温州市食品中沙门菌污染状况及特征分析

目的了解温州市食品中沙门菌的污染状况,分析分离的沙门菌血清型分布、耐药性及脉冲场凝胶电泳(PFGE)分子分型特征。方法依据GB 4789.4—2016《食品安全国家标准食品微生物学检验沙门氏菌检验》进行菌株分离鉴定及血清学分型,采用微量肉汤稀释法进行药敏试验,PFGE法进行分子分型。结果 6类食品2 039份样品中,37份样品检出沙门菌,检出率为1.8%,其中生禽肉和生畜肉检出率较高,分别为6.9%(20/290)和3.4%(10/290)。37株沙门菌分属16种血清型,居前三位分别为鼠伤寒沙门菌、德尔卑沙门菌和肠炎沙门菌。81.1%(30/37)的菌株对17种抗生素产生不同程度的耐药,呈现24种耐药谱,多重耐药率为56.8%(21/37)。PFGE图谱分为31种PFGE带型,呈多态性。结论沙门菌在温州市食品中存在一定的污染率,耐药情况形式严峻,PFGE图谱的聚集性与沙门菌的血清型有一定的联系,与耐药谱之间的关联性并不明确。     

杨凌及周边地区零售分割鸡肉中沙门菌污染状况及耐药和分型特征研究

目的研究陕西杨凌及周边地区零售分割鸡肉中沙门菌的污染状况及其药敏性、血清型和基于脉冲场凝胶电泳(PFGE)的基因型,为预警食源性沙门菌疾病暴发提供数据基础。方法采用GB 4789.4—2010《食品安全国家标准食品微生物学检验沙门氏菌检验》对陕西杨凌及周边地区采集的188份零售分割鸡肉中沙门菌进行分离和鉴定,并进行血清学分型。采用PFGE方法确定沙门菌DNA酶切电泳图谱,使用BioNumerics软件聚类分析电泳结果,确定沙门菌基因型。结果 188份零售分割鸡肉中共有34份(18.1%)样品检出沙门菌,农贸市场样品沙门菌检出率(24.6%,29/118)高于超市(7.1%,5/70)。鸡腿、鸡爪、鸡脖和鸡肝样品中沙门菌检出率高于鸡肠和鸡胗。34株沙门菌中共检出10种血清型,其中科瓦利斯沙门菌最为流行,高于德尔卑沙门菌和鼠伤寒沙门菌等,差异有统计学意义(P0.05)。分离株均对磺胺异噁唑、氯霉素、头孢噻呋和环丙沙星耐药,对甲氧苄啶/磺胺甲噁唑、萘啶酮酸、四环素、链霉素、氨苄西林和阿莫西林/克拉维酸的耐药率均在50%以上。34株沙门菌PFGE分型后可被分为11个簇,同一血清型菌株基本聚于同一大簇,同一时间、从相同市场采集的不同样品,其分离株PFGE型相似度均较高,表明分割鸡肉在加工或销售过程可能存在交叉污染。农贸市场分离菌株基因型多样性比较丰富。结论杨凌及周边地区零售分割鸡肉存在沙门菌污染,沙门菌血清型和基因型多样化,耐药菌株比例较高。     

2016年河南省市售生禽肉中沙门菌血清分型和分子分型研究

目的 了解河南省市售生禽肉中沙门菌污染状况,并对分离株进行血清型和分子分型研究,为河南省食源性疾病溯源数据库提供基础数据。方法 沙门菌检测及血清分型、脉冲场凝胶电泳(PFGE)分子分型分析参照国家食品及食源性疾病监测网工作手册。结果 165份生禽肉样品中检出41株沙门菌,分属13个血清型,优势血清型是科瓦利斯沙门菌、肯塔基沙门菌、鼠伤寒沙门菌及达布沙门菌。经Xba I酶切,获得30种带型,每种带型包括1～5株菌株,相似度为47.5%～100%。部分不同血清型沙门菌PFGE型相似。结论 河南省市售生禽肉沙门菌污染严重,沙门菌血清型和基因型呈现多样化,基因型有一定的地区聚集性。     

济南市零售鸡肉中沙门菌污染状况及可移动黏菌素耐药基因分析

目的 了解2020—2021年济南市零售鸡肉中沙门菌的污染状况,并探究可移动黏菌素耐药基因（mcr）的携带情况。方法 2020年12月至2021年11月在济南市采集零售鸡肉样品260份,依据GB 4789.4—2016《食品安全国家标准食品微生物学检验沙门氏菌检验》对样品中的沙门菌进行分离鉴定,通过聚合酶链式反应（PCR）对分离株进行血清型鉴定和mcr基因筛选,使用微量肉汤法对mcr基因阳性株开展抗生素敏感性试验。结果 260份零售鸡肉样品中共检出阳性样品61份,污染率为23.46%(61/260),秋季污染率最高可达53.33%(32/60);共分离出沙门菌103株,56株为肠炎沙门菌,占比54.37%(56/103)。2株不同产地鸡翅样品来源的印第安纳沙门菌分离株检测出mcr-1基因,阳性率为1.94%(2/103)。2株mcr-1基因阳性印第安纳沙门菌分离株均为多重耐药株,其中1株可对碳青霉烯类和多黏菌素类在内的全部12类测试抗生素同时耐药。结论 2020—2021年济南市零售鸡肉中的沙门菌污染较为严重,秋季采集样品的污染率较高,肠炎沙门菌为优势血清型,检出携带mcr-1基因;同...     

2007年江苏省食源性致病菌监测分析

目的监测江苏省主要食源性致病菌污染状况,确定本地区高危食品,为预防控制食源性疾病提供科学依据。方法依据GB/T 4789—2003食品卫生微生物学检验方法,对样品分别进行沙门菌、单核细胞增生性李斯特菌、大肠杆菌O157∶H7、空肠弯曲菌和副溶血性弧菌进行分离,生化及血清学鉴定。结果共监测生畜禽肉、熟肉制品、生食蔬菜、水产品8类样品共804件,检出致病菌113株,总检出率14.1%(113/804)。其中沙门菌检出33株,检出率为4.1%(33/804),单核细胞增生性李斯特菌检出41株,检出率5.6%(41/738);副溶血性弧菌检出13株,检出率为11.2%(13/116);金黄色葡萄球菌检出率15.9%(24/151);大肠杆菌O157∶H7检出2株,检出率0.41%(2/493);空肠弯曲菌和阪崎肠杆菌未检出。33株沙门菌经血清型鉴定,分离出9种血清型,主要是德尔卑沙门菌,其次为罗米他沙门菌和鸭沙门菌。结论江苏省地区食品存在食源性致病菌污染,其中水产品和生肉是主要污染食品品种,而熟肉和生食水产品导致食源性疾病的风险较高。     

2015—2020年宜宾市肉类食品沙门菌血清型及分子分型研究

目的 研究宜宾市肉类食品中沙门菌分离株的血清型和分子分型特征,分析沙门菌污染的危险因素。方法 收集2015—2020年宜宾市辖区(县)肉类食品沙门菌分离株29株,进行血清型鉴定和脉冲场凝胶电泳(PFGE)分子分型分析,并就地域、物种来源和售卖方式对沙门菌血清群检出构成比的影响进行多因素Logistic回归分析。结果 29株沙门菌分离株共检出14种血清型(分属4个群),主要优势血清型为鼠伤寒沙门菌、吉韦沙门菌和肠炎沙门菌。聚类分析显示PFGE分子分型为18种带型。肠炎沙门菌带型相似度100%,来自同一传染链;吉韦沙门菌有2种带型,鼠伤寒沙门菌有4种带型,相似度较差;多因素Logistic分析显示,影响D群沙门菌检出的主要危险因素为地域分布(OR=1.053,P<0.05);影响E群沙门菌检出的主要危险因素为物种来源(OR=3.887,P<0.05)和地域分布(OR=1.227,P<0.05)。结论 监管部门应从家禽养殖地地域来源和肉类物种来源两个方面加强宜宾市肉类食品安全监督。     

腹泻患儿粪便中沙门菌的血清型、药敏分析及脉冲场凝胶电泳分子分型研究

目的 研究2019年北京市朝阳区0-10岁腹泻患儿粪便中分离出的沙门菌的血清型、PFGE分子分型研究及耐药特点。方法 对分离自腹泻患儿病例的47株沙门菌进行血清分型,采用微量肉汤稀释法进行27种抗生素的药敏实验;采用PFGE脉冲场凝胶电泳进行指纹图谱分型研究。结果 47株沙门分为9种血清型,优势血清型两种,分别为肠炎沙门菌23株占48.94%,鼠伤寒沙门菌14株占29.79%。47株沙门菌对磺胺异恶唑耐药率(57.45%)最高,其次为氨苄西林(48.94%)和链霉素(48.94%)。23株肠炎沙门菌可分成8个PFGE指纹图谱,15株鼠伤寒沙门菌可分成14个PFGE指纹图谱。结论 北京市朝阳区0-10岁儿童食源性沙门菌血清主要为肠炎沙门菌和鼠伤寒沙门菌,各血清型的耐药性有所不同,PFGE指纹图谱呈多样性。     

一起肠炎沙门菌引起的食物中毒检测及菌株同源性分析

检测食物中毒样品中致病菌,分析其同源性,为追踪污染源、明确病因诊断提供帮助,为控制和减少食物中毒提供依据。方法 荧光定量PCR快速筛检致病菌,参照GB 4789.4—2010《食品安全国家标准 食品卫生微生物检验 沙门氏菌检验》分离致病菌,全自动细菌鉴定仪鉴定致病菌,脉冲场凝胶电泳(PFGE)分析同源性。结果 从21份病人和从业人员粪便样品中检出8株肠炎沙门菌,9份食品样品中检出2份肠炎沙门菌,检出率分别为25.00%和6.25%;食堂用水及井水检测均未检出肠炎沙门菌等致病菌。荧光定量PCR法阳性率结果与GB 4789.4—2010方法一致。PFGE分型显示10株肠炎沙门菌的DNA条带图谱完全一致,相似性100%,聚类分析为同一型,表明菌株来自同一克隆系。结论 采用荧光定量PCR筛检能提示食物中毒样品中病原菌是否存在的信息,通过GB 4789.4—2010方法仔细寻找到目标菌,两法联合使用能快速、准确地检测出引起食物中毒的致病菌。运用PFGE对致病菌进行溯源,分析其亲缘关系,能追踪到菌株来源,有利于防止食物中毒的发生。     

市售活鸡和腹泻患者中非伤寒沙门菌分子特征和耐药性研究

分析市售活鸡及腹泻患者中非伤寒沙门菌的分子特征的相似性及耐药性,预防沙门菌的感染流行。方法 收集2012年1月—2013年10月从1 054份腹泻患者粪便样品及440份农贸市场的活鸡肛拭子中分离出的非伤寒沙门菌株93株,进行血清分型,对常见的非伤寒沙门菌采用脉冲场凝胶电泳(PFGE)进行分子分型、Bionumerisc v4.0进行聚类分析、纸片扩散法(K-B法)进行药物敏感性试验。结果 1 054份腹泻样品中共检出非伤寒沙门菌88株,分离率为8.35%,分为25种血清型,肠炎沙门菌居多。其中0～2岁的婴幼儿检出率较高,占52.27%(46/88)。PFGE结果:16株肠炎沙门菌分成14个PFGE型、12株斯坦利沙门菌分成11个PFGE型、14株鼠伤寒沙门菌分成14个PFGE型、6株德尔卑沙门菌分成5个PFGE型;对菌株间的相似性进行比较发现两个100%同源的肠炎沙门菌PFGE型,其他菌株的分子特征的相似性不大,鸡源菌株与人源菌株的分子特征相似性不大;对12种抗菌药物的耐药率在50%以下,不同的血清型耐药率各不相同,耐药较严重的为德尔卑沙门菌。440份活体鸡肛拭子分离出的非伤寒沙门菌5株,分离率为1.14%,共分得4种血清型,其中姆班达卡沙门菌病人中未检出。结论 该地区由非伤寒沙门菌引起腹泻的感染率高,尤以婴幼儿多见,患者与鸡未发现有同一克隆株,对常用抗生素有很好的敏感性。     

2012—2017年广西壮族自治区市售食品中沙门菌监测数据分析

目的 了解广西市售食品中沙门菌污染状况和特征,为减少污染和防控食源性疾病提供科学依据。方法 2012—2017年从广西14个市采集14类市售食品共60 174份,其中生鲜类食品5 712份,即食食品54 462份,按照GB 4789.4—2010《食品安全国家标准 食品微生物学检验 沙门氏菌检验》方法进行沙门菌检验。结果 生鲜类食品中生肉及生肉制品、生水产品及其制品、速冻米面制品、鲜蛋类沙门菌检出率分别为10.3%(399/3 883)、6.2%(50/806)、0.5%(2/440)、0.0%(0/583),即食食品中熟肉制品、餐饮食品、生食蔬菜及其制品沙门菌检出率分别为0.6%(58/10 175)、0.3%(39/14 721)、1.0%(5/489),焙烤及油炸类食品、饮料、水果及其制品均为0.1%,熟蛋制品、豆制品、冷冻饮品、调味品均未检出。生肉及生肉制品共检出51种血清型,德尔卑沙门菌为优势血清型(16.2%,70/432),主要在生猪肉中检出。即食食品共检出32种血清型,德尔卑沙门菌为优势血清型(14.5%,11/76),主要在熟肉制品中检出。结论 生鲜类受沙门菌污染最严重的食品是生畜肉和生禽肉,即食食品受沙门菌污染较严重食品是凉拌类食品。应加强从农场到餐桌的食品安全防控,减少食源性疾病的发生。     

Arsenic content of some edible mushroom species

The arsenic contents of 162 fruit body samples of 37 common edible mushroom taxa were analyzed. The samples were gathered from different habitats of Hungary (mainly from mountains) between 1984 and 1999. The arsenic content of the samples was measured by the inductively coupled plasma spectrometry method. Very low [lower than 0.05 mg/kg dry matter (DM)] concentrations were found in the samples of 13 taxa, while higher (or very high) contents were quantified in other common taxa (the highest arsenic content was recorded in the fruit body of Laccaria amethysthea at 146.9 mg/kg DM). The species of eight genera (Agaricus, Calvatia, Collybia, Laccaria, Langermannia, Lepista, Lycoperdon, Macrolepiota) belong to the so-called accumulating taxa, and this tendency is evident on all habitats. This arsenic accumulation capability is found in two orders of Basidiomycetes (Agaricales and Gasteromycetales), which is to say this phenomenon occurs in the families Agaricaceae, Tricholomataceae and Gasteromycetaceae. The accumulating taxa found all have a saprotrophic type of nutrition; arsenic accumulation is not detectable in xilophagous or in mycorrhizal species. The consumption of the accumulating species found has only a low toxicological risk for three reasons: the consumed fresh fruit bodies contain about a tenfold lower arsenic level than the dried ones, the majority of arsenic occurs not in poisonous inorganic, but in less dangerous (or not poisonous) organic forms, and the frequency of consumption is low.     

Organization and localization of the dnaA and dnaK gene regions on the multichromosomal genome of Burkholderia multivorans ATCC 17616

The Burkholderia multivorans strain ATCC 17616 carries three circular chromosomes with sizes of 3.4, 2.5, and 0.9 Mb. To reveal the distribution and organization of the genes for fundamental cell functions on the genome of this bacterium, the dnaA and dnaK gene regions of ATCC 17616 were cloned and characterized. The gene organization of the dnaA region was rnpA-rmpH-dnaA-dnaN-gyrB with a single consensus DnaA-binding box (TTATCCACA) between the rmpH and dnaA genes. This intergenic region, however, did not work as an autonomously replicating sequence in ATCC 17616. On the other hand, the gene organization of the dnaK region was grpE-orf1 (gene for thioredoxin homologue)-dnaK-dnaJ-pabB (gene for p-aminobenzoate synthetase component homologue). A putative heat-shock promoter that showed good homology to the sigma32-dependent promoter consensus sequence in Escherichia coli was found upstream of the grpE gene, suggesting that these five genes constitute an operon. In M9 succinate minimal medium the dnaJ mutant grew more slowly than the wild-type strain, indicating that this operon is functional. Pulsed-field gel electrophoresis and Southern blot analyses indicated that both the dnaA and dnaK gene regions exist as single copies on the 3.4 Mb chromosome.     

Contamination with storage fungi of human food from Cameroon

In a mycological study, a total of 95 human food samples were investigated to evaluate the incidence of fungal contamination in Cameroon by conventional identification method and partly confirmed by DNA sequencing. The isolated fungal spp. were further studied to determine their toxigenic potentials. The investigation revealed the predominance of Aspergillus and Penicillium with 96% of samples contaminated with at least one species of these fungi, whereas the incidence of co-contamination of samples was 85%. Aspergillus flavus and Aspergillus parasiticus (Flavi section) were the most predominant species contaminating mainly maize and peanuts. In addition, P. crustosum and P. polonicum were the most common contaminants belonging to the genus Penicillium. On the other hand, A. ochraceus (Circumdati section) registered a low incidence rate of 5%, including other members of the Aspergillus group. Other members of the genera Rhizopus and Alternaria spp. were also registered in the study. A majority of fungal strains of A. ochraceus, A. parasiticus, P. crustosum and P. polonicum isolated were toxigenic, producing the mycotoxins tested for, while none was detected in cultures of A. fumigatus. The high incidence rate of fungi contamination coupled with their potentials in producing mycotoxins gives a strong indication that the samples tested may likely be contaminated with various mycotoxins. There is need for further study to assess the incidence of mycotoxins contamination in similar food samples.     

Microbial profiles of frozen trimmings and silver sides prepared at Indian buffalo meat packing plants

To assess microbiological quality of buffalo meat trimmings (TT = 114) and silver sides (SS = 41), samples were collected from four different Indian meat packing plants. The aim of this study was: (i) to evaluate standard plate count (SPC), psychrotrophic count (PTC), Enterococcus feacalis count (EFC), Staphylococcus aureus count (SAC) and Escherichia coli count (ECC) and the presence of Salmonella spp. and Listeria monocytogenes; and (ii) also to determine vero toxic E. coli (VTEC) by polymerase chain reaction (PCR). TT samples had significantly higher (P < 0.001) SPC, PTC, EFC, and SAC than SS, while across the meat types there was no difference (P > 0.05) in ECC. E. coli was recovered from 32.4% TT and 19.5% SS samples. The prevalence rate of Salmonella spp. and L. monocytogenes in TT was 1.75% and 0.87%, respectively. But no SS sample was found to be positive for any of these two pathogens. VTEC was found in 2.58% of all the tested samples. This finding suggests that TT contain higher microbes but only small numbers of pathogens of latent zoonotic importance. The present study confirmed the importance of maintaining good process hygiene at meat plants for microbiological status of buffalo meat.     

Susceptibility of stored product insects to high concentrations of ozone at different exposure intervals

Ozone is a highly reactive gas with insecticidal activity. Past studies have indicated that ozone technology has potential as a management tool to control insect pests in bulk grain storage facilities. The objective of this study was to determine the efficacy of short periods of exposure to high ozone concentrations to kill all life stages of red flour beetle (Tribolium castaneum (Herbst)) (Coleoptera: Tenebrionidae), and Indianmeal moth (Plodia interpunctella (Hübner)) (Lepidoptera: Pyralidae), adult maize weevil (Sitophilus zeamais (Motsch.)) (Coleoptera: Curculionidae) and adult rice weevil (S. oryzae (L)) (Coleoptera: Curculionidae). Insects were treated with six ozone concentrations between 50 and 1800 ppm. The specific objective was to determine minimal time needed to attain 100% mortality. The most ozone-tolerant stages of T. castaneum were pupae and eggs, which required a treatment of 180 min at 1800 ppm ozone to reach 100% mortality. Eggs of P. interpunctella also required 180 min at 1800 ppm ozone to reach 100% mortality. Ozone treatments of 1800 ppm for 120 min and 1800 ppm for 60 min were required to kill all adult S. zeamais and adult S. oryzae, respectively. The results indicate that high ozone concentrations reduce the treatment times significantly over previously described results. Our results also provide new baseline information about insect tolerance to ozone treatment.     

Effect of Zataria multiflora Boiss. essential oil and nisin on Salmonella typhimurium and Staphylococcus aureus in a food model system and on the bacterial cell membranes

The effects of different concentrations of Zataria multiflora Boiss. essential oil (EO: 0, 5, 15 and 30 μl 100 ml⁻¹) and nisin (N: 0, 0.25 and 0.5 μg ml⁻¹), temperatures (T: 25 and 8 °C), and storage times (up to 21 days) on growth of Salmonella typhimurium and Staphylococcus aureus in a commercial barley soup were evaluated in a factorial design study. The growth of S. typhimurium was significantly (P < 0.05) decreased by EO concentrations and their combinations with N concentrations at 8 °C. For S. aureus, the viable count was significantly (P < 0.05) inhibited by EO and N concentrations and their combinations, incubated at both storage temperatures. The mechanism of the antimicrobial action of EO, N, and their combinations against cell membranes of the tested organisms were also studied by measurement of the release of cell constituents and by the electronic microscopy observations of the cells. The significant increase of the cell constituents’ release of both organisms was observed as a result of treatments with EO and EO in combination with N. Electronic microscopy observations revealed that the cell membranes of S. typhimurium treated by EO and EO in combination with N were significantly damaged, while cells treated with only N looked similar to untreated cells. The electron micrographs of treated cells of S. aureus with EO, N, and their combination also showed important morphological damages and disrupted membranes.     

Formation of cereulide and enterotoxins by Bacillus cereus in fermented African locust beans

Afitin, iru and sonru are three spontaneously fermented African locust bean Benin condiments. The fermentation processes are exothermic, with temperatures mostly being above 40 °C. A total of 19 predominant Bacillus cereus isolates from afitin, iru and sonru, were investigated. The enterotoxin genes nhe (A, B, C) were present in all 19 isolates, the hbl (A, C, D) in one (afitin), and the cytK gene in three isolates (afitin). Levels of cytotoxicity to Vero cells and NheA production in BHI-broth was within the range of known diarrheal outbreak strains. Autoclaved cooked African locust beans inoculated with emetic (cereulide producing) B. cereus Ba18H2/RIF supported growth at 25, 30 and 40 °C with highly different maximum cereulide productions of 6 ± 5, 97 ± 3 and 0.04 ± 0.02 μg/g beans, respectively (48 h). For non-autoclaved cooked beans inoculated with 2, 4 and 6 log₁₀B. cereus Ba18H2/RIF spores/g beans, cereulide production was 5 ± 4, 64 ± 8 and 69 ± 34 μg/g beans, respectively at 24 h, while it was 70 ± 43, 92 ± 53 and 99 ± 31 μg/g at 48 h of fermentation at 30 °C. Even though high toxin levels were observed, to date there are no known reports on diarrhea or vomiting due to the consumption or afitin, iru and sonru in Benin, which also according to the present study is likely to be expected from the low levels of cereulide produced at 40 °C.     

Assessment of the microbiological safety of salad vegetables and sauces from kebab take-away restaurants in the United Kingdom

The purpose of this study was to establish the microbiological safety of salad vegetables and sauces served in kebab take-away restaurants. Comparison with published microbiological guidelines revealed that 4.7% of 1213 salad vegetable samples were of unsatisfactory microbiological quality due to Escherichia coli and/or Staphylococcus aureus levels at ≥10² cfu g⁻¹. Another 0.3% of salad samples were of unacceptable quality due to S. aureus at ≥10⁴ cfu g⁻¹ (2 samples) or the presence of Salmonella Kentucky (1 sample). Cucumber was the most contaminated salad vegetable with regards to unsatisfactory levels of E. coli (6.0%) or S. aureus (4.5%). Five percent of 1208 sauce samples were of unsatisfactory microbiological quality due to E. coli, S. aureus at ≥10² cfu g⁻¹ and/or Bacillus cereus and other Bacillus spp. at ≥10⁴ cfu g⁻¹. A further 0.6% of sauce samples were of unacceptable quality due to Bacillus spp. (Bacillus subtilis, Bacillus pumilus, Bacillus licheniformis) at ≥10⁵ cfu g⁻¹ or the presence of Salmonella Agbeni (1 sample). More samples of chilli sauce (8.7%) were of unsatisfactory or unacceptable microbiological quality than any other sauce types. The results emphasize the need for good hygiene practices in kebab take-away restaurants handling these types of ready-to-eat products.