Salmonella and Salmonellosis: An Update on Public Health Implications and Control Strategies

Prevalence, antimicrobial resistance pattern, and associated factors of Salmonella serovars among human-animal interfaces in the Amhara National Regional State, Ethiopia

BACKGROUND

Salmonellosis in humans and animals poses significant public health concerns, leading to substantial economic losses and increased healthcare costs in both developed and developing countries. This study aimed to assess the prevalence, antimicrobial resistance pattern, and associated factors of Salmonella serovars in humans and animals (sheep, chicken, and cattle) in the Amhara National Region state of Ethiopia.

METHODS

A prospective cross-sectional study was conducted using a consecutive convenience sampling technique from September 2022 to January 2024 at public health facilities and 25 randomly selected animal farms surrounding each health facility in the Amhara National Regional State. Socio-demographic data and relevant clinical characteristics were collected using a standardized questionnaire. After enrichment with Selenite F broth, Salmonella serovars were isolated using MacConkey, Xylose Lysine Deoxycholate, and Salmonella Shigella agar. The Salmonella serovars were characterized through a series of biochemical tests. The antimicrobial resistance patterns were determined using the modified Kirby-Bauer disk diffusion technique. Data analysis was performed using SPSS version 29, and the results were summarized in tables and graphs.

RESULT

The overall prevalence of Salmonella serovars among humans and animals was 12.1% (49/404; 95% CI: 9.2-15.6) and 2.7% (9/336; 95% CI: 1.3-4.8), respectively. Human isolates of Salmonella serovars exhibited high resistance rates to ampicillin (79.6%) and tetracycline (71.4%). Similarly, all animal isolates of Salmonella were found to be 100% resistant to both ampicillin and tetracycline. In contrast, a 2% resistance of Salmonella isolates was observed to ciprofloxacin among humans but 11% in animals. Data also showed that 71.4% and 88.9% of Salmonella isolates from humans and animals were resistant to three or more antibiotic classes, respectively. Close contact with patients experiencing diarrhea (AOR = 2.83; 95% CI: 1.05-7.629; P = 0.04) and with animals (AOR = 3.179; 95% CI: 1.574-6.419; P = 0.001) revealed a statistically significant association with the prevalence of culture-confirmed salmonellosis.

CONCLUSION

The prevalence of culture-confirmed Salmonella serovars among humans and animals was significantly high. Many isolates of Salmonella from these groups showed resistance to three or more classes of antibiotics. Individuals who come into contact with those experiencing diarrhea or who handle animals are at an increased risk of developing salmonellosis. To help reduce these infections, public health initiatives should focus on improving animal handling practices and promoting better hygiene in both the environment and personal habits through one health approach.

Antimicrobial Resistant Staphylococcus spp., Escherichia coli, and Salmonella spp. in Food Handlers: A Global Review of Persistence, Transmission, and Mitigation Challenges

Antimicrobial resistance in foodborne pathogens represents a critical global health challenge, with food handlers serving as key contributors in their transmission. This comprehensive review synthesizes evidence on the prevalence, transmission dynamics, and antimicrobial resistance patterns of three major pathogens, Staphylococcus spp., Escherichia coli, and Salmonella spp., among food handlers worldwide. Analysis of studies across diverse geographical regions reveals considerable variation in colonization rates, with Staphylococcus spp. prevalence ranging from 19.5% to 95.0%, Escherichia coli from 2.8% to 89.3%, and Salmonella spp. from 0.07% to 9.1%. Resistance profiles demonstrate alarming trends, including widespread β-lactam resistance and emerging resistance to last-resort antibiotics like carbapenems. Particularly concerning is the high occurrence of multidrug resistant (MDR) strains and extended spectrum β-lactamase (ESBL) producers in low- and middle-income countries. This review identified inadequate handwashing, poor hygiene infrastructure, and asymptomatic carriage as critical factors facilitating the transmission of antimicrobial resistant strains. These findings underscore the urgent need for enhanced surveillance systems, targeted decolonization strategies, improved hygiene protocols, and food handler education to mitigate the spread of resistant pathogens through the food chain.

Development of linear β-turn inducers containing peptides as arc mimetics with DNA topological and sequence selectivity

In general, biological macromolecules such as proteins interact with the major groove of the ds-DNA via hydrogen bonds formation, thus blocking the site access of TFs to specific DNA sequences. Considering that the primary sequence of arc repressor responsible for DNA binding is well-characterized as well as the 3D-conformational requisites for its optimal interactions with the specific DNA base-pairs, a series of well-tailored arc analogues could be designed using computational molecular tools and available structural data. These novel molecular entities have been synthesized following ultrasound assisted-solid phase peptide synthesis (US-SPPS), characterized by NMR experiments and screened for TAGA box selectivity on DNA oligomers using a battery of DNA displacement assays. Data obtained show a clear tendency of peptide ACAS_4 to assume a 3-D β-sheet like structure responsible of the interaction with DNA major groove and to bind selectively to the consensus sequence of DNA. For the best of our knowledge this is the first report on a β-sheet arc mimetic endowed with topological and sequence selectivity for the TAGA box of DNA.

Zoonotic Gastroenteric Diseases of Exotic Animals

Exotic pet ownership has steadily increased over the last decade, and with increased numbers of these species in close contact with humans, the risk of gastrointestinal zoonoses has also increased. Non-typhoidal serovars of Salmonella enterica are one of the most prevalent and important zoonoses of exotic pets, and reptile and backyard poultry are common asymptomatic carriers of these bacteria. Outbreaks of reptile-associated salmonellosis have occurred yearly in the United States since 2019 but contact with backyard poultry has actually been associated with more Salmonella outbreaks in the United States than any other animal species to date.

Knowledge, attitudes, practices (KAP), and risk factors toward zoonotic diseases among smallholder livestock farmers in Bugesera district of Rwanda

Background

Although zoonotic diseases pose significant health and economic threats globally, rural communities in developing countries are more vulnerable due to the increased proximity between animals and humans and the lack of knowledge about these diseases. This study assessed the knowledge, attitudes, practices (KAP), and risk factors regarding zoonotic diseases among smallholder livestock farmers in Bugesera district of Rwanda.

Methods and materials

A convenient sample of 155 livestock smallholder farmers was selected from eight of the fifteen sectors of the district. Data were collected through interviews using a semi-structured questionnaire. Descriptive analyses including frequencies and means were used to summarize the data. Pearson's chi-square test was used to examine associations between knowledge and socio-demographic variables and between knowledge and practices.

Results

Findings showed that 50.3% of respondents knew diseases could be transmitted from animals to humans and just 13.5% recognized reverse zoonotic transmission - humans to animals. When specifically asked if they knew about brucellosis, tuberculosis, and Rift Valley fever; 88, 79, and 41% of respondents, respectively, reported being familiar with these diseases though many were unaware of their zoonotic nature. Risky attitudes and practices were prevalent, including the lack of isolation for sick animals (70.97%) and failure to quarantine newly introduced animals (83.87%). While 81.94% vaccinated their animals, only 16.54% could specify at least one vaccinated disease, and none knew the date of their animals' next vaccination date. Other poor practices were reported, with 64.52% not separating animal and human utensils, and only 25.81% of cattle owners reported using artificial insemination. Additionally, 34.46% consumed raw non-boiled milk, and 24.5% did not use mosquito nets. Regarding roaming animals in the neighborhood, 79% of rats, 55% bats, 68% dogs, 67% cats, and 5.2% monkeys.

Conclusion

The study revealed low awareness and high-risk practices regarding zoonotic diseases among smallholder livestock farmers in Bugesera district, posing a significant One Health concern. Therefore, educational programs to improve KAP and strengthen zoonotic disease prevention efforts in this district.

European Pine Marten (Martes martes) as Natural Definitive Host of Sarcocystis Species in Latvia: Microscopic and Molecular Analysis

Apicomplexan parasites of the genus Sarcocystis utilize a wide range of vertebrate hosts, including reptiles, birds, and mammals, and follow a complex two-host prey-predator life cycle. Sarcocysts develop within the muscle tissue of intermediate hosts, while oocyst sporulation occurs in the intestines of definitive hosts. Despite their broad host range, the role of Mustelidae predators in the transmission and maintenance of Sarcocystis species remains poorly understood, highlighting the need for targeted studies in this area. In 2023, 20 intestinal samples were collected from European pine martens (Martes martes) in Latvia. Light microscopy revealed sporocysts of Sarcocystis spp. in 70.0% of the samples. Sarcocystis species were identified by using the analysis of obtained cox1 and ITS1 sequences. Using molecular methods, Sarcocystis spp. were confirmed in 85.0% of the samples examined, and co-infections with two or more different parasite species were established in 30.0% samples. We detected eight Sarcocystis species (S. arieticanis, S. bertrami, S. capracanis, S. cruzi, S. entzerothi, S. hjorti, S. morae, and S. truncata) associated with intermediate hosts such as cervids, cattle, sheep, goats, and horses. Additionally, a genetically novel species, Sarcocystis sp. 25MmLV, was detected in a single European pine marten. These findings suggest that European pine martens serve as definitive hosts for multiple Sarcocystis species, particularly those infecting cervids.

Evaluation of the virulence characteristics of ST11 Salmonella enterica from different sources using a 2D cell model

This study aimed to evaluate the virulence characteristics of ST11 Salmonella enterica from various sources and explore its pathogenic mechanisms and the molecular basis of antimicrobial resistance. In total, 20 Salmonella isolates collected between 2017 and 2022 from environmental, animal, clinical, and food sources were analyzed. Comprehensive investigations were conducted using whole-genome sequencing, bioinformatic analysis, broth microdilution methods, a two-dimensional (2D) cell model (Caco-2 cells), and a Galleria mellonella infection model. All tested ST11 strains carried major pathogenicity islands (PAIs) SPI-1salmonella pathogenicity island-1 (SPI-1) to SPI-5, and 90 % of the isolates harbored three or more plasmids, facilitating the horizontal transfer of virulence genes. Expression levels of sopA, ssaV, sipA/sspA, and sipB/sspB virulence genes varied significantly among strains, with sipB/sspB playing a key role in the invasion of ST11 strains. The results of invasion assays using the 2D cell model were consistent with those from the Galleria mellonella infection model, validating the 2D model's effectiveness in evaluating Salmonella's virulence. The findings suggest that Salmonella's virulence is not directly associated with the source of the isolates, and plasmid diversity may impact adaptability and transmission patterns. This study provides new insights into the pathogenic mechanisms of ST11 Salmonella and lays the groundwork for developing a novel 3D cell model to assess bacterial virulence.

How Long Do Microorganisms Survive and Persist in Food? A Systematic Review

Foodborne illnesses caused by microorganisms pose a significant threat to public health. Understanding the survival and persistence of these microorganisms in various food matrices is crucial for developing effective control strategies. This systematic review aims to address the current knowledge gaps related to the duration of survival and persistence of microbial pathogens in food, as well as the impact of external environmental conditions on their viability. A comprehensive search was conducted across major databases, including studies published until 3 June 2024. The PRISMA guidelines were followed to ensure a systematic and transparent approach. Foodborne bacteria, such as Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7, were found to persist for extended durations, ranging from days to over a year. The mean duration of persistence for all of the bacteria was 246 days, whereas the survival duration was 16 days. Bacterial survival and persistence were significantly influenced by temperature, with warmer conditions (>25 °C) generally supporting longer persistence. Relative humidity also played a role, with low-humidity environments (<50% RH) favouring the survival of pathogens like Listeria monocytogenes and Escherichia coli. In contrast, viruses, such as hepatitis A virus and Human norovirus, showed only survival patterns, with average durations of 21 days and temperature being the primary environmental factor influencing their survival. Overall, this review provides evidence that a wide range of microbial pathogens, including Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, and the hepatitis A virus, can survive and persist in food for prolonged periods, leading to potential harm. These insights underscore the necessity of stringent food safety measures and continuous monitoring to mitigate the risks posed by these resilient pathogens, contributing to a safer and more secure food supply chain.

Magnetic Prussian blue nanoparticles to enhance dual-readout lateral flow immunoassay for Salmonella typhimurium detection

BACKGROUND

Traditional immunochromatographic assay (ICA) test strips typically utilize colloidal gold nanoparticles as colorimetric signal reporters, but they often suffer from compromised sensitivity and quantitative accuracy, making them inadequate for the stringent demands of trace-level screening. In addition, the heterogeneous nature of food matrices, such as dairy products, meat, and ready-to-eat fruits and vegetables, complicates the accuracy and reliability of ICA for detecting foodborne pathogens. Therefore, enhancing the detection accuracy of ICA is critical to meet the stringent requirements for pathogen detection in complex food samples.

RESULTS

Here, we synthesized a novel Prussian blue-coated Fe3O4 nanoparticle (Fe3O4@PB) via a simple in-situ growth method. The synthesized Fe3O4@PB nanoparticles demonstrate a high magnetization strength and excellent photothermal conversion efficiency, enabling their application as efficient probes in ICA. Leveraging these properties, we developed a dual-readout ICA incorporating both colorimetric and photothermal modalities for the sensitive detection of Salmonella typhimurium in milk and lettuce samples. The detection limit (LOD) for Fe3O4@PB-ICA reached 2.5 × 103 CFU/mL in colorimetric formats and 1.04 × 103 CFU/mL in photothermal formats, representing approximately 4-fold and 10-fold improvements compared to AuNP-ICA (LOD = 1 × 104 CFU/mL). Furthermore, the average recovery rates ranged from 89.1 % to 111.9 %, while the coefficients of variation below 13.7 %, demonstrating excellent accuracy and precision.

SIGNIFICANCE

The proposed Fe3O4@PB serves as effective probe for purifying and enriching target analytes, significantly improving the accuracy and sensitivity of colorimetric and photothermal immunochromatographic analysis applications. By leveraging the magnetic and photothermal capabilities of Fe3O4@PB, the developed Fe3O4@PB-ICA represents a promising rapid diagnostic platform for the sensitive detection of foodborne pathogens and other analytes.

Metal and metal oxide nanoparticle-assisted molecular assays for the detection of Salmonella

This paper provides a comprehensive overview of the diverse applications and innovations of nanoparticles in the detection of Salmonella. It encompasses a comprehensive range of novel methods, including efficient enrichment, nucleic acid extraction, immunoassays, nucleic acid tests, biosensors, and emerging strategies with the potential for future applications. The surface modification of specific antibodies or ligands enables nanoparticles to achieve highly selective capture of Salmonella, while optimizing the nucleic acid extraction process and improving detection efficiency. The employment of nanoparticles in immunological and nucleic acid tests markedly enhances the specificity and sensitivity of the reaction, thereby optimizing the determination of detection results. Moreover, the distinctive physicochemical properties of nanoparticles enhance the sensitivity, selectivity, and stability of biosensors, thereby facilitating the rapid advancement of bio-detection technologies. It is particularly noteworthy that there has been significant advancement in the application and innovative research of nanozymes in molecular assays. This progress has not only resulted in enhanced detection efficiency but has also facilitated innovation and improvement in detection technologies. As nanotechnologies continue to advance, the use of metal and metal oxide nanoparticles in Salmonella detection is likely to become a more promising and reliable strategy for ensuring food safety and public health.

Caffeine as a natural inhibitor of Salmonella biofilms in fruit juices

Caffeine holds promise for applications in food safety due to its antioxidant and antibacterial properties. Given rising antimicrobial resistance, its natural antimicrobial potential is valuable for controlling foodborne pathogens and reducing reliance on synthetic preservatives. This study aimed to explore caffeine as an alternative to control Salmonella biofilms in fruit juice substrates. Salmonella Enteritidis and S. Typhimurium biofilm were developed in brain heart infusion (BHI) broth (control) and grape and apple juice before and after caffeine application. Biofilm inhibition was quantified by crystal violet staining, exopolysaccharide (EPS) production, and visualization through confocal and scanning electron microscopy. Swimming motility assays assessed caffeine's impact on bacterial motility. Both strains formed biofilms in the tested juices. The minimum inhibitory concentration (MIC) of caffeine was 9.37 mM mL-1 for S. Typhimurium and 18.75 mM mL-1 for S. Enteritidis. Biofilm inhibition was observed for treatments before and after caffeine application, with varying levels depending on the matrix. EPS production and inhibition were higher in biofilms formed in grape and apple juices compared to the control (BHI). Sub-inhibitory concentrations of caffeine reduced motility in both strains. These findings suggest that caffeine may be a promising approach to control Salmonella biofilms in the food industry.

A Mini-Review on Multi-Hurdle Control of Salmonella Along Poultry Production Continuum

This mini-review presents common strategies for controlling Salmonella in poultry, addressing combined pre-harvest and post-harvest interventions to create a multi-hurdle approach. The goal is to highlight integrated approaches that enhance overall food safety and sustainability within the poultry industry. Current pre-harvest and post-harvest strategies are discussed, including industry practices and regulatory frameworks. Emphasis is placed on the implementation of biosecurity measures, vaccination, feed management, and environmental control in pre-harvest settings, as well as processing plant interventions such as antimicrobials for carcass decontamination, sanitation, and quality control measures. Pre-harvest strategies that have shown promise include enhanced biosecurity protocols, selective vaccinations for pathogenic Salmonella strains, and advanced feeding regimens. Post-harvest interventions, such as antimicrobial application for decontamination, have improved sanitation practices, and pathogen reduction technologies are also critical in reducing Salmonella prevalence. An integrated approach that combines both pre-harvest and post-harvest measures is essential for an effective Salmonella control program. Implementing a continuum of control strategies for Salmonella in poultry production is vital for ensuring food safety and protecting public health. Collaborative efforts between researchers, industry stakeholders, and policymakers are necessary to address emerging issues and enhance overall effectiveness.

Monitoring antimicrobial resistance in Salmonella enterica serovar Infantis isolates of poultry, livestock, and humans across the United States, 2013-2020

Salmonella enterica serovar Infantis (S. Infantis) is an emerging zoonotic foodborne pathogen. This study used publicly available data on S. Infantis from the National Antimicrobial Resistance Monitoring System (NARMS) to evaluate the prevalence and antimicrobial resistance (AMR) of S. Infantis across the United States of America between 2013 and 2020. The highest prevalence of S. Infantis was identified in chickens (3027 isolated from 18,078 samples; 16.75 %), swine (431/5600; 6.09 %), turkeys (161/4019; 4.01 %), humans (737/18,774; 3.93 %), and cattle (134/8010; 1.67 %). Over the study period, a significant increase in S. Infantis isolates of chickens and turkeys, a moderate in cattle, a low in humans, and no increase in swine was observed. High resistance to tetracycline, nalidixic acid, and sulfisoxazole and low resistance to cefoxitin and amoxicillin-clavulanic acid were detected among livestock, poultry, and human isolates. Reduced susceptibility to ciprofloxacin was observed in 52.46 % of chicken isolates, 62.11 % of turkey, and 18.59 % of human isolates. Multi-drug resistance (MDR; resistant to at least one agent in ≥3 antimicrobial classes) was detected in 93 % of turkeys, 83 % of chickens, 22 % of humans, 16 % of cattle, and 6 % of swine isolates. This study identified differences in the prevalence and AMR of S. Infantis across the food chain, highlighting the importance of a focused One Health approach to mitigate the emergence of AMR and to reduce the health burden of infections with drug-resistant isolates.

Machine learning reveals the dynamic importance of accessory sequences for Salmonella outbreak clustering

Bacterial typing at whole-genome scales is now feasible owing to decreasing costs in high-throughput sequencing and the recent advances in computation. The unprecedented resolution of whole-genome typing is achieved by genotyping the variable segments of bacterial genomes that can fluctuate significantly in gene content. However, due to the transient and hypervariable nature of many accessory elements, the value of the added resolution in outbreak investigations remains disputed. To assess the analytical value of bacterial accessory genomes in clustering epidemiologically related cases, we trained classifiers on a set of genomes collected from 24 Salmonella enterica outbreaks of food, animal, or environmental origin. The models demonstrated high precision and recall on unseen test data with near-perfect accuracy in classifying clonal and short-term outbreaks. Annotating the genomic features important for cluster classification revealed functional enrichment of molecular fingerprints in genes involved in membrane transportation, trafficking, and carbohydrate metabolism. Importantly, we discovered polymorphisms in mobile genetic elements (MGEs) and gain/loss of MGEs to be informative in defining outbreak clusters. To quantify the ability of MGE variations to cluster outbreak clones, we devised a reference-free tree-building algorithm inspired by colored de Bruijn graphs, which enabled topological comparisons between MGE and standard typing methods. Systematic evaluation of clustering MGEs on an unseen dataset of 34 Salmonella outbreaks yielded mixed results that exemplified the power of accessory sequence variations when core genomes of unrelated cases are insufficiently discriminatory, as well as the distortion of outbreak signals by microevolution events or the incomplete assembly of MGEs.

IMPORTANCE

Gene-by-gene typing is widely used to detect clusters of foodborne illnesses that share a common origin. It remains actively debated whether the inclusion of accessory sequences in bacterial typing schema is informative or deleterious for cluster definitions in outbreak investigations due to the potential confounding effects of horizontal gene transfer. By training machine learning models on a curated set of historical Salmonella outbreaks, we revealed an enriched presence of outbreak distinguishing features in a wide range of mobile genetic elements. Systematic comparison of the efficacy of clustering different accessory elements against standard sequence typing methods led to our cataloging of scenarios where accessory sequence variations were beneficial and uninformative to resolving outbreak clusters. The presented work underscores the complexity of the molecular trends in enteric outbreaks and seeks to inspire novel computational ways to exploit whole-genome sequencing data in enteric disease surveillance and management.

Differential infection dynamics in mononuclear and polymorphonuclear cells during Salmonella Typhimurium infection and in vitro exposure to diazoxon

S. Typhimurium bacteria cause one of the most recurrent gastrointestinal diseases worldwide. This bacterium can settle in the gastrointestinal tract and internalize into different cellular strains, causing the formation of cellular reservoirs that subsequently lead to systemic dissemination. Exogenous factors such as pesticide exposure can also cause immunological alterations, increasing susceptibility to bacterial infection. The present work evaluated the infection capacity of Salmonella Typhimurium, during a short period (1 h) on mononuclear and polymorphonuclear cells previously exposed to diazoxon (1 h, during 4 h). Mononuclear cells were infected more frequently and in greater magnitude than polymorphonuclear cells. However, when actin polymerization and the release of reactive oxygen species (ROS) were analyzed, polymorphonuclear cells showed increased activity. These processes were evidenced by conformational changes during infection. This suggests differential dynamics of S. Typhimurium infection in mononuclear and polymorphonuclear cells previously exposed to diazoxon.

The prevalence, distribution, and diversity of Salmonella isolated from pork slaughtering processors and retail outlets in the Shandong Province of China

Salmonella is a foodborne pathogen of global significance and is highly prevalent in pork. This study investigated the prevalence, contamination distribution, virulence genes and antibiotic resistance of Salmonella in 3 pork processors in the Shandong Province of China. Samples were collected from 13 different sampling sources across the slaughter procedures (600 samples) as well as at retail outlets supplied by these processors (45 samples). The prevalence was 18.9 % among all the samples, with the highest prevalence observed in feces (40.0 %), lairage pens (38.0 %), and hides (34.0 %). A total of 6 serotypes were identified, with S. Rissen (46.3 %) and S. typhimurium (32.0 %) found to be the most prevalent serotypes. 86.8 % of Salmonella isolates were multi-drug resistant, with the majority of strains resistant to erythromycin, sulfisoxazole, and ampicillin. The multilocus sequence typing analysis revealed 6 STs were obtained from 45 isolates, with the dominant type ST469 accounting for 40.0 % of the total, which suggested a high possibility of cross-contamination between the plant processing chain and retail outlets. This work reveals the prevalence and correlation of Salmonella isolates between pork slaughter and retail outlets and acts as a case-study for stakeholders wishing to improve pork supply chain hygiene, control cross-contamination between the various slaughtering processes, and obtain continuous updates on Salmonella surveillance.

Salmonella: Infection mechanism and control strategies

Salmonella is a foodborne pathogen that predominantly resides in the intestinal tract of humans and animals. Infections caused by Salmonella can lead to various illnesses, including gastroenteritis, bacteremia, septicemia, and focal infections, with severe cases potentially resulting in host mortality. The mechanisms by which Salmonella invades host cells and disseminates throughout the body are partly understood, but there are still many scientific questions to be solved. This review aims to synthesize existing research on the interactions between Salmonella and hosts, detailing a comprehensive infection mechanism from adhesion and invasion to intracellular propagation and systemic spread. Overuse of antibiotics contributes to the emergence of drug-resistant Salmonella strains. An in-depth analysis of the mechanism of Salmonella infection will provide a theoretical basis for the development of novel Salmonella control strategies. These innovative control strategies include antibiotic adjuvants, small molecules, phages, attenuated vaccines, and probiotic therapies, which show huge potential in controlling Salmonella infection.

The ability of chitosan-stearin as an edible coating on the quality of broiler chicken meat during cold storage

Objective

This study aimed to evaluate how well fresh broiler meat may be preserved in cold storage using chitosan-stearin as an edible coating.

Materials and Methods

A completely randomized design with a 3 x 5 factorial arrangement and three replications was employed. Factor I represented the formula dosage (FD) (FD0 = 0% chitosan + 0% stearin; FD1 = 1.5% chitosan + 1% stearin; FD2 = 3% chitosan + 1% stearin), while Factor II represented storage time (ST) (ST0 = 0 days; ST1 = 3 days; ST2 = 6 days; ST3 = 9 days; ST4 = 12 days).

Results

The results showed that the water content, cooking loss, protein content, and fat content of broiler meat were significantly affected (p < 0.01) by the FD and ST. Nonetheless, no significant difference (p > 0.05) was observed in the meat's ability to hold water. The broiler meat's pH was significantly affected (p < 0.01) by the FD, but it was not significantly affected (p > 0.05) by the ST. Furthermore, no treatment underwent testing, which revealed the presence of Escherichia coli and Salmonella sp.

Conclusion

Chitosan-stearin edible coatings with different formula doses FD and ST consistently preserve the quality of fresh broiler meat during cold storage, with average values of water content ranging from 48.97% to 53.73%, water-holding capacity from 17.52% to 34.30%, cooking loss from 10.03% to 33.19%, pH levels from 4.93 to 5.53, protein content from 14.54% to 17.46%, fat content from 20.55% to 24.21%, and no detectable presence of E. coli and Salmonella sp.

Development of Gelatin-Based Renewable Packaging with Melaleuca alternifolia Essential Oil for Chicken Breast Preservation

The aim of this study was to develop gelatin-based films incorporating Melaleuca alternifolia essential oil (MEO) and assess their application on refrigerated chicken breasts. The results showed that MEO exhibited antimicrobial activity against Pseudomonas aeruginosa and Salmonella sp., with inhibition zones of 17 mm and 9 mm, respectively. The minimum inhibitory concentration (MIC) was 10% for P. aeruginosa and 15% for Salmonella sp., demonstrating greater efficacy against P. aeruginosa. The antioxidant analysis using the ABTS method revealed activity of 1309 ± 18.0 μM Trolox/g, while the FRAP method resulted in 446 ± 5.78 μM FeSO4/g. The characterization of the oil by gas chromatography identified major compounds, including 2-carene, γ-terpinene, terpine-4-ol, and α-terpineol. Incorporating the oil into gelatin films resulted in structural changes, such as an increase in thickness (from 0.059 to 0.127 mm) and water vapor permeability. Furthermore, the addition of MEO conferred homogeneous properties to the films with no visible cracks. The incorporation of MEO into gelatin films has shown ABTS antioxidant activity, and FRAP results showed a significant increase with higher MEO concentrations. The packaged samples retained more mass than the control group, which lost about 90% of its weight during storage. Texture analysis revealed only an 8% variation in the Melaleuca-coated samples compared to 19.6% in the control group. These findings indicate that gelatin films containing Melaleuca essential oil effectively improve the shelf life of chicken breasts.

Detection of Salmonella enterica in food using targeted mass spectrometry

The high prevalence of Salmonella enterica necessitates rapid and efficient detection methods. Targeted mass spectrometry (MS) using multiple reaction monitoring (MRM) and parallel reaction monitoring (PRM) has become a promising technique with improved specificity and sensitivity. We develop a novel targeted MS method for detecting S. enterica in food based on peptide biomarkers. Using a combination of four peptide biomarkers, this newly developed method could accurately distinguish S. enterica from other conventional food-borne pathogens. When combined with buoyant density centrifugation (BDC), Salmonella was efficiently separated from food matrices. Based on this discovery, this method was successfully applied to detect S. enterica in both artificially and naturally contaminated food samples, comparable to the culture method. These results demonstrate the potential of the targeted MS method in various food categories and are expected to be an alternative approach for S. enterica detection in food.

Artesunate, EDTA, and colistin work synergistically against MCR-negative and -positive colistin-resistant Salmonella

Discovering new strategies to combat the multidrug-resistant bacteria constitutes a major medical challenge of our time. Previously, artesunate (AS) has been reported to exert antibacterial enhancement activity in combination with β-lactam antibiotics via inhibition of the efflux pump AcrB. However, combination of AS and colistin (COL) revealed a weak synergistic effect against a limited number of strains, and few studies have further explored its possible mechanism of synergistic action. In this article, we found that AS and EDTA could strikingly enhance the antibacterial effects of COL against mcr-1- and mcr-1+ Salmonella strains either in vitro or in vivo, when used in triple combination. The excellent bacteriostatic effect was primarily related to the increased cell membrane damage, accumulation of toxic compounds and inhibition of MCR-1. The potential binding sites of AS to MCR-1 (THR283, SER284, and TYR287) were critical for its inhibition of MCR-1 activity. Additionally, we also demonstrated that the CheA of chemosensory system and virulence-related protein SpvD were critical for the bacteriostatic synergistic effects of the triple combination. Selectively targeting CheA, SpvD, or MCR using the natural compound AS could be further investigated as an attractive strategy for the treatment of Salmonella infection. Collectively, our work opens new avenues toward the potentiation of COL and reveals an alternative drug combination strategy to overcome COL-resistant bacterial infections.

A new vaccination approach for Salmonellosis employing a multi-epitope vaccine based on live microbial cell factory from Lactococcus lactis

A major health and financial burden in the chicken sector is salmonella infection. It is difficult to create an oral vaccination that can provide strong intestinal mucosal immunity in birds, particularly cross-protection against several Salmonella serotypes. As a result, the poultry industry needs a powerful oral vaccination platform that uses live bacterial vectors to prevent various Salmonella serotypes. The genetically engineered L. lactis was given orally to birds as a vaccine after a multi-epitope vector was created using a reverse vaccinology technique. After the plasmid was digested, the target group produced a 72 kDa protein called multi-epitop. Birds that received the L. lactis/pNZ8121-Multi epitope vaccination showed increased levels of interferon (IFN-γ) and NFkB1α, increased transcription rates of cytokines, and a significant presence of IgY antibodies specific to the multi epitope gene in their serum. Salmonella infection is a severe health and economic burden in the poultry industry, according to spleen sections from the L. lactis/pNZ8121-Multi epitope. Developing an oral vaccine that can provide birds robust intestinal mucosal immunity-specifically, cross-protection against many Salmonella serotypes-is challenging. The results provide a fresh method for creating new immunological candidate multi-epitome genes by using the food-grade, non-pathogenic Lactococcus lactis as a protein cell factory. This method provides a unique technique to assess the long-term sustainability, cost, safety, and usefulness of experimental pharmaceutical products.

Prevalence and transmission of Salmonella collected from farming to egg processing of layer production chain in Jiangsu Province, China

Salmonella is a common foodborne pathogen found in poultry production systems. Contaminated poultry products are a major source of human salmonellosis. Understanding the conditions of contamination and the genetic relationships of Salmonella in poultry production is necessary to develop effective interventions measures for controlling Salmonella transmission. Through epidemiological investigation and whole-genome sequence (WGS) analysis, this study revealed the epidemic law, drug resistance, and genetic characteristics of Salmonella in the production chain. In total, 130 (10.77 %) Salmonella strains were isolated from the collected samples, with Salmonella Enteritidis (S. Enteritidis) and S. Infantis being the predominant serotypes. WGS analysis revealed that the Sequence Type (ST) of all the 22 strains of S. Enteritidis were ST11, and 13 strains of S. Infantis were ST32. Antimicrobial resistance gene analysis showed that 95.45 % of S. Enteritidis carried strA/strB, sul, and blaTEM-1B; 77.3 % contained tetA genes; and 100 % of S. Infantis carried aac(6')-Iaa and mdf(A), which was consistent with the drug resistance phenotype. The phylogenetic tree showed that S. Enteritidis strains with different links were distributed in the same branch which displayed the very close genetic relationship. Combined with epidemiological investigations, it was found that S. Enteritidis infection begins at the chicken breeding stage and spreads vertically and horizontally along the production chain. In addition, phylogenetic tree analysis of S. Infantis showed that the genomes of 13 strains from egg products and egg collection center were very similar and belonged to the same clone cluster. It is speculated that the S. Infantis transmitted in the industrial chain is the same strain; it can spread along the industrial chain, and cross-contamination may occur. This study indicates that Salmonella contamination in the layered industrial chain is more serious and that a cloning relationship exists among the strains of different links. Therefore, more stringent measures should be taken to control Salmonella during the chicken breeding stage, and the importance of implementing good hygiene practices at every level of production should be emphasized.

Prevalence and Antimicrobial Resistance of Salmonella Strains Isolated from Chicken Samples in Southern Italy

Salmonellosis is one of the most frequent foodborne zoonoses, and the consumption of contaminated poultry meat is considered the main source of Salmonella infections in humans. From 2021 to 2023, 384 chicken samples were collected from retailers in Apulia and Basilicata regions and analysed at the Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata (IZSPB) laboratories. The Salmonella isolates were investigated to evaluate their phenotypic characteristics of antimicrobial resistance. A total of 125 (32.55%) samples tested positive for Salmonella spp. Three samples were simultaneously infected with strains of two different serotypes. Strains were classified into nine serotypes. Out of 128 strains, 112 (87.5%) isolates showed multidrug-resistant (MDR) profiles. Moreover, 16 isolates (12.5%) were ESBL producers with MDR profiles. Our data confirm that chicken products are a common source of Salmonella and highlight how S. Infantis was the most prevalent serotype (85.93%). Furthermore, Salmonella isolates showed antimicrobial resistance, which is very worrisome for animals and consumers. The high rate of antibiotic resistance along with the appearance of numerous MDR isolates is considered an actual concern and requires a robust surveillance network in a One Health concept.

In Vitro Characterization of Probiotic Strains Bacillus subtilis and Enterococcus durans and Their Effect on Broiler Chicken Performance and Immune Response During Salmonella Enteritidis Infection

In vitro experiments were conducted to characterize the effect of bile salt supplementation and pH on the proliferation of Bacillus subtilis CE330 and Enterococcus durans CH33 probiotics and in vivo experiments on production performance, cecal Salmonella enterica serovar Enteritidis (S. Enteritidis) load, and the immune response of broilers. A one-way ANOVA was used to examine the effect of bile and pH on probiotic species proliferation. B. subtilis. CE330 was more tolerant to high bile concentrations and pH levels compared to E. durans CH33. Bile concentrations between 3.0 and 4.0% and a pH range between 2 and 4 decreased (p < 0.05) the proliferation of E. durans CH33. In vitro, cell-free supernatants (CFSs) of B. subtilis CE330 and E. durans CH33 at a ratio of 1:1 significantly (p < 0.05) reduced S. Enteritidis proliferation, with the highest inhibition observed at a 5:1 ratio of E. durans CH33 CFS. The cultures of B. subtilis CE330 and E. durans CH33 with 4% bile salt for 72 h had a higher proline concentration of 56.95 (13.1-fold) and 20.09 (2.5-fold) µmol/g of fresh weight, respectively. A total of 144 one-day-old male Cobb broiler chicks were randomly allocated to four treatment groups-basal diet, basal diet + challenge, probiotics (B. subtilis CE330 and E. durans CH33, 0.5 g/kg feed), and probiotics + challenge in six replications. On day 14, birds in the challenge treatment were orally challenged with 1 × 108 CFU of S. Enteritidis. A two-way ANOVA was used to examine the effects of probiotic supplementation and Salmonella challenge on dependent variables after 10 d post-Salmonella infection. Probiotic supplementation did not alter the body weight gain, the feed conversion ratio, the intestinal histomorphology (p > 0.05), or IL-1β and IL-10 gene expression (p > 0.05) at 10 dpi. However, probiotic supplementation decreased the Salmonella load by 38% compared to the control group. In conclusion, B. subtilis CE330 and E. durans CH33 reduced cecal S. Enteritidis load by 38%, thereby demonstrating their potential as probiotic interventions to enhance food safety and serve as alternatives to antibiotics in poultry. Hence, when developing multi-strain probiotic formulations, it is essential to emphasize the biocompatibility of various strains within the host system.

Innovative approaches to controlling Salmonella in the meat industry

Salmonella, a Gram-negative, rod-shaped bacterium from the Enterobacteriaceae family, is a significant cause of illnesses in humans and animals. It resides in the digestive tracts of livestock, poultry, and other warm-blooded animals and can contaminate various environments and foods through fecal matter. Salmonella enterica, the main species that affects humans, is widespread in cattle, pigs, and poultry. Despite efforts to control pathogens in meat systems, over 1.4 million human salmonellosis cases occur annually in the U.S., with serotypes S. enteritidis and S. typhimurium being predominant. Advances in meat processing have targeted pathogen reduction at multiple stages, but more innovative approaches are needed for substantial public health impact. This paper discusses current and future strategies to minimize Salmonella in the food supply. It emphasizes pre- and post-harvest Salmonella prevalence by biomapping it through the whole processing chain, focusing on beef and pork interventions such as probiotics. These interventions have shown promise in reducing pathogen loads in cattle manure and lymph nodes. Techniques such as microbiome, whole genome sequencing (WGS), and electron microscopy (EM) provide detailed insights into Salmonella's genetic and bacterial structural-morphological characteristics, aiding in the development of targeted interventions. Integrating rapid detection, biomapping, and enviromapping enhances pathogen tracking in meat production, reducing Salmonella prevalence and improving risk assessment and food safety. The advanced, current, and innovative techniques allow for timely identification, detailed spatial and quantitative data, and more effective interventions. This leads to safer food products and reduces foodborne illnesses.

Advancements in Detection Methods for Salmonella in Food: A Comprehensive Review

Non-typhoidal Salmonella species are one of the leading causes of gastrointestinal disease in North America, leading to a significant burden on the healthcare system resulting in a huge economic impact. Consequently, early detection of Salmonella species in the food supply, in accordance with food safety regulations, is crucial for protecting public health, preventing outbreaks, and avoiding serious economic losses. A variety of techniques have been employed to detect the presence of this pathogen in the food supply, including culture-based, immunological, and molecular methods. The present review summarizes these methods and highlights recent updates on promising emerging technologies, including aptasensors, Surface Plasmon Resonance (SPR), and Surface Enhanced Raman Spectroscopy (SERS).

Phenotypic Characterization and Genome Analysis of New Broad-Spectrum Virulent Salmophage, Salmonella Phage KKP_3822, for Biocontrol of Multidrug-Resistant Salmonella enterica Strains

Salmonella is one of the main foodborne pathogens. Irrational antibiotic management has led to an increase in the incidence of multidrug-resistant strains. Bacteriophages may be an alternative method of food biopreservation and contribute to reducing the number of food poisonings requiring pharmacotherapy. This study aimed to isolate a bacteriophage (phage) targeting indigenous multidrug-resistant (MDR) Salmonella strains, followed by their biological, morphological, and genomic characterization. In this study we isolated Salmonella phage KKP_3822, targeting MDR Salmonella Manchester strain KKP 1213. Salmonella phage KKP_3822 retained high activity in the temperature range from -20 °C to 40 °C and active acidity from pH 3 to 11. Temperatures of 70 °C and 80 °C and extreme pH values (2 and 12) significantly reduced the phage titer. Its activity decreased proportionally to the time of UV exposure. Genome analysis (linear dsDNA with a length of 114,843 bp) revealed the presence of 27 tRNA genes. Proteins encoded by the vB_Sen-IAFB3822 phage were divided into functional modules related to (i) phage structure/assembly, (ii) DNA replication/modification/regulation, (iii) phage lysis, and (iv) DNA packaging into the capsid. No genes associated with antibiotic resistance or integration into the host genome, markers of temperate bacteriophages, were annotated in the Salmonella phage KKP_3822 genome. Based on morphological features and whole-genome sequence analysis, the newly isolated Salmonella phage KKP_3822 shows the greatest similarity to representatives of tailed phages from the Caudoviricetes class, Demerecviridae family, and Epseptimavirus genus. Genome analysis confirmed the virulent nature of the Salmonella phage KKP_3822, making it a potential candidate for food biocontrol.

Type 3 immune response protects against Salmonella Typhimurium infection in the small intestine of neonatal rats

Bacterial infections, particularly Salmonella, pose a significant health risk to neonates due to their underdeveloped immune systems. Understanding the immune responses in the neonatal intestine during S. Typhimurium infection is crucial for developing effective therapeutic and prevention strategies. This study found neonatal rats exhibited severe symptoms, including significant mortality, body weight loss, diarrhea, and bacterial load increases in the gastrointestinal tract and various organs, particularly in the ileum. Moreover, neonatal rats exhibited a high percentage of type 3 immune cells including Th17, γδT17, and ILC3 after S. Typhimurium infection. Furthermore, cintirorgon treatment during early life, the agonist of RORγt, significantly enhanced IL-17A-secreting type 3 immune response and alleviated the symptoms. Our data reveal targeting RORγt and IL-17A pathways may offer a promising therapeutic strategy for bacterial infections in neonatal populations.

Advancing Phage Therapy: A Comprehensive Review of the Safety, Efficacy, and Future Prospects for the Targeted Treatment of Bacterial Infections

BACKGROUND

Phage therapy, a treatment utilizing bacteriophages to combat bacterial infections, is gaining attention as a promising alternative to antibiotics, particularly for managing antibiotic-resistant bacteria. This study aims to provide a comprehensive review of phage therapy by examining its safety, efficacy, influencing factors, future prospects, and regulatory considerations. The study also seeks to identify strategies for optimizing its application and to propose a systematic framework for its clinical implementation.

METHODS

A comprehensive analysis of preclinical studies, clinical trials, and regulatory frameworks was undertaken to evaluate the therapeutic potential of phage therapy. This included an in-depth assessment of key factors influencing clinical outcomes, such as infection site, phage-host specificity, bacterial burden, and immune response. Additionally, innovative strategies-such as combination therapies, bioengineered phages, and phage cocktails-were explored to enhance efficacy. Critical considerations related to dosing, including inoculum size, multiplicity of infection, therapeutic windows, and personalized medicine approaches, were also examined to optimize treatment outcomes.

RESULTS

Phage therapy has demonstrated a favorable safety profile in both preclinical and clinical settings, with minimal adverse effects. Its ability to specifically target harmful bacteria while preserving beneficial microbiota underpins its efficacy in treating a range of infections. However, variable outcomes in some studies highlight the importance of addressing critical factors that influence therapeutic success. Innovative approaches, including combination therapies, bioengineered phages, expanded access to diverse phage banks, phage cocktails, and personalized medicine, hold significant promise for improving efficacy. Optimizing dosing strategies remains a key area for enhancement, with critical considerations including inoculum size, multiplicity of infection, phage kinetics, resistance potential, therapeutic windows, dosing frequency, and patient-specific factors. To support the clinical application of phage therapy, a streamlined four-step guideline has been developed, providing a systematic framework for effective treatment planning and implementation.

CONCLUSION

Phage therapy offers a highly adaptable, targeted, and cost-effective approach to addressing antibiotic-resistant infections. While several critical factors must be thoroughly evaluated to optimize treatment efficacy, there remains significant potential for improvement through innovative strategies and refined methodologies. Although phage therapy has yet to achieve widespread approval in the U.S. and Europe, its accessibility through Expanded Access programs and FDA authorizations for food pathogen control underscores its promise. Established practices in countries such as Poland and Georgia further demonstrate its clinical feasibility. To enable broader adoption, regulatory harmonization and advancements in production, delivery, and quality control will be essential. Notably, the affordability and scalability of phage therapy position it as an especially valuable solution for developing regions grappling with escalating rates of antibiotic resistance.

Therapeutic effects and mechanisms of berberine on enteritis caused by Salmonella in poultry

The present study aimed to investigate the therapeutic effects of berberine (BBR) on Salmonella enteritis in broiler chickens and to elucidate its mechanisms of action preliminarily. Blood samples were collected from 21- to 35-day-old Sanhuang male chicks to measure immune and biochemical indicators and to calculate the organ coefficients for the liver, spleen, bursa of Fabricius, and thymus. The caecal microbiota was analysed through 16S ribosomal RNA (rRNA) gene sequencing, and transcriptome sequencing was conducted. Compared with the positive control group (S), the berberine-treated group (BS) presented increased serum immunoglobulin M (IgM) levels, serum IgG levels, and total antioxidant capacity; berberine ameliorated the increase in the thymus index caused by Salmonella administration. The addition of berberine to the diet increased the abundance of beneficial bacterial genera, including Bacteroides and Lactobacillus. It also decreased the abundance of harmful bacterial genera, including Faecalibacterium and Streptococcus. Transcriptome analysis revealed that gene expression in the S and BS groups was associated with T cell selection and B cell receptor signalling pathways, which are enriched primarily in multiple immune-related signalling pathways, including the B cell receptor signalling pathway, NF-κ B signalling pathway, intestinal immune network for IgA production, asthma, and African trypanosomiasis. The significantly expressed genes included ATAD5, ERP29, MGST2, PIK3CA, and HSP90AA1. The present study demonstrated that berberine has a good therapeutic effect on Salmonella infection in chicks, as it inhibits the occurrence and development of Salmonella-induced intestinal inflammation by regulating the balance of the gut microbiota and the expression of related genes, including ATAD5, ERP29, MGST2, PIK3CA, and HSP90AA1.

Roles of Response Regulators in the Two-Component System in the Formation of Stress Tolerance, Motility and Biofilm in Salmonella Enteritidis

Two-component systems (TCS) of Salmonella enterica serovar Enteritidis are composed of a histidine kinase and a response regulator (RR) and represent a critical mechanism by which bacteria develop resistance to environmental stress. Here, we characterized the functions of RRs in TCS in the formation of stress tolerance, motility and biofilm using twenty-six S. Enteritidis RR-encoding gene deletion mutants. The viability results unraveled their essential roles in resistance to elevated temperature (GlrR), pH alterations (GlrR, TctD, YedW, ArcA and YehT), high salt (PhoB, BaeR, CpxR, PhoP, UvrY and TctD), oxidative stress (PhoB, YedW, BaeR, ArcA, PhoP, UvrY, PgtA and QseB) and motility (ArcA, GlnG, PgtA, PhoB, UhpA, OmpR, UvrY and QseB) of S. Enteritidis. The results of the crystal violet staining, microscopy observation and Congo red binding assays demonstrated that the absence of ArcA, GlnG, PhoP, OmpR, ZraR or SsrB in S. Enteritidis led to a reduction in biofilms and an impairment in red/dry/rough macrocolony formation, whereas the absence of UvrY exhibited an increase in biofilms and formed a brown/smooth/sticky macrocolony. The results indicated the regulatory effects of these RRs on the production of biofilm matrix, curli fimbriae and cellulose. Our findings yielded insights into the role of TCSs, making them a promising target for combating S. Enteritidis.

Bridging Classical Methodologies in Salmonella Investigation with Modern Technologies: A Comprehensive Review

Advancements in genomics and machine learning have significantly enhanced the study of Salmonella epidemiology. Whole-genome sequencing has revolutionized bacterial genomics, allowing for detailed analysis of genetic variation and aiding in outbreak investigations and source tracking. Short-read sequencing technologies, such as those provided by Illumina, have been instrumental in generating draft genomes that facilitate serotyping and the detection of antimicrobial resistance. Long-read sequencing technologies, including those from Pacific Biosciences and Oxford Nanopore Technologies, offer the potential for more complete genome assemblies and better insights into genetic diversity. In addition to these sequencing approaches, machine learning techniques like decision trees and random forests provide powerful tools for pattern recognition and predictive modeling. Importantly, the study of bacteriophages, which interact with Salmonella, offers additional layers of understanding. Phages can impact Salmonella population dynamics and evolution, and their integration into Salmonella genomics research holds promise for novel insights into pathogen control and epidemiology. This review revisits the history of Salmonella and its pathogenesis and highlights the integration of these modern methodologies in advancing our understanding of Salmonella.

Serovars, virulence factors, and antimicrobial resistance profile of non-typhoidal Salmonella in the human-dairy interface in Northwest Ethiopia: A one health approach

Non-typhoidal Salmonella (NTS) is a zoonotic pathogen that exerts huge public health and economic impacts in the world. The severity of illness is mainly related to the serovars involved, the presence of virulence genes, and antimicrobial resistance (AMR) patterns. However, data are scarce on serovars, virulence genes, and AMR among NTS identified from the human-dairy interface in Northwest Ethiopia. Thus, this study investigated the serovars, common virulence genes, and AMR patterns of NTS isolates in the area. The study was conducted from June 2022 to August 2023 among randomly selected 58 dairy farms. A total of 362 samples were processed to detect NTS using standard bacteriological methods. The presumptive positive colonies were confirmed by Matrix-Assisted Laser Desorption Ionization-Time-of-Flight (MALDi-ToF). Polymerase chain reaction (PCR) was used to detect virulence genes, including invA and spvC. A slide agglutination test according to the White-Kauffmann-Le Minor scheme was employed to identify the serovars of the NTS isolates. The Kirby-Bauer disk diffusion method was used to assess the antimicrobial susceptibility patterns. Of the processed samples (362), 28 (7.7%) NTS isolates were detected. When distributed among samples, the proportions were 11.9%, 10.5%, 10.3%, 5.2%, 4.3%, and 1.7% among cows' feces, dairy farm sewage, pooled raw milk, milk container swabs, milkers' stool, and milkers' hand swab samples, respectively. Six serovars were detected with the dominancy of S. Uganda (39.3%), followed by S. enterica subsp. diarizonae (25.0%) and S. Typhimurium (21.4%). Among the 28 NTS isolates, 100% and 21.4% had the virulence genes invA and spvC, respectively. The susceptibility profile showed that 89.3% of the NTS isolates were resistant to at least one antimicrobial agent and 46.4% were resistant to three or more classes of antimicrobials (multidrug-resistant). Among antimicrobials, isolates were highly resistant to ampicillin (57.1%), followed by tetracycline (42.9%) and chloramphenicol (35.7%). On the other hand, the NTS isolates were 100%, 96.4%, and 96.4% susceptible to ceftriaxone, azithromycin, and norfloxacin, respectively. In conclusion, we detected NTS from humans, dairy cows, raw milk, dairy utensils, and the environment (sewage), showing the potential of the human-dairy farm-environment nexus in the NTS circulation. These further highlight that the interface is a good point of intervention in the control and prevention of NTS infection. The susceptibility profiles of the isolate necessitate interventions including the prudent use of the antimicrobials.

Potential Involvement of Reactive Oxygen Species in the Bactericidal Activity of Eugenol against Salmonella Typhimurium

There is an increasing need to develop alternative antimicrobials to replace currently used antibiotics. Phytochemicals, such as essential oils, have garnered significant attention in recent years as potential antimicrobials. However, the mechanisms underlying their bactericidal activities are not yet fully understood. In this study, we investigated the bactericidal activity of eugenol oil against Salmonella enterica serovar Typhimurium (S. Typhimurium) to elucidate its mechanism of action. We hypothesized that eugenol exerts its bactericidal effects through the production of reactive oxygen species (ROS), which ultimately leads to cell death. The result of this study demonstrated that the bactericidal activity of eugenol against S. Typhimurium was significantly (p < 0.05) mitigated by thiourea (ROS scavenger) or iron chelator 2,2'-dipyridyl, supporting the hypothesis. This finding contributes to a better understanding of the killing mechanism by eugenol oil.

Whole-Genome Sequencing Reveals the Population Structure and Genetic Diversity of Salmonella Typhimurium ST34 and ST19 Lineages

Salmonella Typhimurium is an invasive gastrointestinal pathogen for both humans and animals. To investigate the genetic framework and diversity of S. Typhimurium, a total of 194 S. Typhimurium isolates were collected from patients in a tertiary hospital between 2020 and 2021. Antimicrobial susceptibility testing was used to confirm the resistance phenotype. Whole-genome sequencing and bioinformatics analysis were performed to determine the sequence type, phylogenetic relationships, resistance gene profiles, Salmonella pathogenicity island (SPI) and the diversity of the core and pan genome. The result showed that 57.22% of S. Typhimurium isolates were multidrug resistant and resistance of total isolates to the first-line drug ciprofloxacin was identified in 60.82%. The population structure of S. Typhimurium was categorized into three lineages: ST19 (20.10%, 39/194), ST34-1 (47.42%, 92/194) and ST34-2 (40.65%, 63/194), with the population size exhibiting increasing trends. All lineages harbored variety of fimbrial operons, prophages, SPIs and effectors that contributed to the virulence and long-term infections of S. Typhimurium. Importantly, ST34-1 lineage might potentially be more invasive due to the possession of SPI1-effector gene sopE which was essential for the proliferation, internalization and intracellular presence of S. Typhimurium in hosts. Multiple antimicrobial resistance genes were characteristically distributed across three lineages, especially carbapenem genes only detected in ST34-1&2 lineages. The distinct functional categories of pan genome among three lineages were observed in metabolism, signaling and gene information processing. This study provides a theoretical foundation for the evolved adaptation and genetic diversity of S. Typhimurium ST19 and ST34, among which ST34 lineages with multidrug resistance and potential hypervirulence need to pay more attention to epidemiological surveillance.

Managing a Salmonella Bredeney Outbreak on an Italian Dairy Farm

Salmonellosis in dairy cattle represents an increasing problem for both animal and public health. Nevertheless, in Italy, there is no control plan in place on dairy farms. The aim of this study was to describe a Salmonella Bredeney outbreak that occurred on a dairy farm and the measures that were adopted to control the outbreak. Management consisted in identifying the spread of infection and assessing the environmental contamination of Salmonella spp. and the associated risk factors. After the farm visit, laboratory investigations showed that 48% of rectal swabs collected from calves and 33% of environmental samples were positive for S. Bredeney, and a poor biosecurity level was detected. The farmer and practitioner were provided with a health management plan to control the spread of Salmonella spp., followed by a monitoring period and a follow-up visit in which all samples resulted negative. The results demonstrated the efficacy of indirect prophylaxis measures in reducing the circulation of Salmonella spp., leading to the extinction of the outbreak. Collaboration with farmers, practitioners, and public health veterinarians and the introduction of measures reported in the health management plan constitute a possible model for the management of Salmonella spp. outbreaks in dairy herds, even in complex farm situations.

Prussian-Blue-Nanozyme-Enhanced Simultaneous Immunochromatographic Control of Two Relevant Bacterial Pathogens in Milk

Salmonella typhimurium and Listeria monocytogenes are relevant foodborne bacterial pathogens which may cause serious intoxications and infectious diseases in humans. In this study, a sensitive immunochromatographic analysis (ICA) for the simultaneous detection of these two pathogens was developed. For this, test strips containing two test zones with specific monoclonal antibodies (MAb) against lipopolysaccharides of S. typhimurium and L. monocytogenes and one control zone with secondary antibodies were designed, and the double-assay conditions were optimized to ensure high analytical parameters. Prussian blue nanoparticles (PBNPs) were used as nanozyme labels and were conjugated with specific MAbs to perform a sandwich format of the ICA. Peroxidase-mimic properties of PBNPs allowed for the catalytic amplification of the colorimetric signal on test strips, enhancing the assay sensitivity. The limits of detection (LODs) of Salmonella and Listeria cells were 2 × 102 and 7 × 103 cells/mL, respectively. LODs were 100-fold less than those achieved due to the ICA based on the traditional gold label. The developed double ICA was approbated for the detection of bacteria in cow milk samples, which were processed by simple dilution by buffer before the assay. For S. typhimurium and L. monocytogenes, the recoveries from milk were 86.3 ± 9.8 and 118.2 ± 10.5% and correlated well with those estimated by the enzyme-linked immunosorbent assay as a reference method. The proposed approach was characterized by high specificity: no cross-reactivity with other bacteria strains was observed. The assay satisfies the requirements for rapid tests: a full cycle from sample acquisition to result assessment in less than half an hour. The developed ICA has a high application potential for the multiplex detection of other foodborne pathogens.

Development of a 1-step multiplex PCR assay for the detection of S. Enteritidis, S. Pullorum, S. Typhimurium, and S. Infantis associated with poultry production

Salmonellosis in poultry is detrimental to the advancement of the breeding industry and poses hazards to human health. Approximately 2,600 Salmonella varieties exist, among which S. Enteritidis, S. Pullorum, S. Typhimurium, and S. Infantis are prevalent serotypes in the poultry industry in recent years. They can also infect humans by contaminating poultry eggs and meat. Therefore, identifying these serotypes is crucial for successful preventive and control interventions. The White-Kauffmann-Le Minor scheme is time-consuming and requires expensive reagents. Whole-genome sequencing (WGS) and other molecular biology techniques require skilled technical staff. In comparison, the polymerase chain reaction (PCR) is more accurate, rapid, and inexpensive, thus proving suitable for widespread application in the poultry industry. Here, we selected 4 specific primers: lygD, mdh, ipaJ, and SIN_02055, which correspond to detecting S. Enteritidis, S. Typhimurium, S. Pullorum, and S. Infantis, respectively. They were integrated into a 1-step multiplex PCR method. We optimized the PCR method by utilizing specificity test results to determine the optimal annealing temperature (57°C). The PCR method exhibited excellent sensitivity for genomic DNA and bacterial cultures. We used the developed method to determine 157 clinical Salmonella isolates from various stages of the poultry production chain. The results aligned with serotype data generated via WGS analysis, demonstrating the method's excellent accuracy. In conclusion, this study developed a 1-step multiplex PCR method that simultaneously identifies S. Enteritidis, S. Typhimurium, S. Pullorum, and S. Infantis, allowing routine mass detection in the grass-root poultry industry.

Global Dynamics of Gastrointestinal Colonisations and Antimicrobial Resistance: Insights from International Travellers to Low- and Middle-Income Countries

Gastrointestinal microorganism resistance and dissemination are increasing, partly due to international travel. This study investigated gastrointestinal colonisations and the acquisition of antimicrobial resistance (AMR) genes among international travellers moving between Spain and low- and middle-income countries (Peru and Ethiopia). We analysed 102 stool samples from 51 volunteers collected before and after travel, revealing significantly higher rates of colonisation by both bacteria and protists upon return. Diarrhoeagenic strains of E. coli were the most notable microorganism detected using RT-PCR with the Seegene Allplex™ Gastrointestinal Panel Assays. A striking prevalence of β-lactamase resistance genes, particularly the TEM gene, was observed both before and after travel. No significant differences in AMR genes were found between the different locations. These findings highlight the need for rigorous surveillance and preventive strategies, as travel does not significantly impact AMR gene acquisition but does affect microbial colonisations. This study provides valuable insights into the intersection of gastrointestinal microorganism acquisition and AMR in international travellers, underscoring the need for targeted interventions and increased awareness.

Effectiveness of Oral Azithromycin in Treating Enteric Fever: A Hospital-Based Study on Pediatric Patients

Introduction Enteric fever is prevalent in underdeveloped and developing countries. It is caused by Salmonella Typhi, which has developed resistance over the years to commonly used antimicrobials. Meropenem is an effective treatment for all complicated and uncomplicated extensively drug-resistant (XDR) bacteria, but it is administered intravenously, three times daily, by infusion, and it is quite expensive for the patient. Oral azithromycin is shown by some authors to be effective in extensively drug-resistant enteric fever. Material and methods This retrospective cross-sectional study was conducted in the outpatient department of Lady Reading Hospital Medical Teaching Institution, Peshawar. The duration of the study was one year. Data was collected after approval from the hospital's Ethical and Research Committee. All pediatric patients meeting the inclusion criteria for extensively drug-resistant enteric fever were included. Data on patient demographics, blood culture and laboratory results, treatment given, and effectiveness were documented in a specialized proforma. Statistical Package for Social Sciences (SPSS) version 23 (IBM Corp., Armonk, NY, US) was used for data analysis. Results Out of the total 106 patients, 72 (67.9%) were male and 34 (32.1%) were female. The mean age was 7.51 ± 2.75 years, with a range of 1 to 15 years. Among them, 66 (62.3%) had anemia (hemoglobin less than 11 grams per deciliter for under 5 years and 11.5 for 5-15 years old children), with a mean hemoglobin level of 10.6 ± 1.53 grams per deciliter (g/dl), ranging from 7.2 to 13.8 g/dl. Thrombocytopenia was found in 14 (13%) patients. The mean platelet count was 317 x 103 ± 164 cells per microliter, with a range of 61 x 103 to 834 x 103 cells per liter. The mean total leukocyte count was 9.71x 103 ± 4.321 cells per microliter, with a range of 2.01 x 103 to 30.40 x103 cells per microliter. However, leucopenia was seen in only 5 (4.7%) patients. In 98.1% of cases, azithromycin was found to be effective in treating enteric fever caused by extensively drug-resistant Salmonella. Conclusion Azithromycin is effective in treating extensively drug-resistant enteric fever. It can be confidently used in patients with no or mild complications with extensively drug-resistant enteric fever. Good compliance and complete dosage should be followed to avoid resistance to this drug. Blood cultures should always be sent when prescribing antibiotics, especially when suspecting enteric fever.

Salmonella spp. in Domestic Ruminants, Evaluation of Antimicrobial Resistance Based on the One Health Approach-A Systematic Review and Meta-Analysis

Salmonella spp. pose a global threat as a leading cause of foodborne illnesses, particularly prevalent in the European Union (EU), where it remains the second cause of foodborne outbreaks. The emergence of antimicrobial resistance (AMR) in Salmonella spp. has become a critical concern, complicating treatment strategies and escalating the risk of severe infections. The study focuses on large and small ruminants, identifying a prevalence of Salmonella spp. in slaughterhouses and revealing varied AMR rates across antimicrobial families throughout a meta-analysis. Also, comparison with AMR in human medicine was carried out by a systematic review. The results of the present meta-analysis displayed a prevalence of Salmonella spp. in large and small ruminants at slaughterhouses of 8.01% (8.31%, cattle; 7.04%, goats; 6.12%, sheep). According to the AMR of Salmonella spp., 20, 14, and 13 out of 62 antimicrobials studied were classified as low (<5%), high (>5% but <10%), and very high (>10%), respectively. Salmonella spp. did not display AMR against aztreonam, mezlocillin, ertapenem, meropenem, cefoxitin, ceftazidime, levofloxacin, tilmicosin, linezolid, fosfomycin, furazolidone, quinupristin, trimethoprim and spectinomycin. In contrast, a prevalence of 100% of AMR has been described against ofloxacin, lincomycin, and cloxacillin. In the context of the main antibiotics used in the treatment of human salmonellosis, azithromycin was shown to have the highest resistance among Salmonella spp. isolates from humans. Regarding cephalosporins, which are also used for the treatment of salmonellosis in humans, the prevalence of Salmonella spp. resistance to this class of antibiotics was similar in both human and animal samples. Concerning quinolones, despite a heightened resistance profile in Salmonella spp. isolates from ruminant samples, there appears to be no discernible compromise to the efficacy of salmonellosis treatment in humans since lower prevalences of AMR in Salmonella spp. isolated from human specimens were observed. Although the resistance of Salmonella spp. indicates some degree of concern, most antibiotics are not used in veterinary medicine. Thus, the contribution of cattle, sheep and goats to the rise of antibiotic resistance of Salmonella spp. and its potential impact on public health appears to be relatively insignificant, due to their low prevalence in carcasses and organs. Nevertheless, the observed low prevalence of Salmonella spp. in ruminants at slaughterhouse and the correspondingly low AMR rates of Salmonella spp. to key antibiotics employed in human medicine do not indicate that ruminant livestock poses a substantial public health risk concerning the transmission of AMR. Thus, the results observed in both the meta-analysis and systematic review suggests that AMR is not solely attributed to veterinary antibiotic use but is also influenced by factors such as animal health management (i.e., biosecurity measures, prophylactic schemes) and human medicine.

Emerging Strategies against Non-Typhoidal Salmonella: From Pathogenesis to Treatment

Even with the intensive efforts by public health programs to control and prevent it, non-typhoidal Salmonella (NTS) infection remains an important public health challenge. It is responsible for approximately 150 million illnesses and 60,000 deaths worldwide annually. NTS infection poses significant risks with high rates of morbidity and mortality, leading to potential short- and long-term complications. There is growing concern among health authorities about the increasing incidence of antimicrobial resistance, with multidrug resistance totaling 22.6% in Europe, highlighting an urgent need for new therapeutic approaches. Our review aims to provide a comprehensive overview of NTS infection. We outline the molecular mechanisms involved in the pathogenesis of NTS infection, as well as the events leading to invasive NTS infection and the subsequent complications associated with it. Given the widespread implications of antimicrobial resistance, our review also presents the global landscape of resistance, including multidrug resistance, and delve into the underlying mechanisms driving this resistance. The rising rates of antibiotic resistance frequently lead to treatment failures, emphasizing the importance of investigating alternative therapeutic options. Therefore, in this review we also explore potential alternative therapies that could offer promising approaches to treating NTS infections.

Meat quality and safety issues during high temperatures and cutting-edge technologies to mitigate the scenario

Climate change, driven by the natural process of global warming, is a worldwide issue of significant concern because of its adverse effects on livestock output. The increasing trend of environmental temperature surging has drastically affected meat production and meat product quality, hence result in economic losses for the worldwide livestock business. Due to the increasing greenhouse gas emissions, the situation would get prolonged, and heat exposure-related stress is expected to worsen. Heat exposure causes metabolic and physiological disruptions in livestock. Ruminants and monogastric animals are very sensitive to heat stress due to their rate of metabolism, development, and higher production levels. Before slaughter, intense hot weather triggers muscle glycogen breakdown, producing pale, mushy, and exudative meat with less water-holding capacity. Animals exposed to prolonged high temperatures experience a decrease in their muscle glycogen reserves, producing dry, dark, and complex meat with elevated final pH and increased water-holding capacity. Furthermore, heat stress also causes oxidative stresses, especially secondary metabolites from lipid oxidation, severely affects the functionality of proteins, oxidation of proteins, decreasing shelf life, and food safety by promoting exfoliation and bacterial growth. Addressing the heat-related issues to retain the sustainability of the meat sector is an essential task that deserves an inclusive and comprehensive approach. Considering the intensity of the heat stress effects, this review has been designed primarily to examine the consequences of hot environment temperatures and related stresses on the quality and safety of meat and secondarily focus on cutting edge technology to reduce or alleviate the situational impact.

A Case of Food-Borne Salmonellosis in a Corn Snake (Pantherophis guttatus) after a Feeder Mouse Meal

Reptiles are usually asymptomatic carriers of Salmonella, with the manifestation of typical clinical signs of acute forms in adult and non-immunocompromised animals being considered exceptions. In the present case, an adult male corn snake (Pantherophis guttatus) was found dead due to septic shock 48 h after consuming a feeder mouse purchased online. The snake's tissue samples and faeces were cultured for bacteria isolation. Microbiological examinations of the snake and mouse livers revealed the presence of Salmonella enterica subsp. enterica serovar Midway. A whole-genome analysis of these two isolates showed a high correlation between them: they belonged to the strain type ST-357 for the classic MLST scheme and to the strain type ST 171322 for the cgMLST scheme. Also, a virulence gene analysis revealed the presence of stdB and STM3026 genes. This report conveys a case of food-borne salmonellosis in a pet snake, transmitted from a feeder mouse, likely responsible for the snake's death due to septic shock. It highlights the relevance of feeder mice as a source of Salmonella infections in snakes and the associated risks to human health.

Tackling salmonellosis: A comprehensive exploration of risks factors, impacts, and solutions

Salmonellosis, caused by Salmonella species, is one of the most common foodborne illnesses worldwide with an estimated 93.8 million cases and about 155,00 fatalities. In both industrialized and developing nations, Salmonellosis has been reported to be one of the most prevalent foodborne zoonoses and is linked with arrays of illness syndromes such as acute and chronic enteritis, and septicaemia. The two major and most common Salmonella species implicated in both warm-blooded and cold-blooded animals are Salmonella bongori and Salmonella enterica. To date, more than 2400 S. enterica serovars which affect both humans and animals have been identified. Salmonella is further classified into serotypes based on three primary antigenic determinants: somatic (O), flagella (H), and capsular (K). The capacity of nearly all Salmonella species to infect, multiply, and survive in human host cells with the aid of their pathogenic and virulence arsenals makes them deadly and important public health pathogens. Primarily, food-producing animals such as poultry, swine, cattle, and their products have been identified as important sources of salmonellosis. Additionally, raw fruits and vegetables are among other food types that have been linked to the spread of Salmonella spp. Based on the clinical manifestation of human salmonellosis, Salmonella strains can be categorized as either non-typhoidal Salmonella (NTS) and typhoidal Salmonella. The detection of aseptically collected Salmonella in necropsies, environmental samples, feedstuffs, rectal swabs, and food products serves as the basis for diagnosis. In developing nations, typhoid fever due to Salmonella Typhi typically results in the death of 5%-30% of those affected. The World Health Organization (WHO) calculated that there are between 16 and 17 million typhoid cases worldwide each year, with scaring 600,000 deaths as a result. The contagiousness of a Salmonella outbreak depends on the bacterial strain, serovar, growth environment, and host susceptibility. Risk factors for Salmonella infection include a variety of foods; for example, contaminated chicken, beef, and pork. Globally, there is a growing incidence and emergence of life-threatening clinical cases, especially due to multidrug-resistant (MDR) Salmonella spp, including strains exhibiting resistance to important antimicrobials such as beta-lactams, fluoroquinolones, and third-generation cephalosporins. In extreme cases, especially in situations involving very difficult-to-treat strains, death usually results. The severity of the infections resulting from Salmonella pathogens is dependent on the serovar type, host susceptibility, the type of bacterial strains, and growth environment. This review therefore aims to detail the nomenclature, etiology, history, pathogenesis, reservoir, clinical manifestations, diagnosis, epidemiology, transmission, risk factors, antimicrobial resistance, public health importance, economic impact, treatment, and control of salmonellosis.

The In Vitro Antibacterial Activity of Phytogenic and Acid-Based Eubiotics against Major Foodborne Zoonotic Poultry Pathogens

The aim of the study was to investigate in vitro the antibacterial activity of 8 commercial drinking water additives against major zoonotic poultry pathogens (Campylobacter spp., Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus and Listeria spp.). We tested two essential oil-based phytogenics (Phyto CSC Liquide B, AEN 350 B Liquid), two acid-based eubiotics (Salgard® liquid, Intesti-Flora), and four blends of essential oils and organic acids (ProPhorceTM SA Exclusive, Herbal acid, Rigosol-N and Eubisan 3000). The antibacterial activity was determined by estimating the minimum inhibitory concentration (MIC) using a microdilution method. The MICs of the products against Campylobacter spp. ranged from 0.071% to 0.568% v/v, in which Herbal acid, a blend rich in lactic and phosphoric acids, also containing thyme and oregano oils, exhibited the highest efficacy (MIC: 0.071% v/v) against all the tested strains. The MICs of the tested products against Escherichia coli ranged between 0.071% and 1.894% v/v. Specifically, the MIC of Rigosol-N, a blend of high concentrations of lactic and acetic acid, was 0.142% v/v for both tested strains, whereas the MICs of Intesti-Flora, a mixture rich in lactic and propionic acid, ranged from 0.284% to 0.568% v/v. The MICs of the products against Salmonella Typhimurium were between 0.095% and 1.894% v/v. Specifically, the MIC of Eubisan 3000, a blend rich in oregano oil, was 0.284% v/v. The MICs against Staphylococcus aureus were between 0.142% and 9.090% v/v. The MICs of Phyto CSC Liquide B, which is rich in trans-cinnamaldehyde, were between 3.030% and 9.090% v/v, showing the highest MIC values of all tested products. Finally, the MIC values of the tested commercial products against Listeria spp. were 0.095% to 3.030% v/v. The MICs of ProPhorceTM SA Exclusive, a highly concentrated blend of formic acid and its salts, were 0.095-0.142% v/v against Listeria spp., while the MICs of AEN 350 B Liquid were between 0.284% and 1.894% exhibiting high Listeria spp. strain variability. In conclusion, all the selected commercial products exhibited more or less antibacterial activity against pathogenic bacteria and, thus, can be promising alternatives to antibiotics for the control of zoonotic poultry pathogens and the restriction of antimicrobial-resistant bacteria.

A Proof-of-Concept Protein Microarray-Based Approach for Serotyping of Salmonella enterica Strains

Salmonella enterica, a bacterium causing foodborne illnesses like salmonellosis, is prevalent in Europe and globally. It is found in food, water, and soil, leading to symptoms like diarrhea and fever. Annually, it results in about 95 million cases worldwide, with increasing antibiotic resistance posing a public health challenge. Therefore, it is necessary to detect and serotype Salmonella for several reasons. The identification of the serovars of Salmonella enterica isolates is crucial to detect and trace outbreaks and to implement effective control measures. Our work presents a protein-based microarray for the rapid and accurate determination of Salmonella serovars. The microarray carries a set of antibodies that can detect different Salmonella O- and H-antigens, allowing for the identification of multiple serovars, including Typhimurium and Enteritidis, in a single miniaturized assay. The system is fast, economical, accurate, and requires only small sample volumes. Also, it is not required to maintain an extensive collection of sera for the serotyping of Salmonella enterica serovars and can be easily expanded and adapted to new serovars and sera. The scientific state of the art in Salmonella serotyping involves the comparison of traditional, molecular, and in silico methods, with a focus on economy, multiplexing, accuracy, rapidity, and adaptability to new serovars and sera. The development of protein-based microarrays, such as the one presented in our work, contributes to the ongoing advancements in this field.

Salmonella Control in Swine: A Thoughtful Discussion of the Pre- and Post-Harvest Control Approaches in Industrialized Countries

Pork is among the major sources of human salmonellosis in developed countries. Since the 1990s, different surveys and cross-sectional studies, both national and international (i.e., the baseline studies performed in the European Union), have revealed and confirmed the widespread non-typhoidal Salmonella serotypes in pigs. A number of countries have implemented control programs with different approaches and degrees of success. The efforts could be implemented either at farms, in post-harvest stages, or both. The current review revises the current state of the art in Salmonella in swine, the control programs ongoing or conducted in the past, and their strengths and failures, with particular attention to the weight of pre- and post-harvest control and the implications that both have for the success of interventions or mitigation after outbreaks. This review provides a novel perspective on Salmonella control in swine, a matter that still includes uncertainties and room for improvement as a question of public health and One Health.

A Retrospective Analysis of Salmonella Isolates across 11 Animal Species (1982-1999) Led to the First Identification of Chromosomally Encoded blaSCO-1 in the USA

Antimicrobial resistance (AMR) in non-typhoidal Salmonella is a pressing public health concern in the United States, necessitating continuous surveillance. We conducted a retrospective analysis of 251 Salmonella isolates from 11 animal species recovered between 1982 and 1999, utilizing serotyping, antimicrobial susceptibility testing, and whole-genome sequencing (WGS). Phenotypic resistance was observed in 101 isolates, with S. Typhimurium, S. Dublin, S. Agona, and S. Muenster prevailing among 36 identified serovars. Notably, resistance to 12 of 17 antibiotics was detected, with ampicillin being most prevalent (79/251). We identified 38 resistance genes, primarily mediating aminoglycoside (n = 13) and β-lactamase (n = 6) resistance. Plasmid analysis unveiled nine distinct plasmids associated with AMR genes in these isolates. Chromosomally encoded blaSCO-1 was present in three S. Typhimurium and two S. Muenster isolates from equine samples, conferring resistance to amoxicillin/clavulanic acid. Phylogenetic analysis revealed three distinct clusters for these five isolates, indicating evolutionary divergence. This study represents the first report of blaSCO-1 in the USA, and our recovered isolates harboring this gene as early as 1989 precede those of all other reports. The enigmatic nature of blaSCO-1 prompts further research into its function. Our findings highlight the urgency of addressing antimicrobial resistance in Salmonella for effective public health interventions.