The optimisation of Salmonella surveillance programmes for pullet and layer farms using local farm density as a risk factor.

Human salmonellosis cases are often caused by Salmonella serovars Enteritidis and Typhimurium and associated with the consumption of eggs and egg products. Many countries therefore implemented general surveillance programmes on pullet and layer farms. The identification of risk factors for Salmonella infection may be used to improve the performance of these surveillance programmes. The aims of this study were therefore to determine 1) whether local farm density is a risk factor for the infection of pullet and layer farms by Salmonella Enteritidis and Typhimurium and 2) whether the sampling effort of surveillance programmes can be reduced by accounting for this risk factor, while still providing sufficient control of these serovars. We assessed the importance of local farm density as a risk factor by fitting transmission kernels to Israeli surveillance data during the period from June 2017 to April 2019. The analysis shows that the risk of infection by serovars Enteritidis and Typhimurium significantly increased if infected farms were present within a radius of approximately 4 km and 0.3 km, respectively. We subsequently optimized a surveillance programme that subdivided layer farms into low and high risk groups based on the local farm density with and allowed the sampling frequency to vary between these groups. In this design, the pullet farms were always sampled one week prior to pullet distribution. Our analysis shows that the risk-based surveillance programme is able to keep the between-farm R0 of serovars Enteritidis and Typhimurium below 1 for all pullet and layer farms, while reducing the sampling effort by 32% compared to the currently implemented surveillance programme in Israel. The results of our study therefore indicate that local farm density is an important risk factor for infection of pullet and layer farms by Salmonella Enteritidis and Typhimurium and can be used to improve the performance of surveillance programmes.

Prevalence and characterization of non-typhoidal Salmonella in egg from grading and packing plants in Korea.

Egg washing guidelines vary across countries; however, since 2020, Korea has required that all eggs produced from farms with more than 10,000 laying hens must be washed through egg grading and packing (GP) plant. This study investigated the prevalence and characterization of non-typhoidal Salmonella in eggs after washing at GP plants. In total, 16,800 eggs were collected from 60 egg GP plants located inside commercial layer farms, and 840 pooled eggshell and egg contents were tested for Salmonella, respectively. Of the 60 GP plants tested, 11 (18.3%) and 12 (20.0%) plants were positive for Salmonella spp. In the eggshells and egg contents, respectively. In particular, High Salmonella prevalence in the eggshells and egg contents occurred most often in farms with laying hens older than 80 weeks (33.3% and 40.0%, respectively). However, among 840 pooled eggshells and egg content samples, only 19 (2.3%) of each sample type were positive only for non-typhoidal Salmonella spp. The most common Salmonella serovar in both eggshells and egg contents was S. Infantis, which was found in five (8.3%) of 60 GP plants for both samples types. The other Salmonella serovars detected in eggshells were S. Bareilly (5.0%), S. Agona (3.3%), S. Enteritidis (1.7%), and S. Montevideo (1.7%), whereas those detected in egg contents were S. Enteritidis (5.0%), S. Agona (3.3%), S. Newport (3.3%), S. Senftenberg (3.3%), and S. Derby (1.7%). Of the 19 virulence genes tested, 14 genes were detected in all Salmonella. Interestingly, the spvB gene was detected only in S. Enteritidis, and the sefC gene was detected only in S. Enteritidis and S. Senftenberg. Moreover, all S. Infantis isolates showed multidrug resistance (MDR) against five or more classes, and the other serovars only showed MDR against three to four classes or no MDR. These results suggest that comprehensive surveillance and advanced management approaches for egg GP plants are required to minimize egg contamination with non-typhoidal Salmonella.

Emergence of Salmonella Infantis carrying the pESI megaplasmid in commercial farms of five major integrated broiler operations in Korea.

Considering Salmonella transmission occurs through several routes in integrated broiler operations, control of nontyphoidal Salmonella in commercial farms is essential. This study aimed to compare the distribution of persistent Salmonella serovars in environments and dead chickens between 5 major integrated broiler operations in Korea. The prevalence of Salmonella-positive farms in dust prior to placement by operations was 0 to 25%, but the prevalence in dust and feces at the time of depletion was increased to 16.7 to 41.7% and 16.7 to 66.7%, respectively. Moreover, the prevalence of farms with Salmonella in chickens that died within 1 week old and at 4 to 5 weeks old ranged from 8.3 to 58.3% and 16.7 to 41.7%, respectively. The prevalence of Salmonella enterica serovar Infantis-positive farms in dust prior to placement and in chickens that died within 1 week old was 5.2 and 3.4%, respectively, but the prevalence in dust and feces at the time of depletion and in chickens that died at 4 to 5 weeks old was significantly increased to 27.6, 41.4, and 20.7%, respectively (P < 0.05). Interestingly, the plasmid of emerging S. Infantis (pESI) was only identified in S. Infantis, and the prevalence of multidrug-resistance was significantly higher in pESI-positive S. Infantis (99.2%) than in pESI-negative S. Infantis (6.7%) (P < 0.05). The distribution of pulsotypes between pESI-positive and pESI-negative S. Infantis were varied, but a majority of S. Infantis were clustered only 2 pulsotypes. Moreover, pESI-positive S. Infantis harbored more virulence factors than pESI-negative S. Infantis. This study is the first report on characteristics of S. Infantis carrying the pESI plasmid in commercial broiler farms in Korea.

Phenotypic and genetic characterization of antimicrobial resistance in Salmonella enterica serovar Choleraesuis isolates from humans and animals in Spain from 2006 to 2021.

OBJECTIVES: While an increase in the levels of MDR in Salmonella enterica sevorar Choleraesuis has been reported in Europe, little is known about the situation in Spain. Therefore, we first aimed to assess the phenotypic resistance profile and to determine the presence of genetic determinants of resistance of S. Choleraesuis isolates collected in animal and human. Our second objective was to identify and characterize clusters of highly related isolates. METHODS: We analysed 50 human and 45 animal isolates retrieved from 2006 to 2021 using the disc diffusion method and performed WGS followed by analyses of genetic determinants and phylogenetic analysis. RESULTS: All isolates were of ST145 and corresponded to the variant Kunzendorf. Swine isolates harboured a significantly higher number of antimicrobial resistance genes than human isolates, and often carried plasmid replicons of the IncHI2/IncHI2A type (42% of all animal isolates). In addition, we identified several MDR S. Choleraesuis strains circulating in humans and swine between 2006 and 2021. The phylogenetic analyses identified four clades associated with specific patterns of resistance genes and plasmid replicons. The clades also included isolates that differed in terms of year and region of isolation as well as host of origin. CONCLUSIONS: This One Health approach highlights that reducing human MDR S. Choleraesuis infections may require the adoption of strategies that not only seek to prevent cases in humans but also to characterize and reduce the infection burden in swine.

A Salmonella Pullorum outbreak with neurological signs in adult layers and outbreak investigation using whole genome sequencing.

RESEARCH HIGHLIGHTS: Cerebral granulomas are associated with nervous signs in Salmonella Pullorum outbreak.Bone marrow is also a recommended tissue for isolation of Salmonella Pullorum.Rapid plate agglutination test detects Pullorum antibodies in a vaccinated flock.Phylogenetic analysis showed clonality of isolates within the outbreak.

Antimicrobial resistance in multistate outbreaks of nontyphoidal Salmonella infections linked to animal contact-United States, 2015-2018.

Animal contact is an established risk factor for nontyphoidal Salmonella infections and outbreaks. During 2015-2018, the U.S. Centers for Disease Control and Prevention (CDC) and other U.S. public health laboratories began implementing whole-genome sequencing (WGS) of Salmonella isolates. WGS was used to supplement the traditional methods of pulsed-field gel electrophoresis for isolate subtyping, outbreak detection, and antimicrobial susceptibility testing (AST) for the detection of resistance. We characterized the epidemiology and antimicrobial resistance (AMR) of multistate salmonellosis outbreaks linked to animal contact during this time period. An isolate was considered resistant if AST yielded a resistant (or intermediate, for ciprofloxacin) interpretation to any antimicrobial tested by the CDC or if WGS showed a resistance determinant in its genome for one of these agents. We identified 31 outbreaks linked to contact with poultry (n = 23), reptiles (n = 6), dairy calves (n = 1), and guinea pigs (n = 1). Of the 26 outbreaks with resistance data available, we identified antimicrobial resistance in at least one isolate from 20 outbreaks (77%). Of 1,309 isolates with resistance information, 247 (19%) were resistant to ≥1 antimicrobial, and 134 (10%) were multidrug-resistant to antimicrobials from ≥3 antimicrobial classes. The use of resistance data predicted from WGS increased the number of isolates with resistance information available fivefold compared with AST, and 28 of 43 total resistance patterns were identified exclusively by WGS; concordance was high (>99%) for resistance determined by AST and WGS. The use of predicted resistance from WGS enhanced the characterization of the resistance profiles of outbreaks linked to animal contact by providing resistance information for more isolates.

Phenotypic and genotypic characterization of antibiotic-resistant Salmonella isolated from humans, aquaculture, and poultry in Sri Lanka: A retrospective study.

BACKGROUND: In Sri Lanka, foodborne diseases caused by nontyphoidal Salmonella are of increasing concern. We therefore aimed to characterize the dominant Salmonella serovars in humans, poultry, and aquaculture through a One Health approach. METHODS: We collected isolates from different sectors, confirmed their identities using PCR, screened their antibiotic resistance profiles, and determined their antibiotic resistance genes based on whole-genome sequencing. RESULTS: Of the 75 Salmonella isolates identified, the majority of serotypes were unidentified. Both Salmonella enterica serovar Enteritidis (S. Enteritidis) and Salmonella enterica serovar Typhimurium (S. Typhimurium) could be isolated from human sources and were also found prevalent in the poultry sector. ST36, ST11 and ST1541 were the dominant serotypes of S. Typhimurium and S. Enteritidis, respectively. Alarmingly, 4% (1/25) of poultry Salmonella isolates were resistant to ciprofloxacin, suggesting an emergence of this phenotype. Moreover, virulence genes were very diverse among S. Enteritidis and S. Typhimurium isolates. CONCLUSIONS: With the diversity of unidentified serotypes found and the detection of emerging resistances, our study highlights the importance of a One Health approach to monitoring antibiotic resistance. For public health initiatives in Sri Lanka to be successful in mitigating salmonellosis, all three sectors - humans, aquaculture, and poultry - must be tackled concomitantly in a coordinated manner under the One Health approach because antibiotic resistance genes, and even specific sequence types, may be able to spread across the aforementioned sectors. We anticipate that our results will inform public health policies in Sri Lanka to tackle foodborne illnesses.

The advantage of intergenic regions as genomic features for machine-learning-based host attribution of Salmonella Typhimurium from the USA.

Salmonella enterica is a taxonomically diverse pathogen with over 2600 serovars associated with a wide variety of animal hosts including humans, other mammals, birds and reptiles. Some serovars are host-specific or host-restricted and cause disease in distinct host species, while others, such as serovar S. Typhimurium (STm), are generalists and have the potential to colonize a wide variety of species. However, even within generalist serovars such as STm it is becoming clear that pathovariants exist that differ in tropism and virulence. Identifying the genetic factors underlying host specificity is complex, but the availability of thousands of genome sequences and advances in machine learning have made it possible to build specific host prediction models to aid outbreak control and predict the human pathogenic potential of isolates from animals and other reservoirs. We have advanced this area by building host-association prediction models trained on a wide range of genomic features and compared them with predictions based on nearest-neighbour phylogeny. SNPs, protein variants (PVs), antimicrobial resistance (AMR) profiles and intergenic regions (IGRs) were extracted from 3883 high-quality STm assemblies collected from humans, swine, bovine and poultry in the USA, and used to construct Random Forest (RF) machine learning models. An additional 244 recent STm assemblies from farm animals were used as a test set for further validation. The models based on PVs and IGRs had the best performance in terms of predicting the host of origin of isolates and outperformed nearest-neighbour phylogenetic host prediction as well as models based on SNPs or AMR data. However, the models did not yield reliable predictions when tested with isolates that were phylogenetically distinct from the training set. The IGR and PV models were often able to differentiate human isolates in clusters where the majority of isolates were from a single animal source. Notably, IGRs were the feature with the best performance across multiple models which may be due to IGRs acting as both a representation of their flanking genes, equivalent to PVs, while also capturing genomic regulatory variation, such as altered promoter regions. The IGR and PV models predict that ~45 % of the human infections with STm in the USA originate from bovine, ~40 % from poultry and ~14.5 % from swine, although sequences of isolates from other sources were not used for training. In summary, the research demonstrates a significant gain in accuracy for models with IGRs and PVs as features compared to SNP-based and core genome phylogeny predictions when applied within the existing population structure. This article contains data hosted by Microreact.

Accuracy of testing strategies using antibody-ELISA tests on repeated bulk tank milk samples and/or sera of individual animals for predicting herd status for Salmonella dublin in dairy cattle.

There is currently no perfect test for determining herd-level status for Salmonella Dublin in dairy cattle herds. Our objectives were to evaluate the accuracy, predictive ability, and misclassification cost term of different testing scenarios using repeated measurements for establishing the S. Dublin herd status. Diagnostic strategies investigated used repeated bulk tank milk antibody-ELISA tests, repeated rounds of blood antibody-ELISA tests on non-lactating animals or a combination of both approaches. Two populations hypothesized to have different S. Dublin prevalences were included: (i) a convenience sample of 302 herds with unknown history of infection; and (ii) a cohort of 58 herds that previously tested positive to S. Dublin. Bulk milk samples were collected monthly for 6-7 months and serum were obtained from 10 young animals on two occasions, at the beginning and end of bulk milk sampling period. A series of Bayesian latent class models for two populations and comparing two tests were used to compare bulk milk-based to serum-based strategies. Moreover, Monte Carlo simulations were used to compared diagnostic strategies combining both types of samples. For each diagnostic strategy, we estimated the predictive values using two theoretical prevalences (0.05 and 0.25). Misclassification cost term was also estimated for each strategy using these two prevalences and a few relevant false-negative to false-positive cost ratios. When used for screening a population with an expected low prevalence of disease, for instance for screening herds with no clinical signs and no previous S. Dublin history, a diagnostic strategy consisting of two visits at 6 months interval, and with herd considered positive if bulk milk PP% ≥ 35 and/or ≥ 1/10 animals are positive on one or both visits could be used to confidently rule-out S. Dublin infection (median negative predictive value of 0.99; 95% Bayesian credible intervals, 95BCI: 0.98, 1.0). With this approach, however, positive results should later be confirmed with more specific tests to confirm whether S. Dublin is truly present (median positive predictive value of 0.36; 95BCI: 0.22, 0.57). The same diagnostic strategy could also be used confidently to reassess the S. Dublin status in herds with a previous S. Dublin history. When use for such a purpose, the predictive value of a positive result could be greatly improved, from 0.78 (95BCI: 0.65, 0.90) to 0.99 (95BCI: 0.94, 1.0) by requiring ≥ 1 positive result on both visits, rather than at any of the two visits.

Human Salmonellosis Outbreak Linked to Salmonella Typhimurium Epidemic in Wild Songbirds, United States, 2020-2021.

Salmonella infection causes epidemic death in wild songbirds, with potential to spread to humans. In February 2021, public health officials in Oregon and Washington, USA, isolated a strain of Salmonella enterica serovar Typhimurium from humans and a wild songbird. Investigation by public health partners ultimately identified 30 illnesses in 12 states linked to an epidemic of Salmonella Typhimurium in songbirds. We report a multistate outbreak of human salmonellosis associated with songbirds, resulting from direct handling of sick and dead birds or indirect contact with contaminated birdfeeders. Companion animals might have contributed to the spread of Salmonella between songbirds and patients; the outbreak strain was detected in 1 ill dog, and a cat became ill after contact with a wild bird. This outbreak highlights a One Health issue where actions like regular cleaning of birdfeeders might reduce the health risk to wildlife, companion animals, and humans.

The Importance of Hazard Analysis by Critical Control Point for Effective Pathogen Control in Animal Feed: Assessment of Salmonella Control in Feed Production in Sweden, 1982-2005.

This study is the first to show that Hazard Analysis by Critical Control Point (HACCP)-based monitoring can be an effective tool for ensuring Salmonella-safe feed, by virtually eliminating feedborne Salmonella infection even in broiler production. Data from the control of Salmonella in feed and food animal production during 1982-2005, showed that conventional endpoint testing in feed mills did not ensure a Salmonella-safe feed, and in one feed mill failed to detect Salmonella contamination, resulting in the feed infecting 80 out of 197 (40.6%) recipient broiler flocks. Following implementation in 1991 of a HACCP-based control in feed mills, the annual number of samples tested at specified critical control points during a 15-year period increased from ∼4400 to 10,000, while the proportion of Salmonella-contaminated samples decreased from 2.0% to 0.3%. Thus, introduction of HACCP was followed by a dramatic decrease, from 40 to <5, in the annual number of Salmonella-infected broiler flocks identified by preslaughter monitoring. Incidence has generally remained at that low level, despite production since 1980 increasing from 39 to 112 million chickens per year. Feed mills start using soymeal with an unsafe Salmonella status and possibly with a suboptimal HACCP control, increased their level of Salmonella-contaminated HACCP samples, and their feed subsequently infected 78 swine-producing herds. The results also show that the HACCP concept can be an effective tool to supply feed mills with Salmonella-safe feed ingredients as demonstrated for a soybean crushing plant, which produced Salmonella-safe soymeal over a 19-year period despite frequent (34%) and highly varied (92 different serovars) Salmonella contamination in samples from incoming soybean. Similar results are reported for a plant producing rapeseed meal. It is emphasized that the achievements described through use of the HACCP required interventions of relevant preventive biosecurity measures and corrective actions when the HACCP-based monitoring identified Salmonella contamination.

Impact of genetic diversity and antibiotic-resistance of Salmonella isolated from feral cats: One Health approach.

Free-living cats usually live in colonies in urban areas, especially close to parks and neighbourhoods where people feed them without any sanitary control. This can pose a human, animal and environmental health concern due to the close contact between uncontrolled colonies, the population and other domestic and/or wild animals. Thus, this study aimed to assess the genetic diversity and antimicrobial resistance (AMR) among Salmonella enterica subsp. enterica strains isolated from feral cats in a previous epidemiological study in the Gran Canaria island (Spain). A total of nineteen Salmonella isolates were obtained from November 2018 to January 2019 in a Salmonella epidemiological study in feral cats. All isolates obtained were genotyped by pulsed-field gel electrophoresis (PGFE) and were tested for antimicrobial susceptibility, in accordance with Decision 2013/652/EU. PFGE analysis revealed isolates clustering by serovar, with identical clones for serovars Bredeney and Grancanaria, while differing pulsotypes were observed for serovars Florida (88.89 % similarity) and Nima (83.23 % similarity). All but two isolates were resistant to at least one antimicrobial. The results obtained demonstrate that feral cats in the region investigated are a reservoir of Salmonella strains resistant to gentamicin (94.1 %) and of the critically important antimicrobial tigecycline (23.5 %). Hence, they could excrete AMR strains through their faeces and contaminate the environment, favoring the spread of such bacteria to cohabiting pets. Moreover, this widespread presence of AMR Salmonella clones across various serovars highlights the urgent need to implement efficient antimicrobial stewardship and control programs by the local governments due to the ongoing need to protect human and animal health under a One Health concept.

[Influence of breed and herd size on the intra-herd prevalence of Salmonella enterica subspecies diarizonae serovar 61: k: 1, 5, (7) in sheep]. / Einfluss von Rasse und Herdengröße auf die Intraherdenprävalenz von Salmonella enterica subspecies diarizonae Serovar 61: k: 1, 5, (7) bei Schafen.

SUBJECT AND AIM: At present, only little information is available on the within-flock prevalence of Salmonella enterica subspecies diarizonae serovar 61: k: 1, 5, (7) (SASd) in sheep flocks in Germany as well as their possible influencing factors. The aim of the study was to investigate relationships between flock size, breed and within-flock prevalence. MATERIAL AND METHODS: A total of 1610 clinically healthy ewes from 14 sheep flocks of 9 different breeds aged 2 to 12 years were microbiologically tested for SASd by nasal swab and fecal samples. Linear multivariable models were used to analyse the associations between within-flock prevalence and farm factors (flock size, breed) or detection frequencies in fecal or nasal swabs. RESULTS: SASd was detected in all sheep flocks examined, with 75% of adults having at least one positive nasal or fecal result. In comparison to the 11 flocks in which commercial breeds were kept, the 3 flocks of landraces had a lower apparent within-flock prevalence (p=0.01). No association with herd size was evident. With respect to the age of the ewes, there was a negative relationship (p=0.05) with the frequency of detection of SASd in the nasal swab but not in the fecal swab. The health status and fertility performance of the flocks were in line with a normal range for commercial sheep flocks, with lambing losses of 5% to 10% and lambing scores of 130% to 158%. CONCLUSIONS: Despite the high prevalence of SASd infections particularly within commercial breeds, there was no evidence of a relevant risk to sheep health. Compared with commercial breed flocks, a lower spread of SASd within flocks keeping landraces was evident. CLINICAL RELEVANCE: Despite a high prevalence, infections with SASd are very unlikely to lead to clinical symptoms or disease. Regulation and monitoring of SASd in sheep are of low priority for animal health authorities.

Isolation and Molecular Identification of Salmonella pullorum from Broiler Chicken in Iraqi Fields.

Pullorum disease (PD) is one of the most common diseases in the world, with devastating consequences. In the chicken sector, there have been financial losses. It is brought on by Salmonella enteric subspecies serovar Gallinarum biovar pullorum; definitive detection requires culture followed by biochemistry analysis and serotyping. This study aimed to verify the presence of bacteria by culture, biochemical characterization, PCR assay, and sequencing. One hundred samples were collected from 12 broiler chicken flocks of different ages for 8districts of Baghdad province, including cloacal swabs (65), visceral organs (15), and dropping (20). Salmonella colonies were identified by selective culture broth and agar with biochemical description for 75% of the total samples, with a higher incidence in visceral organs than dropping and cloacal swabs. ،The Sequencing and phylogenetic tree analysis of 16S rRNA gene for representative Salmonella isolates. The presence of Salmonella pullorum isolates in global genetic strains; was revealed a matching NCBI isolates similarity of 99.02% with (MF445124.1) and 98% with (MH352164.1), respectively. In the current state of molecular and genetic research, phlyogentic research announced the real presence of Salmonella pullorum in Baghdadprovince's broiler chicken, also showing the phylogentic characteristics and links to some global isolates. The detection of Salmonella pullorum in broiler flocks of the current study extent of health risks to other uninfected birds present in the free range.

Trends in Salmonella Dublin over time in Denmark from food and animal related isolates.

Salmonella enterica serovar Dublin is highly adapted to cattle and a relatively rare cause of human infections. In Denmark S. Dublin has been endemic in the cattle population for many years. A national surveillance program in the cattle population was established at herd-level to reduce the occurrence of S. Dublin. In this study, we analyzed 421 S. Dublin genomes from cattle and food in order to determine the trend of S. Dublin's population size over time in Denmark and the impact of intervention in the cattle industry on the bacterial population size. A phylogenetic tree based on SNPs exhibited two major clades and one small cluster. All isolates were ST10. The temporal phylogenetic tree for the S. Dublin isolates showed that the most recent common ancestor was estimated to be in ∼1980 for the two major clades. An effective population size over time based on a Bayesian skyline plot showed that the population size of S. Dublin decreased significantly between 2014 and 2019 in both major clades. This result was concordant with the decrease of infected human cases by S. Dublin in Denmark. The strengthening of a surveillance program in Denmark could be the cause for the reduction of S. Dublin's effective population size. This study showed that whole genome sequencing combined with computer intensive phylogenetic analysis estimating the effective size of the S. Dublin's population over time is a strongly relevant measure with respect to assessing the impact of control measures aiming to reduce the bacterial population in the reservoir and the risk for human infection.

Assessing pig farm biosecurity measures for the control of Salmonella on European farms.

Salmonella spp. is a common zoonotic pathogen, causing gastrointestinal infections in people. Pigs and pig meat are a major source of infection. Although farm biosecurity is believed to be important for controlling Salmonella transmission, robust evidence is lacking on which measures are most effective. This study enrolled 250 pig farms across nine European countries. From each farm, 20 pooled faecal samples (or similar information) were collected and analysed for Salmonella presence. Based on the proportion of positive results, farms were categorised as at higher or lower Salmonella risk, and associations with variables from a comprehensive questionnaire investigated. Multivariable analysis indicated that farms were less likely to be in the higher-risk category if they had '<400 sows'; used rodent baits close to pig enclosures; isolated stay-behind (sick) pigs; did not answer that the hygiene lock/ anteroom was easy to clean; did not have a full perimeter fence; did apply downtime of at least 3 days between farrowing batches; and had fully slatted flooring in all fattener buildings. A principal components analysis assessed the sources of variation between farms, and correlation between variables. The study results suggest simple control measures that could be prioritised on European pig farms to control Salmonella.

Dominant Salmonella Serovars in Australian Broiler Breeder Flocks and Hatcheries: a Longitudinal Study.

A longitudinal study was conducted to determine the dominance and prevalence of Salmonella enterica subsp in Australian broiler breeder flocks and hatcheries. Twenty-two flocks (n = 3339 samples) were sampled over 6 time points beginning at placement until week 40. Hatcheries (n = 274 samples) were sampled following removal of chicks hatched from eggs originating from the 22 donor parent flocks. The percent of positive flocks (36%) and frequency of positive samples (15.6%) were highest during rearing at week 7. The frequency of positive samples decreased over the 40 weeks; however, the number of positive flocks remained relatively consistent. Geographical location had a greater influence on Salmonella detection frequency than company sample origin, despite differing management and vaccination protocols within and between companies. Twelve serovars were detected in total. The predominant serovars during rearing were Salmonella Mbandaka (32%), S. Saintpaul (27%), and S. Liverpool (18%). The predominant serovars detected during production were S. Cubana (27%), S. Saintpaul (24%), and S. Havana (13%). Salmonella Typhimurium, S. Ohio, and S. Hessarek were detected in the hatcheries. Of the serovars detected, only S. Typhimurium and S. Ohio were found in both broiler breeder flocks and hatcheries. However, detection did not correspond to the status of the flock eggs feeding into the hatchery. This study provides an up-to-date capture of the current Salmonella serovars circulating in the broiler breeder industry. Continued surveillance within the Australian Chicken Meat industry is imperative to mitigate and reduce the risk of salmonellosis in the community related to chicken meat. IMPORTANCE This study identified prevalent and dominant Salmonella enterica subsp in Australian Broiler Breeder flocks, as well as in hatcheries post chick hatch and removal, from eggs originating from these donor parent flocks. The captured Salmonella data was further compared to the most common Salmonella serovars isolated from broilers, as well as human salmonellosis notification data, which is useful for consideration of the circulating serovars within the chicken meat industry and their significance in public health. As there are multiple entry points for Salmonella during the entire chicken meat production chain that can lead to carcass contamination, it is important to distinguish serovars present between the different stages of vertical integration to implement and enable Salmonella control strategies.

Investigation of the environmental presence of Salmonella spp. in finishing pigs at commercial swine farms in Kansas (USA).

Salmonellosis remains a major foodborne disease threat to public health worldwide. Swine are considered a reservoir for many Salmonella serotypes affecting humans; however, not all serotypes of concern in food animal products cause clinical signs of infection in swine. The objective of this study was to evaluate the presence and distribution of Salmonella spp. in finishing pigs at commercial farms across Kansas (USA). Five farms were selected and sampled when pigs weighed between 125 and 136 kg. Samples were collected and transported to the laboratory for processing following USDA-FSIS guidelines. Susceptibility and resistance profiles were also studied. Fifty-three percent (100/186) of samples were culture positive for Enterobacteriaceae, and 14% (14/100) were confirmed Salmonella positive by PCR with three of five farms having no PCR-positive samples. Salmonella serotype Braenderup was the most common serovar identified in environmental samples, while Salm. Infantis, Agona, and Montevideo were identified in fecal samples. Multidrug resistance patterns were only found in Farm 3, in fecal samples and in one floor sample. The observations reported in this study highlight areas of concern, such as locations prone to fecal contamination, to be considered when cleaning and sanitizing between groups of pigs to decrease presence of Salmonella spp. in farm environments.