Intranasal delivery of Salmonella OMVs decorated with Chlamydia trachomatis antigens induces specific local and systemic immune responses

Chlamydia trachomatis is an obligate intracellular pathogen responsible for the most prevalent bacterial sexually transmitted disease globally. The high prevalence of chlamydial infections underscores the urgent need for licensed and effective vaccines to prevent transmission in populations. Bacterial outer membrane vesicles (OMVs) have emerged as promising mucosal vaccine carriers due to their inherent adjuvant properties and the ability to display heterologous antigens. In this proof-of-concept study, we evaluated the immunogenicity of Salmonella OMVs decorated with C. trachomatis MOMP-derived CTH522 or HtrA antigens in mice. Following a prime-boost intranasal vaccination approach, two OMV-based C. trachomatis vaccines elicited significant humoral responses specific to the antigens in both systemic and vaginal compartments. Furthermore, we demonstrated strong antigen-specific IFN-γ and IL17a responses in splenocytes and cervical lymph node cells of vaccinated mice, indicating CD4+ Th1 and Th17 biased immune responses. Notably, the OMV-CTH522 vaccine also induced the production of spleen-derived CD8+ T cells expressing IFN-γ. In conclusion, these results highlight the potential of OMV-based C. trachomatis vaccines for successful use in future challenge studies and demonstrate the suitability of our modular OMV platform for intranasal vaccine applications.

Added insult to injury? The response of meat-associated pathogens to proposed antimicrobial interventions

Modern requirements for 'green label' meat products have led to the design of novel antimicrobial innovations which prioritise quality, safety and longevity. Plasma-functionalised water (PFW), ultraviolet light and natural antimicrobial compositions have been investigated and optimised for control of foodborne pathogens like Campylobacter jejuni and Salmonella enterica serovar Typhimurium. However, given the adaptive mechanisms present in bacteria under external stresses, it is imperative to understand the effect that sublethal treatment may have on the bacterial transcriptome. In this study, Salmonella Typhimurium and C. jejuni were treated with sublethal doses of ultraviolet light, a citrus juice/essential oil marinade, and 'spark' or 'glow' cold plasma generation system-produced PFW. Immediately after treatment, cells were lysed and RNA was extracted and purified. mRNA was converted to cDNA by reverse transcription-PCR and sequenced by an Illumina MiSeq® system. Sequences were filtered and analysed using the Tuxedo workflow. Sublethal treatment of Campylobacter jejuni and Salmonella Typhimurium led to increased immediate cellular and metabolic activity, as well as diversification in protein and metabolic functioning. There was further expression of pathogenesis and virulence-associated traits associated with spark PFW and marinade treatment of Salmonella Typhimurium. However, similar concerns were not raised with glow PFW or UV-treated samples. This study provides science-based evidence of the efficacy of multi-hurdle antimicrobial system using green-label marinades and PFW or UV to inactivate pathogens without upregulating virulence traits in surviving cells. This study will inform policymakers and food industry stakeholders and reinforces the need to incorporate in-line novel technologies to ensure consumer safety. KEY POINTS: • Salmonella and C. jejuni showed increased cell activity in immediate response to stress. • Virulence genes showed increased expression when treated with natural antimicrobials and sPFW. • Reduced immediate transcriptomic response to gPFW and UV treatment indicates lower risk.

It takes two to attach - endo-1,3-β-d-glucanase as a potential receptor of mannose-independent, FimH-dependent Salmonella Typhimurium binding to spinach leaves

Currently, fresh, unprocessed food has become a relevant element of the chain of transmission of enteropathogenic infections. To survive on a plant surface and further spread the infections, pathogens like Salmonella have to attach stably to the leaf surface. Adhesion, driven by various virulence factors, including the most abundant fim operon encoding type 1 fimbriae, is usually an initial step of infection, preventing physical removal of the pathogen. Adhesion properties of Salmonella's type 1 fimbriae and its FimH adhesin were investigated intensively in the past. However, there is a lack of knowledge regarding its role in interaction with plant cells. Understanding the mechanisms and structures involved in such interaction may facilitate efforts to decrease the risk of contamination and increase fresh food safety. Here, we applied Salmonella genome site-directed mutagenesis, adhesion assays, protein-protein interactions, and biophysics methods based on surface plasmon resonance to unravel the role of FimH adhesin in interaction with spinach leaves. We show that FimH is at least partially responsible for Salmonella binding to spinach leaves, and this interaction occurs in a mannose-independent manner. Importantly, we identified a potential FimH receptor as endo-1,3-β-d-Glucanase and found that this interaction is strong and specific, with a dissociation constant in the nanomolar range. This research advances our comprehension of Salmonella's interactions with plant surfaces, offering insights that can aid in minimizing contamination risks and improving the safety of fresh, unprocessed foods.

Total coliforms, microbial diversity and multiple characteristics of Salmonella in soil-irrigation water-fresh vegetable system in Shaanxi, China

Global occurrences of foodborne disease outbreaks have been documented, involving fresh agricultural produce contaminated by various pathogens. This contamination can occur at any point in the supply chain. However, studies on the prevalence of total coliforms, Salmonella and microbial diversity in vegetable and associated environments are limited. This study aimed to assess 1) the number of total coliforms (n = 299) and diversity of microbial communities (n = 52); 2) the prevalence, antibiotic susceptibility, genomic characteristics, and potential transmission relationships of Salmonella in soil-irrigation water-vegetable system (n = 506). Overall, 84.28 % samples were positive to total coliforms, with most frequently detected in soil (100 %), followed by irrigation water (79.26 %) and vegetables (62.00 %). A seasonal trend in coliform prevalence was observed, with significantly higher levels in summer (P < 0.05). Detection rates of Salmonella in soil, vegetable and irrigation water were 2.21 %, 4.74 % and 9.40 %. Fourteen serotypes and sequence types (STs) were respectively annotated in 56 Salmonella isolates, ST13 S. Agona (30.36 %, 17/56), ST469 S. Rissen (25.00 %, 14/56), and ST36 S. Typhimurium (12.50 %, 7/56) were dominant serotypes and STs. Thirty-one (55.36 %) isolates were multi-drug resistant, and the resistance was most frequently found to ampicillin (55.36 %, 31/56), followed by to sulfamethoxazole (51.79 %, 29/56) and tetracycline (50.00 %, 28/56). The genomic characteristics and antibiotic resistance patterns of Salmonella isolates from soil, vegetables, and irrigation water within a coherent geographical locale exhibited remarkable similarities, indicating Salmonella may be transmitted among these environments or have a common source of contamination. Microbial alpha diversity indices in soil were significantly higher (P < 0.05) than that in vegetable and irrigation water. The microbial phylum in irrigation water covered that in the vegetable, demonstrating a significant overlap in the microbial communities between the vegetables and the irrigation water.

Cananga oil inhibits Salmonella infection by mediating the homeostasis of purine metabolism and the TCA cycle

ETHNOPHARMACOLOGY RELEVANCE

Cananga oil (CO) is derived from the flowers of the traditional medicinal plant, the ylang-ylang tree. As a traditional antidepressant, CO is commonly utilized in the treatment of various mental disorders including depression, anxiety, and autism. It is also recognized as an efficient antibacterial insecticide, and has been traditionally utilized to combat malaria and acute inflammatory responses resulting from bacterial infections both in vitro and in vivo.

AIM OF THE STUDY

The objective of this study is to comprehensively investigate the anti-Salmonella activity and mechanism of CO both in vitro and in vivo, with the expectation of providing feasible strategies for exploring new antimicrobial strategies and developing novel drugs.

METHODS

The in vitro antibacterial activity of CO was comprehensively analyzed by measuring MIC, MBC, growth curve, time-killing curve, surface motility, biofilm, and Live/dead bacterial staining. The analysis of the chemistry and active ingredients of CO was conducted using GC-MS. To examine the influence of CO on the membrane homeostasis of Salmonella, we conducted utilizing diverse techniques, including ANS, PI, NPN, ONPG, BCECF-AM, DiSC3(5), and scanning electron microscopy (SEM) analysis. In addition, the antibacterial mechanism of CO was analyzed and validated through metabolomics analysis. Finally, a mouse infection model of Salmonella typhimurium was established to evaluate the toxic side effects and therapeutic effects of CO.

RESULTS

The antibacterial effect of CO is the result of the combined action of the main chemical components within its six (palmitic acid, α-linolenic acid, stearic acid, benzyl benzoate, benzyl acetate, and myristic acid). Furthermore, CO disrupts the balance of purine metabolism and the tricarboxylic acid cycle (TCA cycle) in Salmonella, interfering with redox processes. This leads to energy metabolic disorders and oxidative stress damage within the bacteria, resulting in bacterial shock, enhanced membrane damage, and ultimately bacterial death. It is worth emphasizing that CO exerts an effective protective influence on Salmonella infection in vivo within a non-toxic concentration range.

CONCLUSION

The outcomes indicate that CO displays remarkable anti-Salmonella activity both in vitro and in vivo. It triggers bacterial death by disrupting the balance of purine metabolism and the TCA cycle, interfering with the redox process, making it a promising anti-Salmonella medication.

Utilizing fab fragment-conjugated surface plasmon resonance-based biosensor for detection of Salmonella Enteritidis

Although antibodies, a key element of biorecognition, are frequently used as biosensor probes, the use of these large molecules can lead to adverse effects. Fab fragments can be reduced to allow proper antigen-binding orientation via thiol groups containing Fab sites that can directly penetrate Au sites chemically. In this study, the ability of the surface plasmon resonance (SPR) sensor to detect Salmonella was studied. Tris(2-carboxyethyl)phosphine was used as a reducing agent to obtain half antibody fragments. Sensor surface was immobilized with antibody, and bacteria suspensions were injected from low to high concentrations. Response units were changed by binding first reduced antibody fragments, then bacteria. The biosensor was able to determine the bacterial concentrations between 103 and 108 CFU/mL. Based on these results, the half antibody fragmentation method can be generalized for faster, label-free, sensitive, and selective detection of other bacteria species.

Unveiling the landscape of resistance against high priority critically important antimicrobials in food-producing animals across Africa: A scoping review

The rapid population growth in Africa is associated with an increasing demand for livestock products which in turn can lead to antimicrobial use. Antimicrobial usage in animals contributes to the emergence and selection of resistant bacteria which constitutes a serious public health threat. This study aims to review and summarize the available information on highest priority critically important antimicrobials (HPCIAs) resistance in livestock production in Africa. This work will help to inform future policies for controlling antimicrobial resistance (AMR) in the food production chain. A scoping review was conducted according to the Cochrane handbook and following PRISMA 2020 guidelines for reporting. Primary research studies published after 1999 and reporting resistance of Escherichia coli, Enterococcus spp, Staphylococcus aureus, Salmonella spp, and Campylobacter spp to HPCIAs in poultry, cattle, pigs, goats, and sheep in Africa were searched in four databases. A total of 312 articles were included in the review. The majority of the studies (40.7) were conducted in North African countries. More than 49.0% of included studies involved poultry and 26.2% cattle. Cephalosporins and quinolones were the most studied antimicrobial classes. Of the bacteria investigated in the current review, E. coli (41.7%) and Salmonella spp (24.9%) represented the most commonly studied. High levels of resistance against erythromycin in E. coli were found in poultry (MR 96.1%, IQR 83.3-100.0%), cattle (MR 85.7%, IQR 69.2-100.0%), and pigs (MR 94.0%, IQR 86.2-94.0%). In sheep, a high level of resistance was observed in E. coli against nalidixic acid (MR 87.5%, IQR 81.3-93.8%). In goats, the low level of sensibility was noted in S. aureus against streptomycin (MR 86.8%, IQR 19.4-99.0%). The study provides valuable information on HPCIAs resistance in livestock production in Africa and highlights the need for further research and policies to address the public health risk of AMR. This will likely require an investment in diagnostic infrastructure across the continent. Awareness on the harmful impact of AMR in African countries is a requirement to produce more effective and sustainable measures to curb AMR.

Growth assessment of Salmonella enterica multi-serovar populations in poultry rinsates with commonly used enrichment and plating media

Isolation of Salmonella from enrichment cultures of food or environmental samples is a complicated process. Numerous factors including fitness in various selective enrichment media, relative starting concentrations in pre-enrichment, and competition among multi-serovar populations and associated natural microflora, come together to determine which serovars are identified from a given sample. A recently developed approach for assessing the relative abundance (RA) of multi-serovar Salmonella populations (CRISPR-SeroSeq or Deep Serotyping, DST) is providing new insight into how these factors impact the serovars observed, especially when different selective enrichment methods are used to identify Salmonella from a primary enrichment sample. To illustrate this, we examined Salmonella-positive poultry pre-enrichment samples through the selective enrichment process in Tetrathionate (TT) and Rappaport Vassiliadis (RVS) broths and assessed recovery of serovars with each medium. We observed the RA of serovars detected post selective enrichment varied depending on the medium used, initial concentration, and competitive fitness factors, all which could result in minority serovars in pre-enrichment becoming dominant serovars post selective enrichment. The data presented provide a greater understanding of culture biases and lays the groundwork for investigations into robust enrichment and plating media combinations for detecting Salmonella serovars of greater concern for human health.

Updates for Reptile Pediatric Medicine

The health of hatchling, juvenile, and young adult reptiles continues to be plagued by historic nutritional deficiencies, old and emerging infectious diseases, and more recent phenotype-selective congenital abnormalities that impact welfare. Knowledge of mating seasonality, average egg counts, gestation times, and age and/or size for sexual maturity is necessary to help guide best practices for care of pediatric reptiles. Calcium, vitamin D3, and ultraviolet B (UVB) lighting recommendations vary in effectiveness amongst different species and can change with age. Phenotype-selective color patterns for spider ball pythons and scalation pattern for bearded dragons have resulted in vestibular disease, and increased evaporative water loss, respectively. Salmonellosis remains the most reported zoonotic disease for captive reptiles in the United States, despite improvements in client education and improvements in captive reptile husbandry.

Cell-free synthesis of the Salmonella specific broad host range bacteriophage, felixO1

Phage-based biocontrol of foodborne Salmonella is limited by the requisite use of Salmonella to propagate the phages. This limitation can be circumvented by producing Salmonella phages using a cell-free gene expression system (CFE) with a non-pathogenic chassis. Here, we produce the Salmonella phage felixO1 using an E. coli-based CFE system.

Investigation of Salmonella, hepatitis E virus (HEV) and viral indicators of fecal contamination in four Italian pig slaughterhouses, 2021-2022

In the pork production chain, the control at slaughterhouse aims to ensure safe food thanks to proper hygienic conditions during all steps of the slaughtering. Salmonella is one of the main foodborne pathogens in the EU causing a great number of human cases, and pigs also contribute to its spreading. Pig is the main reservoir of the zoonotic hepatitis E virus (HEV) that can be present in liver, bile, feces and even rarely in blood and muscle. The aim of this study was to assess the presence of both Salmonella and HEV in several points of the slaughtering chain, including pig trucks. Other viruses hosted in the gut flora of pigs and shed in feces were also assayed (porcine adenovirus PAdV, rotavirus, norovirus, and mammalian orthoreovirus MRV). Torque teno sus virus (TTSuV) present in both feces, liver and blood was also considered. Four Italian pig abattoirs were sampled in 12 critical points, 5 of which were the outer surface of carcasses before processing. HEV and rotavirus (RVA) were not detected. Norovirus was detected once. Salmonella was detected in two of the 4 abattoirs: in the two lairage pens, in the site of evisceration and on one carcass, indicating the presence of Salmonella if carcass is improper handled. The sampling sites positive for Salmonella were also positive for PAdV. MRV was detected in 10 swabs, from only two abattoirs, mainly in outer surface of carcasses. TTSuV was also detected in all abattoirs. Our study has revealed a diverse group of viruses, each serving as indicator of either fecal (NoV, RVA, PAdV, MRV) or blood contamination (TTSuV). TTSuV could be relevant as blood contamination indicators, crucial for viruses with a viremic stage, such as HEV. The simultaneous presence of PAdV with Salmonella is relevant, suggesting PAdV as a promising indicator for fecal contamination for both bacterial and viruses. In conclusion, even in the absence of HEV, the widespread presence of Salmonella at various points in the chain, underscores the need for vigilant monitoring and mitigation strategies which could be achieved by testing not only bacteria indicators as expected by current regulation, but also some viruses (PAdV, TTSuV, MRV) which could represent other sources of fecal contamination.

Prevalence and Serotype of Poultry Salmonellosis in Africa: a Systemic Review and Meta-Analysis

Salmonellosis represents a significant economic and public health concern for the poultry industry in Africa, leading to substantial economic losses due to mortality, reduced productivity, and food safety problems. However, comprehensive information on the burden of poultry salmonellosis at the continental level are scarce. To address this gap, a systemic review and meta-analysis were conducted to consolidate information on the prevalence and circulating serotypes of poultry salmonellosis in African countries. This involved the selection and review of 130 articles published between 1984 and 2021. A detailed systematic review protocol was structured according to Cochrane STROBE and PRISMA statement guidelines. From the 130 selected articles from 23 different African countries, the overall pooled prevalence estimate (PPE) of poultry salmonellosis in Africa was found to be 14.4% (95% CI= 0.145-0.151). Cameroon reported the highest PPE at 71.9%, with the country also noting the highest specific prevalence of 93.3%. The PPE was notably high in meat and meat products at 23%, indicating significant contamination of Salmonella in African poultry meat and meat products. The number of research papers reporting poultry salmonellosis in Africa has been a threefold increase from 1984 to 2021. Salmonella Enteritidis and Typhimurium were the two most prevalent serotypes reported in 18 African countries. Besides, Salmonella Kentucky, Virchow, Gallinarum, and Pullorum were also widely reported. Western Africa had the highest diversity of reported Salmonella serotypes (141), in contrast to southern Africa, which reported only 27 different serotypes. In conclusion, poultry salmonellosis is highly prevalent across Africa, with a variety of known serotypes circulating throughout the continent. Consequently, it is crucial to implement strategic plans for the prevention and control of Salmonella in Africa.

Megaplasmid Dissemination in Multidrug-Resistant Salmonella Serotypes from Backyard and Commercial Broiler Production Systems in the Southeastern United States

Over the past decade, there has been a rise in U.S. backyard poultry ownership, raising concern for residential area antimicrobial-resistant (AMR) Salmonella contamination. This study aims to lay the groundwork to better understand the persistence of AMR Salmonella in residential broiler production systems and make comparisons with commercial systems. Ten backyard and 10 commercial farms were sampled at three time points across bird production. Both fecal (n = 10) and environmental (soil, n = 5, litter/compost, n = 5, feeder, and waterer swabs, n = 6) samples were collected at each visit on days 10, 31, and 52 of production for backyard farms and days 10, 24, and 38 of production for commercial farms. AMR Salmonella was characterized phenotypically by broth microdilution and genotypically by whole-genome sequencing. Overall, Salmonella was more prevalent in commercial farm samples (52.31%) over backyard farms (19.10%). Kentucky (sequence type (ST) 152) was the most common serotype found in both backyard and commercial farms. Multidrug-resistant (MDR, resistance to ≥3 or more antimicrobial classes) isolates were found in both production systems, while ciprofloxacin- and nalidixic acid-resistant and intermediate isolates were more prevalent in commercial (33%) than backyard samples (1%). Plasmids that have been associated with MDR were found in Kentucky and Infantis isolates, particularly IncFIB(K)_1_Kpn3 megaplasmid (Infantis). Our study emphasizes the need to understand the selection pressures in disseminating megaplasmids in MDR Salmonella in distinct broiler production systems.

Development of a sensor for disulfide bond formation in diverse bacteria

In bacteria, disulfide bonds contribute to the folding and stability of proteins important for processes in the cellular envelope. In Escherichia coli, disulfide bond formation is catalyzed by DsbA and DsbB enzymes. DsbA is a periplasmic protein that catalyzes disulfide bond formation in substrate proteins, while DsbB is an inner membrane protein that transfers electrons from DsbA to quinones, thereby regenerating the DsbA active state. Actinobacteria including mycobacteria use an alternative enzyme named VKOR, which performs the same function as DsbB. Disulfide bond formation enzymes, DsbA and DsbB/VKOR, represent novel drug targets because their inhibition could simultaneously affect the folding of several cell envelope proteins including virulence factors, proteins involved in outer membrane biogenesis, cell division, and antibiotic resistance. We have previously developed a cell-based and target-based assay to identify molecules that inhibit the DsbB and VKOR in pathogenic bacteria, using E. coli cells expressing a periplasmic β-Galactosidase sensor (β-Galdbs), which is only active when disulfide bond formation is inhibited. Here, we report the construction of plasmids that allows fine-tuning of the expression of the β-Galdbs sensor and can be mobilized into other gram-negative organisms. As an example, when expressed in Pseudomonas aeruginosa UCBPP-PA14, which harbors two DsbB homologs, β-Galdbs behaves similarly as in E. coli, and the biosensor responds to the inhibition of the two DsbB proteins. Thus, these β-Galdbs reporter plasmids provide a basis to identify novel inhibitors of DsbA and DsbB/VKOR in multidrug-resistant gram-negative pathogens and to further study oxidative protein folding in diverse gram-negative bacteria.

IMPORTANCE

Disulfide bonds contribute to the folding and stability of proteins in the bacterial cell envelope. Disulfide bond-forming enzymes represent new drug targets against multidrug-resistant bacteria because inactivation of this process would simultaneously affect several proteins in the cell envelope, including virulence factors, toxins, proteins involved in outer membrane biogenesis, cell division, and antibiotic resistance. Identifying the enzymes involved in disulfide bond formation in gram-negative pathogens as well as their inhibitors can contribute to the much-needed antibacterial innovation. In this work, we developed sensors of disulfide bond formation for gram-negative bacteria. These tools will enable the study of disulfide bond formation and the identification of inhibitors for this crucial process in diverse gram-negative pathogens.

An Innovative and Efficient Fluorescent Detection Technique for Salmonella in Animal-Derived Foods Using the CRISPR/Cas12a-HCR System Combined with PCR/RAA

Here, we present a method for Salmonella detection using clustered regularly interspaced short palindromic repeats associated with the CRISPR-associated protein 12a-hybridization chain reaction (CRISPR/Cas12a-HCR) system combined with polymerase chain reaction/recombinase-assisted amplification (PCR/RAA) technology. The approach relies on the Salmonella invA gene as a biorecognition element and its amplification through PCR and RAA. In the presence of the target gene, Cas12a, guided by crRNA, recognizes and cleaves the amplification product, initiating the HCR. Fluorescently labeled single-stranded DNA (ssDNA) H1 and H2 were introduced, and the Salmonella concentration was determined based on the fluorescence intensity from the triggered HCR. Both assays demonstrate high specificity, sensitivity, simplicity, and rapidity. The detection range was 2 × 101-2 × 109 CFU/mL, with an LOD of 20 CFU/mL, and the entire process enabled specific and rapid Salmonella detection within 85-105 min. Field-incurred spiked recovery tests were conducted in mutton and beef samples using both assays, demonstrating satisfactory recovery and accuracy in animal-derived foods. By combining CRISPR/Cas12a with hybridization chain reaction technology, this study presents a rapid and sensitive Salmonella detection method that is crucial for identifying pathogenic bacteria and monitoring food safety.

enterica strain QazSL-4

Here, we present the whole-genome sequence of Salmonella enterica subsp. enterica strain QazSL-4 isolated from a chicken fillet in 2018, Almaty, Kazakhstan. The genome obtained using Illumina MiSeq technology consists of 49 contigs with a total length of 4,711,816 bp with a GC content of 52.1%.

Persistent Colonization of Ciprofloxacin-Resistant and Extended-Spectrum β-Lactamase (ESBL)-Producing Salmonella enterica Serovar Kentucky ST198 in a Patient with Inflammatory Bowel Disease

Objective

Salmonella enterica serovar Kentucky ST198 has emerged as a global threat to humans. In this study, we aimed to characterize the prolonged carriage of ciprofloxacin-resistant and extended-spectrum β-lactamase (ESBL)-producing S. Kentucky ST198 in a single patient with inflammatory bowel disease (IBD).

Methods

Three S. Kentucky strains were collected from a single patient with IBD on 11th January, 23rd January, and 8th February, 2022, respectively. Antimicrobial susceptibility testing, whole-genome sequencing, and phylogenetic analysis with 38 previously described Chinese S. Kentucky ST198 strains from patients and food were performed.

Results

All three S. Kentucky isolates belonged to ST198. They carried identical 16 resistance genes, such as blaCTX-M-55, tet(A), and qnrS1, and had identical mutations within gyrA (S83F and D87N) and parC (S80I). Therefore, they exhibited identical multidrug-resistant profiles, including the clinically important antibiotics cephalosporins (ceftazidime and cefepime), fluoroquinolones (ciprofloxacin and levofloxacin), and third-generation tetracycline (tigecycline). Our three S. Kentucky strains were classified into the subclade ST198.2-2, and were genetically identical (2-6 SNPs) to each other. They exhibited a close genetic similarity (15-20 SNPs) to the isolate NT-h3189 from a patient and AH19MCS1 from chicken meat in China, indicating a possible epidemiological link between these S. Kentucky ST198 isolates from the patients and chicken meat.

Conclusion

Long-term colonization of ciprofloxacin-resistant and ESBL-producing S. Kentucky ST198 in a single patient is a matter of concern. Due to the potential transfer of S. Kentucky ST198 from food sources to humans, ongoing surveillance of this particular clone in animals, animal-derived food products, and humans should be strengthened.

Nuclear factor kappa B-dependent persistence of Salmonella Typhi and Paratyphi in human macrophages

Salmonella serovars Typhi and Paratyphi cause a prolonged illness known as enteric fever, whereas other serovars cause acute gastroenteritis. Mechanisms responsible for the divergent clinical manifestations of nontyphoidal and enteric fever Salmonella infections have remained elusive. Here, we show that S. Typhi and S. Paratyphi A can persist within human macrophages, whereas S. Typhimurium rapidly induces apoptotic macrophage cell death that is dependent on Salmonella pathogenicity island 2 (SPI2). S. Typhi and S. Paratyphi A lack 12 specific SPI2 effectors with pro-apoptotic functions, including nine that target nuclear factor κB (NF-κB). Pharmacologic inhibition of NF-κB or heterologous expression of the SPI2 effectors GogA or GtgA restores apoptosis of S. Typhi-infected macrophages. In addition, the absence of the SPI2 effector SarA results in deficient signal transducer and activator of transcription 1 (STAT1) activation and interleukin 12 production, leading to impaired TH1 responses in macrophages and humanized mice. The absence of specific nontyphoidal SPI2 effectors may allow S. Typhi and S. Paratyphi A to cause chronic infections.

IMPORTANCE

Salmonella enterica is a common cause of gastrointestinal infections worldwide. The serovars Salmonella Typhi and Salmonella Paratyphi A cause a distinctive systemic illness called enteric fever, whose pathogenesis is incompletely understood. Here, we show that enteric fever Salmonella serovars lack 12 specific virulence factors possessed by nontyphoidal Salmonella serovars, which allow the enteric fever serovars to persist within human macrophages. We propose that this fundamental difference in the interaction of Salmonella with human macrophages is responsible for the chronicity of typhoid and paratyphoid fever, suggesting that targeting the nuclear factor κB (NF-κB) complex responsible for macrophage survival could facilitate the clearance of persistent bacterial infections.

Occurrence, virulence, and resistance genes in Salmonella enterica isolated from an integrated poultry company in Jordan

Salmonella is considered one of the most common foodborne pathogens worldwide. The annual number of hospitalizations and deaths related to zoonotic salmonellosis, which is transmitted from animals to humans and infects poultry and meat, is expected to be significant. Hence, the primary aims of this research were to isolate and characterize Salmonella species obtained from an integrated poultry company and identify some virulence, and antimicrobial resistance, with a specific concern about colistin resistance genes. A total of 635 samples collected from various sources in an integrated company in Jordan were screened for Salmonella species accompanying their virulence and antimicrobial resistance genes. Samples were collected from parent stock house drag swabs, broiler farms, premix, cecum at the slaughterhouse level, prechilling and postchilling stages, and the final product. Salmonella species were detected in 3% (6/200) of investigated parent stock house drag swabs, 13.8% (11/80) from cloacal swabs from broiler farms, 16.9% (11/65) from boiler farms premix, 24.4% (11/45) from the cecum at slaughterhouse level, 16.4% (9/55) from the prechilling stage, 37.8% (17/45) from the postchilling stage and 53.3% (24/45) from the final product stage. No isolates were detected in feed mills (0/20), parents' premix (0/40), or hatcheries (0/40). Salmonella isolates were resistant to ciprofloxacin (91.0%), nalidixic acid (86.5%), doxycycline (83.1%), tetracycline (83.1%), sulphamethoxazole-trimethoprim (79.8%) and ampicillin (76.4%). Serotyping shows that S. Infantis was the predominant serovar, with 56.2%. Based on the minimum inhibitory concentration (MIC) test, 39.3% (35/89) of the isolates were resistant to colistin; however, no mcr genes were detected. Among antimicrobial-resistant genes, blaTEM was the most prevalent (88.8%). Furthermore, the spvC, ompA, and ompF virulence genes showed the highest percentages (97.8%, 97.8%, and 96.6%, respectively). In conclusion, Salmonella isolates were found at various stages in the integrated company. S. Infantis was the most prevalent serotype. No mcr genes were detected. Cross-contamination between poultry production stages highlights the importance of good hygiene practices. Furthermore, the presence of virulence genes and the patterns of antimicrobial resistance present significant challenges for public health.

Genomic characteristics of Salmonella Montevideo and Pomona: impact of isolation source on antibiotic resistance, virulence and metabolic capacity

Salmonella enterica is known for its disease-causing serotypes, including Montevideo and Pomona. These serotypes have been found in various environments, including river water, sediments, food, and animals. However, the global spread of these serotypes has increased, leading to many reported infections and outbreaks. The goal of this study was the genomic analysis of 48 strains of S. Montevideo and S. Pomona isolated from different sources, including clinical. Results showed that environmental strains carried more antibiotic resistance genes than the clinical strains, such as genes for resistance to aminoglycosides, chloramphenicol, and sulfonamides. Additionally, the type 4 secretion system, was only found in environmental strains. .Also many phosphotransferase transport systems were identified and the presence of genes for the alternative pathway Entner-Doudoroff. The origin of isolation may have a significant impact on the ability of Salmonella isolates to adapt and survive in different environments, leading to genomic flexibility and a selection advantage.

from surface water: A systematic review

Identification of methods for the standardized assessment of bacterial pathogens and antimicrobial resistance (AMR) in environmental water can improve the quality of monitoring and data collected, support global surveillance efforts, and enhance the understanding of environmental water sources. We conducted a systematic review to assemble and synthesize available literature that identified methods for assessment of prevalence and abundance of bacterial fecal indicators and pathogens in water for the purposes of monitoring bacterial pathogens and AMR. After screening for quality, 175 unique publications were identified from 15 databases, and data were extracted for analysis. This review identifies the most common and robust methods, and media used to isolate target organisms from surface water sources, summarizes methodological trends, and recognizes knowledge gaps. The information presented in this review will be useful when establishing standardized methods for monitoring bacterial pathogens and AMR in water in the United States and globally.

Mitigation Potential of Herbal Extracts and Constituent Bioactive Compounds on Salmonella in Meat-Type Poultry

Herbal extracts have been widely evaluated in poultry production for their beneficial effects and potential substitute for antibiotics, which contribute to AMR and risks to human health through the consumption of infected meat. Salmonellosis is a systemic infection caused by Salmonella, an intracellular bacterium with the ability to cause systemic infections with significant implications for both the health and safety of farmers and consumers. The excessive use of antibiotics has escalated the incidence of antibiotic resistance bacteria in the poultry and livestock industry, highlighting the urgent need for alternatives especially in meat-type poultry. Both in vivo usage and in vitro studies of bioactive compounds from herbal extracts have demonstrated the effective antimicrobial activities against pathogenic bacteria, showing promise in managing Salmonella infections and enhancing poultry performance. Phytobiotic feed additives have shown promising results in improving poultry output due to their pharmacological properties, such as stimulating consumption, and enhancing antioxidant properties and preventing the increasing antimicrobial resistance threats. Despite potential for synergistic effects from plant-derived compounds, a further investigation into is essential to fully understand their role and mechanisms of action, for developing effective delivery systems, and for assessing environmental sustainability in controlling Salmonella in poultry production.

Genomic analysis of Salmonella isolated from canal water in Bangkok, Thailand

Antimicrobial resistance (AMR) poses an escalating global public health threat. Canals are essential in Thailand, including the capital city, Bangkok, as agricultural and daily water sources. However, the characteristic and antimicrobial-resistance properties of the bacteria in the urban canals have never been elucidated. This study employed whole genome sequencing to characterize 30 genomes of a causal pathogenic bacteria, Salmonella enterica, isolated from Bangkok canal water between 2016 and 2020. The dominant serotype was Salmonella Agona. In total, 35 AMR genes and 30 chromosomal-mediated gene mutations were identified, in which 21 strains carried both acquired genes and mutations associated with fluoroquinolone resistance. Virulence factors associated with invasion, adhesion, and survival during infection were detected in all study strains. 75.9% of the study stains were multidrug-resistant and all the strains harbored the necessary virulence factors associated with salmonellosis. One strain carried 20 resistance genes, including mcr-3.1, mutations in GyrA, ParC, and ParE, and typhoid toxin-associated genes. Fifteen plasmid replicon types were detected, with Col(pHAD28) being the most common type. Comparative analysis of nine S. Agona from Bangkok and 167 from public databases revealed that specific clonal lineages of S. Agona might have been circulating between canal water and food sources in Thailand and globally. These findings provide insight into potential pathogens in the aquatic ecosystem and support the inclusion of environmental samples into comprehensive AMR surveillance initiatives as part of a One Health approach. This approach aids in comprehending the rise and dissemination of AMR and devising sustainable intervention strategies.IMPORTANCEBangkok is the capital city of Thailand and home to a large canal network that serves the city in various ways. The presence of pathogenic and antimicrobial-resistant Salmonella is alarming and poses a significant public health risk. The present study is the first characterization of the genomic of Salmonella strains from Bangkok canal water. Twenty-two of 29 strains (75.9%) were multidrug-resistant Salmonella and all the strains carried essential virulence factors for pathogenesis. Various plasmid types were identified in these strains, potentially facilitating the horizontal transfer of AMR genes. Additional investigations indicated a potential circulation of S. Agona between canal water and food sources in Thailand. The current study underscores the role of environmental water in an urban city as a reservoir of pathogens and these data obtained can serve as a basis for public health risk assessment and help shape intervention strategies to combat AMR challenges in Thailand.

Detection of Salmonella enterica and Listeria monocytogenes in alternative irrigation water by culture and qPCR-based methods in the Mid-Atlantic U.S

Alternative irrigation waters (rivers, ponds, and reclaimed water) can harbor bacterial foodborne pathogens like Salmonella enterica and Listeria monocytogenes, potentially contaminating fruit and vegetable commodities. Detecting foodborne pathogens using qPCR-based methods may accelerate testing methods and procedures compared to culture-based methods. This study compared detection of S. enterica and L. monocytogenes by qPCR (real-time PCR) and culture methods in irrigation waters to determine the influence of water type (river, pond, and reclaimed water), season (winter, spring, summer, and fall), or volume (0.1, 1, and 10 L) on sensitivity, accuracy, specificity, and positive (PPV), and negative (NPV) predictive values of these methods. Water samples were collected by filtration through modified Moore swabs (MMS) over a 2-year period at 11 sites in the Mid-Atlantic U.S. on a bi-weekly or monthly schedule. For qPCR, bacterial DNA from culture-enriched samples (n = 1,990) was analyzed by multiplex qPCR specific for S. enterica and L. monocytogenes. For culture detection, enriched samples were selectively enriched, isolated, and PCR confirmed. PPVs for qPCR detection of S. enterica and L. monocytogenes were 68% and 67%, respectively. The NPV were 87% (S. enterica) and 85% (L. monocytogenes). Higher levels of qPCR/culture agreement were observed in spring and summer compared to fall and winter for S. enterica; for L. monocytogenes, lower levels of agreement were observed in winter compared to spring, summer, and fall. Reclaimed and pond water supported higher levels of qPCR/culture agreement compared to river water for both S. enterica and L. monocytogenes, indicating that water type may influence the agreement of these results.

IMPORTANCE

Detecting foodborne pathogens in irrigation water can inform interventions and management strategies to reduce risk of contamination and illness associated with fresh and fresh-cut fruits and vegetables. The use of non-culture methods like qPCR has the potential to accelerate the testing process. Results indicated that pond and reclaimed water showed higher levels of agreement between culture and qPCR methods than river water, perhaps due to specific physiochemical characteristics of the water. These findings also show that season and sample volume affect the agreement of qPCR and culture results. Overall, qPCR methods could be more confidently utilized to determine the absence of Salmonella enterica and Listeria monocytogenes in irrigation water samples examined in this study.

Distribution and genetic characterization of fluoroquinolone resistance gene qnr among Salmonella strains from chicken in China

The prevalence and dissemination of the plasmid-mediated fluoroquinolone (FQ) resistance gene qnr in Salmonella are considered serious public health concerns worldwide. So far, no comprehensive large-scale studies have focused on the prevalence and genetic characteristics of the qnr gene in Salmonella isolated from chickens. Herein, this study aimed to investigate the prevalence, antimicrobial resistance (AMR) patterns, and molecular characteristics of chicken-originated qnr-positive Salmonella strains from chicken farms, slaughterhouses, and markets in 12 provinces of China in 2020-2021. The overall prevalence of the qnr gene was 21.13% (56/265), with the highest prevalence in markets (36.11%, 26/72), followed in farms (17.95%, 21/117), and slaughterhouses (10.53%, 9/76). Only the qnrS and qnrB genes were detected, and the prevalence rate of the qnrS gene (19.25%, 51/265) was higher than that of the qnrB gene (1.89%, 5/265). Whole genome sequencing identified 37 distinct AMR genes and 15 plasmid replicons, and the most frequent mutation in quinolone resistance determining regions was parC (T57S; 91.49%, 43/47). Meanwhile, four different qnrS and two qnrB genetic environments were discovered among 47 qnr-positive Salmonella strains. In total, 21.28% (10/47) of the strains were capable of conjugative transfer, and all were qnrS1-positive strains, with the majority of transferable plasmids being IncHI2 types (n = 4). Overall, the prevalence of qnr-positive Salmonella strains from chickens in China and their carriage of multiple resistance and virulence genes and transferable plasmids is a major concern, which calls for continuous surveillance of qnr-positive Salmonella and the development of measures to control its prevalence and transmission.IMPORTANCESalmonella is a common foodborne pathogen responsible for 155,000 deaths annually worldwide. Fluoroquinolones (FQs) are used as first-line drugs for the treatment of Salmonella infections in several countries and regions. However, the emergence and increasing prevalence of the FQ-resistant gene qnr in Salmonella isolated from chickens have been widely reported. Gaining insight into the genetic mechanisms of AMR genes in chicken could lead to the development of preventive measures to control and reduce the risk of drug resistance. In this study, we identified qnr-positive Salmonellae isolated from chickens in different regions of China and their AMR patterns and genome-wide characteristics, providing a theoretical basis for further control of their prevalence and transmission.

Rapid and sensitive detection of Salmonella in agro-Food and environmental samples: A review of advances in rapid tests and biosensors

Salmonella is as an intracellular bacterium, causing many human fatalities when the host-specific serotypes reach the host gastrointestinal tract. Nontyphoidal Salmonella are responsible for numerous foodborne outbreaks and product recalls worldwide whereas typhoidal Salmonella are responsible for Typhoid fever cases in developing countries. Yet, Salmonella-related foodborne disease outbreaks through its food and water contaminations have urged the advancement of rapid and sensitive Salmonella-detecting methods for public health protection. While conventional detection methods are time-consuming and ineffective for monitoring foodstuffs with short shelf lives, advances in microbiology, molecular biology and biosensor methods have hastened the detection. Here, the review discusses Salmonella pathogenic mechanisms and its detection technology advancements (fundamental concepts, features, implementations, efficiency, benefits, limitations and prospects). The time-efficiency of each rapid test method is discussed in relation to their limit of detections (LODs) and time required from sample enrichment to final data analysis. Importantly, the matrix effects (LODs and sample enrichments) were compared within the methods to potentially speculate Salmonella detection from environmental, clinical or food matrices using certain techniques. Although biotechnological advancements have led to various time-efficient Salmonella-detecting techniques, one should consider the usage of sophisticated equipment to run the analysis by moderately to highly trained personnel. Ultimately, a fast, accurate Salmonella screening that is readily executed by untrained personnels from various matrices, is desired for public health procurement.

Lactiplantibacillus plantarum postbiotic protects against Salmonella infection in broilers via modulating NLRP3 inflammasome and gut microbiota

Salmonella infection is a major concern in poultry production which poses potential risks to food safety. Our previous study confirmed that Lactiplantibacillus plantarum (LP) postbiotic exhibited a strong antibacterial capacity on Salmonella in vitro. This study aimed to investigate the beneficial effects and underlying mechanism of LP postbiotic on Salmonella-challenged broilers. A total of 240 one-day-old male yellow-feathered broilers were pretreated with 0.8% deMan Rogosa Sharpe (MRS) medium or 0.8% LP postbiotic (LP cell-free culture supernatant, LPC) in drinking water for 28 d, and then challenged with 1×109 CFU Salmonella enterica serovar Enteritidis (SE). Birds were sacrificed 3 d postinfection. Results showed that LPC maintained the growth performance by increasing body weight (BW), average daily gain (ADG), and average daily feed intake (ADFI) in broilers under SE challenge. LPC significantly attenuated SE-induced intestinal mucosal damage. Specifically, it decreased the intestinal injury score, increased villus length and villus/crypt, regulated the expression of intestinal injury-related genes (Villin, matrix metallopeptidase 3 [MMP3], intestinal fatty acid-binding protein [I-FABP]), and enhanced tight junctions (zona occludens-1 [ZO-1] and Claudin-1). SE infection caused a dramatic inflammatory response, as indicated by the up-regulated concentrations of interleukin (IL)-1β, IL-6, TNF-α, and the downregulation of IL-10, while LPC pretreatment markedly reversed this trend. We then found that LPC inhibited the activation of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome by decreasing the gene expression of Caspase-1, IL-lβ, and IL-18. Furthermore, LPC suppressed NLRP3 inflammasome activation by inhibiting nuclear factor-kappa B (NF-κB) signaling pathway (the reduced levels of toll-like receptor 4 [TLR4], myeloid differentiation factor 88 [MyD88], and NF-κB). Finally, our results showed that LPC regulated gut microbiota by enhancing the percentage of Ligilactobacillus and decreasing Alistipes and Barnesiella. In summary, we found that LP postbiotic was effective to protect broilers against Salmonella infection, possibly through suppressing NLRP3 inflammasome and optimizing gut microbiota. Our study provides the potential of postbiotics on prevention of Salmonella infection in poultry.

Water-soluble microencapsulation using gum Arabic and skim milk enhances viability and efficacy of Pediococcus acidilactici probiotic strains for application in broiler chickens

Objective

This study aimed to develop and evaluate the effectiveness of a water-soluble microencapsulation method for probiotic strains using gum Arabic (GA) and skim milk (SKM) over a three-month storage period following processing.

Methods

Four strains of Pediococcus acidilactici (BYF26, BYF20, BF9, and BF14) that were typical lactic acid bacteria (LAB) isolated from the chicken gut were mixed with different ratios of gum Arabic (GA) and skim milk (SKM) as coating agents before spray drying at an inlet temperature 140°C. After processing, the survivability and probiotic qualities of the strains were assessed from two weeks to three months of storage at varied temperatures, and de-encapsulation was performed to confirm the soluble properties. Finally, the antibacterial activity of the probiotics was assessed under simulated gastrointestinal conditions.

Results

As shown by scanning electron microscopy, spray-drying produced a spherical, white-yellow powder. The encapsulation efficacy (EE percent) was greatest for a coating containing a combination of 30% gum Arabic: 30% skim milk (w/v) (GA:SKM30) compared to lower concentrations of the two ingredients (p<0.05). Coating with GA:SKM30 (w/v) significantly enhanced (p<0.05) BYF26 survival under simulated gastrointestinal conditions (pH 2.5-3) and maintained higher survival rates compared to non-encapsulated cells under an artificial intestinal juices (AIJ) condition of pH 6. De-encapsulation tests indicated that the encapsulated powder dissolved in water while keeping viable cell counts within the effective range of 106 for 6 hours. In addition, following three months storage at 4°C, microencapsulation of BYF26 in GA:SKM30 maintained both the number of viable cells (p<0.05) and the preparation's antibacterial efficacy against pathogenic bacteria, specifically strains of Salmonella.

Conclusion

Our prototype water-soluble probiotic microencapsulation GA:SKM30 effectively maintains LAB characteristics and survival rates, demonstrating its potential for use in preserving probiotic strains that can be used in chickens and potentially in other livestock.

growth behavior in cooked and raw chicken samples: Real-time PCR quantification approach and model assessment in different handling scenarios

The increasing prevalence of Salmonella contamination in poultry meat emphasizes the importance of suitable predictive microbiological models for estimating Salmonella growth behavior. This study was conducted to evaluate the potential of chicken juice as a model system to predict the behavior of Salmonella spp. in cooked and raw chicken products and to assess its ability to predict cross-contamination scenarios. A cocktail of four Salmonella serovars was inoculated into chicken juice, sliced chicken, ground chicken, and chicken patties, with subsequent incubation at 10, 15, 20, and 25°C for 39 h. The number of Salmonella spp. in each sample was determined using real-time polymerase chain reaction. Growth curves were fitted into the primary Baranyi and Roberts model to obtain growth parameters. Interactions between temperature and growth parameters were described using the secondary Ratkowsky's square root model. The predictive results generated by the chicken juice model were compared with those obtained from other chicken meat models. Furthermore, the parameters of the chicken juice model were used to predict Salmonella spp. numbers in six worst-case cross-contamination scenarios. Performance of the chicken juice model was evaluated using the acceptable prediction zone from -1.0 (fail-safe) to 0.5 (fail-dangerous) log. Chicken juice model accurately predicted all observed data points within the acceptable range, with the distribution of residuals being wider near the fail-safe zone (75%) than near the fail-dangerous zone (25%). This study offers valuable insights into a novel approach for modeling Salmonella growth in chicken meat products, with implications for food safety through the development of strategic interventions. PRACTICAL APPLICATION: The findings of this study have important implications in the food industry, as chicken juice could be a useful tool for predicting Salmonella behavior in different chicken products and thus reducing the risk of foodborne illnesses through the development of strategic interventions. However, it is important to recognize that some modifications to the chicken juice model will be necessary to accurately mimic all real-life conditions, as multiple factors particularly those related to food processing can vary between different products.

Targeted Next-Generation Sequencing Assay for Direct Detection and Serotyping of Salmonella from Enrichment

In this study, an automated, targeted next-generation sequencing (tNGS) assay to detect and serotype Salmonella from sample enrichments was evaluated. The assay generates millions of reads to detect multiple Salmonella-specific genes and serotype-specific alleles, detecting all Salmonella spp. tested to date, and serotyping 62 common Salmonella serotypes. Accuracy was tested on 291 pure reference cultures (251 Salmonella, 40 non-Salmonella), 21 artificially contaminated poultry carcass rinse samples, and 363 naturally contaminated poultry environmental samples. Among the 291 pure reference cultures, the automated tNGS assay resulted in 100% detection accuracy, 100% serotyping accuracy for the claimed serotypes, and 0% false positives. The limit of detection was estimated at 5 × 104 CFU/mL by testing enumerated cultures of strains representative of six serotypes. In cocontamination studies with mixtures of two serotypes (Enteritidis, Typhimurium, Kentucky, Infantis, and Newport) at a 1:1 ratio, tNGS detected both serotypes with 100% accuracy. The assay demonstrated 100% accuracy in artificially contaminated poultry carcass rinse sample enrichments. Targeted NGS was highly effective in detecting Salmonella in samples collected from poultry production facilities. Results demonstrated that tNGS could detect Salmonella and provide accurate serotyping information consistent with conventional serology. These findings highlight the reliable and efficient performance of a fully automated tNGS Salmonella assay in detecting and identifying Salmonella strains in complex matrices, reducing the time to results from 4 to 5 days required by the traditional isolation and serotyping to 10-12 h for tNGS after primary enrichment.

An electrochemical biosensor based on phage-encoded protein RBP 41 for rapid and sensitive detection of Salmonella

Salmonellosis caused by Salmonella contaminated food poses a serious threat to human health. The rapid and accurate detection of Salmonella is critical for preventing foodborne illness outbreaks. In this study, an electrochemical biosensor was developed using a newly identified biorecognition element, RBP 41, which is capable of specifically recognizing and binding to Salmonella. The biosensor was constructed through a layer-by-layer assembly of graphene oxide (GO), gold nanoparticles (GNPs), and RBP 41 on a glassy carbon electrode (GCE), with the GNPs amplifying the detection signal. The established biosensor was able to detect Salmonella in concentrations ranging from 3 to 106 CFU/mL within approximately 30 min by using differential pulse voltammetry (DPV) signal, and the estimated detection limit was to be 0.2984 Log10 CFU/mL. The biosensor demonstrated excellent specificity and was effective in detecting Salmonella in food matrices, such as skim milk and lettuce. Overall, this study highlights the potential of phage tail receptor binding proteins in biosensing and the proposed biosensor as a promising alternative for rapid and sensitive Salmonella detection in various samples.

Bacteriophages as an alternative for biological control of biofilm-forming Salmonella enterica

Salmonellosis is one of the most common foodborne diseases worldwide. Surface adherence and biofilm formation are among the main strategies evolved by Salmonella to survive under harsh conditions and are risk factors for its spread through the food chain. Owing to the increase in antimicrobial resistance, there is a growing need to develop other methods to control foodborne pathogens, and bacteriophages have been suggested as a potential alternative for this purpose. The aim of this study was to evaluate bacteriophages as a biological control of Salmonella enterica serotypes to inhibit and remove bacterial biofilms. A total of 12 S. enterica isolates were selected for this study, all of which were biofilm producers. Seven bacteriophages were tested, individually and in a cocktail, for their host range and efficiency of plating (EOP). The phage cocktail was evaluated for its antibiofilm effect against the Salmonella biofilms. Phages UPF_BP1, UPF_BP2, UPF_BP3, UPF_BP6, and 10:2 possessed a broad lytic spectrum and could infect all S. enterica strains. Phages 10:2, UPF_BP6, and UPF_BP3 had high EOP in 10, 9, and 9 out of the 12 S. enterica strains, respectively. The cocktail was able to infect all S. enterica strains and had a high EOP in 10 out of 12 S. enterica isolates, presenting a broader host range than any of the tested single phages. A wide variation of inhibition among strains was observed, ranging from 14.72% to 88.53%. Multidrug-resistant and strong biofilm producer strains showed high biofilm inhibition levels by phage cocktail. Our findings demonstrate the ability of the cocktail to prevent biofilm formation and remove formed biofilms of Salmonella. These results indicate that the phage cocktail is a promising candidate to be used as an alternative for the control of Salmonella biofilms through surface conditioning.

Reduction Foodborne Pathogens and Surrogate Microorganism on Citrus Fruits after Lab- and Pilot-scale Finishing Wax Application

After finishing waxes are applied, citrus fruits are typically dried at 32-60°C for 2-3 min before final packing. The survival of Listeria monocytogenes, Salmonella, and Enterococcus faecium NRRL B-2354 was evaluated under laboratory conditions on lemons after applying one of four finishing waxes (F4, F6, F8, and F15) followed by an ambient hold or heated (50 or 60°C) drying step. The reduction of inoculated microorganisms during drying was significantly influenced by wax type and temperature, with greater reductions at higher temperatures. Greater reductions after waxing and drying at 60°C were observed with L. monocytogenes (2.84-4.44 log) than with Salmonella (1.65-3.67 log), and with Salmonella than with E. faecium (0.99-2.93 log). The survival of Salmonella inoculated at 5.8-5.9 log/fruit on lemons and oranges after applying wax F6 and drying at 60°C was evaluated during storage at 4 and 22°C. The reductions of Salmonella after waxing and drying were 1.7 log; additional reductions during storage at 4 or 22°C were 1.40-1.43 or 0.18-0.29 log, respectively, on waxed lemons, and 0.56-1.02 or 0.54-0.57 log, respectively, on waxed oranges. Under pilot-scale packinghouse conditions with wax F4, mean and minimum reductions of E. faecium ranged from 2.15 to 2.89 and 1.64 to 2.12 log, respectively. However, E. faecium was recovered by whole-fruit enrichment (limit of detection: 0.60 log CFU/lemon) but not by plating (LOD: 1.3 log CFU/lemon) from uninoculated lemons run with or after the inoculated lemons. The findings should provide useful information to establish and implement packinghouse food safety plans.

Dynamics of Listeriamonocytogenes and Salmonella enterica on Cooked Vegetables During Storage

Fresh vegetables have been linked to multiple foodborne outbreaks in the U.S., with Listeria monocytogenes and Salmonella enterica identified as leading causes. Beyond raw vegetables, cooked vegetables can also pose food safety concerns due to improper cooking temperature and time combinations or postcooking contamination. Cooked vegetables, having had their native microbiota reduced through heat inactivation, might provide an environment that favors the growth of pathogens due to diminished microbial competition. While the risks associated with raw vegetables are recognized, the survival and growth of pathogens on cooked vegetables remain inadequately studied. This study investigated the growth kinetics of both L. monocytogenes and S. enterica on various cooked vegetables (carrot, corn, onions, green bell pepper, and potato). Vegetables were cooked at 177°C until the internal temperature reached 90°C and then cooled to 5°C. Cooled vegetables were inoculated with a four-strain cocktail of either L. monocytogenes or S. enterica at 3 log CFU/g, then stored at different temperatures (5, 10, or 25°C) for up to 7 days. Both pathogens survived on all vegetables when stored at 5°C. At 10°C, both pathogens proliferated on all vegetables, with the exception of L. monocytogenes on pepper. At 25°C, the highest growth rates were observed by both pathogens on carrot (5.55 ± 0.22 and 6.42 ± 0.23 log CFU/g/d for L. monocytogenes and S. enterica, respectively). S. enterica displayed higher growth rates at 25°C compared to L. monocytogenes on all vegetables. Overall, these results bridge the knowledge gap concerning the growth kinetics of both S. enterica and L. monocytogenes on various cooked vegetables, offering insights to further enhance food safety.

Interventions to reduce Salmonella and Campylobacter during chilling and post-chilling stages of poultry processing: a systematic review and meta-analysis

Salmonella and Campylobacter are common bacterial hazards causing foodborne illnesses worldwide. A large proportion of Salmonella and Campylobacter illnesses are attributed to contaminated poultry products that are mishandled or under cooked. Processing interventions such as chilling and post-chill dip are critical to reducing microbial contamination of poultry. A comprehensive search of the literature published between 2000 and 2021 was conducted in the databases Web of Science, Academic Search Complete, and Academic OneFile. Studies were included if they were in English and investigated the effects of interventions against Salmonella and/or Campylobacter on whole carcasses and/or parts during the chilling or post-chill stages of poultry processing. Random-effects meta-analyses were performed using the "meta" package in the R programming language. Subgroup analyses were assessed according to outcome measure reported, microorganism tested, processing stage assessed, and chemical treatment used. The results included 41 eligible studies. Eighteen studies reported results of 28 separate interventions against Salmonella and 31 reported results of 50 separate interventions against Campylobacter. No significant difference (P> 0.05) was observed when comparing the combined mean difference of all interventions targeting Salmonella to the combined mean difference of all interventions targeting Campylobacter or when comparing chilling times within each pathogen subgroup. For analyses examining antimicrobial additives, peroxyacetic acid (PAA) had the largest reduction against Salmonella population regardless of chilling time (P< 0.05). PAA also had the largest reduction against Campylobacter population and prevalence during primary chilling (P< 0.01). Air chilling showed a lower reduction for Campylobacter than any immersion chilling intervention (P< 0.05). Chilling time and antimicrobial used during poultry processing had varying effects depending on the pathogen and outcome measure investigated (concentration or prevalence). High heterogeneity and low sample numbers in most analyses suggest that more high-quality research that is well-designed and has transparent reporting of methodology and results is needed to corroborate the results.

Frequency of isolation and phenotypic antimicrobial resistance of fecal Salmonella enterica recovered from dairy cattle in Canada

Salmonellosis is one of the leading causes of gastrointestinal infections in humans. In Canada, it is estimated that approximately 87,500 cases of salmonellosis occur every year in humans, resulting in 17 deaths. In the United States, it is estimated that 26,500 hospitalizations and 420 deaths occur every year. In dairy cattle, infections caused by nontyphoidal Salmonella enterica can cause mild to severe disease, including enteritis, pneumonia, and septicemia. Our study objectives were to determine the proportion of fecal samples positive for Salmonella in dairy cattle in Canada and determine the resistance pattern of these isolates. We used data collected through the Canadian Dairy Network for Antimicrobial Stewardship and Resistance (CaDNetASR). Pooled fecal samples from preweaning calves, postweaning heifers, lactating cows, and manure storage were cultured for Salmonella, and the isolates were identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Antimicrobial susceptibilities were determined using the minimum inhibitory concentration test, and resistance interpretation was made according to the Clinical and Laboratory Standards Institute. A 2-level, multivariable logistic regression model was built to determine the probability of recovering Salmonella from a sample, accounting for province, year, and sample source. The proportion of farms with at least one positive sample were 12% (17/140), 19% (28/144), and 17% (24/144) for the sampling years 2019, 2020, and 2021, respectively. Out of the 113 Salmonella isolates, 23 different serovars were identified. The occurrence of Salmonella appeared to be clustered by farms and provinces. The most common serovars identified were Infantis (14%) and Typhimurium (14%). Overall, 21% (24/113) of the Salmonella isolates were resistant to at least one antimicrobial. Resistance to tetracycline was commonly observed (17%); however, very limited resistance to category I antimicrobials (categorization according to Health Canada that includes third-generation cephalosporins, fluoroquinolones, polymyxins, and carbapenems) was observed, with one isolate resistant to amoxicillin and clavulanic acid. The proportion of Salmonella isolates resistant to 2 and 3 antimicrobial classes was 3.5% and 8.8%, respectively. Our study provided valuable information on the proportion of fecal samples positive for Salmonella, the serovars identified, and the associated resistance patterns across CaDNetASR herds, at regional and national levels.

Poultry Food Assess Risk Model for Salmonella and Chicken Gizzards: III. Dose Consumed Step

The Dose Consumed step of the Poultry Food Assess Risk Model (PFARM) for Salmonella and chicken gizzards was presented and compared to the Exposure Assessment step of Quantitative Microbial Risk Assessment (QMRA). The specific objectives were 1) to demonstrate the dose consumed step of PFARM for Salmonella and chicken gizzards; 2) to compare Salmonella dose consumed from cooked chicken gizzards to that from cross-contaminated and temperature-abused lettuce; 3) to determine if Salmonella dose consumed changed over time in a production chain; and 4) to compare PFARM and QMRA predictions of Salmonella dose consumed. The PFARM and QMRA were developed in an Excel notebook and simulated with @Risk. Salmonella prevalence and number data (P = 100) for chicken gizzards (56 g) and scenario analysis were used to address objectives 1, 2, and 4, whereas running windows of 60 consecutive chicken gizzard samples and scenario analysis were used to address objective 3. A lot size of 1,000 kg of chicken gizzards was simulated. Mean portion size was 168 g resulting in the simulation of 5,952 meals per lot. Of these, 3.69 ± 0.32% and 0.49 ± 0.07% (mean ± SD) resulted in Salmonella dose consumed of ≥1 per meal from cooked chicken gizzards and lettuce, respectively. However, the total Salmonella dose consumed per lot from cooked chicken gizzards (272 ± 27) was less (P ≤ 0.05) than from lettuce (6,050 ± 4,929) because of a few highly contaminated (>310 Salmonella) lettuce portions at consumption. Over time in the production chain, Salmonella prevalence and total dose consumed per lot changed (P ≤ 0.05) but the patterns differed. The QMRA predicted higher (P ≤ 0.05) Salmonella dose consumed per meal than PFARM. In part, this was because QMRA only simulated contaminated grams, whereas PFARM simulated contaminated and non-contaminated meals. However, other factors, which are discussed, also contributed to the overestimation of Salmonella dose consumed by QMRA.

Rapid detection of Salmonella in milk by labeling-free electrochemical immunosensor based on an Fe3O4-ionic liquid-modified electrode

Electrochemical sensors show distinct advantages over other types of sensors in the rapid detection of microorganisms. Here, we attempted to construct a label-free electrochemical immunosensor based on an Fe3O4-ionic liquid (IL)-modified electrode to rapidly detect Salmonella in milk. The excellent ionic conductivity of the IL facilitated sensor construction, and the large surface area of nano-Fe3O4 provided numerous sites for subsequent experiments. An antibody was fixed on the Fe3O4-IL complex with polyglutamic acid modification by a simple infusion method. The microstructure of the Fe3O4-IL composites was investigated by scanning electron microscopy, and the elements and structures of the composites were analyzed by energy dispersive X-ray and Fourier transform infrared spectroscopy. Under optimized experimental conditions, the detection range of the constructed sensor was 3.65 × 102-3.65 × 108 CFU mL-1, and the LOD was 1.12 × 102 CFU mL-1 (S/N = 3). In addition, the prepared electrochemical immunosensor is convenient for detecting foodborne pathogens because of its outstanding stability, good selectivity, and repeatability.

Effects of Salmonella Outer Membrane Vesicles on Intestinal Microbiota and Intestinal Barrier Function

Salmonella enterica is one of the most important zoonotic pathogens causing foodborne gastroenteritis worldwide. Outer membrane vesicles (OMVs) are lipid-bilayer vesicles produced by Gram-negative bacteria, which contain biologically active components. We hypothesized that OMVs are an important weapon of S. enterica to initiate enteric diseases pathologies. In this study, the effects of S. enterica OMVs (SeOMVs) on intestinal microbiota and intestinal barrier function were investigated. In vitro fecal culture experiments showed that alpha diversity indexes and microbiota composition were altered by SeOMV supplementation. SeOMV supplementation showed an increase of pH, a decrease of OD630 and total short chain fatty acid (SCFA) concentrations. In vitro IPEC-J2 cells culture experiments showed that SeOMV supplementation did not affect the IPEC-J2 cell viability and the indicated genes expression. In vivo experiments in mice showed that SeOMVs had adverse effects on average daily gain (p < 0.05) and feed:gain ratio (p < 0.05), and had a tendency to decrease the final body weight (p = 0.073) in mice. SeOMV administration decreased serum interleukin-10 level (p < 0.05), decreased the relative abundance of bacteria belonging to the genera BacC-u-018 and Akkermansia (p < 0.05). Furthermore, SeOMV administration damaged the ileum mucosa (p < 0.05). These findings suggest that SeOMVs play an important role in the activation of intestinal inflammatory response induced by S. enterica, and downregulation of SCFA-producing bacteria is a possible mechanism.

Prevalence, antibiotic resistance, virulence genes and molecular characteristics of Salmonella isolated from ducks and wild geese in China

Salmonella is a major foodborne pathogen and the cause of significant morbidity and mortality via consumption of contaminated meat and meat-products. The prevalence of Salmonella in ducks and wild geese in China are poorly characterized and these sources represent a potential pool that could be transferred to farm-reared fowl. In this study, we isolated 335 (18.3%) Salmonella from 1830 samples and identified 24 serotypes and most prevalent were Salmonella Indiana, Salmonella Kentucky and Salmonella Typhimurium. Whole genome sequencing revealed the presence of the dominant sequence types ST17, ST198 and ST19 for these three serotypes, respectively. In addition, these isolates were most likely clonally spread across different regions while S. Kentucky also crossed the species barrier. The majority of the Salmonella isolates possessed β-lactam and fluoroquinolone resistance and these were consistent with antibiotic resistance gene profiles. We also identified 8 plasmid replicon types and all isolates possessed virulence genes and the numbers were greatest for S. Enteritidis and S. Typhimurium isolates. This study provides novel insights concerning the epidemiology of Salmonella in ducks and wild geese and provides basic data for public health screening and management.

Characterization of Salmonella phages isolated from poultry coops and its effect with nisin on food bio-control

Salmonella is a bacterium associated with food contaminated by various animals, primarily poultry. Interest and research on bacteriophages are increasing because they can be used as an alternative against increasing antibiotic resistance. In our study, eight Salmonella-specific lytic bacteriophages were isolated from chicken feces. Two of the isolated phages (AUFM_Sc1 and AUFM_Sc3) were chosen for their characterization due to their broader host range. Based on morphological and genomic analysis, AUFM_Sc1 was identified to be close to similar Enterobacteria spp. CC31 (Myoviridae) and AUFM_Sc3 was identified to be close to Salmonella phage vB_Sen_I1 (Demerecviridae (formerly Siphoviridae)). Although these phages have shown promise for use in phage therapy applications for chickens, further studies are needed on their suitability. When a cocktail of these phages (AUFM_Sc1 + AUFM_Sc3) and nisin combination was applied on chicken breast meat, it was determined that it was effective against Salmonella contamination and while a good inhibitory effect was observed on the food, especially during the first 48 h, the effect decreased later, but the bacterial concentration was still low compared to the control group. Therefore, it is considered that the combination of AUFM_Sc1 + AUFM_Sc3 + nisin can be used as a food preservative against Salmonella.

Independent evaluation of a DNA microarray system for Salmonella detection in ground beef

A new DNA microarray test kit has been developed to detect foodborne pathogens in various food matrices. This study focuses on evaluating the PathogenDx microarray-based system to detect Salmonella in ground beef and verify critical parameters that could interfere with the method's effectiveness, such as enrichment incubation time, ground beef fat content, inclusivity, exclusivity, and analytical sensitivity. Sample preparation protocols were evaluated at 6, 8, 12, 18, and 24 h enrichment times at varying bacterial levels to identify optimal conditions to detect the invA gene using the PathogenDx microarray. An 8 h enrichment step was selected based on 100% detection when initial inoculum levels were ≥5 CFU/g, and fractional detection was achieved when the concentration was as low as 1 CFU/g. Thus, the detection of Salmonella using the PathogenDx microarray system can be conducted in 12.5 h, including sample preparation, labeling PCR, hybridization, and analysis. Regarding fat content, there was no significant difference in detection rates of PathogenDx protocol among the highest and lowest commercially sold lean-to-fat ratios of ground beef. Inclusivity and exclusivity experiments showed that Salmonella was correctly identified 100% of the time. Using the ground beef matrix, PathogenDx method is comparable to the United States Department of Agriculture's Microbiology Laboratory Guidebook methodology for detection, which correctly identified Salmonella in 100% of the samples. Salmonella was detected between 93.33 and 100% when ground beef was inoculated with 1 and 5 CFU/g, respectively.

Comparison of Three Preharvest Sampling Strategies to Monitor Pathogens in Cattle Lairage Areas

The objective of this study was to compare preharvest monitoring strategies by evaluating three different sampling methods in the lairage area to determine pathogen recovery for each sampling method and incoming pathogen prevalence from the cattle to inform in-plant decision making. Samples were gathered over a 5-month period, from February to June 2022, at a harvesting and processing facility located in Eastern Nebraska. Sampling methods included (i) fecal pats, (ii) boot swabs, and (iii) MicroTally swab. A total of 329 samples were collected over the study period (fecal pats: n = 105, boot swabs: n = 104, and MicroTally swabs: n = 120). Specific media combinations, an incubation temperature of 42°C, and incubation timepoints (18-24 h) were utilized for each matrix and the prevalence of Salmonella, Escherichia coli O157:H7, and six non-O157 Shiga-toxin producing E. coli (STEC) was evaluated using the BAX system Real-Time PCR assay. Overall, results from the study concluded that boot swabs were an effective sampling method for pathogen detection in the cattle lairage area. Boot swabs (97.1%) were statistically more likely to detect for Salmonella (p < 0.05) when compared to fecal pats (67.6%) and MicroTally swab (77.5%) methods. For E. coli O157:H7 and STEC - O26, O121, O45, and O103 prevalence, boot swabs were significantly better at detecting for these pathogens (p < 0.05) than MicroTally swabs (OR = 3.16 - 11.95) and a comparable sampling method to fecal pats (OR = 0.93 - 2.01, p > 0.05). Lastly, all three sampling methods detected a very low prevalence for E. coli O111 and O145; therefore, no further analysis was conducted. The boot swab sampling method was strongly favored because they require little training to implement, are inexpensive, and they do not require much sampling labor; therefore, would be a simple and effective sampling method to implement within the industry to evaluate pathogen prevalence preharvest.

SiRNA-HIF-1α delivered by attenuated Salmonella enhances the efficacy of Lenvatinib against hepatocellular carcinoma

The treatment of hepatocellular carcinoma (HCC) remains a major challenge in the medical field. Lenvatinib, a multi-target tyrosine kinase inhibitor, has demonstrated anti-HCC effects by targeting and inhibiting pathways such as vascular endothelial growth factor receptor 1-3 (VEGFR1-3). However, the therapeutic efficacy of Lenvatinib is subject to various influences, with the hypoxic microenvironment of the tumor being a pivotal factor. Consequently, altering the hypoxic milieu of the tumor emerges as a viable strategy to augment the efficacy of Lenvatinib. Hypoxia-inducible factor-1α (HIF-1α), synthesized by tumor cells in response to oxygen-deprived conditions, regulates the expression of resistance genes, promotes tumor angiogenesis and cell proliferation, enhances tumor cell invasion, and confers resistance to radiotherapy and chemotherapy. Thus, we constructed a self-designed siRNA targeting HIF-1α to suppress its expression and improve the efficacy of Lenvatinib in treating HCC. The therapeutic efficacy of siRNA-HIF-1α in combination with Lenvatinib on HCC were evaluated through in vivo and in vitro experiments. The results showed that the recombinant Salmonella delivering siRNA-HIF-1α in combination with Lenvatinib effectively inhibited tumor growth and prolonged the survival of tumor-bearing mice. This treatment approach reduced cell proliferation and angiogenesis in HCC tissues while promoting tumor cell apoptosis. Additionally, this combined therapy significantly increased the infiltration of T lymphocytes and M1 macrophages within the tumor microenvironment, as well as elevated the proportion of immune cells in the spleen, thereby potentiating the host's immune response against the tumor.

Persistence of vaccine origin Salmonella Typhimurium through the poultry production continuum, and development of a rapid typing scheme for their differentiation from wild type field isolates

Salmonella enterica serovar Typhimurium is one of the top Salmonella serovars annually linked to poultry production and corresponding human illnesses. Because of this, vaccination of commercial poultry against Salmonella Typhimurium has been a focal point in recent years. There are several commercially available Salmonella Typhimurium vaccines available for use in poultry production. Among these are modified live vaccines, including Poulvac ST (Zoetis), Megan Egg (AviPro), and Megan Vac 1 (AviPro). In this study, analyses of 27 field isolates of Salmonella Typhimurium from poultry sources indicated evidence for the persistence of some vaccine-origin strains through the commercial production cycle. Further analyses of 26,812 database isolates indicated vaccine-origin isolates are persisting frequently through processing, are present on retail meat products, and are even occasionally found in human patients. A novel polymerase chain reaction (PCR) was created and validated which enables simultaneous identification of Salmonella enterica sp., the Salmonella Typhimurium serovar, and differentiation of wild type Salmonella Typhimurium from live attenuated vaccines involving mutations in the cya/crp or aroA genes. The PCR was developed considering whole genome differences between the vaccines and wild type field isolates and was validated using different field isolates and recovered vaccine strains. This method enables poultry producers to rapidly determine if recovered field isolates have a vaccine origin.

Antimicrobial Resistance Analysis and Whole-Genome Sequencing of Salmonella Isolates from Environmental Sewage - Guangzhou City, Guangdong Province, China, 2022-2023

What is already known about this topic?

S.1,4,[5],12:i:- and S. Rissen are emerging serotypes of Salmonella that require close monitoring for antimicrobial resistance and containment of their spread.

What is added by this report?

The study aimed to identify antimicrobial resistance genes (ARGs) in S.1,4,[5],12:i:- and S. Rissen strains isolated from environmental sewage in Guangzhou City, Guangdong Province, China. A phylogenetic tree was constructed using single nucleotide polymorphism data to assess genetic relatedness among strains, offering insights for Salmonella infection outbreak investigations in the future.

What are the implications for public health practice?

It is crucial to implement strategies, such as integrating different networks, to control the spread of drug-resistant Salmonella. Novel technologies must be utilized to disinfect sewage and eliminate ARGs. Ensuring food safety and proper sewage disinfection are essential to curb the dissemination of Salmonella.

Rapid Dot-Blot Immunoassay for Detecting Multiple Salmonella enterica Serotypes

Salmonella, a major contributor to foodborne infections, typically causes self-limiting gastroenteritis. However, it is frequently invasive and disseminates across the intestinal epithelium, leading to deadly bacteremia. Although the genus is subdivided into >2,600 serotypes based on their antigenic determinants, only few serotypes are responsible for most human infections. In this study, a rapid dot-blot immunoassay was developed to diagnose multiple Salmonella enterica serotypes with high incidence rates in humans. The feasibility of 10 commercial antibodies (four polyclonal and six monoclonal antibodies) was tested using the 18 serotypes associated with 67.5% Salmonella infection cases in the United States of America (U.S.A) in 2016. Ab 3 (polyclonal; eight of 18 serotypes), Ab 8 (monoclonal; 13 of 18 serotypes), and Ab 9 (monoclonal; 10 of 18 serotypes) antibodies exhibited high detection rates in western blotting and combinations of two antibodies (Ab 3+8, Ab 3+9, and Ab 8+9) were applied to dot-blot assays. The combination of Ab 3+8 identified 15 of the tested 18 serotypes in 3 h, i.e., S. Enteritidis, S. Typhimurium, S. Javiana, S. I 4,[5],12:i:-, S. Infantis, S. Montevideo, S. Braenderup, S. Thompson, S. Saintpaul, S. Heidelberg, S. Oranienburg, S. Bareilly, S. Berta, S. Agona, and S. Anatum, which were responsible for 53.7% Salmonella infections in the U.S. in 2016. This cost-effective and rapid method can be utilized as an on-site colorimetric method for Salmonella detection.

Antimicrobial efficacy of a citric acid/hydrochloric acid blend, peroxyacetic acid, and sulfuric acid against Salmonella and background microbiota on chicken hearts and livers

This study aimed at evaluating the efficacy of a blend of citric acid and hydrochloric acid (CP), peroxyacetic acid (PAA), and sulfuric acid (SA) against Salmonella and mesophilic aerobic plate counts (APC) on chicken hearts and livers. Samples were inoculated with a five-serovar cocktail of Salmonella at ca. 4.8 log CFU/g and treated by immersion with a water control (90 s), CP (5% v/v, 30 s), PAA (0.05% v/v or 500 ppm, 90 s), or SA (2% v/v, 30 s), all at 4°C and with mechanical agitation. Samples were vacuum packed and stored for up to 3 days at 4°C. Three independent replications were performed for each product, treatment, and time combination. The average Salmonella reductions in chicken hearts after 3 days were 1.33 ± 0.25, 1.40 ± 0.04, and 1.32 ± 0.12 log CFU/g for PAA, SA, and CP, respectively. For chicken livers, the values were 1.10 ± 0.12, 1.09 ± 0.19, and 0.96 ± 0.27 for PAA, SA, and CP, respectively. All antimicrobials reduced Salmonella counts in both chicken hearts and livers by more than one log, in contrast to the water control. All treatments effectively minimized the growth of APC for up to 3 days of refrigerated storage, and no differences in objective color values (L, a, or b) were observed. The poultry industry may use these antimicrobials as components of a multifaceted approach to mitigate Salmonella in nonconventional chicken parts.

Plant phenolics inhibit focal adhesion kinase and suppress host cell invasion by uropathogenic Escherichia coli

Traditional folk treatments for the prevention and management of urinary tract infections (UTIs) and other infectious diseases often include plants and plant extracts that are rich in phenolic compounds. These have been ascribed a variety of activities, including inhibition of bacterial interactions with host cells. Here, we tested a panel of four well-studied phenolic compounds-caffeic acid phenethyl ester (CAPE), resveratrol, catechin, and epigallocatechin gallate-for the effects on host cell adherence and invasion by uropathogenic Escherichia coli (UPEC). These bacteria, which are the leading cause of UTIs, can bind and subsequently invade bladder epithelial cells via an actin-dependent process. Intracellular UPEC reservoirs within the bladder are often protected from antibiotics and host defenses and likely contribute to the development of chronic and recurrent infections. In cell culture-based assays, only resveratrol had a notable negative effect on UPEC adherence to bladder cells. However, both CAPE and resveratrol significantly inhibited UPEC entry into the host cells, coordinate with attenuated phosphorylation of the host actin regulator Focal Adhesion Kinase (FAK or PTK2) and marked increases in the numbers of focal adhesion structures. We further show that the intravesical delivery of resveratrol inhibits UPEC infiltration of the bladder mucosa in a murine UTI model and that resveratrol and CAPE can disrupt the ability of other invasive pathogens to enter host cells. Together, these results highlight the therapeutic potential of molecules like CAPE and resveratrol, which could be used to augment antibiotic treatments by restricting pathogen access to protective intracellular niches.IMPORTANCEUrinary tract infections (UTIs) are exceptionally common and increasingly difficult to treat due to the ongoing rise and spread of antibiotic-resistant pathogens. Furthermore, the primary cause of UTIs, uropathogenic Escherichia coli (UPEC), can avoid antibiotic exposure and many host defenses by invading the epithelial cells that line the bladder surface. Here, we identified two plant-derived phenolic compounds that disrupt activation of the host machinery needed for UPEC entry into bladder cells. One of these compounds, resveratrol, effectively inhibited UPEC invasion of the bladder mucosa in a mouse UTI model, and both phenolic compounds significantly reduced host cell entry by other invasive pathogens. These findings suggest that select phenolic compounds could be used to supplement existing antibacterial therapeutics by denying uropathogens shelter within host cells and tissues and help explain some of the benefits attributed to traditional plant-based medicines.

Salmonella enterica serotype Choleraesuis: a rare pathogen isolated from perianal abscess

Infections with non-typhoidal salmonella (NTS) most commonly cause localised infections such as cutaneous abscesses in humans and are a leading source of foodborne illness. Here, we present a unique case of NTS Choleraesuis in a perianal abscess in an immunocompetent patient without any comorbidities.A woman in her late 40s was diagnosed with a perianal abscess with an unknown origin of infection. The patient has undergone an incision and drainage. Her pus culture and sensitivity report yielded Salmonella enterica serotype Choleraesuis. Then, the patient recovered after treatment with intravenous antibiotics and supportive treatment.We present an unusual case of S. enterica serotype Choleraesuis, which is rarely reported as a causative agent of perianal abscess in India. This case has been reported for its rarity in India.