Antimicrobial Resistance and Genomic Characterization of Campylobacter jejuni and Campylobacter coli Isolated from Retail Chickens in Beijing, China.

Objective Campylobacter species are the main causes of foodborne illness worldwide, posing significant threats to public health. This study aimed to investigate the antibiotic resistance and genomic characterization of C. jejuni/C.coli from retail chickens in Beijing. Methods Antimicrobial susceptibility testing was conducted on 126 C. jejuni/C. coli isolated from retail chickens in Beijing, following CLSI protocols. Whole genomes of all isolates were sequenced using the Illumina platform. Results More C. coli (83.82%) showed multi-drug resistance than C. jejuni (8.62%). Genomic analysis demonstrated 42 sequence types (STs) and 12 clonal complexes (CCs), from which CC828 and CC52 were dominant. cdtA, cdtB and cdtC encoding cytotoxic protein were present spontaneously in most C. jejuni but not found in any C. coli isolates. The abundances of antibiotic resistance genes (ARGs) and virulence genes (VGs) in C. jejuni and C. coli were significantly different, with ARGs numbered in C. coli and VGs in C. jejuni. Conclusions High prevalence of multi-drug resistance C. coli and C. jejuni isolated from Beijing chickens were challenging clinical antibiotic usages in the treatment of Campylobacter infection. The surveillance of particular C. jejuni and C. coli STs correlated with higher resistance and virulence needs to be strengthened in the future.

Nicotinamide riboside alleviates ionizing radiation-induced intestinal senescence by alleviating oxidative damage and regulating intestinal metabolism.

INTRODUCTION: The intestine, frequently subjected to pelvic or abdominal radiotherapy, is particularly vulnerable to delayed effects of acute radiation exposure (DEARE) owing to its high radiation sensitivity. Radiation-induced intestinal senescence, a result of DEARE, profoundly affects the well-being and quality of life of radiotherapy patients. However, targeted pharmaceutical interventions for radiation-induced senescence are currently scarce. Our findings showcase that nicotinamide riboside(NR) effectively alleviates radiation-induced intestinal senescence, offering crucial implications for utilizing NR as a pharmacological agent to combat intestinal DEARE. OBJECTIVES: The aim of this study was to investigate the ability of NR to reduce radiation induced intestinal senescence and explore its related mechanisms. METHODS: Male C57BL/6J mice were randomly divided into CON, IR, and IR + NR groups. The mice in the IR and IR + NR groups were subjected to a 6.0 Gy γ-ray total body exposure. After 8 weeks, the mice in the IR + NR group received NR via gavage at a dose of 400 mg/kg/d for 21 days. Then the mice were used for sample collection. RESULTS: Our results demonstrate that NR can significantly mitigate radiation-induced intestinal senescence. Furthermore, our findings indicate that NR can mitigate oxidative damage, restore the normal function of intestinal stem cells, regulate the disruption of the intestinal symbiotic ecosystem and address metabolic abnormalities. In addition, the underlying mechanisms involve the activation of SIRT6, SIRT7 and the inhibition of the mTORC1 pathway by NR. CONCLUSION: In conclusion, our results reveal the substantial inhibitory effects of NR on radiation-induced intestinal senescence. These findings offer valuable insights into the potential therapeutic use of NR as a pharmacological agent for alleviating intestinal DEARE.

Prevalence, antibiotic susceptibility, and genomic analysis of Vibrio alginolyticus isolated from seafood and freshwater products in China.

Introduction: This study characterized Vibrio alginolyticus isolated from seafood and freshwater products in China (2020). Methods and Results: In total, 122 (95.31%) V. alginolyticus isolates were resistant to at least 1 antibiotic category, and 2 (1.56%) isolates were resistant to at least 3 antibiotic categories and belong to multi-drug resistance (MDR) isolates. A high prevalence rate was observed to be blaCARB (98.04%) encoding beta-lactam resistance, followed by tet (97.06%) encoding tetracycline resistance and fos (4.90%) encoding resistance to fosfomycin. Among the 57 V. alginolyticus isolates, the commonest virulence genes were type III secretion system translocated gene vopD, vopB, and vcrH (54.4%, 31/57), type III secretion system regulated gene tyeA (54.39%), followed by vscI and vscF (50.88%) encoded type III secretion system inner rod protein and needle protein, respectively. Multilocus sequence typing (MLST) showed considerable genetic diversity, with 34 distinct sequence types (STs) identified among 55 isolates. ST421 (n = 5), ST166 (n = 4), ST523 (n = 3), ST516 (n = 3), and ST507 (n = 3) were dominant STs among 55 V. alginolyticus isolates. Discussion: These findings highlight the widespread occurrence of V. alginolyticus in both freshwater and seafood products, underscoring the critical need for vigilant monitoring of these bacteria. Such measures are essential for ensuring effective food safety management and safeguarding public health.

Antimicrobial susceptibility and genomic characterization of Vibrio parahaemolyticus isolated from aquatic foods in 15 provinces, China, 2020.

Prevalent in marine, estuarine and coastal environments, Vibrio parahaemolyticus is one of the major foodborne pathogens which can cause acute gastroenteritis through consumption of contaminated food. This study encompassed antimicrobial resistance, molecular characteristics and phylogenetic relationships of 163 V. parahaemolyticus isolated from aquatic foods across 15 provinces in China. The isolates showed high resistance rates against ampicillin (90.80 %, 148/163) and cefazolin (72.39 %, 118/163). Only 5 isolates demonstrated multi-drug resistance (MDR) phenotypes. A total of 37 different antibiotic resistance genes (ARGs) in correlation with seven antimicrobial categories were identified. tet(34) and tet(35) were present in all 163 isolates. Other most prevalent ARGs were those conferring resistance to ß-lactams, with prevalence rate around 18.40 % (30/163). The virulence genes tdh and trh were found in 17 (10.43 %) and 9 (5.52 %) isolates, respectively. Totally 121 sequence types (STs) were identified through whole genome analysis, among which 60 were novel. The most prevalent sequence type was ST3 (9.20 %, 15/163), which shared the same genotype profile of trh_, tdh+ and blaCARB-22+. Most of the tdh+V. parahaemolyticus isolates was clustered into a distinctive clade by the phylogenetic analysis. Our study showed that the antimicrobial resistance of V. parahaemolyticus in aquatic foods in China was moderate. However, the emerging of MDR isolates implicate strengthened monitoring is needed for the better treatment of human V. parahaemolyticus infections. High genetic diversity and virulence potential of the isolates analyzed in this study help better understanding and evaluating the risk of V. parahaemolyticus posed to public health.

Empagliflozin attenuates radiation-induced hematopoietic damage via NOX-4/ROS/p38 pathway.

PURPOSE: Damage to the hematopoietic system and functional inhibition are severe consequences of radiation exposure. In this study, we have investigated the effect of empagliflozin on radiation-induced hematopoietic damage, with the aim of providing new preventive approach to such injuries. METHODS AND MATERIALS: Mice were given 4 Gy total body irradiation (TBI) 1 h after the oral administration of empagliflozin, followed by the continuous administration of the same dose of empagliflozin for 6d, and then sacrificed on the 10th day after irradiation. The reactive oxygen species (ROS) levels in hematopoietic cells and their regulatory mechanisms were also been investigated. Colony forming unit granulocyte macrophage assay and bone marrow transplantation assays were performed to detect the function of the bone marrow cells. KEY FINDINGS: Empagliflozin increased the cell viability, reduced ROS levels, and attenuated apoptosis in vitro after the bone marrow cells were exposed to 1 Gy radiation. Empagliflozin significantly attenuated ionizing radiation injuries to the hematopoietic system, increased the peripheral blood cell count, and enhanced the proportion and function of hematopoietic stem cells in mice exposed to 4 Gy TBI. These effects may be related to the NOX-4/ROS/p38 pathway-mediated suppression of MAPK in hematopoietic stem cells. Empagliflozin also influenced the expression of Nrf-2 and increased glutathione peroxidase activity, thereby promoting the clearance of reactive oxygen species. Furthermore, empagliflozin mitigated metabolic abnormalities by inhibiting the mammalian target of rapamycin. SIGNIFICANCE: Our study has demonstrated that empagliflozin can reduce radiation-induced injury in hematopoietic stem cells. This finding suggests that empagliflozin is a promising novel agent for preventing radiation-induced damage to the hematopoietic system.

Time-restricted feeding prevents ionizing radiation-induced hematopoietic stem cell damage by inhibiting NOX-4/ROS/p38 MAPK pathway.

Ionizing radiation (IR)-induced damage to the hematopoietic system is a prominent symptom following exposure to total body irradiation (TBI). The exploration of strategies aimed at to mitigating radiation-induced hematopoietic damage assumes paramount importance. Time-restricted feeding (TRF) has garnered attention for its beneficial effects in various diseases. In this study, we evaluated the preventive effects of TRF on TBI-induced hematopoietic damage. The results suggested that TRF significantly enhanced the proportion and function of hematopoietic stem cells in mice exposed to 4 Gy TBI. These effects might be attributed to the inhibition of the NOX-4/ROS/p38 MAPK pathway in hematopoietic stem cells. TRF also influenced the expression of nuclear factor erythroid2-related factor 2 and increased glutathione peroxidase activity, thereby promoting the clearance of reactive oxygen species. Furthermore, TRF alleviated aberrations in plasma metabolism by inhibiting the mammalian target of rapamycin. These findings suggest that TRF may represent a novel approach to preventing hematopoietic radiation damage.

Emergence and genomic characteristics of multi-drug-resistant Salmonella in pet turtles and children with diarrhoea.

Pet turtles are a well-recognized source of human salmonellosis, posing a threat to human health, particularly children who commonly keep pet turtles. To date, the genomic characteristics of Salmonella among pet turtles and children has not been well described. We investigated the prevalence, antimicrobial resistance (AMR) and genomic characteristics of Salmonella from pet turtles in Beijing, China. In total, 9.6 % (46/480) of pet turtles were positive for Salmonella with S. Thompson being the dominant serovar (19/46) in 2019. Moreover, 80.4 % of Salmonella were multi-drug resistant (MDR) and 60.7 % were resistant to ampicillin, streptomycin, sulfonamides and tetracycline (ASSuT). We further compared the genomes of S. Thompson isolates from pet turtles (n=19) with those from children with diarrhoea (n=28) in the same region and year, most of which were sequence type (ST)26, with one novel ST7937 identified from a child-associated isolate. S. Thompson isolates from children with diarrhoea exhibited less resistance than isolates from pet turtles. Most MDR isolates possessed multiple AMR genes, including the AmpC ß-lactamase-encoding genes bla DHA-15 and bla DHA-1 which co-occurred with the IncA/C and IncHI plasmid replicon types. To the best of our knowledge, this is the first time that the bla DHA-15 gene has been detected from Salmonella. Several pet turtle-associated S. Thompson isolates comprised phylogenetically close clusters with those from children with diarrhoea (<20 SNP differences). Bayesian analysis demonstrated that the Chinese ST26 S. Thompson strains had a recent evolutionary history and evolved into two major clades, with one clade acquiring various resistant plasmids. Our findings revealed the emergence of MDR Salmonella among pet turtles in China and provided evidence for the interspecies transmission of S. Thompson.

Convergence of resistance and evolutionary responses in Escherichia coli and Salmonella enterica co-inhabiting chicken farms in China.

Sharing of genetic elements among different pathogens and commensals inhabiting same hosts and environments has significant implications for antimicrobial resistance (AMR), especially in settings with high antimicrobial exposure. We analysed 661 Escherichia coli and Salmonella enterica isolates collected within and across hosts and environments, in 10 Chinese chicken farms over 2.5 years using data-mining methods. Most isolates within same hosts possessed the same clinically relevant AMR-carrying mobile genetic elements (plasmids: 70.6%, transposons: 78%), which also showed recent common evolution. Supervised machine learning classifiers revealed known and novel AMR-associated mutations and genes underlying resistance to 28 antimicrobials, primarily associated with resistance in E. coli and susceptibility in S. enterica. Many were essential and affected same metabolic processes in both species, albeit with varying degrees of phylogenetic penetration. Multi-modal strategies are crucial to investigate the interplay of mobilome, resistance and metabolism in cohabiting bacteria, especially in ecological settings where community-driven resistance selection occurs.

Nicotinamide riboside intervention alleviates hematopoietic system injury of ionizing radiation-induced premature aging mice.

Radiotherapy destroys cancer cells and inevitably harms normal human tissues, causing delayed effects of acute radiation exposure (DEARE) and accelerating the aging process in most survivors. However, effective methods for preventing premature aging induced by ionizing radiation are lacking. In this study, the premature aging mice of DEARE model was established after 6 Gy total body irradiation (TBI). Then the therapeutic effects and mechanism of nicotinamide riboside on the premature aging mice were evaluated. The results showed that 6 Gy TBI induced premature aging of the hematopoietic system in mice. Nicotinamide riboside treatment reversed aging spleen phenotypes by inhibiting cellular senescence and ameliorated serum metabolism profiles. Further results demonstrated that nicotinamide riboside supplementation alleviated the myeloid bias of hematopoietic stem cells and temporarily restored the regenerative capacity of hematopoietic stem cells probably by mitigating the reactive oxygen species activated GCN2/eIF2α/ATF4 signaling pathway. The results of this study firstly indicate that nicotinamide riboside shows potential as a DEARE therapeutic agent for radiation-exposed populations and patients who received radiotherapy.

Machine learning and metagenomics reveal shared antimicrobial resistance profiles across multiple chicken farms and abattoirs in China.

China is the largest global consumer of antimicrobials and improving surveillance methods could help to reduce antimicrobial resistance (AMR) spread. Here we report the surveillance of ten large-scale chicken farms and four connected abattoirs in three Chinese provinces over 2.5 years. Using a data mining approach based on machine learning, we analysed 461 microbiomes from birds, carcasses and environments, identifying 145 potentially mobile antibiotic resistance genes (ARGs) shared between chickens and environments across all farms. A core set of 233 ARGs and 186 microbial species extracted from the chicken gut microbiome correlated with the AMR profiles of Escherichia coli colonizing the same gut, including Arcobacter, Acinetobacter and Sphingobacterium, clinically relevant for humans, and 38 clinically relevant ARGs. Temperature and humidity in the barns were also correlated with ARG presence. We reveal an intricate network of correlations between environments, microbial communities and AMR, suggesting multiple routes to improving AMR surveillance in livestock production.

High-fat diet alters the radiation tolerance of female mice and the modulatory effect of melatonin.

High-fat diet (HFD) increases the risk of developing malignant tumors. Ionizing radiation (IR) is used as an adjuvant treatment in oncology. In this study, we investigated the effects of an 8-week 35% fat HFD on the tolerance to IR and the modulatory effect of melatonin (MLT). The results of lethal dose irradiation survival experiments revealed that the 8-week HFD altered the radiation tolerance of female mice and increased their radiosensitivity, whereas it had no comparable effects on males. Pre-treatment with MLT was, however, found to attenuate the radiation-induced hematopoietic damage in mice, promote intestinal structural repair after whole abdominal irradiation (WAI), and enhance the regeneration of Lgr5+ intestinal stem cells. 16S rRNA high-throughput sequencing and untargeted metabolome analyses revealed that HFD consumption and WAI sex-specifically altered the composition of intestinal microbiota and fecal metabolites and that MLT supplementation differentially modulated the composition of the intestinal microflora in mice. However, in both males and females, different bacteria were associated with the modulation of the metabolite 5-methoxytryptamine. Collectively, the findings indicate that MLT ameliorates the radiation-induced damage and sex-specifically shapes the composition of the gut microbiota and metabolites, protecting mice from the adverse side effects associated with HFD and IR.

Ferrostatin-1 mitigates ionizing radiation-induced intestinal injuries by inhibiting apoptosis and ferroptosis: an in vitro and in vivo study.

PURPOSE: Intestinal injuries caused by ionizing radiation (IR) are a major complication of radiotherapy. Ferrostatin-1 (Fer-1) exerts antioxidant and anti-inflammatory effects. We investigated the influence of Fer-1 on IR-induced intestinal damage and explored the possible mechanisms. MATERIALS AND METHODS: IEC-6 cells were administrated with Fer-1 for 30 min and subsequently subjected to 9.0 Gy-irradiation. Flow cytometry, qPCR, and WB were used to detect changes. For in vivo experiments, Fer-1 was given intraperitoneally to mice at 1 h before and 24 h after 9.0 Gy total body irradiation (TBI) respectively. Three days after TBI, the small intestines were isolated for analysis. The diversity and composition of the gut microbiota were analyzed by 16S rRNA gene sequencing. RESULTS: In vitro, Fer-1 protected IEC-6 cells from IR injury by reducing the production of ROS and inhibiting both ferroptosis and apoptosis. In vivo, Fer-1 enhanced the survival rates of mice subjected to lethal doses of IR and restored intestinal structure and physiological function. Further investigation showed that Fer-1 protected IEC-6 cells and mice by inhibiting the p53-mediated apoptosis signaling pathway and restoring the gut-microbe balance. CONCLUSION: This study confirms that Fer-1 protects intestinal injuries through suppressing apoptosis and ferroptosis.

Tetrabromobisphenol a exacerbates the overall radioactive hazard to zebrafish (Danio rerio).

The major health risks of dual exposure to two hazardous factors of plastics and radioactive contamination are obscure. In the present study, we systematically evaluated the combinational toxic effects of tetrabromobisphenol A (TBBPA), one of the most influential plastic ingredients, mainly from electronic wastes, and γ-irradiation in zebrafish for the first time. TBBPA (0.25 µg/mL for embryos and larvae, 300 µg/L for adults) contamination aggravated the radiation (6 Gy for embryos and larvae, 20 Gy for adults)-induced early dysplasia and aberrant angiogenesis of embryos, further impaired the locomotor vitality of irradiated larvae, and worsened the radioactive multiorganic histologic injury, neurobehavioural disturbances and dysgenesis of zebrafish adults as well as the inter-generational neurotoxicity in offspring. TBBPA exaggerated the radiative toxic effects not only by enhancing the inflammatory and apoptotic response but also by further unbalancing the endocrine system and disrupting the underlying gene expression profiles. In conclusion, TBBPA exacerbates radiation-induced injury in zebrafish, including embryos, larvae, adults and even the next generation. Our findings provide new insights into the toxicology of TBBPA and γ-irradiation, shedding light on the severity of cocontamination of MP components and radioactive substances and thereby inspiring novel remediation and rehabilitation strategies for radiation-injured aqueous organisms and radiotherapy patients.

Genomic characterization of Salmonella isolated from retail chicken and humans with diarrhea in Qingdao, China.

Salmonella, especially antimicrobial resistant strains, remains one of the leading causes of foodborne bacterial disease. Retail chicken is a major source of human salmonellosis. Here, we investigated the prevalence, antimicrobial resistance (AMR), and genomic characteristics of Salmonella in 88 out of 360 (24.4%) chilled chicken carcasses, together with 86 Salmonella from humans with diarrhea in Qingdao, China in 2020. The most common serotypes were Enteritidis and Typhimurium (including the serotype I 4,[5],12:i:-) among Salmonella from both chicken and humans. The sequence types were consistent with serotypes, with ST11, ST34 and ST19 the most dominantly identified. Resistance to nalidixic acid, ampicillin, tetracycline and chloramphenicol were the top four detected in Salmonella from both chicken and human sources. High multi-drug resistance (MDR) and resistance to third-generation cephalosporins resistance were found in Salmonella from chicken (53.4%) and humans (75.6%). In total, 149 of 174 (85.6%) Salmonella isolates could be categorized into 60 known SNP clusters, with 8 SNP clusters detected in both sources. Furthermore, high prevalence of plasmid replicons and prophages were observed among the studied isolates. A total of 79 antimicrobial resistant genes (ARGs) were found, with aac(6')-Iaa, blaTEM-1B, tet(A), aph(6)-Id, aph(3″)-Ib, sul2, floR and qnrS1 being the dominant ARGs. Moreover, nine CTX-M-type ESBL genes and the genes blaNMD-1, mcr-1.1, and mcr-9.1 were detected. The high incidence of MDR Salmonella, especially possessing lots of mobile genetic elements (MGEs) in this study posed a severe risk to food safety and public health, highlighting the importance of improving food hygiene measures to reduce the contamination and transmission of this bacterium. Overall, it is essential to continue monitoring the Salmonella serotypes, implement the necessary prevention and strategic control plans, and conduct an epidemiological surveillance system based on whole-genome sequencing.

The protective effects of Xuebijing injection on intestinal injuries of mice exposed to irradiation.

BACKGROUND: Gastrointestinal (GI) injury is one of the most common side effects of radiotherapy. However, there is no ideal therapy method except for symptomatic treatment in the clinic. Xuebijing (XBJ) is a traditional Chinese medicine, used to treat sepsis by injection. In this study, the protective effects of XBJ on radiation-induced intestinal injury (RIII) and its mechanism were explored. METHODS: The effect of XBJ on survival of irradiated C57BL/6 mice was monitored. Histological changes including the number of crypts and the length of villi were evaluated by H&E. The expression of Lgr5+ intestinal stem cells (ISCs), Ki67+ cells, villin and lysozymes were examined by immunohistochemistry. The expression of cytokines in the intestinal crypt was detected by RT-PCR. DNA damage and apoptosis rates in the small intestine were also evaluated by immunofluorescence. RESULTS: In the present study, XBJ improved the survival rate of the mice after 8.0 and 9.0 Gy total body irradiation (TBI). XBJ attenuated structural damage of the small intestine, maintained regenerative ability and promoted proliferation and differentiation of crypt cells, decreased apoptosis rate and reduced DNA damage in the intestine. Elevation of IL-6 and TNF-α was limited, but IL-1, TNF-𝛽 and IL-10 levels were increased in XBJ-treated group after irradiation. The expression of Bax and p53 were decreased after XBJ treatment. CONCLUSIONS: Taken together, XBJ provides a protective effect on RIII by inhibiting inflammation and blocking p53-related apoptosis pathway.

Antimicrobial resistance of Salmonella Indiana from retail chickens in China and emergence of an mcr-1-harboring isolate with concurrent resistance to ciprofloxacin, cefotaxime, and colistin.

Salmonella enterica serotype Indiana (S. Indiana) in Chinese poultry meat has aroused widespread concern because of its high prevalence and strong antimicrobial resistance. In consideration of the relationship in our previous study between S. Indiana and co-resistance to ciprofloxacin and cefotaxime (CIP-CTX), which were the first-line drug which were used in Salmonella infection in clinical, the antimicrobial resistance (AMR) of 224 CIP-CTX co-resistant S. Indiana isolated from retail chicken samples in China were investigated, with the aim of characterizing the AMR profiles and related resistance mechanisms to ciprofloxacin and cefotaxime among these CIP-CTX co-resistant S. Indiana isolates, all of which showed multi-drug-resistant (MDR) phenotypes. GyrA (S83F and D87N/G) with ParC (T57S and S80R) were the dominant amino acid substitution types, with oqxA, oqxB, and aac (6')-Ib-cr identified as common plasmid-mediated quinolone resistance (PMQR)-encoding genes. Five bla CTX-M gene subtypes were identified with bla CTX-M-65 ranking at the top. Equally important, we obtained one isolate CFSA664 harboring the mcr-1 gene was ESBL producer with co-resistance to nine in ten classes of tested drugs inclduing colistin. A single circular chromosome and 3 circular plasmids were found in its genome. Among the 26 AMR genes identified, 24 were located on plasmid pCFSA664-1, including three ESBL genes, while plasmid pCFSA664-3 owning only the mcr-1 gene and sharing the same backbone structure with plasmids from Enterobacteriaceae. No insertion sequences were found near the mcr-1 gene but a relaxase-encoding gene in the flank, which could transfer into E. coli J53 at a relatively high frequency. S. Indiana in this study exhibited highly drug-resistant phenotypes, contributing to the acceleration of the dissemination and emergence of this pathogen among different sources. Surveillance and a One Health strategy are needed to limit the emergence of S. Indiana along the food chain.

A Family Outbreak of Type E Botulism Caused by Contaminated Vacuum-Packed Ambient-Stored Chili Chicken Feet in Zhangjiakou, China.

The epidemiological investigation and laboratory-based confirmation were performed on samples from a family botulism outbreak in Zhangjiakou, Hebei province, China. Forty-four samples, including 14 samples (leftover food, and swabs taken of both food packaging bags and dishes, and serum and vomitus of the victims) related to outbreak and 30 causative food products after outbreak, were collected and analyzed. Isolation, bacterial identification, toxin detection, and whole-genome sequencing of Clostridium spp. cultured from the latter samples and animal assays were performed. Mice injected with the cultures of the leftover chili chicken feet, together with the inner layer of its packaging bag, the plate for serving it, and supernatant of two patients' serum that demonstrated the typical signs of botulism. The polyvalent anti-botulinum neurotoxin (BoNT) and the monovalent anti-BoNT/E exhibited protective effects when administered to mice. Three Clostridium botulinum cultures were obtained and verified to be positive for BoNT/E. The whole genome analysis of the isolates revealed that the classic bont/e gene orfX cluster was found to be located on the chromosomes of all three isolates. Single nucleotide polymorphism analysis suggested that these might be from the same source. Our findings indicated that this botulism outbreak occurred following the ingestion of vacuum-packed chili chicken feet contaminated with BoNT/E produced by C. botulinum.

Molecular Evolution and Genomic Insights into Community-Acquired Methicillin-Resistant Staphylococcus aureus Sequence Type 88.

Sequence type 88 (ST88) methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as an important pathogen that causes infections in humans, especially when it has strong biofilm production and multidrug resistance (MDR). However, knowledge of the determinants of resistance or virulence and genomic characteristics of ST88 MRSA from China is still limited. In this study, we employed the antimicrobial resistance (AMR), biofilm formation, and genomic characteristics of ST88 MRSA collected from various foods in China and estimated the worldwide divergence of ST88 MRSA with publicly available ST88 genomes. All ST88 isolates studied were identified as having resistance genes, while 50% (41/82) harbored MDR genes. All isolates carried core virulence genes related to immune modulation, adherence, secreted enzymes, and hemolysin. In addition, all 20 Chinese ST88 isolates showed biofilm production capacity, three strongly so. Bayesian phylogenetic analysis showed that Chinese ST88 clones formed an independent MRSA lineage, with two subclades associated with acquisition of type IVc staphylococcal cassette chromosome mec (SCCmec) elements. In contrast, all African ST88 strains were subtyped as SCCmecIVa, where the African clades were mixed with a few European and American isolates, suggesting potential transmission from Africa to these regions. In summary, our results revealed the evolution of ST88 MRSA in humans, animals, and foods in Africa and Asia. The food-associated ST88 genomes in this study will remedy the lack of food-associated ST88 isolates, and the study in general will extend the discussion of the potential exchanges of ST88 between humans and foods or food animals. IMPORTANCE ST88 MRSA has frequently been detected in humans, animals, and foods mainly in Africa and Asia. It can colonize and cause mild to severe infections in humans, especially children. Several studies from African countries have described its genotypic characteristics but, limited information is available on the evolution and characterization of ST88 MRSA in Asia, especially China. Meanwhile, the molecular history of its global spread remains largely unclear. In this study, we analyzed the genomic evolution of global ST88 MRSA strains in detail and identified key genetic changes associated with specific hosts or regions. Our results suggested geographical differentiation between ST88 MRSA's evolution in Africa and its evolution in Asia, with a more recent clonal evolution in China. The introduction of ST88 MRSA in China was aligned with the acquisition of SCCmecIVc elements, specific virulent prophages, and AMR genes.

Evaluation and Optimization of Microdrop Digital PCR for Detection of Serotype A and B Clostridium botulinum.

Clostridium botulinum is the causative pathogen of botulism. Laboratory detection of C. botulinum is essential for clinical therapy treatment of botulism due to the difficulty in diagnosis, especially in infant botulism. The extreme toxicity of botulinum neurotoxin (BoNT) requires a sensitive detection method. Due to the detection limit of real-time quantitative PCR (q-PCR), a more sensitive detection method, micro-drop digital PCR (ddPCR) was applied in C. botulinum main serotypes A and B. The following performance criteria were evaluated by ddPCR: analytical sensitivity; repeatability; and diagnostic specificity. The limit of detection (LOD) was 0.84 and 0.88 copies/µl for BoNT A and B genes, respectively, by ddPCR with high specificity, compared to 5.04×102 and 6.91×102 copies/µl by q-PCR. It was increased 10 times compared with q-PCR in spiked stool samples. This improvement in sensitivity was especially important in clinical samples as more positive samples were detected by digital PCR compared with q-PCR. Meanwhile, enrichment time for low bacteria content samples was shortened by four hours both in serotypes A and B C. botulinum by ddPCR compared with q-PCR, which are important for laboratory diagnosis and epidemiology work.

Proteomic Analysis Revealed Metabolic Inhibition and Elongation Factor Tu Deamidation by p-Coumaric Acid in Cronobacter sakazakii.

Screening drugs and compounds to fight against Cronobacter sakazakii (C. sakazakii), one of the most common pathogens that can cause fatal necrotizing enterocolitis, septicema and meningitis, is still needed. We found that p-coumaric acid (pCA) has an inhibitory effect on C. sakazakii in vitro and in vivo. Proteomic changes of C. sakazakii BAA-894 exposed to pCA were studied to reveal the antibacterial mechanisms involved. A total of 1,553 proteins were identified in C. sakazakii BAA-894 by label-free proteomics analysis. Fuzzy cluster analysis showed that 33 were up-regulated, and 110 were down-regulated with pCA treatment. Gene Ontology (GO) analysis concluded that pCA caused the change of metabolic state of bacteria and generally in the state of metabolic inhibition. KEGG Enrichment Analysis (KEGG) analysis showed that pCA inhibited energy metabolism and distorted the balance of amino acid metabolism. Posttranslational modification analysis showed that pCA affected the deamidation of three proteins, including Elongation factor Tu, one of the vital proteins in bacteria. Molecular docking suggested the hydrogen bond between the pCA carboxyl group and Elongation factor Tu Asn-64 might contribute to deamidation. Overall, we found that pCA interfered with cellular energy and amino acid metabolism and promoted elongation factor Tu deamidation, suggesting that pCA can be an effective natural substitute to control C. sakazakii.