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Water and environmental health
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2023
Indicator bacteria have been used for many years to assess the microbiological quality of water. These are not typically disease-causing organisms but are found universally in faeces, and ideally nowhere else, and so their presence in water indicates faecal contamination and, therefore, the risk of gastrointestinal disease-causing organisms also being present. The larger the number of faecal indicator bacteria, the higher the risk. The most widely used indicator bacteria are of the total coliform, thermotolerant coliform (formerly faecal coliform), intestinal enterococci groups and E. coli. Bacteriological tests are used to assess the sanitary quality of water and the potential public health risk from waterborne diseases. The Fourth Edition of the WHO Guidelines for Drinking-Water Quality [10] provides a summary of the characteristics of each indicator and an assessment of their value for assessing the risk of the presence of enteric pathogens and overall health risk.
Monitoring Inequalities in Wash Service Levels
Published in Oliver Cumming, Tom Slaymaker, Equality in Water and Sanitation Services, 2018
Faecal contamination is usually identified through the detection of indicator bacteria such as E. coli or thermotolerant coliforms in a 100 mL sample of water although the frequency of testing and the methods used vary across country. The results may vary, depending on the location of tests within the distribution system,51 but for the purpose of global monitoring the JMP uses data on the quality of water at the point of delivery/collection, which may be a household tap, community stand-post, borehole or well. Contamination can be highly variable, so brief events may escape detection even with regular testing. Effective water treatment should deactivate indicator bacteria along with other microbes, but certain pathogens such as Cryptosporidium parvum may be more resistant to some disinfection processes such as chlorination.52 Furthermore, indicator bacteria may attenuate more rapidly in the environment than some pathogens. So, while the presence of E. coli is considered a reliable indicator that drinking water is faecally contaminated and unsafe, the absence of E. coli does not guarantee safety. In 2015, water-quality data were available for less than half the global population. It was estimated that three out of four people used improved sources free from contamination, but low levels of compliance were reported in many low- and middle-income countries with data.47
Water and environmental health
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2016
Indicator bacteria have been used for many years to assess the microbiological quality of water. These are not typically disease-causing organisms but are found universally in faeces, and ideally nowhere else, and so their presence in water indicates faecal contamination and, therefore, the risk of gastrointestinal disease-causing organisms also being present. The larger the number of faecal indicator bacteria, the higher the risk. The most widely used indicator bacteria are of the total coliform, thermotolerant coliform (formerly faecal coliform), intestinal enterococci groups, and E. coli. Bacteriological tests are used to assess the sanitary quality of water and the potential public health risk from water-borne diseases. The fourth edition of the WHO Guidelines for Drinking-water Quality [10] provide a summary of the characteristics of each indicator and an assessment of their value for assessing the risk of the presence of enteric pathogens and overall health risk.
Modelling the effect of chlorination/chloramination on induction of viable but non-culturable (VBNC) Escherichia coli
Published in Environmental Technology, 2020
Sheng Chen, Jie Zeng, Yahong Wang, Chengsong Ye, Shuai Zhu, Lin Feng, Shenghua Zhang, Xin Yu
In order to ensure the biological safety of drinking water, indicator bacteria, such as Escherichia coli, are typically monitored using culture-based methods to confirm that water meets quality standards [1]. Bacteria that can grow on routine bacteriological media and develop into colonies under suitable incubation conditions could be enumerated by using these methods. The rationale behind is reported that measuring bacterial populations using these methods may lead to the underestimation of cell numbers [2–5]. Because bacterial can entered into viable but not culturable (VBNC) state under harsh environmental stresses such as pH change, heavy metals, oxygen stress, and antibiotics [6–9]. Bacteria in a VBNC state are able to retain certain features of viable cells and can also be resuscitated under suitable conditions [10,11]. Many bacteria have been verified to enter into the this state, including Lactobacillus plantarum [12], V. vulnificus [13], Escherichia coli [14], Legionella pneumophila [15], Shigella spp. [16], Salmonella spp. [17,18] and so on. The occurrence of VBNC bacteria in drinking water would lead to underestimation of numbers of pathogenic bacteria and pose a public health risk.
Multivariate drug resistance and microbial risk assessment in tropical coastal communities
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Murugaiah Santhosh Gokul, Hans-Uwe Dahms, Krishnan Muthukumar, Santhaseelan Henciya, Thanamegam Kaviarasan, Rathinam Arthur James
High levels of sewage indicator bacteria (coliforms) in aquatic ecosystem are a common problem in all areas that often lead to an impairment of beneficial uses and human health. A motivation for this study were numerous reports about the occurrence of pathogenic microorganisms in drinking water and associated diseases (Mulamattathil et al. 2014). In water samples, the mean total viable count (TVC) ranged from 3600 to 7800 mL−1 during the summer season (March, April, May), and from 1800 to 3800 mL−1 during the postmonsoon season (December, January, February). Variations in TVC were large, both season and location-wise (Table 2). Similar to TVC, the total coliforms (TC), fecal coliforms (FC), total streptococci (TS), and fecal streptococci (FS) ranges were higher in summer than during postmonsoon. High counts were noticed in groundwater (P1 > R1 > P2 > P3 > R2) of densely populated slum areas. Therefore, these contribute to high levels of pollution in those locations (Figure 3). Environmental persistence or growth of bacterial indicators during the summer months could confound the interpretation of baseline dynamics. The highest TVC values may be attributed to the presence of large populations residing along the coastline. These activities mainly deteriorate microbial water quality as fecal matter is increasing (Chahinian et al.2012).
Copper nanoparticles toxicity: Laboratory strains verses environmental bacterial isolates
Published in Journal of Environmental Science and Health, Part A, 2018
Absar Alum, Ali Alboloushi, Morteza Abbaszadegan
Escherichia coli are the indicator bacteria most widely used for determination of the microbial quality of water and foods. Their occurrence correlates with fecal contamination and typically highlights the potential for the presence of enteric pathogens. In addition, they have been used as surrogate to predict the survival, fate and transport of pathogens in environments, however, their reliability and relevance as indicator or surrogate has been always questioned. In recent years, E. coli O157:H7 has emerged as one of the major microbial threats in the food supply chain in the United States and across the globe.[1]