Combining targeted sampling and fluorometry to identify human fecal contamination in a freshwater creek

Many bacterial source tracking (BST) methods are too expensive for most communities to afford. In an effort to develop an inexpensive method of detecting human sources of fecal contamination in a freshwater creek during baseflow and stormflow conditions, we combined targeted sampling with fluorometry. Targeted sampling is a prelude to BST and finds sources of fecal contamination by continued sampling and resampling over ever-decreasing distances. Fluorometry identifies human fecal contamination in water by detecting fluorescing compounds, optical brighteners, from laundry detergents. Potato Creek, a freshwater creek in Georgia (U.S.A.), had three reaches identified as containing high numbers of fecal bacteria, and these reaches were sampled by targeted sampling and fluorometry. Targeted sampling quickly and inexpensively identified humans, cattle, and dogs as the major sources of fecal contamination in the first, second, and third reaches, respectively. Fluorometric values were consistent with these identifications, but high fluorometric values were sometimes observed in areas with no fecal contamination. One likely cause of these false-positive signals was fluorescence from organic matter. For targeted sampling, the cost of each sample was $6, with a one-time equipment cost of $3,650; for fluorometry, the cost of each sample was negligible, with a one-time equipment cost of $14,250. This was the first study of this relatively inexpensive combination in freshwater during both baseflow and stormflow conditions.     

Factors associated with post-treatment E. coli contamination in households practising water treatment: a study of rural Cambodia

The purpose of this study was to assess factors associated with Escherichia coli (E. coli) contamination in rural households in Cambodia that have adopted household water treatment. The following factors were significantly associated (α < 0.05) with apparent E. coli contamination: cleaning the drinking vessel with untreated water, not drying the cup (with a cloth), accessing treated water by the use of a scoop (ref: using a tap), having more than one untreated water storage container, having an untreated water storage container that appeared dirty on the outside, and cows living within 10 m of the household. This study provides further evidence confirming previous studies reporting an association between inadequate cleanliness of water storage containers and household drinking water contamination, and identifies practical recommendations statistically associated with reduced post-treatment E. coli contamination in the household setting in rural Cambodia.     

Combining targeted sampling and fluorometry to identify human fecal contamination in a freshwater creek

Many bacterial source tracking (BST) methods are too expensive for most communities to afford. In an effort to develop an inexpensive method of detecting human sources of fecal contamination in a freshwater creek during baseflow and stormflow conditions, we combined targeted sampling with fluorometry. Targeted sampling is a prelude to BST and finds sources of fecal contamination by continued sampling and resampling over ever-decreasing distances. Fluorometry identifies human fecal contamination in water by detecting fluorescing compounds, optical brighteners, from laundry detergents. Potato Creek, a freshwater creek in Georgia (U.S.A.), had three reaches identified as containing high numbers of fecal bacteria, and these reaches were sampled by targeted sampling and fluorometry. Targeted sampling quickly and inexpensively identified humans, cattle, and dogs as the major sources of fecal contamination in the first, second, and third reaches, respectively. Fluorometric values were consistent with these identifications, but high fluorometric values were sometimes observed in areas with no fecal contamination. One likely cause of these false-positive signals was fluorescence from organic matter. For targeted sampling, the cost of each sample was $6, with a one-time equipment cost of $3,650; for fluorometry, the cost of each sample was negligible, with a one-time equipment cost of $14,250. This was the first study of this relatively inexpensive combination in freshwater during both baseflow and stormflow conditions.     

Microbial groundwater quality and its health implications for a border-strip irrigated dairy farm catchment, South Island, New Zealand

Intensification of dairying on irrigated pastures has led to concern over the microbial quality of shallow groundwater used for drinking purposes. The effects of intensive dairying and border-strip irrigation on the leaching of E. coli and Campylobacter to shallow groundwater were assessed over a three-year period in the Waikakahi catchment, Canterbury, New Zealand. Well selection excluded other sources of contamination so that the effect of dairying with border-strip irrigation could be assessed. Groundwater samples (135) were collected, mostly during the irrigation season, with E. coli being detected in 75% of samples. Campylobacter was identified in 16 samples (12%). A risk assessment of drinking water with these levels of Campylobacter was undertaken. A probability distribution was fitted to the observed Campylobacter data and the @RISK modeling software was used, assuming a dose response relationship for Campylobacter and consumption of 1 L/day of water. The probability of infection on any given day in the study area was estimated at 0.50% to 0.76%, giving an estimated probability of infection during the irrigation season of 60% to 75%. An epidemiological assessment of the Canterbury region comparing areas encompassing dairy within major irrigation schemes (~55% border-strip irrigation) to two control groups was undertaken. Control group 1 (CG1) encompasses areas of dairying without major irrigation schemes, and a second larger control group (CG2) comprises the rest of the Canterbury region. Comparisons of the subject group to control groups indicated that there was a statistically significant increase in age-standardised rates of campylobacteriosis (CG1 Relative Risk (RR)=1.51 (95% CI = 1.31-1.75); CG2 RR = 1.51 (1.33–1.72)); cryptosporidiosis (CG1 RR = 2.08 (1.55–2.79); CG2 RR = 5.33 (4.12–6.90)); and salmonellosis (CG2 RR = 2.05 (1.55–2.71)).     

2003～2006年广东省食品中致泻性大肠埃希菌污染状况调查分析

目的调查致泻性大肠埃希菌在广东省食物中的分布特征和污染状况,了解地区因素对于致泻性大肠埃希菌分布的影响,以预防和控制食品污染,保证食品安全.方法随机采集食品样品,用改良EC肉汤进行增菌,用麦康凯琼脂和O157H7专用培养基进行致泻性大肠埃希菌的分离、培养,应用bioMérieux VITEK32 AMS system,GNI+、API-20E试条和血清学的方法进行鉴定.结果检测各类样本706份,检出47株致泻性大肠埃希菌,检出率为6.7%,其中生鸡肉、生猪肉、生牛肉的检出率分别为10.7%、16.9%、11.1%,熟肉制品的检出率也有5.2%,EPEC和ETEC的检出率分别为34.0%和40.4%,检出EHEC O157H75株,经济发达地区的检出率(2.8%)明显低于经济状况中等地区(6.6%),经济状况中等地区检出率明显低于经济状况相对落后地区(16.1%).2003～2006年各年的检出率总体无显著差异.结论广东省多种食品中均可检出致泻性大肠埃希菌,经济相对落后地区尤其是农村的污染情况严重.有潜在EHEC O157H7食物中毒暴发的可能.有关部门应采取措施,预防致泻性大肠埃希菌的污染.     

水源水中致泻大肠埃希菌的检测与分析

目的　调查致泻大肠埃希菌在不同年限、不同季节、不同水源水中的分布规律以及菌型分布特点 ,为制定相应的防治对策提供参考依据。方法　在六安市区 3个主要饮用水源各设 5个采水点 ,每点分上、中、下游间隔10 0m各采集 1份水样 ,每月 1次 ,连续 5年检测致泻大肠埃希菌的分布 ,并对分离菌株进行生化学、血清学鉴定和药物敏感试验。结果　检测水源水 10 80份 ,分离到致泻大肠埃希菌 14 9株 ,阳性率为 13 80 % ,河水、塘水的检出率分别为 13 6 1%和 14 17% ,无显著性差异 (χ2 =0 0 6 2 ,P >0 0 5 )。 14 9株致泻大肠埃希菌分属 2 3个血清型 ;2 0 0 0年 5月份在河水中检出 1株H2 S肠道致病性大肠埃希菌O12 8∶K67。结论　检测结果揭示了水源水中致泻大肠埃希菌的分布规律及菌型分布特点 ;发现了产H2 SPEECO12 8∶K67。     

Knowledge,awareness and practice of the importance of hand-washing amongst children attending state run primary schools in rural Malawi

A study was undertaken to determine the efficacy of hygiene practices in 2 primary schools in Malawi. The study determined: (1) presence of Escherichia coli on the hands of 126 primary school pupils, (2) knowledge, awareness and hygiene practices amongst pupils and teachers and (3) the school environment through observation. Pupil appreciation of hygiene issues was reasonable; however, the high percentage presence of E. coli on hands (71%) and the evidence of large-scale open defaecation in school grounds revealed that apparent knowledge was not put into practice. The standard of facilities for sanitation and hygiene did not significantly impact on the level of knowledge or percentage of school children’s hands harbouring faecal bacteria. Evidence from pupils and teachers indicated a poor understanding of principles of disease transmission. Latrines and hand-washing facilities constructed were not child friendly. This study identifies a multidisciplinary approach to improve sanitation and hygiene practices within schools.     

Social agents and news media as risk amplifiers: a case study on the public debate about the E. coli outbreak in Germany 2011

The social amplification of risk framework highlights the role which the news media play in risk communication by interacting with other agents in amplifying risk. However, the precise ways in which the media and other social agents actually amplify risks in public debates are unclear. In this article we draw on insights from the sociology of news to examine whether and to what extent social agents and news media amplify an emerging health risk. We use the debate about the Escherichia coli outbreak in Germany in 2011 to examine three issues: the amount of risk reporting by news media and social agents in their function as news sources; their evaluation of risk; and how they contribute to the escalation of risk, also known as ripple effects. In this article we draw on data from a content analysis of press releases from public health authorities and affected stakeholders and of news items in leading German news media. We found that the affected stakeholders were amplifying the risk to the greatest extent. We also found that there was a shift over time in the use of dominant frames. At the start of the debate the risk was framed as a public health issue and linked to medical-scientific progress. As the debate developed, more attention was given to political and economic consequences of the outbreak and the original health risk event was layered by other risk-related events.     

An outbreak of Escherichia coli 0157 and campylobacteriosisassociated with contamination of a drinking water supply

Stream water into which treated sewage discharged contaminated the public water supply of a Fife village with a population of about 1100. Of 765 residents and workers who reported illness 711 had gastrointestinal symptoms and 633 were defined as cases. Mains water analysis revealed high faecal coliform counts. An outbreak of Campylobacter and E coli 0157 infection was bacteriologically confirmed in eight and six people respectively. Two of the latter developed haemolytic uraemic syndrome. All affected individuals made full recoveries. Human normal immunoglobulin was offered to those aged between six months and 40 years of age and 618 individuals were immunised. Salivary tests four months after the incident confirmed that no Hepatitis A outbreak had occurred. In a follow-up questionnaire residents generally expressed happiness with the medical response to the incident although many reported that they still had worries. The two major medical issues which emerged from this outbreak were the importance of effective communications and the appropriateness of offering post-exposure human normal immunoglobulin.     

农村生活饮用水安全调查及安全策略

  目的  探索地理信息系统（GIS）技术应用于农村饮用水水质监测分析及疾病监测预警的可行性和适用性。  方法  监测100个有代表性的农村水厂水源水样微生物污染状况,利用健康管理大数据分析平台获取水质监测、法定肠道传染病和感染性腹泻病例信息,应用地理信息系统对数据进行整合与可视化处理,实现农村饮水安全的监测预警和地图展示。  结果  河水（水源水）菌落总数与大肠菌群、大肠埃希菌检出值呈显著正相关（r = 0.850、0.566,P < 0.01）,大肠菌群与大肠埃希菌检出值呈显著正相关（r = 0.501,P < 0.01）,大肠埃希菌与沙门菌检出值呈明显相关性（r = 0.632,P < 0.05）。应用GIS技术将农村水源、水厂、供水区域范围、覆盖人群、疾病、水质监测等数据整合与可视化处理,绘制出农村饮水安全风险监测与预警展示地图,地理信息系统对水质监测和病例聚集情况可直观展示和智能预警。  结论  河水可采用大肠埃希菌作为沙门菌的指示菌,基于GIS技术的农村饮用水微生物污染风险监测预警系统可作为疾病防控和卫生应急处置的重要技术支撑。     

广州市番禺区2007-2011年食品污染物监测结果分析

目的研究近年来番禺区食品污染物监测情况。方法 2007-2011年对区内粮食等人们经常食用的20类食品开展金属铅等71个指标监测,并对监测结果进行综合分析。结果番禺区农药以及大部分食品中的食品添加剂、生物污染得到有效控制,但金属污染普遍存在于各类食品中,动物性食物中的抗生素、蜜饯中的食品添加剂污染严重,水产品、熟肉制品的生物污染应引起重视。结论为食品安全监督管理和食品安全预警提供了依据,为进一步开展食品污染物研究提供了基础数据。     

2001年中国食源性致病菌及其耐药性主动监测研究

目的　旨在监测中国食源性致病菌及其耐药性。方法　中国疾病预防控制中心营养与食品安全所建立的全国食品污染物监测网的食源性致病菌监测部分 ,2 0 0 1年在全国 11个省市设点采样并检测了七大类 (生肉、熟肉、生奶、冰激淋、酸奶、水产品和蔬菜 )共 4 0 34份样品。结果　沙门氏菌、大肠杆菌O15 7∶H7和单核细胞增生李斯特氏菌 ,总阳性率 5 5 0 %。其中沙门氏菌 3 32 % ,单核细胞增生李斯特氏菌 1 2 9% ,大肠杆菌O15 7∶H70 82 %。生肉的污染情况最为严重 ,阳性率 12 96 %。共分离出沙门氏菌 137株 ,德比沙门氏菌、阿贡纳沙门氏菌、肠炎沙门氏菌、里定沙门氏菌、鸭沙门氏菌、明斯特沙门氏菌及鼠伤寒沙门氏菌 7种血清型占 80 %。结论　沙门氏菌的血清型分布和耐药性各个省不同。自生、熟肉中分离到O15 7∶H7的强毒株。对分离的沙门氏菌、大肠杆菌检测了 14种抗生素的耐药性 ,结果表明沙门氏菌和大肠杆菌中都有多重耐药株。     

宁波市某区农村生活饮用水现状调查及风险因素分析

目的通过监测宁波市某区农村生活饮用水水质情况并进行风险因素评估,为制定农村饮用水安全发展规划,推进社会主义新农村建设提供依据。方法 2013年-2017年对该地区13个乡镇水厂的水源水、出厂水和管网末梢水进行监测,检验结果按照GB 5749-2006《生活饮用水卫生标准》进行评价。结果共检测水样1 891份,水样总体合格率为78. 42%,其中水源水合格率为89. 23%,出厂水合格率为83. 67%,管网末梢水合格率为77. 50%,3种水样的合格率差异有统计学意义(χ^2=7. 645,P <0. 05),不合格项目主要为浑浊度和锰。比较3种水样在丰水期和枯水期的合格率,只有管网末梢水提示差异有统计学意义(χ^2=59. 114,P <0. 05)。分析历年管网末梢水的不合格率,发现水样的不合格率呈现逐渐降低的趋势。结论宁波市某区的农村生活饮用水水质总体较好,但部分监测指标不合格率较高,仍需保护水源,提高水处理工艺,以提高生活饮用水水质合格率。     

Use of viral pathogens and indicators to differentiate between human and non-human fecal contamination in a microbial source tracking comparison study

Assays for the detection and typing of adenoviruses, enteroviruses and F+ specific coliphages were performed on samples created as part of a national microbial source tracking methods comparison study. The samples were created blind to the researchers, and were inoculated with a variety of types of fecal contamination source (human, sewage, dog, seagull and cow) and mixtures of sources. Viral tracer and pathogen assays demonstrated a general ability to discriminate human from non-human fecal contamination. For example, samples inoculated with sewage were correctly identified as containing human fecal contamination because they contained human adenovirus or human enterovirus. In samples containing fecal material from individual humans, human pathogen analysis yielded negative results probably because the stool samples were taken from healthy individuals. False positive rates for the virus-based methods (0-8%) were among the lowest observed during the methods comparison study. It is suggested that virus-based source tracking methods are useful for identification of sewage contamination, and that these methods may also be useful as an indication of the public health risk associated with viral pathogens. Overall, virus-based source tracking methods are an important approach to include in the microbial source tracking 'toolbox'.     

产H2S致泻大肠埃希菌的发现与研究

[目的]对新发现的产H2S致泻大肠埃希菌进行一系列实验研究，确认该菌在临床实践中的重要意义和流行病学价值。[方法]不同时间、不同标本中分离的不同血清型的产H2S致泻大肠埃希菌，经形态学、培养特性、生化学、血清学等微生物学鉴定，初步判定后，报送国家权威实验室成都生物制品研究所鉴定并命名。[结果]在腹泻、食物中毒病人标本、水源水中分离的5株产H2S致泻大肠埃希菌，经全面鉴定后，其中4株为EPEC O128：K67，1株为ETEC O25：K19。[结论]产H2S致泻大肠埃希菌的发现使致泻大肠埃希菌家族增加了新的成员，为微生物学研究拓展了新的领域；该菌与大肠埃希菌有密切的亲缘关系，是变异的致泻大肠埃希菌；因其具有较强的致病性，故应引起有关部门的高度重视并采取相应的防治对策防止该菌造成新的腹泻病的传播和蔓延。     

连续消毒中大肠埃希菌O157:H7对洗必泰抵抗力的变化和与质粒pO157的关系

目的研究连续消毒中大肠埃希菌O157：H7对洗必泰抵抗力的变化及其与质粒pO157关系。方法用洗必泰连续消毒6株大肠埃希菌O157：H7 10代，消除连续消毒前后试验菌的质粒；对比消毒前后试验菌对该消毒剂的抵抗力、质粒图谱以及质粒酶切谱。结果连续消毒10代后，试验菌对洗必泰的抵抗力不变；试验菌的质粒图谱以及质粒pO157的ClaⅠ酶切图谱均无明显变化；消除连续消毒前后试验菌的质粒后，试验菌对洗必泰的抵抗力不变。结论连续消毒不会使试验菌对洗必泰的抵抗力增加，且试验菌对洗必泰的抵抗力与质粒pO157无直接关系。     

淮北市2009～2011年农村生活饮用水水质监测结果分析

目的了解淮北市农村生活饮用水水质卫生状况,为提高全市农村饮用水卫生质量提供科学依据。方法采集2009—2011年淮北市农村生活饮用水,按照国家标准进行采样、检测和评价。结果共检测水样763份,平均合格率48．4％。农村饮用水集中式供水与分散式供水合格率分别为53．0％和20．4％,差异有统计学意义（P〈0．01）。丰水期与枯水期合格率分别为47．9％和48．8％,不合格项目主要为氟化物、总硬度、浑浊度、肉眼可见物、总大肠菌群、硫酸盐。结论淮北市农村生活饮用水水质状况不佳,仍需加大农村饮水工程建设力度,同时加强农村饮水工程质量的管理和监测。     

连续消毒中大肠埃希菌O_(157)∶H_7对洗必泰抵抗力的变化和与质粒pO_(157)的关系

目的　研究连续消毒中大肠埃希菌O157∶H7对洗必泰抵抗力的变化及其与质粒 pO157关系。方法　用洗必泰连续消毒 6株大肠埃希菌O157∶H710代 ,消除连续消毒前后试验菌的质粒 ;对比消毒前后试验菌对该消毒剂的抵抗力、质粒图谱以及质粒酶切谱。结果　连续消毒 10代后 ,试验菌对洗必泰的抵抗力不变 ;试验菌的质粒图谱以及质粒pO157的ClaⅠ酶切图谱均无明显变化 ;消除连续消毒前后试验菌的质粒后 ,试验菌对洗必泰的抵抗力不变。结论　连续消毒不会使试验菌对洗必泰的抵抗力增加 ,且试验菌对洗必泰的抵抗力与质粒 pO157无直接关系。     

Too much of a good thing: Adaption to iron (II) intoxication in Escherichia coli

BackgroundThere has been an increased usage of metallic antimicrobial materials to control pathogenic and multi-drug resistant bacteria. Yet, there is a corresponding need to know if this usage leads to genetic adaptations that could produce more harmful strains.MethodologyExperimental evolution was used to adapt Escherichia coli K-12 MG1655 to excess iron (II) with subsequent genomic analysis. Phenotypic assays and gene expression studies were conducted to demonstrate pleiotropic effects associated with this adaptation and to elucidate potential cellular responses.ResultsAfter 200 days of adaptation, populations cultured in excess iron (II), showed a significant increase in 24-h optical densities compared to controls. Furthermore, these populations showed increased resistance toward other metals [iron (III) and gallium (III)] and to traditional antibiotics (bacitracin, rifampin, chloramphenicol and sulfanilamide). Genomic analysis identified selective sweeps in three genes; fecA, ptsP and ilvG unique to the iron (II) resistant populations, and gene expression studies demonstrated that their cellular response may be to downregulate genes involved in iron transport (cirA and fecA) while increasing the oxidative stress response (oxyR, soxS and soxR) prior to FeSO₄ exposure.Conclusions and implicationsTogether, this indicates that the selected populations can quickly adapt to stressful levels of iron (II). This study is unique in that it demonstrates that E. coli can adapt to environments that contain excess levels of an essential micronutrient while also demonstrating the genomic foundations of the response and the pleiotropic consequences. The fact that adaptation to excess iron also causes increases in general antibiotic resistance is a serious concern. Lay summary: The evolution of iron resistance in E. coli leads to multi-drug and general metal resistance through the acquisition of mutations in three genes (fecA, ptsP and ilvG) while also initiating cellular defenses as part of their normal growth process.     

Atypical enteropathogenic Escherichia coli infection and prolonged diarrhea in children

Some clinical isolates of enteropathogenic Escherichia coli (EPEC) lack bundle-forming pili and are termed atypical EPEC. The aim of this study was to determine if atypical EPEC are pathogens by comparing the clinical features of patients infected with atypical EPEC with those of children infected with other causative agents of diarrhea. Fecal samples obtained from children attending the Royal Children's Hospital in Melbourne for investigation of diarrhea were examined for adenovirus, rotavirus, Campylobacter spp., Salmonella spp., protozoa, and pathogenic E. coli. Clinical data were obtained by using a standardized pro forma and analyzed separately. Patients infected with atypical EPEC experienced mild, nondehydrating, and noninflammatory diarrhea that was not particularly associated with fever, vomiting, or abdominal pain. However, the duration of diarrhea in patients infected with atypical EPEC was significantly longer than that caused by the other species or where no pathogens were identified. Infection with atypical EPEC is associated with prolonged diarrhea.