CO2-Triggered Hierarchical-Pore UiO-66-Based Pickering Emulsions for Efficient and Recyclable Suzuki-Miyaura Cross-Coupling in Biphasic Systems.

Hierarchical-pore metal-organic frameworks (H-MOFs) are considered to be emerging stabilizers for Pickering emulsion formation because of their hierarchically arranged pores, tailorable structures, and ultrahigh surface areas. However, stimulus-triggered Pickering emulsions built by H-MOFs have been seldom presented to date despite their great significance in diverse applications. Herein, by grafting Pd(OAc)2 on the hierarchical-pore zirconium MOF UiO-66, namely, H-UiO-66, with the aid of 1-alkyl-3-methylimidazolium 2-cyanopyrrolide salts ([CnMIM][2-CN-Pyr], n = 4, 6, and 8), a series of Pd(OAc)2-[CnMIM][2-CN-Pyr]@H-UiO-66 have been developed and utilized as emulsifiers for constructing CO2-switching Pickering emulsions. It was found that Pd(OAc)2-[CnMIM][2-CN-Pyr]@H-UiO-66 was able to stabilize the n-hexane-water mixture to form a Pickering emulsion even at an amount of 0.5 wt %. Upon alternate addition of CO2 and N2 at normal pressure, Pickering emulsions could be smartly converted between demulsification and re-emulsification. Through combining varieties of spectroscopic techniques, the mechanism of the switchable phase transformation lay in the acid-base reaction of ionic liquids with CO2 on H-UiO-66 and the creation of more hydrophilic salts, which reduced the wettability of the emulsifier and destabilized the emulsion. As an example of application, the stimulus-triggered Pickering emulsion was employed as a palladium-catalyzed Suzuki-Miyaura cross-coupling microreactor to achieve the combination of chemical reactions, isolation of products, and recovery of catalysts.

TSPAN8 alleviates high glucose-induced apoptosis and autophagy via targeting mTORC2.

TSPAN8 mediates signal transduction from extracellular cues and regulates cell development, activation, growth, and motility. However, whether TSPAN8 is involved in the progression of diabetic nephropathy (DN) remains unclear. This study aimed to explore the potential functional roles of TSPAN8 in regulating autophagy and apoptosis of HK-2 cells induced by high glucose (HG). RT-PCR and western blot analysis (WB) were employed to detect TSPAN8 levels in the blood samples of DN patients as well as in HG-induced HK-2 cells. Cell proliferation of HK-2 cells was examined by CCK-8 assay, and apoptosis was analyzed by flow cytometry. The functional role of TSPAN8 was evaluated by the transfection of TSPAN8 expression plasmid. Results showed that TSPAN8 level was significantly reduced in the blood samples of DN patients and HG-induced HK-2 cell lines. TSPAN8 overexpression rescued HG-induced apoptosis in HK-2 cells. TSPAN8 could form a complex with Rictor and mTORC2. TSPAN8 overexpression suppressed HG-induced autophagy in HK-2 cells, which was dependent on mTOR activity. In conclusion, the present study showed that TSPAN8 mitigates HG-induced autophagy and apoptosis in HK-2 cells, which may serve as candidate target for DN treatment.

miR-543 regulates high glucose-induced fibrosis and autophagy in diabetic nephropathy by targeting TSPAN8.

BACKGROUND: Diabetic nephropathy (DN) is one of the most common and serious complications of diabetes, which can lead to renal failure and fatality. miRNAs are an important class of endogenous non-coding RNAs implicated in a wide range of biological processes and pathological conditions. This study aims to investigate the potential functional roles of miR-543 in DN and its underlying mechanisms. METHODS: qRT-PCR was performed to detect the expression levels of miR-543 and TSPAN8 in kidney tissues of mice with DN. Western blot (WB) was used to measure the protein levels. CCK8 assay was employed to evaluate the proliferation of HK2 cells. Dual luciferase reporter assay was conducted to verify the functional interaction between miR-543 and TSpan8. RESULTS: The downregulation of miR-543 and upregulation of TSPAN8 were observed in kidney tissues of mice with DN. miR-543 mimic significantly decreased cell proliferation and autophagy in high-glucose (HG)-induced HK2 cells, and promoted cell fibrosis. We further identified a putative binding site between miR-543 and TSPAN8, which was validated by Dual luciferase reporter assay. The treatment of miR-543 mimic and miR-543 inhibitor could reduce or increase TSPAN8 protein level respectively. We further showed that the overexpression of TSPAN8 could attenuate HG-induced cell injury by reducing fibrosis and increase autophagy. The effects of miR-543 mimic in proliferation, fibrosis, and autophagy were rescued by TSPAN8 overexpression. CONCLUSIONS: Our study indicate that miR-543 mediates high-glucose induced DN via targeting TSPAN8. Interfering miR-543/TSPAN8 axis could serve as potential approach to ameliorate DN.

[Microbial contamination in dried fruit products in China in 2019].

OBJECTIVE: To investigate the microbial contamination in dried fruit products in China. METHODS: In 2019, 2917 samples of dried fruit products on the market were collected, and examined for aerobic bacterial count, coliforms, molds, yeasts, Salmonella and Listeria monocytogenes according to the method specified in GB 4789. RESULTS: A total of 34.42%(1004/2917)of the samples had molds above 50 CFU/g and 9.46%(276/2917)of the samples had yeast above 50 CFU/g. The occurrence of aerobic plate count above 10~4 CFU/g and coliforms above 10~2 CFU/g was 5.01%(146/2917)and 2.98%(87/2917), respectively. The detection rate of Salmonella and Listeria monocytogenes were 0.14%(4/2917) and 0.03%(1/2917), respectively. Microbial contamination in different kinds of dried fruit products varied widely, with dried wolfberries and dried durian having the worst overall hygiene. There were differences in microbial contamination of dried fruit products in different regions. In general, samples collected in South China, Southwest China and Central China had more serious microbial contamination. There was no significant difference in microbial contamination between dried fruit products with different packaging and sampling places. CONCLUSION: The hygienic condition of dried fruit products is generally poor in 2019.

The China National Foodborne Pathogen Surveillance System: Twenty Years of Experience and Achievements.

National foodborne pathogen surveillance is a system that collects data regarding food contamination by pathogenic bacteria, viruses, parasites, and other harmful microbial factors. The surveillance data are used to understand the potential microbial risks in different categories of food and to provide science-based data for risk assessment and development of reference standards in the form of maximum limits. This review introduces stepwise expansion of the foodborne pathogen surveillance in China, relevant policies, function and duties of different organizations and institutions, surveillance plans, and quality control. Achievements of the surveillance system and future challenges are also presented.

Analysis of long non-coding RNA expression profiles in high-glucose treated vascular endothelial cells.

BACKGROUND: Diabetes mellitus is often associated with microvascular and macrovascular lesions, and hyperglycemia-induced vascular endothelial cell damage is a key factor. METHODS: We investigated long non-coding RNAs (lncRNAs) and mRNAs that are affected by hyperglycemia-induced damage using human umbilical vein endothelial cells (HUVECs) as a model. HUVECs were cultured under high (25 mmol/L) or normal (5 mmol/L) glucose conditions for 6 d, and then lncRNAs and protein-coding transcripts were profiled by RNA-seq. RESULT: Among 40,379 lncRNAs screened, 214 were upregulated (log2 [fold-change] > 1, FDR < 0.05) and 197 were downregulated (log2 [fold-change] < - 1, FDR < 0.05) in response to high-glucose. Furthermore, among 28,431 protein-coding genes screened, 778 were upregulated and 998 were downregulated. A total of 945 lncRNA/mRNA pairs were identified, including 126 differentially expressed lncRNAs predicted to target 201 mRNAs, among which 26 were cis-regulatory interactions. The corresponding lncRNA-mRNA network was composed of 354 lncRNA nodes, 1167 mRNA nodes and 9735 edges. Dozens of lncRNAs with high degree may play important roles in high-glucose-induced HUVEC damage, including ENST00000600527, NONHSAT037576.2, NONHSAT135706.2, ENST00000602127, NONHSAT200243.1, NONHSAT217282.1, NONHSAT176260.1, NONHSAT199075.1, NONHSAT067063.2, NONHSAT058417.2. CONCLUSION: These observations may provide novel insights into the regulatory molecules and pathways of hyperglycemia-related endothelial dysfunction in diabetes-associated vascular disease.

Recirculating Th2 cells induce severe thymic dysfunction via IL-4/STAT6 signaling pathway.

Thymic involution happened early in life, but a certain ratio of activated CD4+ T cells will persistently recirculate into the thymus from the periphery and it have been suggested to be able to inhibit the development of embryonic thymocytes. Our present study was aimed to elucidate the specific mechanism how activated CD4+ T cells could influence upon developing thymocytes by using fetal thymic organ culture (FTOC) and kidney capsule transplantation. Our results demonstrated that Th2 cells were found to play a fundamental role in the inhibition of embryonic thymocyte development since a very low concentration of Th2 cells could obviously reduce the total number of thymocytes. And this effect was not tenable in other Th cell type. Notably, IL-4, the major cytokine secreted by Th2 cells, was suggested the key factor playing the inhibition role. In addition to reduced cell population, the proportion of double positive (DP) T cells was also heavily decreased. Furthermore, we demonstrated that it was the downstream effector signal transducer and activator of transcription 6 (STAT6) of IL-4 partially manipulate this inhibition. Together, these findings reveal a novel influence of Th2 cells re-entering the thymus on thymic involution.

Reversible Phase Transfer of Carbon Dots between an Organic Phase and Aqueous Solution Triggered by CO2.

Carbon dots (CDs) have attracted increasing attention in applications such as bio-imaging, sensors, catalysis, and drug delivery. However, unlike metallic and semiconductor nanoparticles, the transfer of CDs between polar and non-polar phases is little understood. A class of amine-terminated CDs is developed and their phase transfer behavior has been investigated. It is found that these CDs can reversibly transfer between aqueous and organic solvents by alternatively bubbling and removing CO2 at atmospheric pressure. The mechanism of such CO2 -switched phase transfer involves reversible acid-base reaction of amine-terminated CDs with CO2 and the reversible formation of hydrophilic ammonium salts. By using the CDs as catalysts, the phase transfer is applied in the Knoevenagel reaction for efficient homogeneous reaction, heterogeneous separation, and recycling of the catalysts.

Structural Transition of Cinnamate-Based Light-Responsive Ionic Liquids in Aqueous Solutions and Their Light-Tunable Rheological Properties.

Light-responsive wormlike micelles have important applications in fields such as microfluids, photoswichable fluids, and rheology control. However, single-component light-responsive wormlike micelles formed only from a single tail surfactant have not been reported in literature. In this work, self-assembly behavior of 1-alkyl-3-methylimidazolium trans-ortho-methoxycinnamate [Cnmim][OMCA] (n = 8, 10, 12, 14, 16) ionic liquids in aqueous solutions is studied by UV-vis spectroscopy, viscosity, rheology, conductivity, and cryo-TEM measurements. It is found for the first time that, among the single tail ionic liquid surfactants studied, [C16mim][OMCA] can form wormlike micelles in aqueous solutions without any additives and light irradiation. Then these wormlike micelles are able to transform into cylindrical micelles under UV light irradiation, resulting in significantly tunable rheological properties of the solutions. The photoisomerization of anion of [C16mim][OMCA] from trans- to cis-isomer as well as the relative hydrophilicity and structural feature of the cis-isomer are suggested to be responsible for such transition.

Suspension of thymic emigration promotes the maintenance of antigen-specific memory T cells and the recall responses.

Thymic involution is evolutionarily conserved and occurs early in life. However, the physiological significance remains elusive of this seemingly detrimental process. The present study investigated the potential impact of altered thymic output on T cell memory using ovalbumin (OVA) expressed by Listeria monocytogenes as a model antigen. Suspension of thymic emigration by thymectomy was shown to lead to a marked increase in the frequency and total number of OVA-specific memory T cells. In contrast, oversupply of thymic emigrants through thymic grafting caused a significant decrease of such cells. When rechallenged with L. monocytogenes expressing OVA, the thymectomized mice mounted a more potent recall response as evidenced by the enlarged population of OVA-specific tetramer⁺ cells and the accelerated clearance of the bacteria. Notably, the memory-enhancing effect of thymectomy was abrogated following weekly adoptive transfer of naive T cells. Together, data from the present study indicate that reduced thymic output favors the maintenance of the memory T cell pool.

[Study on detection of Salmonella in poultry samples by real-time PCR with Taqman probes].

OBJECTIVE: To develop a RT-PCR method for a rapid and sensitive detection of Salmonella in poultry samples. METHODS: The RT-PCR method was established and its specificity was testified on the basis of invA gene. Serial 10-fold diluted pure suspension culture of CMCC 50041 was detected by RT-PCR, the standard curve was constructed and the amplification efficiency was calculated. Artificially contaminated experiment was done, six artificially-inoculated samples containing final concentration of Salmonella CMCC 50041 (1, 10, 10(2), 10(3), 10(4), 10(5) and 10(6) CFU per 25 g poultry samples) were prepared respectively. All the samples were incubated for 0, 4, 8, 12 and 18 h and the DNA was extracted for RT-PCR detection, meanwhile by PCR detection and the traditional method. The sensitiveness and specificity were compared among the three methods. At the same time, 16 samples of retail whole poultry were collected from markets and detected by the above three methods as well, and thereby to further compare the positive detection among the three methods. RESULTS: The established RT-PCR method was specific for the detection of Salmonella. The sensitivity was 5.2×10(3) CFU/ml for pure Salmonella culture without enrichment. Correlation coefficients of standard curves constructed using the Ct versus log value of concentration of Salmonella showed good linearity over a 8-log dynamic range (5.2×10(3)-5.2×10(10) CFU/ml), with the R(2) at 0.999. RT-PCR detection limit for artificially contaminated samples after enriching for 12 h was 1 CFU/25 g sample, which was the same with the limit of PCR and 10 times more sensitive than the limit of traditional method. Standard curve of sample after enrichment for 12 h was established. Seven of 16 samples were detected positive by RT-PCR, which were also tested positive by PCR, while only five samples were positive by traditional method. The positive ones were quantitatively analyzed using standard curve of sample and determined the initial Salmonella numbers of CFU/25 g. CONCLUSION: The established RT-PCR technology was simple, rapid, sensitive and specific, which was suitable to quickly detect Salmonella in poultry samples.

[Analysis of molecular features of clinical Vibrio parahaemolyticus strains in China].

OBJECTIVE: To explore the phenetic and genetic features of clinical Vibrio parahaemolyticus strains from 2007-2009 in China. METHODS: A total of 135 clinical Vibrio parahaemolyticus strains, isolated from Zhejiang, Jiangsu, Sichuan, Guangxi, Liaoning Provinces during 2007 to 2009, were selected for the research. The occurrence of virulence genes thermostable direct hemolysin (tdh) and TDH-related hemolysin (trh), species-specific genes thermolabile hemolysin (tlh), toxR, VPM and gyrB, the pandemic clone gene markers(GS-PCR, PGS-PCR, orf8 and HU-α) in 135 Vibrio parahaemolyticus strains was detected by PCR. The antimicrobial susceptibilities to eight antimicrobial agents of the experimental strains were determined by the broth microdilution method. All strains were serotyped and underwent the cluster analysis with pulsed-field gel electrophoreses. RESULTS: The results of PCR methods claim that all experiment strains carry species-specific genes such as tlh, toxR, gyrB, VPM. Among clinical strains, 85.9% (116/135) carry tdh and/or trh. 85.2% (115/135) were positive for tdh, and 3.0% (4/135) were positive for trh; while 3 strains carried both.66.7% (90/135) , 80.7% (109/135) , 65.2% (88/135) , 66.7% (90/135) clinical strains carried the genes of GS-PCR, PGS-PCR, orf8, HU-α, respectively. The results of antibiotics susceptibility test showed that 8.1% (11/135) strains were resistant to at least one agent, including 9 strains were resistant to ampicillin, 2 strains were resistant to trimethoprim and sulphamethoxazole, and 1 strain were resistant to tetracycline. All clinical strains were sensitive to cefotaxime, ceftazidime, gentamicin, ciprofloxacin and chloromycetin.Serological analysis of the O and K antigens claimed that a total of 29 serotypes were identified for clinical strains, predominantly O3, O4 and O1 groups, accounting for 89.6% (121/135). O3: K6 was dominant serotype, accounting for 56.3% (76/135). The pandemic flora in China included O3: K6, O4: K68, O1: K36, O1: K25, O1: K5 and O3: K29 serotypes.Genomic DNAs of 135 clinical strains were digested with SfiI and NotI, the molecular size of PFGE restriction fragments used for analysis mainly ranged from 30-700 kb.When subjected to UPGMA clustering, 6 and 9 clusters were grouped by SfiI and NotI, and the minimal similarity was 52.6% and 58.7%, and pandemic flora were located in C groups and D group, respectively. CONCLUSION: Most of Vibrio parahaemolyticus strains isolated from clinical sources in China were pathogenic. The pandemic clone, especially O3: K6 was prevalent. The GS-PCR and HU-α genes were reliable markers to identify the pandemic flora. The serotype by PFGE was reliable to distinguish the pandemic flora and the sporadic strains.

[Occurrence of Bacillus cereus in infants and young children foods in 8 provinces in China].

OBJECTIVE: To investigate the contamination status of infants and young children foods by Bacillus cereus. METHODS: 1716 food samples were collected from retail market in 8 provinces in China and examined for Bacillus cereus by the plate count method. RESULTS: Bacillus cereus was isolated from 9.85% of all the samples (169/1716). 14.08% of the powered formula for infants and young children were contaminated with B. cereus as well as 6.01% of the ready-to-eat cereal-based complementary foods for infants and young children. Counts higher than 100 CFU/g were found in 18 samples of the powered formula (2.20%) and 10 samples of the ready-to-eat cereal-based complementary foods (1.11%). CONCLUSION: Inspection and management of infants and young children foods should be enhanced to prevent Bacillus cereus infection.

[Rapid detection of Listeria monocytogenes in pork samples by real-time PCR with Taqman probe].

OBJECTIVE: To develop a real-time PCR method for detection Listeria monocytogenes in pork samples. METHODS: Listeria monocytogenes specific primers and Taqman probe were chosen on the basis of hlyA gene. Real-time PCR method was developed and its specificity was proved. Serial 10-fold diluted pure suspension culture of CMCC 540004 were detected by real-time PCR, and standard curve was constructed. Artificially contaminated experiment was done, six artificially-inoculated samples containing final concentration of Listeria monocytogenes CMCC 540004 (1.3 x 10(0), 1.3 x 10(1), 1.3 x 10(2), 1.3 x 10(3), 1.3 x 10(4), 1.3 x 10(5) and 1.3 x 10(6) CFU per 25 g pork samples) were preparated respectively, meanwhile one sample without inoculation was as control of background value. All the samples were incubated in LB1 enrichment for 24 h and then take 0.1 ml culture solutions to 10 ml LB2 enrichment for 18 - 24 h. All the samples were incubated for 0, 4, 8, 12, 18, 24, 30, 36 and 46 h, and detected Listeria monocytogenes bacteria by PCR, respectively. Twenty-four samples of retail pork were collected from markets in Beijing and detected by the above three methods. RESULTS: Real-time PCR method established was specific for the detection of Listeria monocytogenes. The sensitivity was 1.3 x 10(3) CFU/ml for pure culture without enrichment. Real-time PCR detection limit for artificially contaminated samples after enriching for 24 h was 1.3 CFU/ 25 g, which is the same with the limit of PCR and traditional method after enrichment for 46 h. Standard curve of sample after enrichment for 24 h was established. The positive rate out of total 24 samples was 70.83% (17/24) by real-time PCR, which is the same with the result of PCR and traditional method. The positive ones were quantitative analyzed using standard curve of sample and determined the initial Listeria monocytogenes numbers of CFU/25 g. CONCLUSION; The established real-time PCR technology was simple, rapid, sensitive and specific, which was suitable to rapid detect Listeria monocytogenes in pork samples and the process was finished in 27 h.

Antimicrobial resistance profiles of common mastitis pathogens on large Chinese dairy farms.

The primary objective of this study was to determine the antimicrobial resistance (AMR) profile of common mastitis pathogens on large Chinese dairy farms. A total of 673 isolates, including Staphylococcus aureus (14.41%, 97/673), coagulase-negative staphylococci (CNS, 52.30%, 352/673), Streptococcus agalactiae (5.64%, 38/673), non-agalactiae streptococci (7.42%, 50/673), Acinetobacter spp. (7.72%, 52/673), Escherichia spp. (6.39%, 43/673), and Klebsiella spp. (6.09%, 41/673), were collected from 15 large Chinese dairy farms in 12 provinces. The AMR profiles were measured using a microdilution method. Our results showed that more than 75% of Staph. aureus (87/97) and CNS (291/352) were resistant to penicillin (PEN). More than 30% of Escherichia spp. (15/43) showed resistance to ampicillin (AMP). However, less than 10% CNS and non-agalactiae streptococci showed resistance to amoxicillin/clavulanate (AMC; 1/352; 0/50), cephalexin (LEX; 1/352; 0/50), ceftiofur (EFT; 10/352; 0/50), and rifaximin (RIX; 21/352; 2/50); less than 10% Staph. aureus showed resistance to AMC (1/97), oxacillin (OX; 3/97), LEX (1/97), EFT (2/97), and RIX (2/97); less than 10% Strep. agalactiae showed resistance to PEN (3/38), AMC (0/38), LEX (0/38), EFT (0/38), and RIX (0/38); and less than 10% Escherichia spp. showed resistance to AMC (1/43) and EFT (4/43). These results suggested that most mastitis pathogens were susceptible to most antimicrobials with exceptions of Staph. aureus tested against penicillin or ampicillin and CNS against penicillin or oxacillin. To control the AMR threat in Chinese dairy farms, a nationwide surveillance program for AMR of bovine mastitis pathogens is needed.

Cattle hair as a bioindicator for short- and medium-chain chlorinated paraffin monitoring on cattle farms.

Short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) are hazardous industrial chemicals that tend to bioaccumulate in animal-derived foodstuffs through the food supply chain. However, the lack of reliable noninvasive bioindicators hinders the monitoring of farm animal exposure to CPs. In this study, 169 cattle hair samples were collected from beef cattle farms in six Chinese provinces, with further beef, feed, and soil samples being collected in Hebei province. Geographical differences in CP concentrations were observed in the hair samples, and CP concentrations in samples collected from Hebei province decreased in the following order: hair > feed > beef > soil. C10-11Cl6-7 and C14Cl7-8 were the predominant SCCPs and MCCPs, respectively, in all the hair, beef, feed, and soil samples. CP concentrations in hair samples significantly correlated with those in beef, feed, and soil samples, indicating that hair can be used as a bioindicator of cattle exposure to CPs. The possible health risks associated with exposure to CPs through beef consumption, especially for children and high-volume beef consumers, should be further investigated.

Pseudohypoparathyroidism Type IB with Subclinical Hypothyroidism: a Pedigree Investigation and Literature Review.

Pseudohypoparathyroidism (PHP) is a rare genetic disease characterized by hypocalcemia, hyperphosphatemia, and elevated parathyroid hormone (PTH) in serum. Here, we report a case of a patient with pseudohypoparathyroidism type IB (PHPIB) and subclinical hypothyroidism, analyze the clinical and genetic data of his family members, review the relevant literature, and classify and discuss the pathogenesis and clinical characteristics of each subtype. Finally, we discuss the treatment approach to improve clinicians' understanding of the disease.

Mechanistic insights into the changes of biological activity and physicochemical characteristics in Lacticaseibacillus paracasei fortified milk powder during storage.

To clarify the change mechanism of biological activity and physicochemical characteristics in Lacticaseibacillus paracasei JY025 fortified milk powder (LFMP) during storage, morphological observation, JY025 survival, storage stability, and metabolomics of LFMP were determined during the storage period in this study. The results showed that the LFMP had a higher survival rate of JY025 compared with the bacterial powder of JY025 (LBP) during storage, which suggested that milk powder matrix could reduce strain JY025 mortality under prolonged storage in the LFMP samples. The fortification of strain JY025 also affected the stability of milk powder during the storage period. There was lower water activity and higher glass transition temperature in LFMP samples compared with blank control milk powder (BCMP) during storage. Moreover, the metabolomics results of LFMP indicated that vitamin degradation, Maillard reaction, lipid oxidation, tricarboxylic acid cycle, and lactobacilli metabolism are interrelated and influence each other to create complicated metabolism networks.

Relevance of genetic causes and environmental adaptation of Cronobacter spp. isolated from infant and follow-up formula production factories and retailed products in China: A 7-year period of continuous surveillance based on genome-wide analysis.

The possible contamination routes, environmental adaptation, and genetic basis of Cronobacter spp. in infant and follow-up formula production factories and retailed products in mainland China have been determined by laboratory studies and whole-genome comparative analysis in a 7-year nationwide continuous surveillance spanning from 2012 to 2018. The 2-year continuous multicenter surveillance of the production process (conducted in 2013 and 2014) revealed that the source of Cronobacter spp. in the dry-blending process was the raw dry ingredients and manufacturing environment (particularly in the vibro sieve and vacuum cleaner), while in the combined process, the main contamination source was identified as the packing room. It is important to note that, according to the contamination control knowledge obtained from the production process surveillance, the contamination rate of retail powdered infant formula (PIF) and follow-up formula (FUF) products in China decreased significantly from 2016 onward, after improving the hygiene management practices in factories. The prevalence of Cronobacter spp. in retailed PIF and FUF in China in 2018 was dramatically reduced from 1.55 % (61/3925, in 2012) to an average as low as 0.17 % (13/7655 in 2018). Phenotype determination and genomic analysis were performed on a total of 90 Cronobacter spp. isolates obtained from the surveillance. Of the 90 isolates, only two showed resistance to either cefazolin or cefoxitin. The multilocus sequence typing results revealed that C. sakazakii sequence type 1 (ST1), ST37, and C. malonaticus ST7 were the dominant sequence types (STs) collected from the production factories, while C. sakazakii ST1, ST4, ST64, and ST8 were the main STs detected in the retailed PIF and FUF nationwide. One C. sakazakii ST4 isolate (1.1 %, 1/90) had strong biofilm-forming ability and 13 isolates (14.4 %, 13/90) had weak biofilm-forming ability. Genomic analysis revealed that Cronobacter spp. have a relatively stable core-genome and an increasing pan-genome size. Plasmid IncFIB (pCTU3) was prevalent in this genus and some contained 14 antibacterial biocide- and metal-resistance genes (BMRGs) including copper, silver, and arsenic resistant genes. Plasmid IncN_1 was predicted to contain 6 ARGs. This is the first time that a multi-drug resistance IncN_1 type plasmid has been reported in Cronobacter spp. Genomic variations with respect to BMRGs, virulence genes, antimicrobial resistance genes (ARGs), and genes involved in biofilm formation were observed among strains of this genus. There were apparent differences in copies of bcsG and flgJ between the biofilm-forming group and non-biofilm-forming group, indicating that these two genes play key roles in biofilm formation. The findings of this study have improved our understanding of the contamination characteristics and genetic basis of Cronobacter spp. in PIF and FUF and their production environment in China and provide important guidance to reduce contamination with this pathogen during the production of PIF and FUF.

[Prevalence and antibiogram distribution of Salmonella isolated from broiler production and processing course in four provinces, China].

OBJECTIVE: To determine the contamination condition of Salmonella in broiler breeding and slaughter processing in China and to investigate the distribution of antimicrobial resistance profiles. METHODS: Five large-scale broiler holdings and fourteen slaughterhouses were chosen to detect Salmonella in Henan, Jiangsu, Sichuan and Shandong provinces in 2010. A total of 835 anal swabs and 744 chicken carcasses were sampled to compare the difference of Salmonella contamination rate.Salmonella isolates were identified by serotyping according to Kauffmann-White scheme.The antimicrobial susceptibilities of Salmonella isolates were determined by broth microdilution method and sixteen antimicrobial agents were chosen and examined. RESULTS: In total, Salmonella isolates were recovered in 56 (6.7%) specimens among 835 collected anal swabs and 122 (16.4%) specimens among 744 broiler carcasses. Positive rate of Salmonella in broiler carcasses was higher than anal swabs (χ(2) = 36.94, P < 0.05). The dominant Salmonella serovars isolated from broiler anal swabs were S.enterica serovar Indiana and S.enterica serovar Enteritidis, accounting for 58.9% (33/56) and 32.1% (18/56) respectively. The prevalent serovars in broiler carcasses were also the two serovars and occupied 29.8% (37/124), 32.2% (40/124) respectively. Nearly 95.0% (171/180) Salmonella isolates were resistant to at least one antimicrobial, 78.3% (141/180) Salmonella strains were multi-drug resistant isolates and 20 (11.1%) Salmonella isolates were resistant to 14 antimicrobials. CONCLUSION: Our findings indicated that Salmonella contamination was common and serious in commercial broiler production and processing course in China. Salmonella contamination rate in broiler slaughter processing performance was higher than broiler flocks. Additionally, antibiotic resistance of Salmonella was in serious situation.