2009—2014年马鞍山市食品中李斯特菌污染状况调查

目的 了解马鞍山市食品中李斯特菌污染状况。方法 2009年1月至2014年12月,对马鞍山市部分餐饮店、超市及零售市场中的12类食品(包括畜肉、禽肉、鱼虾、动物内脏、熟食制品、蔬菜、米面制品、豆制品、禽蛋、果汁、乳制品、冷饮)进行随机抽样,共采集2 372份样品进行李斯特菌分离检测,并对检出的单增李斯特菌进行了毒力基因检测。结果 2 372份样品中332份存在李斯特菌,检出率为14.00%,其中畜肉检出率为25.15%(82/326),禽肉为23.98%(82/342),鱼虾为16.20%(104/642),动物内脏为11.66%(26/223),熟食为8.49%(31/365),蔬菜为2.88%(4/139),米面制品为2.20%(2/91),豆制品为1.33%(1/75),各类食品李斯特菌检出率比较,差异有统计学意义(χ²=65.64,P<0.05),禽蛋、果汁、乳制品、冷饮中未检出李斯特菌。2009年李斯特菌的检出率最高(23.97%,70/292),其次分别为2011年(15.62%,67/429),2012年(15.36%,49/319),2014年(11.65%,48/412),2013年(11.11%,47/423),2010年(10.26%,51/497),各年度食品中李斯特菌检出率比较差异有统计学意义(χ²=26.80,P<0.05)。对检出的48株单增李斯特菌进行6个毒力基因(hly、prfA、plcB、inlA、actA和iap)的聚合酶链式反应(PCR)检测,结果显示所有分离菌株均具有6个毒力基因。结论 马鞍山市食品存在不同程度的李斯特菌污染,具有食源性李斯特菌感染疾病暴发的潜在风险,应加强监督监测,预防李斯特菌所引起的食源性疾病发生。     

生防菌BJ1离子辐照突变高效菌株筛选及对黄瓜枯萎病的生防效果

枯草芽孢杆菌BJ1是一种在真菌病害防治中发挥重要作用的生防因子,为进一步提高它的抑菌能力,获得生防效果更好的高效菌种,利用不同能量和剂量的12C6+对生防菌BJ1进行了离子辐照处理。研究结果表明:离子辐照生防菌BJ1的最适宜剂量为200~400 Gy,传能线密度(LET)为60 keV/μm;突变菌株的抑菌能力比BJ1提高了2%~21%;不仅防病效果比BJ1提高了17.48%,而且对植物具有更好的促生长作用。     

Antibacterial effects of American cranberry (Vaccinium macrocarpon) concentrate on foodborne pathogens

Antibacterial effects of American cranberry (Vaccinium macrocarpon) concentrate on foodborne pathogens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, and Staphylococcus aureus in vitro were investigated. Cranberry concentrate at various concentrations was prepared in distilled water (DW) or Brain Heart Infusion (BHI) broth. Pathogens were inoculated in each sample and incubated at 21 and 4 °C for 0, 1, 5, 7, and 24 h (DW samples) and 0, 1, 3, and 5 days (BHI samples). Transmission electron microscopy (TEM) was used to study the effects of cranberry concentrate on cellular structure of pathogens. DW results showed that S. Typhimurium and L. monocytogenes were reduced to non-detectable levels at 5 h in 100 μl/ml treatment at 21 and 4 °C. At 24 h, no target pathogens were detected from the 100 μl/ml treatment. BHI data indicated that the 100 μl/ml treatment reduced the four pathogens by 3-8 log CFU/ml compared with the control on Day 5 at 21 and 4 °C. TEM revealed damage to the bacterial cell walls and membranes. Cranberry concentrate has antibacterial effects on the four foodborne pathogens. Based on potential health benefits and proven antimicrobial effects, American cranberry concentrate may have dual applications as a food preservative.     

Reduction by gaseous ozone of Salmonella and microbial flora associated with fresh-cut cantaloupe

This research investigates the efficacy of gaseous ozone, applied under partial vacuum in a controlled reaction chamber, for the elimination of Salmonella inoculated on melon rind. The performance of high dose, short duration treatment with gaseous ozone, in this pilot system, on the microbial and sensory quality of fresh-cut cantaloupes was also evaluated. Gaseous ozone (10,000 ppm for 30 min under vacuum) reduced viable, recoverable Salmonella from inoculated physiologically mature non-ripe and ripe melons with a maximum reduction of 4.2 and 2.8 log CFU/rind-disk (12.6 cm(2)), respectively. The efficacy of ozone exposure was influenced by carrier matrix. Salmonella adhering to cantaloupe was more resistant to ozone treatment when suspended in skim-milk powder before aqueous inoculation to the rind. This indicated that organic matter interferes with the contact efficiency and resultant antimicrobial activity of gaseous ozone applied as a surface disinfectant. Conversely, in the absence of an organic carrier, Salmonella viability loss was greater on dry exocarp surfaces than in the wetted surfaces, during ozone treatment, achieving reductions of 2.8 and 1.4 initial log CFU/rind-disk, respectively. Gaseous ozone treatment of 5000 and 20,000 ppm for 30 min reduced total coliforms, Pseudomonas fluorescens, yeast and lactic acid bacteria recovery from fresh-cut cantaloupe. A dose Ct-value (concentration x exposure time) of 600,000 ppm min achieved maximal log CFU/melon-cube reduction, under the test conditions. Finally, fresh-cut cantaloupe treated with gaseous ozone, maintained an acceptable visual quality, aroma and firmness during 7-day storage at 5 degrees C. Conclusions derived from this study illustrate that gaseous ozone is an effective option to risk reduction and spoilage control of fresh and fresh-cut melon. Moreover, depending on the timing of contamination and post-contamination conditions, rapid drying combined with gaseous ozone exposure may be successful as combined or sequential disinfection steps to minimize persistence of Salmonella on the surface of cantaloupe melons and transference during fresh-cut processing of home preparation. Based on these results, greater efficacy would be anticipated with mature but non-ripe melons while ripe tissues reduce the efficacy of these gaseous ozone treatments, potentially by oxidative reaction with soluble refractive solids.     

A review of microbial injury and recovery methods in food

The existence of injured microorganisms in food and their recovery during culturing procedures is critical. Microbial injury is characterized by the capability of a microorganism to return to normalcy during a resuscitation process in which the damaged essential components are repaired. Injury of microorganisms can be induced by sublethal heat, freezing, freeze-drying, drying, irradiation, high hydrostatic pressure, aerosolization, dyes, sodium azide, salts, heavy metals, antibiotics, essential oils, sanitizing compounds, and other chemicals or natural antimicrobial compounds. Injured microorganisms present a potential threat in food safety since they may repair themselves under suitable conditions. Detection of injured microorganisms can be important to practical interpretations of data in food microbiology. This review provides an overview of microbial injury in food and discusses the development of recovery methods for detecting injured foodborne microorganisms.     

2017—2021年安徽省食源性腹泻病例病原学分析

目的 分析安徽省2017—2021年食源性腹泻病例病原学特征,为制定相关防控措施提供依据。方法采用横断面研究方法,收集2017—2021年安徽省22家食源性疾病病原学监测医院上报被采集肛拭子/粪便的腹泻病例信息,并按要求对采集的患者标本开展病原学检测。分类资料采用χ_趋势²或χ²进行组间比较。结果 2017—2021年共采集标本15 484份,病原体总检出率为23.75%(3 678/15 484)。其中,诺如病毒检出率最高,为10.01%(1 550/15 484);其次是沙门菌(6.16%,954/15 484)、致泻大肠埃希菌(6.10%,944/15 484)、副溶血性弧菌(1.66%,257/15 484)、志贺菌(1.00%,155/15 484)。不同年份(χ_趋势²=11.249,P<0.05)和不同季度(χ_趋势²=146.119,P<0.05)病原体的检出率,均差异有统计学意义。各年龄段人群中,年龄<1...     

3种流通模式下生猪肉中单增李斯特菌的暴露评估

本研究通过对3 种生猪肉流通模式进行简化,根据生猪肉中单增李斯特菌初始污染水平抽检数据及调研环境参数,评估对比了3 种流通模式下单增李斯特菌在生猪肉中的最终暴露量。结果显示：基于全程非冷链的热鲜猪肉最终阳性检出率约为42.12%,超过风险阈值概率约为21.05%;基于部分冷链的冷鲜猪肉最终阳性检出率约为12.07%,超过风险阈值概率约为1.61%;基于全程冷链的冷鲜猪肉最终阳性检出率约为6.50%,超过风险阈值概率约为0%。相关性分析表明,初始污染水平与最终暴露量Pearson相关系数均为0.70以上,影响最大。因此,冷鲜猪肉较热鲜猪肉更有利于避免食源性疾病的发生,基于全程冷链的冷鲜猪肉应被积极推广。同时在生猪肉供应链中,更应注重源头控制,严格设置并控制各流通环节的环境条件。     

食源性致病菌菌株多相异质性对微生物风险评估的影响研究进展

微生物风险评估是当前保障食品安全的重要科学工具之一,被广泛应用于食品安全政策、法规和标准的制定。菌株多相异质性是微生物的固有特性,普遍存在于各类致病菌之中,影响着风险评估的准确性和不确定性。本文概述了国内外食品微生物菌株多相异质性的相关研究,总结了菌株多相异质性的概念,从生长和失活异质性、被膜形成异质性、毒力异质性和耐药异质性4 个方面全面系统地分析了菌株多相异质性的存在形式。在此基础上探讨了菌株多相异质性对微生物风险评估的影响,进一步展望了降低该影响的4 种解决措施,提出微生物风险评估宏模型的概念,以期提高食品安全风险评估的准确性和可靠性。     

2017年山西省食源性疾病流行病学特征及空间聚集性分析

目的 分析2017年山西省食源性疾病流行病学特征,重点探索其空间聚集情况,为科学地开展防控措施提供依据。方法 运用地理信息系统技术和描述性流行病学方法分析2017年山西省食源性疾病流行病学特征,并运用空间自相关方法研究其空间聚集性。结果 2017年山西省共报告食源性疾病病例27 727例,报告发病率为7.5/万。男女性别比为1.02∶1,20～39岁报告病例数最多(27.6%,7 661/27 727);农民(40.6%,11 266/27 727)、低龄学生(13.2%,3 652/27 727)报告病例数较多。可疑暴露食品主要为水果类及其制品(26.0%,7 207/27 719)、粮食类及其制品(17.9%,4 963/27 719)和肉与肉制品(11.6%,3 207/27 719)。进食场所以家庭为主(73.2%,23 429/31 988)。三维趋势分析得到的疾病报告发病率总体分布情况为:由北向南逐渐升高,由西向东缓慢下降,与报告发病率分布图所呈现的结果一致。食源性疾病报告发病率呈空间正相关,高-高聚集地区为浮山县、隰县、大宁县、永和县、古县、吉县。结论 山西省食源性疾病发病存在明显的空间聚集性。     

单核细胞增生性李斯特菌的增殖和抑制

单核细胞增生性李斯特菌(Listeria Monocytogenes)引起的突发性中毒症是一种很特殊的食物中毒病症.本文阐述了单增李斯特菌的生长特性,包括营养需求、流行病学和溶血素O的一些研究,同时综述了影响李斯特菌增殖的因素,并介绍了一些对食品中单增李斯特菌的抑制方法.