Molecular epidemiology of Listeria monocytogenes isolated from ready-to-eat food in 2017 in China / 中华预防医学杂志

To analyze the molecular characteristics of strains from ready-to eat food in China. A total of 239 strains isolated from ready-to-eat food in 2017, all strains underwent whole-genome sequencing (WGS) , and comparisons uncovered population structure derived from lineages, clonal complex, serogroups, antimicrobial susceptibility and virulence, which were inferred in silico from the WGS data. Core genome multilocus sequence typing was used to subtype isolates. All strains were categorized into three different lineages, lineage Ⅱ was the predominant types in food, and IIa was the main serogroups. CC8, CC101 and CC87 were the first three prevalent CCs among 23 detected CCs, accounting for 49.4%. Only 4.6% (11 isolates) of tested strains harbored antibiotic resistance genes, which were mostly trimethoprim genes (7 isolates, 2.9%). All strains were positive for LIPI-1, and only a part of strains harbored LIPI-3 and LIPI-4, accounting for 13.8% (33 isolates) and 14.2% (34 isolates), respectively. ST619 carried both LIPI-3 and LIPI-4. 51.5% (123 isolates) of strains carried SSI-1, and all CC121 strains harbored SSI-2. Different lineages, serogroups and CCs can be separated obviously through cgMLST analysis, and 24 sublineages were highly concordant with CCs. Ⅱa was the main serogroups in ready-to-eat food isolates in China; CC8, CC101 and CC87 were the prevalent CCs, and CC87 isolates was hypervirulent isolates, cgMLST method can be adopted for prospective foodborne disease surveillance and outbreaks detection.

The Survey of Cronobacter spp. (formerly Enterbacter sakazakii) in Infant and Follow-up Powdered Formula in China in 2012 / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To determine Cronobacter spp. contamination in infant and follow-up powdered formula in China.</p><p><b>METHODS</b>All of 2282 samples were collected from the retail markets in China from January 2012 to December 2012, and analyzed for Cronobacter spp. by the Chinese National Food Safety Standard. Characterization of the isolates was analyzed by pulsed-field gel electrophoresis (PFGE) with XbaI and SpeI restriction enzymes.</p><p><b>RESULTS</b>Cronobacter spp. strains were isolated from 25 samples, and the positive rates in infant powdered formulas and follow-up powdered formulas were 0.90% (10/1011) and 1.18% (15/1271), respectively. Analysis of variable data regarding different purchasing store formats, seasonality, and production locations as well as comparison of infant versus follow-up formulas did not reveal statistically significant factors. During the sampling period, one of six surveillance zones did exhibit a statistically significant trend towards higher positive rate. PFGE characterization of Cronobacter spp. to elucidate genetic diversity revealed only three pairs of Cronobacter spp. out of 25 having the same PFGE patterns.</p><p><b>CONCLUSION</b>The current investigation indicated a lower positive rate of Cronobacter spp. in the powdered formula in China. This evidence suggested contamination originating from multiple different sources during the manufacturing process.</p>

Prevalence and antibiogram distribution of Salmonella isolated from broiler production and processing course in four provinces, China / 中华预防医学杂志

<p><b>OBJECTIVE</b>To determine the contamination condition of Salmonella in broiler breeding and slaughter processing in China and to investigate the distribution of antimicrobial resistance profiles.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Quantitative analysis of foodborne salmonella-the study of mini-modified semi solid rappaport vassiliadis most probable number method / 中华预防医学杂志

<p><b>OBJECTIVE</b>To improve the mini-modified semi solid rappaport vassiliadis most probable number (mini-MSRV MPN) method for Salmonella detection.</p><p><b>METHODS</b>Based on the mini-MSRV MPN method,Buffered Peptone Water (BPW) was modified as one step enrichment medium and Modified Semi Solid Rappaport Vassiliadis (MSRV) medium was ameliorated as modified MSRV for Salmonella detection under standard Salmonella addition recovery. A total of 154 raw chicken samples, 48 swabs of pheasantry and 48 poultry dung samples were collected to compare the detection results of Salmonella by using improved mini-MSRV MPN, mini-MSRV MPN and regular most probable number (MPN) method.</p><p><b>RESULTS</b>Salmonella recovery was < 2.7 MPN/g when the standard Salmonella addition was at the concentration of 0.9 CFU/g when the mini-MSRV MPN method was employed. If the standard Salmonella addition were at 9.0 and 90.0 CFU/g, the recoveries of bacteria were 10.1 and 94.0 MPN/g, and the average recovery rate was 112% and 104%, respectively. Salmonella detection rate of modified mini-MSRV MPN, mini-MSRV MPN and regular MPN method was 18.4% (46/250), 5.2% (13/250) and 6.0% (15/250), respectively. The detection rate was higher for modified mini-MSRV MPN method than of the other two methods (χ(2) values were 19.68 and 17.82, respectively, all P values < 0.05). The detection quantity of Salmonella (medians were 21.0, < 2.7 and < 3.0 MPN/g, respectively). The quantity detected by modified mini-MSRV MPN method was higher than that of the other two methods (both Z values were 5.71, both P values < 0.05).</p><p><b>CONCLUSION</b>Modified mini-MSRV MPN method is an accurate method for foodborne Salmonella detection.</p>

Prevalence and risk assessment of Campylobacter jejuni in chicken in China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To understand the occurrence and distribution of Campylobacter jejuni in chicken in China, assess its health risk to the Chinese population, and provide recommendations for effective risk control.</p><p><b>METHODS</b>Data from the National Food Safety Risk Surveillance Network on Campylobacter jejuni between 2007 and 2010 and from published articles were analyzed. Eleven parameters were used based on the whole chicken preparation process and prevalence of Campylobacter jejuni for risk assessment by using the Ross-Sumner Method.</p><p><b>RESULTS</b>The detection rates of Campylobacter jejuni in raw chicken were between 0.29% and 2.28% during 2007-2010 in China (more than 20 provinces). The probability of illness caused by Campylobacter jejuni due to chicken consumption was around six out of one million consumers per day in urban areas and around one out of one million consumers per day in rural areas. Total predicted illnesses per year was about 736 000, accounting for 1.6‰ of the general population in urban areas and about 301 000, accounting for 0.37‰ of the total population in rural areas. The risk rankings of Campylobacter jejuni in chicken were 52 and 49 in urban and rural areas, respectively.</p><p><b>CONCLUSION</b>A high risk score for Campylobacter jejuni in chicken was obtained in China. This result may contribute to development of food safety management strategies. Key efforts should be made to control the risk of Campylobacter jejuni in chicken in China, especially in chick breeding and chicken preparation processes.</p>

Virulent gene prevalence of foodborne Listeria monocytogenes in China in 2005 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the virulent gene prevalence of foodborne Listeria monocytogenes (LM) isolated from China.</p><p><b>METHODS</b>78 LM isolates derived from raw meat, cooked food, aquatic products and vegetables of 13 provinces and cities.LM isolates were investigated for prevalence of virulence genes (LIPI-1 (prfA, plcA, hly, mpl, actA, plcB); LIPI-2 (inlA, inlB), and iap) by PCR method.</p><p><b>RESULTS</b>87.2% (68/78) of the isolates were prfA positive, 98.7% (77/78) of the isolates were plcA, actA and plcB positive, 97.4% (76/78) of the isolates were hly positive, 87.2% (68/78) of the isolates were mpl positive, 92.3% (72/78) of the isolates were inlA positive, 100% (78/78) of the isolates were inlB positive, 98.7% (77/78) of the isolates were iap positive. Among 21 virulent gene negative isolates, there was 7 isolates lack of two or more virulence genes. The rate of virulence genes deletion isolates from cooked meat was 31.3% (10/32), the rate of virulence genes deletion isolates from raw meat was 16.1% (5/31), the rate of virulence genes deletion isolates from vegetables was 36.4% (4/11) and rate of virulence genes deletion isolates from seafood was 50% (2/4). No significant difference was found (χ(2) = 3.721, P > 0.05). The virulence gene array-1 strains were dominant among these isolates.</p><p><b>CONCLUSION</b>Among 78 LM isolates, prevalent of virulent genes were different except inlB, virulence genes of LIP-1 were deleted prevalently among isolates, virulence gene deletion patterns were diverse.</p>

Study on the automatic ribotyping for Enterobacter sakazakii / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analyze the ribotyping fingerprint of Enterobacter sakazakii (E. sakazakii) isolated from food and its typing power.</p><p><b>METHODS</b>Two standard strains and twenty-eight isolates of E.sakazakii were analyzed by the DuPont Riboprinter(TM) microbial characterization system. The relevant database was established and the fingerprint patterns were analyzed with BioNumerics software.</p><p><b>RESULTS</b>This system grouped two standard strains and twenty-eight E.sakazakii isolates into 26 ribotypes, and four ribotypes included two strains respectively, the other twenty-two strains showed different ribotypes. The lowest similarity was 31.58%. The number of bands by ribotyping was approximately ten and the molecular weight of these bands ranged from 1 to 50 kb. By the clustering program in BioNumerics, these isolates could be grouped into four clusters.</p><p><b>CONCLUSION</b>The automatic ribotyping method is convenient and fast in E.sakazakii typing.</p>

The effects of acrylonitrile on cell apoptosis, proliferation and related genes expression of rat normal and tumor glial cells / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the effect of acrylonitrile (ACN) to cell growth, apoptosis, proliferation and related gene expression of rat normal glial cells (DI TNC1) and tumor glial cells (C6).</p><p><b>METHODS</b>The concentration of ACN on DI TNC1 and C6 were 25, 50 and 75 microg/ml. For cell growth, proliferation and apoptosis assay, the treated time was 24 hours, for microarray assay, the treated time was 4 and 24 hours.</p><p><b>RESULTS</b>After treatment of DI TNC1 cell with 25,50 and 75 microg/ml ACN, the DNA synthesis index were decreased 93.1%, 81.3% and 74.9% as compared to control respectively, the apoptosis index was increased 118%, 122% and 143% as compared to controls respectively. The DNA synthesis and apoptosis indexes of C6 cell showed no change after treatment with ACN. The cell cycle and apoptosis pathway related genes, such as cyclin and p53, also showed changes after treatment with ACN.</p><p><b>CONCLUSION</b>ACN inhibited the cell proliferation of DI TNC1, induced the apoptosis of DI TNC1 and had no effect on cell proliferation and apoptosis of C6 cells, and the related regulation gene expression changes further confirmed the results.</p>

Effects of cell growth and apoptosis of preneoplastic Syrian hamster embryo cells by green tea constituent epigallocatechin-3-gallate / 中华预防医学杂志

<p><b>OBJECTIVE</b>The co-culture model of Syrian hamster embryo (SHE) normal (primary cell) and preneoplastic cells mimicking in vivo status was established and used to study the chemopreventive effects of epigallocatechin-3-Gallate (EGCG) on cell growth, proliferation, apoptosis and regulated genes expression of SHE preneoplastic cells and discussed on the mechanism of EGCG's chemopreventive effect of carcinogenesis.</p><p><b>METHODS</b>The SHE cell preneoplastic and normal cells were cultured on the plates with 1:10,000, 1:1000, 1:100, 1:10 rates for 7 days, and the co-culture model was established. The different concentration of EGCG (0, 0.5, 1, 5, 10, 50 micromol/L) were used to treat the cells and the SHE cells growth assay, in situ cell apoptosis assay, in situ cell proliferation assay and microarray assay were used to determined the growth, apoptosis and proliferation of SHE preneoplastic cells.</p><p><b>RESULTS</b>The co-culture model of SHE cells with the 1:100 rate between SHE preneoplastic cells and normal cells was established. 0.5, 1, 5, 10 micromol/L EGCG increased the colony growth and proliferation of SHE normal cells. In the coculture model of SHE cells with 1:200 rate, compared the the control group, 5, 10 micromol/L EGCG suppressed the growth of different size of SHE preneoplastic cells clone. The DNA proliferation index and apoptosis index in the control group were 39.3% and 6.5%, respectively. After treatment of 5, 10 micromol/L EGCG, the proliferation index were decreased to 25.6% and 24.8%, and the apoptosis index were increased to 12.65% and 14.5%. EGCG suppressed the growth and proliferation of SHE preneoplastic cells in co-culture model and increased its apoptosis. The pathway of cell apoptosis was regulated through the P53, NF-kappaB, bcl-2 signal pathway, and the pathway of cell proliferation was regulated through the growth arrest at G1/S phase of cell cycle.</p><p><b>CONCLUSION</b>The selective regulation of EGCG to normal and preneoplastic cells, the interaction of EGCG, SHE normal cells and SHE preneoplastic cells in co-culture model indicate that the suppression of proliferation and induction of apoptosis of preneoplastic cells by EGCG might be the mechanism of green tea' s chemopreventive effects to tumorigenicity.</p>