Presence Of Pathogens In Water Research Articles

Microbial assessment of water, sanitation, and hygiene (WaSH) in temporary and permanent settlements two years after Nepal 2015 earthquake

Disaster-induced displacement often causes people to live in temporary settlements that have limited infrastructure and access to water, sanitation, and hygiene (WaSH). Reducing the risk of diarrheal diseases in such situations requires knowing how housing influences the presence of pathogens in water and the interaction between human settlements and exposure to pathogens. A cross-sectional study was conducted in May 2017 in two communities hard-hit by the Nepal 2015 earthquake: one recovered with newly reconstructed houses, and one recovered with residents still living in sheet metal temporary shelters constructed after the earthquake. We collected 60 water (30 drinking water and 30 cleaning water), 30 hand rinse, and 90 environmental swab samples (30 toilet handles, 30 utensils, and 30 water vessels) from selected households in each location and quantified 22 bacterial pathogens using microfluidic quantitative polymerase chain reaction (mfqPCR). A total of 59 samples were randomly selected for amplicon-based sequencing of the 16S rRNA, and it identified bacterial community profiles between these two settlements and their association with target genes of pathogenic bacteria. Target genes like uidA of Escherichia coli and the mip gene of Legionella pnuemophila showed significantly high frequency in specific sample types in temporary settlements than in permanent settlements. A significantly high concentration was observed in temporary settlements for Enterococcus spp. and S. typhimurium, specifically in swab samples. There was a sharp distinction of microbial community profiles between water and hand rinse samples with environmental swab samples, with a large abundance of potentially pathogenic bacteria in swab samples in both settlements. This observation highlighted that fomite could be an important transmission route for pathogens in rural settings and designing key interventions to target different stages of transmission pathways is essential. Overall findings from this study suggest that the recovered settlement with higher quality housing may be less impacted by fecal contamination than recovering settlements and that interventions should be designed to disrupt multiple transmission pathways to reduce pathogen exposure.

Biosensor Chip for Monitoring of Water Pollution as Novel Test Tool in Public Health: Proof of Principle

Humans are generally exposed to a variety of pollutions present in the air they breathe, the food they eat or in the water they drink. Some of the most dangerous pollutions are metals and heavy metals. These are naturally occurring substances which are harmless when present in the environment at low levels. However, due to many pollutants such as industry processes or war activities, the heavy metal concentration can exceed the limit of tolerance and become very toxic for the natural environment and living organisms in it, including humans. Unlike organic pollutants, the heavy metals (as ions and as particulate matter) once introduced into the environment cannot be biodegraded and remain there indefinitely. By rainfall these pollutants can be partially transferred from air or soil into the rivers and drinking water sources, where they accumulate in even higher toxic levels. The high concentrations of heavy metals in contaminated natural water reservoirs have an impact on the microbial community composition which resides there. This type of water pollution can cause the changes in life cycles of natural bacterial populations, influencing their metabolic processes and proliferation. The presence of pathogens in water is normally indirectly determined by the testing for “indicator organism” such as coliform bacteria. Coliforms are usually present in larger numbers in contaminated water and at the same time they are indicators of whether other pathogenic bacteria are present, too. In crisis situations, like war or some natural disasters, where trusted sources of drinking water are not available anymore, the military and residents of affected areas are forced to use some alternative water resources that cannot be tested for their microbial or metal contamination properly. Therefore, the existence of some fast test that would detect not only dangerous bacterial pathogens in water, but also the presence of metals and heavy metals as well, would be of great help and importance for the human health. Even though the number of pathogens can be drastically reduced by the boiling of water, the heavy metals are not destroyed by high temperature. Hence the main objective of our work was to optimize the biosensor chip for microbial detection in contaminated water that would serve at the same time as an indicator for the chemical composition of the water, such as presence of metals and heavy metals, with potential to be used as a novel test tool in public health.

Graphene-Based Nanosensor Device for Rapid, Onsite Detection of E.coli in Water

E. coli bacteria are widely accepted as the indicator bacteria to predict the presence of pathogens in water intended for human consumption. One of the strains of E. coli is the specific subspecies serotype E. coli O157:H7, which is the most prevalent bacterial contaminant and responsible for most E. coli outbreaks in the US. E. coli O157:H7 can cause bloody diarrhea, kidney failure and may even lead to death. E. coli infection in the U.S. afflicts ~70,000 people per year mostly from food, and ~ 15% of the cases are from tainted water according to the CDC. In May 2014, E. coli-contaminated water supply in Portland, OR, which covers several suburban cities, affected ~670,000 people. Several approaches have been developed to detect E. coli O157:H7, including the culture and colony counting method, polymerase chain reaction (PCR), and immunological methods; however, all these methods require long detection time and are unsuitable for in situ detection. We propose a novel method for real-time, in situ detection of E. coli in water by using a graphene-based sensor. Graphene has excellent electrical conductivity and is very sensitive to surface changes enabling it to detect E. coli bacteria down to a few colony forming units (cfu). The proposed sensor is based on a novel, micro-sized amperometric sensor that outperforms existing E. coli sensing methods and is simple to implement, eliminating many of the disadvantages associated with current practices. Additionally, we plan to integrate this sensor in a handheld electronic device with features such as high sensitivity and selectivity, rapid response, ease of use and affordability.

Integrated site-specific quantification of faecal bacteria and detection of DNA markers in faecal contamination source tracking as a microbial risk tracking tool in urban Lake ecosystems

The presence of feacal-derived pathogens in water is responsible for several infectious diseases and deaths worldwide. As a solution, sources of fecal pollution in waters must be accurately assessed, properly determined and strictly controlled. However, the exercise has remained challenging due to the existing overlapping characteristics by different members of faecal coliform bacteria and the inadequacy of information pertaining to the contribution of seasonality and weather condition on tracking the possible sources of pollution. There are continued efforts to improve the Faecal Contamination Source Tracking (FCST) techniques such as Microbial Source Tracking (MST). This study aimed to make contribution to MST by evaluating the efficacy of combining site specific quantification of faecal contamination indicator bacteria and detection of DNA markers while accounting for seasonality and weather conditions’ effects in tracking the major sources of faecal contamination in a freshwater system (Donghu Lake, China). The results showed that the use of cyd gene in addition to lacZ and uidA genes differentiates E. coli from other closely related faecal bacteria. The use of selective media increases the pollution source tracking accuracy. BSA addition boosts PCR detection and increases FCST efficiency. Seasonality and weather variability also influence the detection limit for DNA markers.

DETECTION OF POTENTIALLY PATHOGENIC BACTERIA IN THE BRACKISH RIVERS FLOWING INTO THE ELTON LAKE BY HIGH-THROUGHPUT SEQUENCING

Aim. To indicate potentially pathogenic bacteria in plankton of the brackish rivers flowing into the Elton Lake by high-throughput sequencing of 16S ssuRNA gene. Materials and methods. The water samples from brackish rivers Lantsug and Chernavka, flowing into the Elton Lake, were taken up in a volume of 50 ml, filtered through membrane filters (pore diameter - 0.22 pm). Total DNAwas obtained by phenol-chloroform extraction with preliminary homogenization and enzymatic lysis. DNA libraries for sequencing were created by protocol Illumina with primers to a variable V3-V4 region of 16S ssuRNA gene. Sequencing was performed on a platform MiSeq («Illumina», США). Results.There were found the phylotypes of potentially pathogenic bacteria of Proteobacteria phylum from the families Enterobacteriaceae, Pseudomonadaceae, Campylobacteraceae, Vibrionaceae, Aeromonadaceae, Moraxellaceae, Legionellaceae, Alcaligenaceae, Campylobacteraceae, and also of Firmicutes, Bacteroidetes, Actinobacteria phyla in the plankton samples of the brackish rivers. Probable source of bacterial contamination is large and small cattle. Conclusion. These data demonstrate that the continental brackish waters, along with freshwater and marine habitats perform a reservoir function to potentially pathogenic microorganisms. High-throughput sequencing can be used to screen the presence of pathogens in water.

Feasibility of methods based on nucleic acid amplification techniques to fulfil the requirements for microbiological analysis of water quality

Molecular methods based on nucleic acid recognition and amplification are valuable tools to complement and support water management decisions. At present, these decisions are mostly supported by the principle of end-point monitoring for indicators and a small number of selected measured by traditional methods. Nucleic acid methods show enormous potential for identifying isolates from conventional culture methods, providing data on cultivable and noncultivable micro-organisms, informing on the presence of pathogens in waters, determining the causes of waterborne outbreaks, and, in some cases, detecting emerging pathogens. However, some features of water microbiology affect the performance of nucleic acid-based molecular techniques and thus challenge their suitability for routine water quality control. These features include the variable composition of target water samples, the generally low numbers of target micro-organisms, the variable water quality required for different uses and the physiological status or condition of such micro-organisms. The standardization of these molecular techniques is also an important challenge for its routine use in terms of accuracy (trueness and precision) and robustness (reproducibility and reliability during normal usage). Most of national and international water regulations recommend the application of standard methods, and any new technique must be validated respect to established methods and procedures. Moreover, molecular methods show a high cost-effectiveness value that limits its practicability on some microbial water analyses. However, new molecular techniques could contribute with new information or at least to supplement the limitation of traditional culture-based methods. Undoubtedly, challenges for these nucleic acid-based methods need to be identified and solved to improve their feasibility for routine microbial water monitoring.

Physico-chemical and bacteriological analyses of water used for drinking and swimming purposes in abeokuta, nigeria.

Physicochemical and bacteriological analyses were carried out on well water, stream water and river water used for drinking and swimming purposes in Abeokuta, Nigeria. The results obtained were compared with WHO and EPA standards for drinking and recreational water. With the exception of Sokori stream and a well water that did not comply with Turbidity and Mg2+ standards respectively, all others were within the standards set for PH, Color, Total solids, Total dissolved solids, acidity, total hardness, Ca2+ hardness, chloride and Iron. None of the samples complied with bacteriological standards as Total coliform counts generally exceeded 1,600 MPN/ml, and pathogen count such as Salmonella-Shigella counts and Vibrio cholerae counts were very high. The presence of pathogens in water for drinking and swimming purposes is of public health significance considering the possibility of the presence of other bacteria, protozoa and enteric viruses that are implicated in gastro-intestinal water borne diseases and the low infectious dose for these water borne pathogens. (Afr. J. Biomed. Res. 11: 285- 290) Key words: drinking water, swimming, bacteria, analysis, Abeokuta

Mutagens and carcinogens in drinking water

Water is the basic constituent of all living beings; it is, therefore, an essential dietary element and a primary resource. The D. Lgs. 31/2001 is the Italian standard reference concerning drinking-water issues. The purpose of this article is, firstly, to highlight that chlorination, as a water purifying treatment, does not guarantee an absolute absence of risk. On the contrary, it causes the formation of various by-products, many of which are known to be carcinogenic and mutagenic. Secondly, some drinking-water pollutants have mutagenic and carcinogenic properties, giving an appreciable risk for the user. As a result, water reserves, because of their importance to public health, should be properly safeguarded and protected to prevent possible contamination. Although disinfection brings about mutagenic and carcinogenic molecules, we cannot do without it if we want to prevent the much more severe risks due to the presence of pathogens in water used for human consumption.

Molecular Biology and DNA Microarray Technology for Microbial Quality Monitoring of Water

Public concern over polluted water is a major environmental issue worldwide. Microbial contamination of water arguably represents the most significant risk to human health on a global scale. An important challenge in modern water microbial quality monitoring is the rapid, specific, and sensitive detection of microbial indicators and waterborne pathogens. Presently, microbial tests are based essentially on time-consuming culture methods. Rapid microbiological analyses and detection of rare events in water systems are important challenges in water safety assessment since culture methods present serious limitations from both quantitative and qualitative points of view. To circumvent lengthy culture methods, newer enzymatic, immunological, and genetic methods are being developed as an alternative. DNA microarray technology is a new and promising tool that allows the detection of several hundred or even thousands DNA sequences simultaneously. Recent advances in sample processing and DNA microarray technologies provide new perspectives to assess microbial water quality.The aims of this review are to (1) summarize what is currently known about microbial indicators, (2) describe the most important waterborne pathogens, (3) present molecular methods used to monitor the presence of pathogens in water, and (4) show the potential of DNA microarrays in water quality monitoring.

Microbiological Pollution of Ria Formosa (South of Portugal)

A 24-month survey on the microbiological quality of recreational shore marine waters in three sampling stations located at Ria Formosa (South of Portugal) was conducted. The classical indicators of faecal pollution, such as total coliforms (TC), faecal (thermotolerant) coliforms (FC), faecal streptococci (FS) and somatic coliphages, as well as several physico-chemical parameters (temperature, salinity, dissolved oxygen (DO) and transparency) were determined in the sampling stations, which exhibited different degrees of faecal pollution. The relationships between faecal indicators and several pathogenic microorganisms ( Salmonella, Pseudomonas aeruginosa and Candida albicans) were also established in these recreational marine zones. The results obtained indicate that none of the indicators tested may be considered as a universal index of the presence of pathogens in water; however, faecal streptococci showed a higher and significant relationship with sewage discharges.