ARGs), virulence factors (VFs), mobile genetic elements (MGEs) and the bacterial community composition in feces of pigs, processing areas as well as the end pork products in a large-scale pig slaughterhouse in China using metagenomics. The abundance and diversity of microbial community was higher in arrival and slaughtering room area and decreased sharply in the end pork products. Furthermore, the relative abundance of some clinically relevant pathogens and opportunity pathogens were greater in the end pork products and cutter samples. We identified 1412 subtypes of ARGs related to 30 antibiotic classes, in which ARGs related to multidrug resistance and β-lactamase were dominant. Resistance determinants to clinically critical important antibiotics, including sequences related to mcr, optrA, poxtA, tetX and β-lactamase genes (i.e. blaOXA, blaVIM, blaIMP, blaGES, blaNDM, blaKPC and blaSME) were detected. More than 42 general virulence features, mainly adherence, secretion system, iron uptake, toxin, antiphagocytosis and immune evasion, were identified. A total of 1922 types of MGEs, mainly plasmids were observed. Most of the ARGs are predicted to be associated with MGEs. The prevalence of ARGs, VFs and MGEs decreased over subsequential processing steps. Most of the remaining ARGs, VFs and MGEs in end pork products were also present on other samples, indicating the flow of these genes through the production line. These results broaden our understanding of the global ARGs, VFs and MGEs diversity along the pork production chain, with the suggestion of implementing improved control measures to reduce the risk of spread of pathogenic bacteria and their associated resistome, virulome and mobilome from animal to the food chain and the surrounding environment.

Profiles of Non-aureus Staphylococci in Retail Pork and Slaughterhouse Carcasses: Prevalence, Antimicrobial Resistance, and Genetic Determinant of Fusidic Acid Resistance.

As commensal colonizers in livestock, there has been little attention on staphylococci, especially non-aureus staphylococci (NAS), contaminating meat production chain. To assess prevalence of staphylococci in retail pork and slaughterhouse carcass samples in Korea, we collected 578 samples from Korean slaughterhouses (n=311) and retail markets (n=267) for isolation of staphylococci and determined antimicrobial resistance phenotypes in all the isolates. The presence of and prevalence of fusB-family genes (fusB, fusC, fusD, and fusF) and mutations in fusA genes were examined in fusidic acid resistant isolates. A total of 47 staphylococcal isolates of 4 different species (Staphylococcus aureus, n=4; S. hyicus, n=1; S. epidermidis, n=10; Mammaliicoccus sciuri, n=32) were isolated. Fusidic acid resistance were confirmed in 9/10 S. epidermidis and all of the 32 M. sciuri (previously S. sciuri) isolates. Acquired fusidic acid resistance genes were detected in all the resistant strains; fusB and fusC in S. epidermidis and fusB/C in M. sciuri. Multi-locus sequence type analysis revealed that ST63 (n=10, 31%) and ST30 (n=8, 25%) genotypes were most prevalent among fusidic acid resistant M. sciuri isolates. In conclusion, the high prevalence of fusB-family genes in S. epidermidis and M. sciuri strains isolated from pork indicated that NAS might act as a reservoir for fusidic acid resistance gene transmissions in pork production chains.

Distribution and Characteristics of Listeria spp. in Pigs and Pork Production Chains in Germany.

Listeria (L.) monocytogenes is a foodborne pathogen that can cause disease, mainly in elderly, pregnant or immunocompromised persons through consumption of contaminated food, including pork products. It is widespread in the environment and can also be found in asymptomatic carrier animals, for example, in different tissues of pigs. To learn more about their nature, 16 Listeria spp. isolates found in tonsils and intestinal content of pigs and 13 isolates from the slaughterhouse environment were characterized using next-generation sequencing (NGS). A wide distribution of clonal complexes was observed in pigs, as well as in the pork production chain, suggesting multiple sources of entry. Hypervirulent clones were found in pig tonsils, showing the potential risk of pigs as source of isolates causing human disease. The presence of closely related isolates along the production chain suggests a cross-contamination in the slaughterhouse or recontamination from the same source, strengthening the importance of efficient cleaning and disinfection procedures. The phenotypical antimicrobial resistance status of L. monocytogenes isolates was examined via broth microdilution and revealed a low resistance level. Nevertheless, genotypical resistance data suggested multiple resistances in some non-pathogenic L. innocua isolates from pig samples, which might pose a risk of spreading resistances to pathogenic species.

Whole-genome sequencing analysis reveals pig as the main reservoir for persistent evolution of Salmonella enterica serovar Rissen causing human salmonellosis

Salmonella enterica serovar Rissen is recognized as one of the most common serotypes in pigs and pig products in many countries and can be transmitted to human through the consumption of contaminated food. To reveal the genetic characteristics of S. Rissen, 39 isolates from human and animal food were subjected to whole-genome sequencing analysis combined with 337 genome sequences downloaded from the NCBI Assembly database. Core genome single nucleotide polymorphism (cgSNP) divided these S. Rissen isolates into two clusters, of which cluster A included 78.3% of American isolates, while cluster B was mainly composed of isolates from China, Asia, and the UK. The 39 S. Rissen isolates located in cluster B were further divided into two subclusters with cluster B-1 of 26 isolates from both humans and food, while cluster B-2 consisted of 13 isolates from animal food, mainly pork. CRISPR typing and cgMLST of the 39 isolates showed perfect correspondence to cgSNP results of their phylogenetic relationship. Virulence factors analysis revealed that ABZJ_0085 and ABZJ_0086 genes presenting in cluster B-2 were lost in cluster B-1. Additionally, antimicrobial resistance gene profiles showed qnrS1, cmlA1, and tet(M) could be detected in cluster B-2 other than cluster B-1. The findings of the divergent difference between cluster B-1 and cluster B-2 demonstrated that S. Rissen was continuously evolved through the pork production chain. In conclusion, pigs are the main reservoir for S. Rissen capable of causing human nontyphoid salmonellosis.

Characterization of the transfer probability of Salmonella ser. Typhimurium between pork and a cutting knife in an experimental model

Cross-contamination is an important event for bacterial transfer throughout the pork production chain. In Brazil, Salmonella sp. is the most relevant hazard in the pork industry, and further knowledge concerning its contamination is essential for in-depth risk assessments. Thus, we aimed to assess the transfer probability of Salmonella sp. between a knife and pork in a domestic kitchen scenario to provide parametrization for incorporating transfer of Salmonella sp. in risk assessment models. To estimate Salmonella Typhimuium transfer rates between contaminated pork and a knife blade during cutting, 23 independent experiments were performed. A Bayesian inference was utilized to determine the transfer probability, capturing the uncertainty generated in the transfer probability experiments. The mean transfer probability was 0.03 for knife to pork [0.029; 0.032] 95% credible interval (CrI) and 0.0042 for pork to knife [0.0041; 0.0043] 95% CrI. The probabilistic estimate of the transfer probability of Salmonella sp. during pork cutting gives insights on a relevant parameter for the consumer phase of the pork production industry in Brazil, allowing for enhanced risk assessment models.

Tracing enterococci persistence along a pork production chain from feed to food in China.

The prevalence and transmission of vancomycin-resistant Enterococcus (VRE) in enterococci being as probiotics has been neglected in the scientific literature. The application of enterococci in feed, food and health products may cause VRE transmission through the food chain. This study evaluated phenotypic resistance of Enterococcus species to 20 antibiotics along a pork production chain from feed to food. It also assessed the genetic diversity of Enterococcus faecium isolates. A total of 510 samples (feed, n = 70; swine manure, n = 400; swine carcasses, n = 20, and retail pork, n = 20) were collected in Beijing, China. A total of 328 enterococci isolates with 275 E. faecium and 53 Enterococcus faecalis were identified using 16 S rRNA. Antimicrobial susceptibility to all enterococci isolates was conducted using the K–B method for 20 antibiotics from 9 categories. Multilocus sequence typing (MLST) was conducted on the E. faecium isolates to survey the dissemination of enterococci in the pig industry. The results showed that only 26 enterococci isolates were sensitive to the 20 antibiotics, while half of the isolates (164/328) had acquired multi-drug resistance. The resistant rate to furazolidone was 68.60%, followed by 42.99% to tetracycline. One vancomycin-resistant E. faecium isolates were isolated from feed origin and 2 from manure origin, with minimum inhibitory concentrations to vancomycin of 1,024, 64, and 64 μg/mL, respectively. The MLST outcomes showed that the 275 E. faecium isolates belonged to 11 sequence types (ST) including ST40, ST60, ST94, ST160, ST178, ST296, ST361, ST695, ST726, ST812 and ST1014. The ST of the feed-sourced VRE was ST1014, while the 2 manure-sourced VRE was ST69. ST1014 evolved from ST78, which was the dominant clonal complex in most cities of China, leading to the spreading of VRE. These findings revealed the potential safety hazards of commercial probiotic enterococci in China and showed that there is a risk of the VRE horizontally transferring from feed to food.

Comparative genomics and antibiotic resistance of Yersinia enterocolitica obtained from a pork production chain and human clinical cases in Brazil

Previous work found a high similarity of macro-restriction patterns for isolates of Yersinia enterocolitica 4/O:3 obtained at a pork production chain from Minas Gerais, Brazil. Herein we aimed to determine the clonality and the antibiotic resistance profiles of a subset of these isolates (n = 23) and human clinical isolates (n = 3). Analysis based on whole genome sequencing (WGS) showed that the isolates were distributed into two major clades based on single nucleotide polymorphisms (SNP) with one isolate defining Clade A (isolate R31) and remaining isolates (n = 25, 96.2%) defining Clade B. Seven clonal groups were identified. The inclusion of isolate R31 as a distinct clonal group was due to the presence of several phage-related genes, allowing its characterization as serotype O:5 by WGS. Disk-diffusion assays (14 antibiotics) identified 13 multidrug resistant isolates (50.0%). Subsequent sequence analysis identified 17 different antibiotic resistance related genes. All isolates harbored blaA (y56 beta-lactamase), vatF, rosA, rosB and crp, while nine isolates harbored a high diversity of antibiotic resistance related genes (n = 13). The close genetic relationship among Y. enterocolitica obtained from a pork production chain and human clinical isolates in Brazil was confirmed, and we can highlight the role of swine in the potential transmission of an antibiotic-resistant clones of a pathogenic bio-serotype to humans, or the transmission of these resistant bacteria from people to animals. The role of veterinary antibiotic use in this process is unclear.

Phylogenetic Analysis and Genome-Wide Association Study Applied to an Italian Listeria monocytogenes Outbreak.

From May 2015 to March 2016, a severe outbreak due to Listeria monocytogenes ST7 strain occurred in Central Italy and caused 24 confirmed clinical cases. The epidemic strain was deeply investigated using whole-genome sequencing (WGS) analysis. In the interested area, the foodborne outbreak investigation identified a meat food-producing plant contaminated by the outbreak strain, carried by pork-ready-to-eat products. In the same region, in March 2018, the epidemic strain reemerged causing one listeriosis case in a 10-month-old child. The aim of this study was to investigate the phylogeny of the epidemic and reemergent strains over time and to compare them with a closer ST7 clone, detected during the outbreak and with different pulsed-field gel electrophoresis (PFGE) profiles, in order to identify genomic features linked to the persistence and the reemergence of the outbreak. An approach combining phylogenetic analysis and genome-wide association study (GWAS) revealed that the epidemic and reemergent clones were genetically closer to the ST7 clone with different PFGE profiles and strictly associated with the pork production chain. The repeated detection of both clones was probably correlated with (i) the presence of truly persistent clones and the repeated introduction of new ones and (ii) the contribution of prophage genes in promoting the persistence of the epidemic clones. Despite that no significant genomic differences were detected between the outbreak and the reemergent strain, the two related clones detected during the outbreak can be differentiated by transcriptional factor and phage genes associated with the phage LP-114.

Dissection of Highly Prevalent qnrS1-Carrying IncX Plasmid Types in Commensal Escherichia coli from German Food and Livestock.

Plasmids are mobile genetic elements, contributing to the spread of resistance determinants by horizontal gene transfer. Plasmid-mediated quinolone resistances (PMQRs) are important determinants able to decrease the antimicrobial susceptibility of bacteria against fluoroquinolones and quinolones. The PMQR gene qnrS1, especially, is broadly present in the livestock and food sector. Thus, it is of interest to understand the characteristics of plasmids able to carry and disseminate this determinant and therewith contribute to the resistance development against this class of high-priority, critically important antimicrobials. Therefore, we investigated all commensal Escherichia (E.) coli isolates, with reduced susceptibility to quinolones, recovered during the annual zoonosis monitoring 2017 in the pork and beef production chain in Germany (n = 2799). Through short-read whole-genome sequencing and bioinformatics analysis, the composition of the plasmids and factors involved in their occurrence were determined. We analysed the presence and structures of predominant plasmids carrying the PMQR qnrS1. This gene was most frequently located on IncX plasmids. Although the E. coli harbouring these IncX plasmids were highly diverse in their sequence types as well as their phenotypic resistance profiles, the IncX plasmids-carrying the qnrS1 gene were rather conserved. Thus, we only detected three distinct IncX plasmids carrying qnrS1 in the investigated isolates. The IncX plasmids were assigned either to IncX1 or to IncX3. All qnrS1-carrying IncX plasmids further harboured a β-lactamase gene (bla). In addition, all investigated IncX plasmids were transmissible. Overall, we found highly heterogenic E. coli harbouring conserved IncX plasmids as vehicles for the most prevalent qnr gene qnrS1. These IncX plasmids may play an important role in the dissemination of those two resistance determinants and their presence, transfer and co-selection properties require a deeper understanding for a thorough risk assessment.

Pork safety – challenges and opportunities

As pork and pork products represent an important part of the diet, the issue of pork safety and quality has become more prominent. Food safety concerns are shaping consumers’ attitudes toward safe food. The farm and meat sectors aim at producing healthy animals in a protected environment, which is a key point for food/meat safety. The most common biological hazards in the pork production chain are Salmonella spp., Yersinia enterocolitica, Trichinella spp. and Toxoplasma gondii. These hazards are not detectable by conventional meat inspection, and measures rely on prevention or reduction of contamination along the production chain.

Pathogenic potential and antibiotic resistance of Yersinia enterocolitica, a foodborne pathogen limited to swine tonsils in a pork production chain from Southern Brazil.

In this study, we aimed to characterize the distribution of Yersinia enterocolitica in a pork production chain in Brazil, as well as the virulence profile and antibiotic resistance of the obtained isolates. Samples from 10 pig lots obtained from finishing farms (water, feed, and barn floors, n = 30), slaughterhouse (lairage floors, carcasses at four processing steps, tonsils, and mesenteric lymph nodes, n = 610), and processing (end cuts, processing environment, n = 160) were obtained in Paraná state, Brazil, and subjected to Y. enterocolitica detection by ISO 10,273. The obtained isolates were identified based on biochemical and molecular features (16s rRNA, inv, bioserotyping) and subjected to PCR assays to detect virulence (ail, ystA, ystB, virF, myfA, fepA, fepD, fes, tccC, ymoA, hreP, and sat) and multidrug resistance-related genes (emrD, yfhD, and marC). Also, isolates were subjected to disk diffusion test to characterize their resistance against 17 antibiotics from 11 classes and to pulsed field gel electrophoresis (PFGE) after XbaI macro-restriction. Y. enterocolitica was detected in a single sample (tonsil), and the obtained three isolates were characterized as serotype O:3, harboring ail, ystA, virF, myfA, tccC, ymoA, hreP, emrD, yfhD, and marC, and resistant to all tested antibiotics. The three isolates presented identical macro-restriction profiles by PFGE, also identical to isolates obtained from Minas Gerais, other Brazilian state; one selected isolate was identified as biotype 4. Despite the low occurrence of Y. enterocolitica in the studied pork production, the virulence potential and the antibiotic resistance profiles of the isolates demonstrated their pathogenic potential, and the macro-restriction profiles indicate strains descending from a common subtype in the pork production chain of two Brazilian States.

Prevalence and Characteristics of Salmonella spp. from a Pig Farm in Shanghai, China.

Salmonella spp. is a major foodborne pathogen that is distributed among most pork production chains worldwide. This study aimed to investigate the dynamic changes in Salmonella spp. along the pig breeding process monthly from April 2018 to March 2019 in a pig farm in Shanghai, China, and identify the potential critical control points during the production. In total, 239 Salmonella spp. isolates were obtained from 1389 samples, in which Salmonella were detected from 26.3% (222/843) of fecal samples, 7.1% (17/240) of feed samples, and 0.0% (0/306) of both water and insect samples. Seven different serotypes were identified, with the predominant serotype being Salmonella Derby (21.8%), followed by Salmonella Typhimurium (18.8%), Salmonella Rissen (16.3%), Salmonella Mbandaka (12.6%), and Salmonella 1,4,[5],12:i:- (11.8%). Most probable number (MPN) analysis revealed that the load of Salmonella spp. gradually increased along the pig production chain, while the highest number of Salmonella spp. isolates was at the fattening stage (MPN value, 11-15 MPN/g). The pulsed-field gel electrophoresis showed that both Salmonella Typhimurium and Salmonella Derby isolates were grouped to six clusters. The antimicrobial resistance analyzed demonstrated that 80.0% of the isolates were of multidrug resistance and resistant to sulfamethoxazole (84.5%), lincomycin (89.4%), ampicillin (96.9%), oxytetracycline (93.8%), and tetracycline (95.1%). We further evaluated the Salmonella spp. Resistance to quaternary ammonium compounds (QACs) showed an increasing trend along with the testing period indicating that the use of QACs could induce the resistance of Salmonella spp. to QACs. Our study confirmed the dynamic changes in Salmonella spp. over time and space in this pig farm and identified feed and the fattening house as the key points for the prevention and control of Salmonella spp. contamination.

Prevalence and Antimicrobial Resistance of Salmonella and Staphylococcus aureus in Fattening Pigs in Hubei Province, China.

Pig is usually the carrier of Salmonella and Staphylococcus aureus, and can transmit the bacteria along the pork production chain to cause severe public health problems. In this study, we investigated the prevalence of Salmonella and S. aureus in fattening pigs in Hubei Province, China. The overall prevalence of Salmonella in rectal swab among 896 samples from 22 farms was 17.30%, and that of S. aureus in nasal swab among 814 samples from 20 farms was 28.26%. Antimicrobial resistance (AMR) analysis showed that 95.33% of the Salmonella strains exhibited resistance to more than three classes of antimicrobial agents tested. The highest resistance proportions were for chloramphenicol (100%), sulfamethoxazole/trimethoprim (SXT) (100%), and tetracycline (TET) (93.46%), while the lowest proportions were for cefotaxime (37.38%), gentamicin (GEN) (34.58%), and ciprofloxacin (24.30%). On the other hand, 98.42% of the S. aureus strains were resistant to more than three classes of antimicrobial agents tested. The most common resistance among the S. aureus strains was against SXT (100.00%), followed by TET (98.43%), erythromycin (91.34%), and clindamycin (91.34%), while the lowest frequent resistances were against GEN (34.65%) and oxacillin (16.54%). The prevalence and AMR of Salmonella and S. aureus exhibited an obvious diversity among different pig farms. Our results provided the epidemiological data for risk analysis of foodborne bacteria and AMR in pig farms.

Antimicrobial resistance genes and class 1 integrons in MDR Salmonella strains isolated from swine lymph nodes

Food safety is essential to the development of a society, and foodborne diseases affect thousands of people worldwide every year. Among the main foodborne disease agents, Salmonella stands out as the most often associated with hospitalizations and deaths. Pork products are an important source of nutrients for the population, considered the most consumed meat in the world. Several reports revealed the presence of Multidrug-Resistant (MDR) Salmonella strains along the pork production chain, and the occurrence of elements that allow for the transference of resistance genes between bacterial populations is a public health concern. The present work aimed to evaluate the resistance genes and integrons in MDR Salmonella strains isolated from swine mesenteric lymph nodes. Nine strains had the genome sequenced with the Illumina NextSeq system. The results were submitted to the Resfinder server for evaluation of acquired genes and point mutations related to AMR and the presence and sequences of integrons were determined with a BLAST search. Different resistance genes for the same antimicrobial class were present in each strain. In two samples, resistance genes for olaquindox, a growth promoter outlawed in Brazil since 2004, were found. All observed phenotypic resistance had a genetic basis. Five isolates harbored class 1 integrons, which were classified in three distinct Integron Profiles (IPs). The IPs were also reported in animal source food and human clinical isolates. The diversity of resistance genes for the same antimicrobial class in each strain and the presence of Class 1 Integrons, reflect the high selection pressure that these bacterial lineages face along the pork production chain, and reinforces the role of animal production as a reservoir and disseminator of AMR genes.

Evidence for the Dissemination to Humans of Methicillin-Resistant Staphylococcus aureus ST398 through the Pork Production Chain: A Study in a Portuguese Slaughterhouse.

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) ST398 was recovered from infections in humans exposed to animals, raising public health concerns. However, contact with food producing chain as a means of transmission of LA-MRSA to humans remains poorly understood. We aimed to assess if pork production chain is a source of MRSA ST398 for human colonization and infection. MRSA from live pigs, meat, the environment, and slaughterhouse workers were analyzed by Pulsed-Field Gel Electrophoresis (PFGE), spa, MLST typing, SNPs and for antibiotic resistance and virulence gene profiles. We compared core and accessory genomes of MRSA ST398 isolated from slaughterhouse and hospital. We detected MRSA ST398 (t011, t108, t1451) along the entire pork production chain (live pigs: 60%; equipment: 38%; meat: 23%) and in workers (40%). All MRSA ST398 were multidrug resistant, and the majority carried genes encoding biocide resistance and enterotoxins. We found 23 cross-transmission events between live pigs, meat, and workers (6–55 SNPs). MRSA ST398 from infection and slaughterhouse environment belonged to the same clonal type (ST398, t011, SCCmec V), but differed in 321–378 SNPs. Pork production chain can be a source of MRSA ST398 for colonization of human slaughterhouse workers, which can represent a risk of subsequent meat contamination and human infection.

Effect of different cleaning procedures on water use and bacterial levels in weaner pig pens.

Pork is one of the most globally eaten meats and the pig production chain contributes significantly to the water footprint of livestock production. However, very little knowledge is available about the on-farm factors that influence freshwater use in the pig production chain. An experiment was conducted to quantify the effect of three different washing treatments on freshwater use, bacterial levels [(total bacterial counts; TBC), Enterobacteriaceae and Staphylococcus] and cleaning time in washing of pens for weaning pigs. Three weaner rooms were selected with each room having 10 pens and a capacity to hold up to 14 pigs each. Pigs were weaned and kept in the pens for 7 weeks. Finally, the pens were cleaned before the next batch of pigs moved in. The washing treatments used were power washing and disinfection (WASH); presoaking followed by power washing and disinfection (SOAK), and presoaking followed by detergent, power washing and disinfection (SOAK + DETER). A water meter was used to collect water use data and swab samples were taken to determine the bacterial levels. The results showed that there was no overall effect of washing treatments on water use. However, there was an effect of treatment on the washing time (p<0.01) with SOAK and SOAK+DETER reducing the washing time per pen by 2.3 minutes (14%) and 4.2 minutes (27%) compared to WASH. Nonetheless, there was an effect of sampling time (before or after washing) (p<0.001) on the levels of TBC and Staphylococcus, but no effect was seen on Enterobacteriaceae levels. Thus, the washing treatments used in this study had no effect on the water use of the pork production chain. Although there was no difference in both water use and bacterial load, from a producer perspective, presoaking and detergent use can save time and labour costs, so this would be the preferred option.

Persistence of Yersinia enterocolitica bio-serotype 4/O:3 in a pork production chain in Minas Gerais, Brazil

Yersinia enterocolitica bio-serotype 4/O:3 was previously identified in a pork production chain in Brazil and the obtained isolates presented high identity by pulsed-field gel electrophoresis (PFGE, XbaI). For the current study, an additional 147 porcine samples (tonsils = 100, palate = 30, head meat = 17) were collected from the same pork production chain 2-years later and 14 (9.5%) tested positive for Y. enterocolitica. Isolates (n = 24, 1 to 2 per positive sample) were bio-serotype 4/O:3 and harbored virulence genes ail, inv, wbbU, virF, myfA, ystA, ymoA, hreP and sat, and the multidrug resistance related genes emrD, marC and yfhD. PFGE (XbaI) demonstrated no differences among isolates (100% similarity) and were identical to some Y. enterocolitica isolates (n = 13) obtained previously from the same pork chain. A second PFGE analysis (NotI) confirmed the high degree of similarity among isolates obtained over time, demonstrating the persistence of an apparent clonal Y. enterocolitica bio-serotype 4/O:3 in this particular pork production chain in Brazil.