Salmonellosis Including Enteric Fever

Characterization and release of casein‑sodium alginate embedding phage edible film and the application in controlling of Salmonella contamination in food

Salmonella remains a major foodborne pathogen responsible for food poisoning and poses a serious threat to public health. This study has developed an edible antimicrobial film using bacteriophage (phage) SaTp-04, specifically designed to capture and eliminate Salmonella in food. Optimal film conditions were achieved using casein (CA) and sodium alginate (SA) as the matrix, glycerol as the plasticizer, and phage protector. The mechanical properties and phage encapsulation rate were used as response variables. The presence of phage SaTp-04 did not significantly alter the thickness, tensile strength, elongation at break, water vapor permeability, moisture content, or water solubility of the film. Furthermore, the Fourier Transform Infrared spectroscopy, X-ray diffraction, and microscopic morphology of the phage film were similar to those of the phage-free film. The phage titer in the film remained stable for up to five weeks at 4 °C. Phage release from the film in water followed a first-order kinetics model (y = 85.312 × (1-e-0.106x), R2 = 0.9687). The release amount and rate were lower at 4 °C on LB plate surfaces than at 25 °C. The phage film inhibited Salmonella growth on fresh chicken breast and carrots at 4 and 10 °C. The surface of chicken breast packaged with the phage film showed a reduction of approximately 6 log CFU/cm2 in Salmonella compared to the control, while the carrot surface demonstrated a reduction in Salmonella to below the detection limit (10 CFU/cm2) at 37 °C. These results confirm the feasibility of using phage SaTp-04 CA-SA edible films for food safety, providing a viable strategy for developing targeted capture packaging for foodborne pathogenic bacteria.

Using pathology images and artificial intelligence to identify bacterial infections and their types

Bacterial infections pose a significant biosafety concern, making early and accurate diagnosis essential for effective treatment and prognosis. Traditional diagnostic methods, while reliable, are often slow and fail to meet urgent clinical demands. In contrast, emerging technologies offer greater efficiency but are often costly and inaccessible. In this study, we utilized easily accessible pathology images to diagnose bacterial infections. Our initial findings indicate that, in the absence of postmortem phenomena, microscopic examination of pathological images can confirm the presence of a bacterial infection. However, distinguishing between different types of bacterial infections remains challenging due to similarities in pathological changes. To address this limitation, we applied a computational pathology approach by integrating pathology images with artificial intelligence (AI) algorithms. Our model classified bacterial infections at both the patch-level and whole slide image (WSI)-level. The results demonstrated strong performance, with an overall AUC consistently above 0.950 across training, testing, and external validation datasets, indicating high accuracy, robustness, and generalizability. This study highlights AI's potential in identifying bacterial infection types and provides valuable technical support for clinical diagnostics, paving the way for faster and more precise infection management.

Purpurin suppresses Salmonella invasion of host cells by reducing the secretion of T3SS-1 effector proteins

Salmonella Typhimurium (S. Typhimurium, ST) is a food-borne pathogen that can be transmitted from animals to humans and causes symptoms such as diarrhea, fever, and vomiting. While antibiotics are commonly used to treat clinical infections, the increase in drug resistance has limited their effectiveness. Antivirulence drugs offer a new approach to treating bacterial infections by targeting specific virulence factors without affecting bacterial growth, thus helping to combat infection without exerting selective pressure on bacteria or inducing resistance. Salmonella pathogenicity island 1 (SPI-1), encoding type three secretion system 1 (T3SS-1), serves as a crucial virulence factor for the invasion of ST into host cells, making it an ideal target for screening anti-Salmonella virulence drugs. This project involved screening of ST invasion inhibitors through a gentamicin protection assay and identified purpurin (PPR) as capable of inhibiting the ST invasion of HeLa cells. Subsequent studies revealed that PPR had no effect on the natural growth of bacteria and was not cytotoxic to host cells. A mechanistic study revealed that PPR effectively inhibits the secretion of T3SS-1 in ST. The results from animal experiments indicated that PPR exhibited significant efficacy in a mouse enteritis model caused by ST infection, increasing the survival rate of mice infected with a lethal dose by 50%, reducing spleen colonization in infected mice, and alleviating tissue damage resulting from ST infection. Therefore, PPR represents a promising antivirulence drug that targets the T3SS of ST and may serve as a hit compound for the development of novel antivirulence drugs for the treatment of ST.

Galleria mellonella (Greater Wax Moth) as a Reliable Animal Model to Study the Efficacy of Nanomaterials in Fighting Pathogens

The spread of multidrug-resistant microbes has made it necessary and urgent to develop new strategies to deal with the infections they cause. Some of these are based on nanotechnology, which has revolutionized many fields in medicine. Evaluating the safety and efficacy of these new antimicrobial strategies requires testing in animal models before being tested in clinical trials. In this context, Galleria mellonella could represent a valid alternative to traditional mammalian and non-mammalian animal models, due to its low cost, ease of handling, and valuable biological properties to investigate host-pathogen interactions. The purpose of this review is to provide an updated overview of the literature concerning the use of G. mellonella larvae as an animal model to evaluate safety and efficacy of nanoparticles and nanomaterials, particularly, of those that are used or are under investigation to combat microbial pathogens.

Triple Co-infection With Salmonella typhi, Leptospira, and Campylobacter coli in a Patient From Guayaquil, Ecuador: Clinical and Diagnostic Challenges

This case report describes the unusual presentation of a 32-year-old male from Guayaquil, Ecuador, who was diagnosed with a rare triple infection caused by Salmonella typhi, Leptospira, and Campylobacter coli. The patient presented with persistent high fever, severe gastrointestinal symptoms, abdominal pain, and jaundice, following the consumption of street food in a resource-limited area. Important clinical findings included hepatosplenomegaly and elevated liver enzymes, which initially complicated the differential diagnosis. Laboratory tests confirmed the presence of all three pathogens, presenting significant diagnostic and therapeutic challenges due to overlapping symptoms and potential antimicrobial resistance (AMR). The main diagnoses included typhoid fever, leptospirosis, and campylobacteriosis, each requiring distinct yet coordinated treatment approaches. The patient was managed with a combination of antibiotics targeting each pathogen and supportive care to address dehydration and liver dysfunction. After a prolonged hospital stay, the patient recovered with no residual symptoms, underscoring the success of a tailored, multidisciplinary approach in the context of limited healthcare resources. This case underscores the importance of clinical awareness regarding co-infections, particularly in areas with inadequate sanitation, where infectious diseases are endemic. The successful management of this complex case highlights the necessity of rapid, accurate diagnostics and coordinated therapeutic strategies to improve outcomes in patients with multi-pathogen infections. This report also emphasizes the critical need for surveillance and tailored interventions in regions facing rising AMR, enhancing our understanding of how to approach emerging infectious diseases in underserved populations.

Salmonella Weltevreden lung abscess and empyema without preceding gastrointestinal symptoms: an emerging pathogen in Australia?

Non-typhoidal Salmonella lung infections are rare and are usually confined to immunocompromised hosts. Previous case reports have found that usually patients have either gastroenteritis or bacteraemia in addition to pulmonary involvement. We present the first known reported case of a Salmonella Weltevreden lung abscess and empyema in an immunocompetent patient without gastroenteritis. Despite the use of antimicrobials active against the pathogen, the patient needed surgical intervention to achieve adequate source control. While S. Weltevreden has previously been associated with returned travellers, especially from Southeast Asia, its incidence in Queensland is now increasing. Therefore, it is important for clinicians to be aware of its potential severity as well as the range of presentations.

Typhoid and paratyphoid fever epidemiological indicators and spatiotemporal analysis in China from 2004 to 2019

Typhoid and paratyphoid fever are systemic infections caused by Salmonella Typhi and Salmonella Paratyphi. These diseases are endemic in many parts of China, occurring periodically throughout the year. Epidemiological features, temporal trends, and spatial distribution of these fevers were analyzed using GraphPad Prism 9 with data collected by China's Public Health Science Data Center from 2004 to 2019. Charts were generated to depict their incidence across provinces, years, age groups, and occupations. Spatial clustering was assessed using ArcGIS 10.5 and Moran's I index. SaTScan 9.5 was employed to analyze their spatiotemporal distribution. From 2004 to 2019, China reported 197,623 cases of typhoid fever, resulting in 72 deaths, and 84,583 cases of paratyphoid fever, with 17 fatalities, showing a yearly reduction. Epidemic zones for these diseases are primarily in Yunnan, Guangxi, Guizhou, and other southwestern regions, affecting predominantly peasants and students. Children and adolescents are particularly vulnerable. Due to the epidemic nature of these diseases, they can occur year-round, with peaks in the summer months. This study provides a comprehensive understanding of their epidemiological characteristics and geographic distribution in China, emphasizing the need for authorities to improve living conditions, implement preventive measures, and develop effective treatments and vaccines in these high-risk areas.

Convergent synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-polysaccharide of Salmonella milwaukee (group U) O:43 strain

Synthesis of the pentasaccharide repeating unit of the cell O-polysaccharide produced by Salmonella milwaukee O:43 strain (group U) has been achieved in very good yield adopting a convergent stereoselective [3 + 2] block glycosylation strategy. Thioglycosides and glycosyl trichloroacetimidate derivative were used as glycosyl donors in the presence of a combination of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) as thiophilic activator and TMSOTf as trichloroacetimidate activator respectively. The stereochemical outcome of all glycosylation reactions was excellent.

Nontyphoidal Salmonella Outbreaks Associated With Chocolate Consumption: A Systematic Review

BACKGROUND

A large, cross-border outbreak of nontyphoidal salmonellosis connected to chocolate product consumption was recently reported. This occurrence motivated us to conduct a comprehensive review of existing literature concerning outbreaks of nontyphoidal salmonellosis associated with chocolate consumption.

METHODS

We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO CRD42022369023) in 3 databases: U.S. National Library of Medicine, Web of Science and Excerpta Medica. Google Scholar and the bibliography of each identified report were also screened. Eligible were articles published after 1970, describing outbreaks of more than 10 patients with a nontyphoidal salmonellosis associated with chocolate consumption.

RESULTS

Twenty-three articles were included, which described 12 outbreaks involving a total of 3266 patients. All outbreaks occurred in high-income countries: 1 was limited to 1 city, 6 involved 1 country and the remaining 5 involved 2 or more countries. Six outbreaks peaked in winter, 3 in autumn, 2 in spring and 1 in summer. Children were mainly affected. No predominant serotype was identified.

CONCLUSIONS

Our data documents that chocolate is an optimal medium for the transmission of nontyphoidal salmonellosis. A connected worldwide reporting system including high-income, middle-income and low-income countries is crucial to detect infectious diseases outbreaks in an early phase and avoid their spread.

Diverse Prophage Elements of Salmonella enterica Serovars Show Potential Roles in Bacterial Pathogenicity

Nontyphoidal salmonellosis is an important foodborne and zoonotic infection that causes significant global public health concern. Diverse serovars are multidrug-resistant and encode several virulence indicators; however, little is known on the role prophages play in driving these traits. Here, we extracted prophages from seventy-five Salmonella genomes which represent the fifteen important serovars in the United Kingdom. We analyzed the intact prophages for the presence of virulence genes and established their genomic relationships. We identified 615 prophages from the Salmonella strains, from which 195 prophages are intact, 332 are incomplete, while 88 are questionable. The average prophage carriage was found to be 'extreme' in S. Heidelberg, S. Inverness, and S. Newport (10.2-11.6 prophages/strain), 'high' in S. Infantis, S. Stanley, S. Typhimurium, and S. Virchow (8.2-9.0 prophages/strain), 'moderate' in S. Agona, S. Braenderup, S. Bovismorbificans, S. Choleraesuis, S. Dublin, and S. Java (6.0-7.8 prophages/strain), and 'low' in S. Javiana and S. Enteritidis (5.8 prophages/strain). Cumulatively, 61 virulence genes (1500 gene copies) were detected from representative intact prophages and linked to Salmonella delivery/secretion system (42.62%), adherence (32.7%), magnesium uptake (3.88%), regulation (5%), stress/survival (1.6%), toxins (10%), and antivirulence (1.6%). Diverse clusters were formed among the intact prophages and with bacteriophages of other enterobacteria, suggesting different lineages and associations. Our work provides a strong body of data to support the contributions diverse prophages make to the pathogenicity of Salmonella, including thirteen previously unexplored serovars.

The influence of cigR gene on the pathogenicity of Salmonella paratyphi A in vitro and in vivo

Salmonella Paratyphi A is the causative agent of paratyphoid fever A which is a serious threat to human health in many countries. The cigR gene located in Salmonella pathogenicity island 3 is a type III secretion system 2 effector gene. However, the influence of cigR gene on the pathogenicity of Salmonella Paratyphi A remains unclear. Here, a cigR gene deletion mutant of Salmonella Paratyphi A was constructed and its pathogenic changes were also evaluated. It was found that both the growth and biochemical features have not changed after the loss of cigR, but the absence of cigR significantly enhanced the replication and/or survival ability in phorbol-12-myristate-13-acetate (PMA)-differentiated human macrophage THP-1 cells and in mouse; the proliferative activity and apoptosis of PMA-differentiated THP-1 cell were significantly decreased and increased, respectively, after the lack of cigR gene; and the mutant showed increased virulence to a mouse infection model by decreased half-lethal dose (LD50) value and enhanced the proliferation ratio of bacteria in vivo. These results demonstrated that CigR is an anti-virulence factor and plays an important role in the pathogenicity of Salmonella Paratyphi A.

Bilateral hip septic arthritis caused by nontyphoidal Salmonella group D in a 16-year-old girl with COVID-19: A case report

Introduction and importance

Nontyphoidal Salmonella infection can lead to gastroenteritis, enteric fever, and bacteremia. However, joint infections due to this bacterium are rare, and usually associated with immunosuppressive disorders.

Case presentation

A 16-year-old girl, with a recent history of acute lymphocytic leukemia (ALL) presented with bacteremia, and bilateral hip pain after COVID-19 symptoms. Clinical presentation, laboratory features and imaging showed bilateral nontyphoidal Salmonella septic arthritis. We administered antibiotics, based on antibiotics susceptibility pattern of the isolated Salmonella.

Clinical discussion

The case is presented because reports of bilateral hip joint infection due to nontyphoidal Salmonella are rare especially after COVID-19. When the patient presents with joint discomfort, the clinician should think infection especially in immunocompromised hosts.

Conclusion

It illustrates successful management of septic arthritis requires prompt clinical diagnosis, microorganism identification, administration of appropriate systemic antibiotics and hip joint surgery.

•

Nontyphoidal Salmonella is one of the most important organisms involved in septic shock and arthritis.

•

Acute lymphocytic leukemia (ALL) is a type of cancer that affects white blood cells (WBC).

•

COVID-19 is a contagious disease caused by severe acute respiratory syndrome coronavirus.