用水体中大肠菌群的含量检测水质污染程度

微生物污染是水质污染的主要原因之一,常用某些与病原微生物有密切关系的微生物的含量来反映水体中病原微生物存在的可能性。水体中病原微生物污染主要来自人畜粪便。因而常选用存在于人体和哺乳动物肠道中的微生物如大肠菌群作为水质污染指示菌。利用指示菌反映水质污染状况具有快速、灵敏的优点。测定大肠菌群含量常用多管发酵法和滤膜法。     

水中粪大肠菌群测定方法-纸片快速法与多管发酵法的比较

2015年10月国家环境保护部发布了行业标准《水质总大肠菌群和粪大肠菌群的测定纸片快速法》(HJ755-2015)(以下简称纸片快速法)。之前环境监测部门一直在使用国家环境保护部于2007年3月发布的行业标准《水质粪大肠菌群的测定多管发酵法和滤膜法(试行)》(HJ/T347-2007)(以下简称多管发酵法)。纸片快速法操作简单快速,在标准中对采样瓶的处理、样品的保存、水样的稀释接种等做出了详细的规定,而多管发酵法中没有相应规定。本文对两个标准的异同点进行比较,提出了将这两种方法的优点应用于实际环境监测工作中。     

时空监测海水浴场粪大肠菌群和人类腺病毒方法的探讨（英文稿）

[目的]人类腺病毒(40/41)与人类急性胃肠炎显著相关,被用作娱乐水体中人类病毒污染的指示生物.粪大肠菌群(FC)作为传统的细菌指示生物,用来估计水环境中病原微生物的潜在风险.了解水传播的病原微生物的时空分布对公众健康和疾病的预防具有十分重要的意义.[方法]于2008年5月到10月,在中国10个典型海水浴场共采集30个表层海水样品,分别用定量PCR和细胞培养的方法分析人类腺病毒和FC.[结果]腺病毒的含量为1.7×106-1.1×108基因拷贝/L,其阳性检出率为30％,而普通PCR的阳性检出率为26.7％.其中7个海水浴场的FC超出了景观娱乐水质标准(2 000 CFU/L).时间分布趋势表明,人类腺病毒从8月份到10月份的污染较其他月份严重(P＜0.05).在该实验条件下,不论是在同一浴场的不同站位还是在不同浴场,腺病毒的空间分布差异都不明显(P＞0.05).同样,FC在不同浴场的时空分布也无明显差异(P＞0.05),但是其分布与离岸距离的远近显著相关(P＜0.05).此外,在我们所研究的浴场,细菌和病毒这两种指示生物之间并没有相关性.[结论]为避免在游泳季节胃肠道疾病的大规模爆发,必须加强卫生设施建设和肠道细菌、病毒两种指示生物的监测.     

应用不同方法检测食品中大肠菌群结果的比较

评价检测食品中大肠菌群不同方法。比较国家标准、行业标准和显色培养基检测方法检测大肠菌群结果的差别。国家标准和行业标准检测结果基本一致,但有差异,应用显色培养基检测大肠菌群优于目前使用的国家标准和出口食品检验行业标准方法。检测食品中大肠菌群,显色培养基检测方法快速、灵敏、特异。     

滤膜法测定水中大肠菌群简便方法的研究

本研究方法为ＩＳＯ９３０８－１规定的滤膜法测定水中大肠菌群的方法,该方法操作简便只需分离和证实两步实验即可得出结果;分离培养基上的阴阳性菌落颜色分明,易于分辩;所用培养基不含致癌物质。本研究方法的准确度高,回收率的均值为９４７％,批内变异系数小于１０％,检出限为５００ｍｌ水样可检出１个ＣＦＵ,检出率是传统方法的３１倍。本研究还探讨了分离培养基的ｐＨ值对菌落颜色的影响。本研究内容经查新在国内尚无报道。     

PCR技术检测水体中大肠菌群的研究

大肠菌群被广泛用作饮用水的卫生学检测指标。传统的检测方法耗时长、专一性差、干扰因素多。因此 ,迫切需要开发快速、灵敏的新方法。近年来 ,应用PCR技术检测水体中大肠菌群的研究报道不断增多。利用PCR技术扩增编码lacZ基因 ( β 半乳糖苷酶基因 )和uidA基因 ( β D 半乳糖苷酶基因 )的DNA片段 ,可以分别检测总大肠菌群和E .coli。但目前利用PCR进行定量分析还缺乏精度 ,需要进行更深入的研究。     

噬菌体-指示菌模型检测固型板材抗病毒性能的方法研究

在抗病毒材料检测方法中.大多利用具有高致病性的病毒直接进行实验室操作,这会给研究人员带来一定的不安全性.为了建立一种安全、快速、灵敏的检测固型板材抗病毒性能的方法,利用噬菌体-指示菌模型.分别对风干法、玻片覆盖法和薄膜覆盖法检测固型板材抗病毒性能进行研究.利用大肠埃希菌噬菌体M13和大肠埃希菌作为噬菌体-指示菌模型,以固型板材抗菌不锈钢板作为试验材料.抗菌不锈钢板与噬菌体作用18 h后.测定噬菌体存活数量.实验结果表明,风干法、玻片覆盖法和薄膜覆盖法检测的噬菌体杀死率分别为66.0%、30.4%和19.3%.风干法的检测效果明显优于其他2种方法.利用噬菌体-指示菌模型,采用风干法检测固型板材抗病毒性能具有可行性和实用性.     

基于区域协同医疗的检测技术需求分析与解决方案

在分析县级医院及基层医疗机构医疗服务能力基础上,为提出提升基层医疗机构检测水平的方法,探讨通过区域医疗信息化手段建立面向三级医疗机构的区域协同医疗共享平台及系列信息化系统,提升基层医疗机构检测水平,推动多级医疗协同服务模式的实现,提升区域协同医疗业务能力。     

猪圆环病毒2型的PCR检测方法应用

本研究登录Genbank对猪圆环病毒2型基因的序列进行分析,用Primer 5.0设计了ORF2基因的扩增引物,试图选择一种比较合理的PCR方法检查PCV2感染的病原,以期这种PCR方法可以有效分析猪综合征障碍病毒(PRRSV)、猪细小病毒(PPV)、猪瘟病毒的扩增(HCV)、猪伪狂犬病毒(PRV)等比较常见的病原。研究结果表明,在PCV2进行扩增阳性样品检测中,发现一条异常447 bp的DNA条带,对产物测序结果进行扩增分析,证明其是PCV ORF2基因序列。敏感性检验分析表明检测样本DNA浓度时达到了9.8×10^-4ng/μL。PCR实验具有良好的稳定性和重复性。根据对66例临床病猪的分析表明,在PCV2的检测中阳性感染率是27.26%,这可能受到HCV、PRRSV、PRV、PPV等多种病毒的感染,其中混合感染的比例达到了72.23%。     

Resistance to antibiotics in injured coliforms isolated from drinking water

We studied the antibiotic sensitivity of injured coliforms isolated from drinking water of La Plata, Argentina. The antibiotic sensitivity test by the agar diffusion method were proved in: Klebsiella oxytoca (14 strains), Enterobacter aerogenes (4 strains) and Enterobacter cloacae genomic group 3 (14 strains). We found that while these impaired total coliforms were sensitive to piperacillin-tazobactam (TAZ), netilmicin (NTL), ofloxacin (OFLX), and norfloxacin (NFLX) (100%), they had resistant to aminopenicillin-sulbactam (AMS) and nitrofurantoin (NIT) (100%). The resistance to antibiotics demonstrated in these strains would point to the need to promote a rational and judicious use of antimicrobial agents while at the same time implementing a program of active vigilance aimed at ensuring the highest quality of drinking water throughout the system.     

Enumeration of heterotrophs, fecal coliforms and Escherichia coli in water: comparison of 3M Petrifilm plates with standard plating procedures

A total of 177 naturally contaminated water samples were analyzed by membrane filtration according to the Standard Methods for the Examination of Water and Wastewater published by the American Public Health Association. Filters were incubated in parallel on mHPC-agar and 3M™ Petrifilm™ Aerobic Count Plates (Petrifilm™ AC plates) for heterotrophic counts. Fecal coliforms and Escherichia coli were enumerated on mFC-agar and 3M™ Petrifilm™ E. coli/Coliform Count Plates (Petrifilm™ EC plates). Typical colonies on each media type were confirmed following standard procedures. Heterotrophic counts were between 10³ and 10⁴ CFU/mL and the average log₁₀ counts obtained on Petrifilm™ AC plates were about two-fold lower than on mHPC-agar. Counts for fecal coliforms and E. coli were between 10² and 10³ CFU/mL. Average log₁₀ counts for confirmed fecal coliforms obtained on Petrifilm™ EC plates were slightly lower than on mFC agar with a correlation coefficient of 0.949. The average log₁₀ counts for confirmed E. coli on Petrifilm™ EC plates and on mFC agar were statistically not different (P=0.126) with a correlation coefficient of 0.879. Specificity of Petrifilm™ EC plates and mFC agar was evaluated by comparing typical colony counts with confirmed counts. On mFC agar, counts for typical colonies were by 2 log₁₀ CFU higher than the actual confirmed counts. In contrast, on Petrifilm™ EC plates typical colony counts were almost identical to confirmed colony counts for both fecal coliforms and E. coli. This comparison illustrates the high specificity of Petrifilm™ EC plates for enumeration of both fecal coliforms and E. coli in water.     

Significance and suitability of <Emphasis Type="Italic">Aeromonas hydrophila</Emphasis> vs. fecal coliforms in assessing microbiological water quality

We examined the significance and suitability of Aeromonas hydrophila versus fecal coliforms in assessing microbiological water quality. For this, we used the membrane filtration method to simultaneously estimate the abundance level of A. hydrophila and fecal coliforms in waters from the Mfoundi river watershed at Yaoundé, and compared how fluctuations in A. hydrophila abundance matched those observed with fecal coliforms index as an indicator of water quality in the system under study. Our results revealed that waters were not safe according to the standards for water quality established by the Word Health Organization (WHO). They also indicated the prevalence of A. hydrophila as compared to fecal coliforms, and suggested that water from the Mfoundi River and its tributaries could be classified as hypereutrophic based on the density of Aeromonas. Moreover, the spatial distribution of fecal coliforms and A. hydrophila exhibited similar trends within the different water bodies investigated, suggesting that A. hydrophila can be used as indicator of water quality in highly polluted waters. We concluded that waters from the Mfoundi River watershed at Yaoundé represent a great potential risk of infection for users, and foresee that the next challenge will be to determine, among other factors, the physico-chemical factors influencing the observed spatial distribution.     

Multiple antibiotic resistance indexing of coliforms to identify high risk contamination sites in aquatic environment

Bacteriological analysis of the water samples collected from upstream, midstream and downstream points along the bank of the river revealed high populations of Escherichia coli, Citrobacter freundii, Citrobacter diversus, Enterobacter aerogens and Klebsiella species. All these isolates were screened against eight antibiotics to determine the prevalence of multiple antibiotic resistance among isolates at different sites of the river. The study revealed that multiple antibiotic resistance was prominently seen in coliforms at downstream sites (Average multiple antibiotic resistance index, MAR Index = 0.43) while it was low in coliforms at upstream sites (MAR Index = 0.15). These differences in MAR indices provide a method for distinguishing high risk contamination sites in aquatic environment.     

Injured coliforms in drinking water

Coliforms were enumerated by using m-Endo agar LES and m-T7 agar in 102 routine samples of drinking water from three New England community water systems to investigate the occurrence and significance of injured coliforms. Samples included water collected immediately after conventional treatment, during the backwash cycle, at various points in the distribution system, and 1 week after the break and subsequent repair of a distribution main. Injured coliforms in these samples averaged greater than 95%. m-T7 agar yielded 8- to 38-fold more coliforms than did m-Endo agar LES. The geometric mean of coliforms recovered by m-Endo agar LES was less than 1 confirmed coliform per 100 ml, although m-T7 agar yielded 5.7 to 67.5 confirmed coliforms per 100 ml. In addition, the majority of these samples giving positive results on m-T7 agar produced no detectable counts on m-Endo agar LES. These findings indicated that coliforms were injured and largely undetected by use of accepted analytical media in the systems examined.     

Injured coliforms in drinking water.

Coliforms were enumerated by using m-Endo agar LES and m-T7 agar in 102 routine samples of drinking water from three New England community water systems to investigate the occurrence and significance of injured coliforms. Samples included water collected immediately after conventional treatment, during the backwash cycle, at various points in the distribution system, and 1 week after the break and subsequent repair of a distribution main. Injured coliforms in these samples averaged greater than 95%. m-T7 agar yielded 8- to 38-fold more coliforms than did m-Endo agar LES. The geometric mean of coliforms recovered by m-Endo agar LES was less than 1 confirmed coliform per 100 ml, although m-T7 agar yielded 5.7 to 67.5 confirmed coliforms per 100 ml. In addition, the majority of these samples giving positive results on m-T7 agar produced no detectable counts on m-Endo agar LES. These findings indicated that coliforms were injured and largely undetected by use of accepted analytical media in the systems examined.     

Detection and persistence of fecal Bacteroidales as water quality indicators in unchlorinated drinking water

The results of this study support the use of fecal Bacteroidales qPCR as a rapid method to complement traditional, culture-dependent, water quality indicators in systems where drinking water is supplied without chlorination or other forms of disinfection. A SYBR-green based, quantitative PCR assay was developed to determine the concentration of fecal Bacteroidales 16S rRNA gene copies. The persistence of a Bacteroides vulgatus pure culture and fecal Bacteroidales from a wastewater inoculum was determined in unchlorinated drinking water at 10 °C. B. vulgatus 16S rRNA gene copies persisted throughout the experimental period (200 days) in sterile drinking water but decayed faster in natural drinking water, indicating that the natural microbiota accelerated decay. In a simulated fecal contamination of unchlorinated drinking water, the decay of fecal Bacteroidales 16S rRNA gene copies was considerably faster than the pure culture but similar to that of Escherichia coli from the same wastewater inoculum.     

Modification of delayed-incubation procedure for detection of fecal coliforms in water

Three holding media, including the vitamin-free Casitone holding medium (m-VFC) recommended by Standard Methods for the Examination of Water and Wastewater for use with the delayed-incubation membrane filter procedure, were compared for their ability to maintain viability of fecal coliforms. Each medium was tested according to the procedure described in the above reference with 60 to 80 pure cultures of fecal coliforms and a variety of natural water samples containing fecal coliforms. Fecal coliform recovery with m-ST holding medium (containing ethanol, sulfanilamide, and Tris [pH 8.6] was significantly greater than recovery with m-VFC (containing vitamin-free casein hydrolysate, sodium benzoate, sulfanilamide, and ethanol). Recovery with m-VFC, was, in turn, significantly greater than with NSB medium (containing nutrient broth, boric acid, and NaCl as major ingredients). Fecal coliform counts obtained with m-ST by the delayed-incubation membrane filter procedure were higher than counts obtained by the standard immediate incubation. This result suggested that some of the sublethally injured fecal coliforms in natural water samples may have recovered during the incubation period. We propose that m-ST be used in place of m-VFC for the delayed-incubation membrane filter procedure.