Complete genome of a rare Salmonella enterica subsp. enterica serovar Hessarek from human stool.

We present a complete genome of Salmonella enterica subsp. enterica serovar Hessarek isolated from a human stool from an outbreak linked to egg consumption in South Australia. Orientation of the rrn operon and characteristics of the Salmonella virulence plasmid indicates that this serovar is virulent toward humans and birds.

Salmonella Peritonitis Secondary to Gastroduodenal Perforation: An Unusual Presentation of Enteric Fever.

Salmonella-induced peritonitis, secondary to spontaneous gastrointestinal perforation, is a rare but potentially life-threatening condition. We present a case of a 62-year-old female with a history of systemic hypertension, who presented with diffuse abdominal pain and altered bowel habits. Initial evaluation suggested acute gastroenteritis, but worsening symptoms led to emergent exploratory laparotomy, revealing a gastric/duodenal perforation. Peritoneal fluid analysis and culture confirmed Salmonella Paratyphi A infection. The patient underwent an emergency laparotomy with omental patch repair and received intravenous ceftriaxone, leading to a full recovery. This case underscores the importance of considering Salmonella infection in the differential diagnosis of peritonitis, prompt surgical intervention, and appropriate antimicrobial therapy for optimal management and outcomes. Further research on epidemiological trends, host-pathogen interactions, and antibiotic resistance should be explored. Clinical studies should refine diagnostic criteria and treatment protocols, while animal models can aid in understanding pathophysiology and vaccine development for Salmonella peritonitis. Public health interventions and environmental studies will enhance prevention and control strategies.

[Detection of Salmonella and Enumeration of Hygienic Indicator Bacteria in Dried Wood Ear Mushrooms].

An outbreak of Salmonella Stanley in the United States associated with dried wood ear mushrooms imported from China prompted us to conduct serotyping of Salmonella isolated from dried wood ear mushrooms in voluntary testing, and quantitative test for Salmonella along with enumeration of hygienic indicator bacteria in positive samples in order to evaluate the risk of Salmonella outbreak from dried wood ear mushrooms. The major serovars of Salmonella isolates obtained from 20 samples were as follows: O3,10 group-London (n=3) and Weltevreden (n=5) etc, totaling 9 strains; O4 serogroup-Saintpaul (n=2), Stanley (n=1), Typhimurium (including monophasic variant; n=3), totaling 6 strains. O7 serogroup (Potsdam) and O8 serogroup (Newport) were one strain each. Qualitative and quantitative tests for Salmonella were conducted on 10 samples with remaining amounts. As a result, one sample was 220 MPN/g, six samples were<0.6 MPN/g, and three samples were negative for Salmonella per 25 g. The mean aerobic bacterial counts and coliforms in these samples were 7.8 and 6.1 log10 CFU/g, respectively. Furthermore, qualitative test for Salmonella and enumeration of hygienic indicator bacteria were conducted on dried wood ear mushroom products (33 domestic and 30 imported products) retailed in Japan. No samples showed positive for Salmonella per 25 g, and the mean aerobic bacterial counts and coliforms were approximately 2 log10 CFU/g lower than those in the 10 samples where Salmonella was isolated during voluntary testing. While no Salmonella was detected in domestically retailed wood ear mushrooms products, the serovars associated with foodborne diseases were isolated from voluntary testing samples. It indicates that potential for consumption of Salmonella contaminated wood ear mushrooms, which is at risk of causing food poisoning.

Serovar and sequence type distribution and phenotypic and genotypic antimicrobial resistance of Salmonella originating from pet animals in Chongqing, China.

A total of 334 Salmonella isolates were recovered from 6,223 pet rectal samples collected at 50 pet clinics, 42 pet shops, 7 residential areas, and 4 plazas. Forty serovars were identified that included all strains except for one isolate that did not cluster via self-agglutination, with Salmonella Typhimurium monophasic variant, Salmonella Kentucky, Salmonella Enteritidis, Salmonella Pomona, and Salmonella Give being the predominant serovars. Fifty-one sequence types were identified among the isolates, and ST198, ST11, ST19, ST451, ST34, and ST155 were the most common. The top four dominant antimicrobials to which isolates were resistant were sulfisoxazole, ampicillin, doxycycline, and tetracycline, and 217 isolates exhibited multidrug resistance. The prevalence of ß-lactamase genes in Salmonella isolates was 59.6%, and among these isolates, 185 harbored blaTEM, followed by blaCTX-M (66) and blaOXA (10). Moreover, six PMQR genes, namely, including qnrA (4.8%), qnrB (4.2%), qnrD (0.9%), qnrS (18.9%), aac(6')-Ib-cr (16.5%), and oqxB (1.5%), were detected. QRDR mutations (76.6%) were very common in Salmonella isolates, with the most frequent mutation in parC (T57S) (47.3%). Furthermore, we detected six tetracycline resistance genes in 176 isolates, namely, tet(A) (39.5%), tet(B) (8.1%), tet(M) (7.7%), tet(D) (5.4%), tet(J) (3.3%), and tet(C) (1.8%), and three sulfonamide resistance genes in 303 isolates, namely, sul1 (84.4%), sul2 (31.1%), and sul3 (4.2%). Finally, we found 86 isolates simultaneously harboring four types of resistance genes that cotransferred 2-7 resistance genes to recipient bacteria. The frequent occurrence of antimicrobial resistance, particularly in dogs and cats, suggests that antibiotic misuse may be driving multidrug-resistant Salmonella among pets.IMPORTANCEPet-associated human salmonellosis has been reported for many years, and antimicrobial resistance in pet-associated Salmonella has become a serious public health problem and has attracted increasing attention. There are no reports of Salmonella from pets and their antimicrobial resistance in Chongqing, China. In this study, we investigated the prevalence, serovar diversity, sequence types, and antimicrobial resistance of Salmonella strains isolated from pet fecal samples in Chongqing. In addition, ß-lactamase, QRDR, PMQR, tetracycline and sulfonamide resistance genes, and mutations in QRDRs in Salmonella isolates were examined. Our findings demonstrated the diversity of serovars and sequence types of Salmonella isolates. The isolates were widely resistant to antimicrobials, notably with a high proportion of multidrug-resistant strains, which highlights the potential direct or indirect transmission of multidrug-resistant Salmonella from pets to humans. Furthermore, resistance genes were widely prevalent in the isolates, and most of the resistance genes were spread horizontally between strains.

Battling Salmonella enteritidis infections: integrating proteomics and in vivo assessment of Galla Chinensis tannic acid.

Salmonella infections pose a significant threat to animal and human health. Phytochemicals present a potential alternative treatment. Galla chinensis tannic acid (GCTA), a hydrolyzable polyphenolic compound, inhibits bacterial growth and demonstrates potential as an alternative or supplement to antibiotics to prevent Salmonella infections. However, little is known about the antimicrobial mechanism of GCTA against Salmonella. Here, we revealed 456 differentially expressed proteins upon GCTA treatment, impacting pathways related to DNA replication, repair, genomic stability, cell wall biogenesis, and lipid metabolism using TMT-labeled proteomic analysis. TEM analysis suggested altered bacterial morphology and structure post-treatment. A Salmonella-infected-mouse model indicated that GCTA administration improved inflammatory markers, alleviated intestinal histopathological alterations, and reduced Salmonella enterica serovar Enteritidis (S. Enteritidis) colonization in the liver and spleen of Salmonella-infected mice. The LD50 of GCTA was 4100 mg/kg with an oral single dose, vastly exceeding the therapeutic dose. Thus, GCTA exhibited antibacterial and anti-infective activity against S. Enteritidis. Our results provided insight into the molecular mechanisms of these antibacterial effects, and highlights the potential of GCTA as an alternative to antibiotics.

Curing of a field strain of Salmonella enterica serovar Infantis isolated from poultry from its highly stable pESI like plasmid.

Salmonella enterica serovar Infantis (S. infantis) is an important emerging pathogen, associated with poultry and poultry products and related to an increasing number of human infections in many countries. A concerning trend among S. infantis isolates is the presence of plasmid-mediated multidrug resistance. In many instances, the genes responsible for this resistance are carried on a megaplasmid known as the plasmid of emerging S. infantis (pESI) or pESI like plasmids. Plasmids can be remarkably stable due to the presence of multiple replicons and post-segregational killing systems (PSKs), which contribute to their maintenance within bacterial populations. To enhance our understanding of S. infantis and its multidrug resistance determinants toward the development of new vaccination strategies, we have devised a new method for targeted plasmid curing. This approach effectively overcomes plasmid addiction by leveraging the temporal overproduction of specific antitoxins coupled with the deletion of the partition region. By employing this strategy, we successfully generated a plasmid-free strain from a field isolate derived from S. infantis 119,944. This method provides valuable tools for studying S. infantis and its plasmid-borne multidrug resistance mechanisms and can be easily adopted for plasmid curing from other related bacteria.

Colonization, spread and persistence of Salmonella (Typhimurium, Infantis and Reading) in internal organs of broilers.

Transfer of Salmonella to internal organs of broilers over a 35 d grow-out period was evaluated. A total of 360 one-day old chicks were placed in 18 floor pens of 3 groups with 6 replicate pens each. On d 0, broilers were orally challenged with a cocktail of Salmonella (equal population of marked serovars; nalidixic acid-resistant S. Typhimurium, rifampicin-resistant S. Infantis, and kanamycin-resistant S. Reading) to have 3 groups: L (low; ∼2 log CFU/bird); M (medium; ∼5 log CFU/bird); and H (High; ∼8 log CFU/bird). On d 2, 7 and 35, 4 birds/pen were euthanized and ceca, liver, and spleen samples were collected aseptically. Gizzard samples (4/pen) were collected on d 35. The concentration of Salmonella in liver and spleen were transformed to binary outcomes (positive and negative) and fitted in glm function of R using cecal Salmonella concentrations (log CFU/g) and inoculation doses (L, M, and H) as inputs. On d 2, H group showed greater (P ≤ 0.05) cecal colonization of all 3 serovars compared to L and M groups. However, M group showed greater (P ≤ 0.05) colonization of all 3 serovars in the liver and spleen compared to L group. Salmonella colonization increased linearly in the ceca and quadratically in the liver and spleen with increasing challenge dose (P ≤ 0.05). On d 35, L group had greater (P ≤ 0.05) S. Infantis colonization in the ceca and liver compared to M and H groups (P ≤ 0.05). Moreover, within each group on d 35, the concentration of S. Reading was greater than those of S. Typhimurium and S. Infantis for all 3 doses in the ceca and high dose in the liver and gizzard (P ≤ 0.05). Salmonella colonization diminished in the ceca, liver, and spleen during grow-out from d 0 to d 35 (P ≤ 0.05). On d 35, birds challenged with different doses of Salmonella cocktail showed a similar total Salmonella spp. population in the ceca (ca. 3.14 log CFU/g), liver (ca. 0.54 log CFU/g), spleen (ca. 0.31 log CFU/g), and gizzard (ca. 0.42 log CFU/g). Estimates from the fitted logistic model showed that one log CFU/g increase in cecal Salmonella concentration will result in an increase in relative risk of liver and spleen being Salmonella-positive by 4.02 and 3.40 times (P ≤ 0.01), respectively. Broilers from H or M group had a lower risk (28 and 23%) of being Salmonella-positive in the liver compared to the L group when the cecal Salmonella concentration is the same (P ≤ 0.05). Oral challenge of broilers with Salmonella spp. with various doses resulted in linear or quadratic increases in Salmonella colonization in the internal organs during early age and these populations decreased during grow-out (d 35). This research can provide guidance on practices to effectively mitigate the risk of Salmonella from chicken parts and enhance public health.

The usefulness of nanopore sequencing in whole-genome sequencing-based genotyping of Listeria monocytogenes and Salmonella enterica serovar Enteritidis.

Bacterial genotyping through whole-genome sequencing plays a crucial role in disease surveillance and outbreak investigations in public health laboratories. This study assessed the effectiveness of Oxford Nanopore Technologies (ONT) sequencing in the genotyping of Listeria monocytogenes and Salmonella enterica serovar Enteritidis. Our results indicated that ONT sequences, generated with the R10.4.1 flow cell and basecalled using the Dorado 0.5.0 Super Accurate 4.3 model, exhibited comparable accuracy to Illumina sequences, effectively discriminating among bacterial strains from outbreaks. These findings suggest that ONT sequencing has the potential to be a promising tool for rapid whole-genome sequencing of bacterial pathogens in public health laboratories for epidemiological investigations. IMPORTANCE: This study unveils that Oxford Nanopore Technologies sequencing, by itself, holds the potential to serve as a whole-genome sequencing-based genotyping tool in public health laboratories, enabling routine subtyping of bacterial isolates for disease surveillance and outbreak investigations.

Antimicrobial resistance profile in Salmonella enterica serovar Choleraesuis isolates from diseased pigs in Taiwan.

This study investigated antimicrobial resistance in Salmonella enterica serovar Choleraesuis (S. Choleraesuis) isolates from diseased pigs in Taiwan (2015-2020). Among 272 isolates, florfenicol (96.7%), enrofloxacin (96.3%), doxycycline (91.2%), gentamicin (84.6%), and tiamulin (80.5%) exhibited high resistance. 99.3% of the isolates were resistant to at least one antibiotic, and 97.8% of the isolates were multidrug resistant. This study illustrated that S. Choleraesuis isolates exhibited high resistance to antimicrobials currently used in the Taiwanese swine industry.

Genetic diversity and antimicrobial susceptibility of Streptococcus suis from diseased Swiss pigs collected between 2019 - 2022.

Streptococcus suis is an important pathogen causing severe disease in pigs and humans, giving rise to economic losses in the pig production industry. Out of 65 S. suis isolates collected from diseased pigs in Switzerland between 2019 and 2022, 57 isolates were thoroughly examined by phenotypic and whole genome sequence (WGS) based characterization. The isolates' genomes were sequenced allowing for a comprehensive analysis of their distribution in terms of serovar, sequence type (ST), clonal complex (CC), and classical virulence markers. Antimicrobial resistance (AMR) genes were screened, and phenotypic susceptibility to eight classes of antimicrobial agents was examined. Serovar 6, devoid of any resistance genes, was found to be most prevalent, followed by serovars 1, 3, 1/2, and 9. Thirty STs were identified, with ST1104 being the most prevalent. Serovar 2 and serovar 1/2 were associated with CC1, potentially containing the most virulent variants. Based on single nucleotide polymorphism (SNP) analyses, fifteen isolates belonged to one of seven putative transmission clusters each consisting of two or three isolates. High phenotypic AMR rates were detected for tetracyclines (80%) and macrolides (35%) and associated with the resistance genes tet(O) and erm(B), respectively. In contrast, susceptibility to ß-lactam antibiotics and phenicols was high. Determination of phenotypic AMR profiling, including the minimum inhibitory concentrations (MICs) of the tested antimicrobial agents, sets a baseline for future studies. The study provides valuable insights into the genetic diversity and antimicrobial susceptibility of Swiss S. suis isolates, facilitating the identification of emerging clones relevant to public health concerns.

Rapid discrimination of four Salmonella enterica serovars: A performance comparison between benchtop and handheld Raman spectrometers.

Foodborne illnesses, particularly those caused by Salmonella enterica with its extensive array of over 2600 serovars, present a significant public health challenge. Therefore, prompt and precise identification of S. enterica serovars is essential for clinical relevance, which facilitates the understanding of S. enterica transmission routes and the determination of outbreak sources. Classical serotyping methods via molecular subtyping and genomic markers currently suffer from various limitations, such as labour intensiveness, time consumption, etc. Therefore, there is a pressing need to develop new diagnostic techniques. Surface-enhanced Raman spectroscopy (SERS) is a non-invasive diagnostic technique that can generate Raman spectra, based on which rapid and accurate discrimination of bacterial pathogens could be achieved. To generate SERS spectra, a Raman spectrometer is needed to detect and collect signals, which are divided into two types: the expensive benchtop spectrometer and the inexpensive handheld spectrometer. In this study, we compared the performance of two Raman spectrometers to discriminate four closely associated S. enterica serovars, that is, S. enterica subsp. enterica serovar dublin, enteritidis, typhi and typhimurium. Six machine learning algorithms were applied to analyse these SERS spectra. The support vector machine (SVM) model showed the highest accuracy for both handheld (99.97%) and benchtop (99.38%) Raman spectrometers. This study demonstrated that handheld Raman spectrometers achieved similar prediction accuracy as benchtop spectrometers when combined with machine learning models, providing an effective solution for rapid, accurate and cost-effective identification of closely associated S. enterica serovars.

Metabolite profiling and bioactivity guided fractionation of Lactobacillaceae and rice bran postbiotics for antimicrobial-resistant Salmonella Typhimurium growth suppression.

Probiotic-fermented supplements (postbiotics) are becoming increasingly explored for their activity against antibiotic-resistant enteropathogens. Prebiotics are often incorporated into postbiotics to enhance their efficacy, but due to strain differences in probiotic activity, postbiotic antimicrobial effects are poorly understood. To improve postbiotic antimicrobial efficacy, we investigated and compared metabolite profiles of postbiotics prepared with three lactic acid bacteria strains (L. fermentum, L. paracasei, and L. rhamnosus) cultured with and without rice bran, a globally abundant, rich source of prebiotics. At their minimum inhibitory dose, L. fermentum and L. paracasei postbiotics + rice bran suppressed S. Typhimurium growth 42-55% more versus their respective probiotic-alone postbiotics. The global, non-targeted metabolome of these postbiotics identified 109 metabolites increased in L. fermentum and L. paracasei rice bran postbiotics, including 49 amino acids, 20 lipids, and 12 phytochemicals metabolites. To identify key metabolite contributors to postbiotic antimicrobial activity, bioactivity-guided fractionation was applied to L. fermentum and L. paracasei rice bran-fermented postbiotics. Fractionation resulted in four L. fermentum and seven L. paracasei fractions capable of suppressing S. Typhimurium growth more effectively versus the negative control. These fractions were enriched in 15 metabolites that were significantly increased in the global metabolome of postbiotics prepared with rice bran versus postbiotic alone. These metabolites included imidazole propionate (enriched in L. fermentum + rice bran, 1.61-fold increase; L. paracasei + rice bran 1.28-fold increase), dihydroferulate (L. fermentum + rice bran, 5.18-fold increase), and linoleate (L. fermentum + rice bran, 1.82-fold increase; L. paracasei + rice bran, 3.19-fold increase), suggesting that they may be key metabolite drivers of S. Typhimurium growth suppression. Here, we show distinct mechanisms by which postbiotics prepared with lactic acid bacteria and rice bran produce metabolites with antimicrobial activity capable of suppressing S. Typhimurium growth. Probiotic strain differences contributing to postbiotic antimicrobial activity attract attention as adjunctive treatments against pathogens.

In silico and PCR Screening for a Live Attenuated Salmonella Typhimurium Vaccine Strain.

The application of live attenuated Salmonella Typhimurium vaccines has significantly helped control Salmonella in poultry products. Because the U.S. Department of Agriculture-Food Safety Inspection Service (USDA-FSIS) scores all Salmonella as positive, regardless of serovar, attenuated vaccine strains that are identified at processing contribute negatively toward Salmonella performance standards. This study was designed to determine the incidence of a live attenuated Salmonella serovar Typhimurium vaccine identified in broiler products by FSIS and to develop a PCR assay for screening of isolates. Salmonella Typhimurium short-read sequences from broiler samples uploaded to the National Center for Biotechnology Information (NCBI) Pathogen Detection database by the USDA-FSIS from 2016 to 2022 were downloaded and assembled. These were analyzed using the Basic Local Alignment Search Tool (BLAST) with a sequence unique to field strains, followed by a sequence unique to the vaccine strain. The PCR assays were developed against field and vaccine strains by targeting transposition events in the crp and cya genes and validated by screening Salmonella serovar Typhimurium isolates. Between 2016 and 2022, 1708 Salmonella Typhimurium isolates of chicken origin were found in the NCBI Pathogen Detection database, corresponding to 7.99% of all Salmonella identified. Of these, 104 (5.97%) were identified as the vaccine strain. The PCR assay differentiated field strains from the vaccine strain when applied to isolates and was also able to detect the vaccine strain from DNA isolated from mixed serovar overnight Salmonella enrichment cultures. Live attenuated Salmonella vaccines are a critical preharvest tool for Salmonella control and are widely used in industry. With forthcoming regulations that will likely focus on Salmonella Typhimurium, along with other serovars, there is a need to distinguish between isolates belonging to the vaccine strain and those that are responsible for causing human illness.

Detección in silico y por PCR de una cepa vacunal viva atenuada de Salmonella Typhimurium. La aplicación de vacunas vivas atenuadas contra Salmonella Typhimurium ha ayudado significativamente a controlar Salmonella en productos avícolas. Debido a que el Servicio de Inspección de Seguridad Alimentaria del Departamento de Agricultura de los Estados Unidos. (USDA-FSIS) califica todas las Salmonella como positivas, independientemente del serovar. Las cepas atenuadas de la vacuna que se identifican en el procesamiento contribuyen negativamente a los estándares de desempeño de Salmonella. Este estudio fue diseñado para determinar la incidencia de una vacuna viva atenuada de Salmonella serovar Typhimurium identificada en productos de pollo de engorde por el FSIS y para desarrollar un ensayo de PCR para la detección de aislados. Se recolectaron y ensamblaron secuencias de lectura corta de Salmonella Typhimurium de muestras de pollos de engorde introducidas en la plataforma de detección de patógenos del Centro Nacional de Información Biotecnológica (NCBI) por el USDA-FSIS entre los años 2016 al 2022. Estos se analizaron utilizando la herramienta de búsqueda de alineación local básica con una secuencia exclusiva para las cepas de campo, seguida de una secuencia exclusiva para la cepa vacunal. Los ensayos de PCR se desarrollaron contra cepas de campo y vacunales centrándose en eventos de transposición en los genes crp y cya y se validaron mediante la detección de aislados de Salmonella serovar Typhimurium. Entre 2016 y 2022, se encontraron 1708 aislados de Salmonella Typhimurium de origen avícola en el sistema de detección de patógenos del NCBI, lo que corresponde al 7.99 % de todas las Salmonellas identificadas. De ellas, 104 (5.97%) fueron identificadas como cepa vacunal. El ensayo de PCR diferenció las cepas de campo de la cepa de la vacuna cuando se aplicó a los aislados y también fue capaz de detectar la cepa de la vacuna a partir del ADN aislado de cultivos de enriquecimiento por toda la noche de Salmonella con serovares mixtos. Las vacunas vivas atenuadas contra Salmonella son una herramienta fundamental para el control de Salmonella y se utilizan ampliamente en la industria. Con las próximas regulaciones que probablemente se centrarán en Salmonella Typhimurium, junto con otros serovares, es necesario distinguir entre los aislados que pertenecen a la cepa vacunal y los que son responsables de causar enfermedades humanas.

ß-lactam-induced OMV release promotes polymyxin tolerance in Salmonella enterica sv. Typhi.

The rise of multidrug-resistant bacteria is a global concern, leading to a renewed reliance on older antibiotics like polymyxins as a last resort. Polymyxins, cationic cyclic peptides synthesized nonribosomally, feature a hydrophobic acyl tail and positively charged residues. Their antimicrobial mechanism involves initial interaction with Gram-negative bacterial outer-membrane components through polar and hydrophobic interactions. Outer membrane vesicles (OMVs), nano-sized proteoliposomes secreted from the outer membrane of Gram-negative bacteria, play a crucial role in tolerating harmful molecules, including cationic peptides such as polymyxins. Existing literature has documented environmental changes' impact on modulating OMV properties in Salmonella Typhimurium. However, less information exists regarding OMV production and characteristics in Salmonella Typhi. A previous study in our laboratory showed that S. Typhi ΔmrcB, a mutant associated with penicillin-binding protein (PBP, a ß-lactam antibiotic target), exhibited hypervesiculation. Consequently, this study investigated the potential impact of ß-lactam antibiotics on promoting polymyxin tolerance via OMVs in S. Typhi. Our results demonstrated that sub-lethal doses of ß-lactams increased bacterial survival against polymyxin B in S. Typhi. This phenomenon stems from ß-lactam antibiotics inducing hypervesiculation of OMVs with higher affinity for polymyxin B, capturing and diminishing its biologically effective concentration. These findings suggest that ß-lactam antibiotic use may inadvertently contribute to decreased polymyxin effectivity against S. Typhi or other Gram-negative bacteria, complicating the effective treatment of infections caused by these pathogens. This study emphasizes the importance of evaluating the influence of ß-lactam antibiotics on the interaction between OMVs and other antimicrobial agents.

Low interleukin-10 level indicates a good prognosis in Salmonella enterica serovar typhimurium-induced pediatric hemophagocytic lymphohistiocytosis: A case report.

BACKGROUND: Secondary hemophagocytic lymphohistiocytosis (sHLH) triggered by Salmonella enterica serovar Typhimurium is rare in pediatric patients. There is no consensus on how to treat S. typhimurium-triggered sHLH. CASE SUMMARY: A 9-year-old boy with intermittent fever for 3 d presented to our hospital with positive results for S. typhimurium, human rhinovirus, and Mycoplasma pneumoniae infections. At the time of admission to our institution, the patient's T helper 1/T helper 2 cytokine levels were 326 pg/mL for interleukin 6 (IL-6), 9.1 pg/mL for IL-10, and 246.7 pg/mL for interferon-gamma (IFN-γ), for which the ratio of IL-10 to IFN-γ was 0.04. In this study, the patient received meropenem, linezolid, and cefoperazone/sulbactam in combination with high-dose methylprednisolone therapy (10 mg/kg/d for 3 d) and antishock supportive treatment twice. After careful evaluation, this patient did not receive HLH chemotherapy and recovered well. CONCLUSION: S. Typhimurium infection-triggered sHLH patient had a ratio of IL-10 to IFN-γ ≤ 1.33, an IL-10 concentration ≤ 10.0 pg/mL, and/or an IFN-γ concentration ≤ 225 pg/mL at admission. Early antimicrobial and supportive treatment was sufficient, and the HLH-94/2004 protocol was not necessary under these conditions.

A One Health Perspective on Salmonella enterica Serovar Infantis, an Emerging Human Multidrug-Resistant Pathogen.

Salmonella enterica serovar Infantis presents an ever-increasing threat to public health because of its spread throughout many countries and association with high levels of antimicrobial resistance (AMR). We analyzed whole-genome sequences of 5,284 Salmonella Infantis strains from 74 countries, isolated during 1989-2020 from a wide variety of human, animal, and food sources, to compare genetic phylogeny, AMR determinants, and plasmid presence. The global Salmonella Infantis population structure diverged into 3 clusters: a North American cluster, a European cluster, and a global cluster. The levels of AMR varied by Salmonella Infantis cluster and by isolation source; 73% of poultry isolates were multidrug resistant, compared with 35% of human isolates. This finding correlated with the presence of the pESI megaplasmid; 71% of poultry isolates contained pESI, compared with 32% of human isolates. This study provides key information for public health teams engaged in reducing the spread of this pathogen.

High Salmonella load with serovar virchow dominance pose major public safety risk in postchill broiler carcasses.

The objective of this study was to determine Salmonella contamination levels, presence and serovar distribution in broiler carcasses before and after chilling, as well as to evaluate the effectiveness of chilling process. A total of 96 pooled neck skin samples (PNSS) of 48 prechill (PreC) and 48 postchill (PosC) carcasses, representing 480 broilers collected in 6 mo' period were analyzed using ISO 6579-2:2012 Miniaturized Most Probable Number (ISO-mMPN) technique. Species confirmation and serovar identification was performed by Salmonella-specific real-time PCR (Salm-PCR) and conventional serotyping, respectively. Mean Salmonella count was 1.84 log10 MPN/g in PreC, and 1.48 log10 MPN/g in PosC samples, indicating a statistically significant reduction of 0.36 log10 MPN/g (p < 0.05) in the counts by plant's air chill system. Salmonella positivity reduced from 97.9% (47/48) in PreC to 85.42% (41/48) in PosC samples, confirmed by Salm-PCR with identified serovars as S. Virchow (89.77 %) followed by S. Schwarzengrund (9.09%) and S. Bredeney (1.14%). Persistence of high load and prevalence of Salmonella with serovar Virchow dominance (other than the ones mandated in current guidelines) in the final product contributes significant and up to date data to relevant literature, and provides unbiased epidemiological reference to legal authorities for future relevant revisions.

Pyelonephritis with bacteremia caused by Salmonella Choleraesuis in a Japanese patient with carcinoma of unknown primary origin: A case report.

Salmonella enterica subspecies enterica serovar Choleraesuis (S. Choleraesuis) is a nontyphoidal Salmonella pathogen that causes swine paratyphoids. S. Choleraesuis is a zoonotic pathogen transmitted to humans via contaminated food and causes sepsis. Here, we report a rare case of pyelonephritis caused by S. Choleraesuis in a Japanese patient with a carcinoma of unknown primary origin. On the day of admission, the patient was diagnosed with pyelonephritis associated with ureteral stent obstruction. He had no history of raw pork consumption or gastrointestinal symptoms. Gram-negative rods were isolated from urine and blood cultures, identified as Salmonella enterica subsp. enterica using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The serological typing results were O7: -: 1 and 5; however, the serotypes could not be determined. The isolate was identified as S. Choleraesuis using multilocus sequence typing, nucleotide sequence analysis of the fliC gene, and biochemical examination. Four days after a 14-day course of intravenous piperacillin-tazobactam (9 g/day), the patient showed relapse of the condition. Subsequently, the patient was treated with intravenous ceftriaxone (2 g/day) and oral amoxicillin (1000 mg/day) for 14 days each; recurrence was not observed. This novel case of pyelonephritis with bacteremia was caused by S. Choleraesuis in Japan. Conventional testing methods could not identify the serotypes; however, the case highlights the importance of adopting advanced diagnostic techniques based on molecular biology to ensure accurate pathogen identification.

Antimicrobial Resistance and the Genomic Epidemiology of Multidrug-Resistant Salmonella enterica serovar Enteritidis ST11 in China.

BACKGROUND: With the recent evolution of multidrug-resistant strains, the genetic characteristics of foodborne Salmonella enterica serovar Enteritidis and clinical isolates have changed. ST11 is now the most common genotype associated with S. Enteritidis isolates. METHODS: A total of 83 strains of S. Enteritidis were collected at the General Hospital of the People's Liberation Army. Of these, 37 were from aseptic sites in patients, 11 were from the feces of patients with diarrhea, and the remaining 35 were of chicken-origin. The minimum inhibitory concentration of S. Enteritidis was determined by the broth microdilution method. Genomic DNA was extracted using the QiAamp DNA Mini Kit, and whole-genome sequencing (WGS) was performed using an Illumina X-ten platform. Prokka was used for gene prediction and annotation, and bioinformatic analysis tools included Resfinder, ISFinder, Virulence Factor Database, and PlasmidFinder. IQ-TREE was used to build a maximum likelihood phylogenetic tree. The phylogenetic relationship and distribution of resistance genes was displayed using iTOL. Comparative population genomics was used to analyze the phenotypes and genetic characteristics of antibiotic resistance in clinical and chicken-origin isolates of S. Enteritidis. RESULTS: The chicken-origin S. Enteritidis isolates were more resistant to antibiotics than clinical isolates, and had a broader antibiotic resistance spectrum and higher antibiotic resistance rate. A higher prevalence of antibiotic-resistance genes was observed in chicken-origin S. Enteritidis compared to clinical isolates, along with distinct patterns in the contextual characteristics of these genes. Notably, genes such as blaCTX-M and dfrA17 were exclusive to plasmids in clinical S. Enteritidis, whereas in chicken-origin S. Enteritidis they were found in both plasmids and chromosomes. Additionally, floR was significantly more prevalent in chicken-origin isolates than in clinical isolates. Careful analysis revealed that the delayed isolation of chicken-origin S. Enteritidis contributes to accelerated gene evolution. Of note, certain resistance genes tend to integrate seamlessly and persist steadfastly within the chromosome, thereby expediting the evolution of resistance mechanisms against antibiotics. Our comparative analysis of virulence genes in S. Enteritidis strains from various sources found no substantial disparities in the distribution of other virulence factors. In summary, we propose that chicken-origin S. Enteritidis has the potential to cause clinical infections. Moreover, the ongoing evolution and dissemination of these drug-resistant genes poses a formidable challenge to clinical treatment. CONCLUSIONS: Constant vigilance is needed to monitor the dynamic patterns of drug resistance in S. Enteritidis strains sourced from diverse origins.

A TonB dependent transporter YncD of Salmonella enterica Serovar Typhi possesses vaccine potential.

Multiple TonB dependent transporters (TBDTs) contribute to bacterial virulence due to the importance roles that their substrates play in bacterial growth, and possess vaccine potential. A putative TBDT, YncD, had been identified as one of in vivo induced antigens during human infection of typhoid fever, and is required for the pathogenicity of Salmonella enterica Serovar Typhi. The present study was aimed to determine the function and immunogenicity of YncD. Homologous recombination method was used to construct an yncD-deletion mutant and cirA-iroN-fepA-deletion mutant from the wild-type S. Typhi Ty2. The growth of mutants and the wild-type strain were assessed in iron-deficient medium, as well as in human macrophage cells. Recombinant YncD protein was expressed and purified using Ni-NTA affinity chromatography and anion exchange. A mouse model was then used to evaluate the immunogenicity and protection efficacy of the recombinant YncD. Antibody levels, serum bactericidal efficiency, passive immune protection, opsonophagocysis were assayed to analyse the immunoprotection mechanism of the recombinant YncD. Our results showed that YncD is associated with the iron-uptake of S. Typhi. The yncD-deletion mutant displayed impaired growth in iron-deficient medium, comparable to that the cirA-iroN-fepA-deletion mutant did. The mutation of yncD markedly decreased bacterial growth within human macrophage cells. Moreover, subcutaneous immunization of mice with recombinant YncD elicited high levels of specific anti-YncD IgG, IgG1 and IgG2a, which protected the immunized mice against the intraperitoneal challenge of S. Typhi, and decreased bacterial burdens in the livers and spleens of the infected mice. Passive immunization using the immunized sera also efficiently protected the mice from the challenge of S. Typhi. Moreover, the immunized sera enhanced in vitro bactericidal activity of complement, and opsonophagocytosis. Our results showed that YncD displays a role in the iron-uptake of S. Typhi and possesses immunogenicity.