DETECTION AND CHARACTERIZATION OF ESCHERICHIA COLI O157:H7 AND SALMONELLA IN FOOD

Escherichia coli O157:H7 and Salmonella are among the most important foodborne pathogens that cause millions cases of infections and hundreds deaths each year in the United States. Beef and poultry products are frequently recognized transmission media for these two organisms. Rapid detection and isolation methods applied to beef or chicken products are expected for these two bacteria. A rapid sample preparation method for E. coli O157:H7 detection by PCR method in ground beef samples was developed by combining different techniques, including filtration, centrifugation, enzyme digestion, and DNA extraction. The detection limit of this method was 103 cells/g without enrichment, and 100 cells/g can be detected after 6 h en-richment. For Salmonella, a poultry specific isolation method was modified from the USDA/FSIS manual by considering the specific characteristics of poultry products. Higher than 95% of the suspect colonies isolated by using the modified method were confirmed as Salmonella by PCR/API 20 E tests. This method was applied on retail organic and conventional chicken samples for Salmonella isolation. All Salmonella isolates were further characterized by serotyping, PFGE and antibiotics susceptibility tests. The results indicated that organic and conventional chicken samples were frequently contaminated with Salmonella, and that Salmonella from organic chicken were more susceptible to antimicrobials commonly used in human and veterinary medicine. High acid resistance capability is another unique characteristic of E. coli O157:H7 which is correlated with low infection dose of this pathogen. Survival mechanism of E. coli O157:H7 cells in gastric juice or acidified LB (pH 2.5) was studied, it was found that the limited availability of glutamate and/or arginine creates an illusion of cell-density-dependent acid sensitive phenotype of E. coli O157:H7 during acid-challenge

A Kind of New Surface Modeling Method Based on DEM Data

Surface elevation changes greatly in the river erosion area. Due to the limitation of the acquisition equipment and cost, the traditional seismic acquisition data has sparse physical points both horizontally and longitudinally, the density of surface measurement data is not enough to survey the surface structure in detail. With the development of science and technology, and the application of satellite technology, the DEM elevation data obtained from the geographic information system (GIS) are becoming more and more accurate. In this paper, a precise modeling is performed on the surface based on the geographic information from the river erosion area and combined with the results of the surface survey control points, a good effect is achieved.Key words: River erosion area; Geographic information; Similarity coefficient; Kriging interpolation; Surface modeling; High and low frequency static

Whole genome sequencing of foodborne pathogens and global data sharing development

With the rapid development of molecular typing techniques for monitoring foodborne pathogens and outbreak investigations, whole genome sequencing (WGS) is gradually revealing its importance. In the context of the globalization of food trade, it’s urgent to establish details of the links between foodborne pathogens and human exposure in order to accurately monitor and reduce their occurrence. The accuracy of WGS is significantly better than prior analysis tools in the aspect. In this paper, we take Listeria monocytogenes as example to expound the monitoring of foodborne pathogens and the investigation of infection outbreaks, emphasizing the value of WGS in trace-back of foodborne diseases. The technologies for data generation and analysis are summarized, the practical application progress of WGS in the worldwide foodborne pathogen typing is emphasized, and the challenges in the future are prospected

Driving forces and impacts of food system nitrogen flows in China, 1990 to 2012

Food nitrogen (N), which includes animal-food (AN) and plant-food N (PN), has been driven by population growth (PG), dietary changes associated with incomegrowth (DC) andrural-urban migration (M) over the past three decades, andthese changes combined with theirNcost, have caused some effect onNuse in China's food system. Although there is an increasing literature on food N and its environmental impacts in China, the relative magnitude of these driving forces are notwell understood. Here we first quantify the differences in per capita AN and PNconsumption in urban and rural areas and their impacts on N input to the food system during 1990–2012, and then quantify the relative contributions of DC, PG andMin the overall N change during this period. Our results show that a resident registered as living in city required 0.5 kg more AN yr−1 and 0.5 kg less PN yr−1 than one living in a rural area, in 2012. DC, PG and M accounted for 52%, 31% and 17% of the total AN increase, respectively. These three factors caused 46% of the increased N use for food production over the past two decades. Another 54% was mainly caused by the declining in N use efficiencies of the food system. Foodsourced N loss intensity in urban and rural areas were 502 and 162 kg N hm−2 in 2012, a three-fold difference due to the increasing amount and a linear rural-urbanflowofNinput, and inadequateNrecovery via solid waste and wastewater treatment in cities. Our study highlights China is facing higher risks of environmental N pollution with urbanization, because of the high demand for AN and higher food-sourced N loss intensity in urban than in rural areasThis manuscript is based on the several projects, sponsored by the National Basic Research Program of China (2014CB953801), the Young Talents Projects of the Institute of Urban Environment, the Chinese Academy of Sciences (IUEMS201402) and the National Natural Science Foundation of China (31500391)

Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration

This work was funded by National Basic Research Program of China (2014CB953800), Young Talents Projects of the Institute of Urban Environment, Chinese Academy of Sciences (IUEMS201402), National Natural Science Foundation of China (41471190, 41301237, 71704171), China Postdoctoral Science Foundation (2014T70144) and Discovery Early Career Researcher Award of the Australian Research Council (DE170100423). The work contributes to the UK-China Virtual Joint Centres on Nitrogen “N-Circle” and “CINAg” funded by the Newton Fund via UK BBSRC/NERC (grants BB/N013484/1 and BB/N013468/1, respectively).Peer reviewedPostprintPostprin

Food safety analysis and management of Shiga toxin-producing Escherichia coli in edible agricultural products and kitchen

The sources and transmission routes of Shiga toxin-producing Escherichia coli (STEC) in edible agricultural products are analyzed. And the relationship between STEC contamination and food safety in home kitchen is discussed. The current supervision of STEC in edible agricultural products around the world is introduced. The solution and suggestion for the control of STEC in the home kitchen of China are proposed

Antimicrobial susceptibility, variation and relative expression of relative genes of Salmonella screened from different quinolone and fluoroquinolones

Objective To study the mutation and expression of genes of Salmonella when screened by different concentrations of quinolone and fluoroquinolones during propagation and their relation with antibiotic resistance. Methods Salmonella strain was cultured in broth medium and screened on nutrition plate with different concentration of quinolone and fluoroquinolones. Antimicrobial susceptibility of the screened subculture was tested by broth microdilution method, mutation of genes in quinolone resistance-determining region (QRDR) was detected using polymerase chain reaction (PCR) and DNA sequencing method, and expression level of the encoding genes of multi-drug associated efflux pump AcrAB-TolC was detected by real-time qPCR. Results Antibiotic resistance level of the subcultures screened from LB plate with quinolone and fluoroquinolones inducement increased in different extents. Mutation of Asp87Tyr in gyrA in QRDR was detected from the fifth to the seventh generation of nalidixic acid screened strains. Mutation of Asp87Asn in gyrA in QRDR was detected from the fourth to the seventh generation of ciprofloxacin screened strains. No amino acid mutation was detected from gyrA in the first to the seventh generation of gatifloxacin, levofloxacin and delafloxacin screened strains. Compared to the expression level of the multi-drug efflux pump AcrAB-TolC encoding genes of the original strain, those of the screened strains had significantly (P<0.05) increased resistance. No significant difference was detected among the expression level of AcrAB-TolC encoding genes in the seventh generation of screened strains. The ratio of the minimal inhibitory concentrations (MICs) of the screened strains and that of Salmonella Typhimurium (ATCC 14028s), gene variation and relative expression level of acrAB-tolC of Salmonella significantly positive correlated with subculture generation and antibiotic concentration. Conclusion Under the selective pressure of antibiotics, Salmonella strain could adapt the stress environment through QRDR mutation and increase the expression level of multi-drug efflux pump AcrAB-TolC. When the next generation fluoroquinolone was used, the mutation frequency of QRDR decreased. After subcultured several times, the expression level of acrAB-tolC of the screened strains increased, however, no significant difference was detected among the expression level, which avoided the antibiotic resistance of Salmonella to be further increased

Discriminatory Power Evaluation of Nuclear Ribosomal RNA Barcoding Sequences Through Ophiocordyceps sinensis Related Samples

Since the cost of Ophiocordyceps sinensis has increased dramatically and the counterfeits may have adverse effect to health, a rapid and precise species-level DNA barcoding identification system could be a potent approach and significantly enhance the regulatory capacity. The discrimination power of three subunits sequences from nuclear ribosomal RNA gene cluster were determined by Simpson’s index of discrimination using 43 wild O. sinensis fruiting bodies, pure cultures, commercial mycelium fermented powder and counterfeits. The internal transcribed spacer (ITS) sequences showed the highest variance and discrimination power among 43 samples, as determined by Simpson’s index of discrimination (D = 0.972), followed by large subunit (LSU; D = 0.963) and small subunit (SSU; D = 0.921). ITS-2 sequences showed the highest discrimination power for 43 samples among ITS-1, ITS-2, and 5.8S region of ITS sequences. All O. sinensis samples were grouped into a unique ITS sequence cluster under 95% similarity and two O. sinensis samples and six non-O. sinensis samples showed false claims. Our data showed that the ITS region could provide accurate species identification for O. sinensis samples, especially when macroscopic and microscopic method could not be applied in the highly processed commercial products. Since the authentication of O. sinensis related products is essential to ensure its safety and efficacy, identification of O. sinensis through ITS sequence comparison or unique PCR amplification of the species specific target, such as the ITS region, should be considered in the next revision of Chinese pharmacopeia

Association of GSDMD with microvascular-ischemia reperfusion injury after ST-elevation myocardial infarction

ObjectivesLittle is known about the clinical prognosis of gasdermin D (GSDMD) in patients with ST-elevation myocardial infarction (STEMI). The purpose of this study was to investigate the association of GSDMD with microvascular injury, infarction size (IS), left ventricular ejection fraction (LVEF), and major adverse cardiac events (MACEs), in STEMI patients with primary percutaneous coronary intervention (pPCI).MethodsWe retrospectively analyzed 120 prospectively enrolled STEMI patients (median age 53 years, 80% men) treated with pPCI between 2020 and 2021 who underwent serum GSDMD assessment and cardiac magnetic resonance (CMR) within 48 h post-reperfusion; CMR was also performed at one year follow-up.ResultsMicrovascular obstruction was observed in 37 patients (31%). GSDMD concentrations ≧ median (13 ng/L) in patients were associated with a higher risk of microvascular obstruction and IMH (46% vs. 19%, P = 0.003; 31% vs. 13%, P = 0.02, respectively), as well as with a lower LVEF both in the acute phase after infarction (35% vs. 54%, P &lt; 0.001) and in the chronic phase (42% vs. 56%, P &lt; 0.001), larger IS in the acute (32% vs. 15%, P &lt; 0.001) and in the chronic phases (26% vs. 11%, P &lt; 0.001), and larger left ventricular volumes (119 ± 20 vs. 98 ± 14, P = 0.003) by CMR. Univariable and multivariable Cox regression analysis results showed that patients with GSDMD concentrations ≧ median (13 ng/L) had a higher incidence of MACE (P &lt; 0.05).ConclusionsHigh GSDMD concentrations in STEMI patients are associated with microvascular injury (including MVO and IMH), which is a powerful MACE predictor. Nevertheless, the therapeutic implications of this relation need further research

Open-source genomic analysis of Shiga-toxin–producing E. coli O104:H4

An outbreak caused by Shiga-toxin–producing Escherichia coli O104:H4 occurred in Germany in May and June of 2011, with more than 3000 persons infected. Here, we report a cluster of cases associated with a single family and describe an open-source genomic analysis of an isolate from one member of the family. This analysis involved the use of rapid, bench-top DNA sequencing technology, open-source data release, and prompt crowd-sourced analyses. In less than a week, these studies revealed that the outbreak strain belonged to an enteroaggregative E. coli lineage that had acquired genes for Shiga toxin 2 and for antibiotic resistance