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Escherichia coli isoladas de agua de consumo : caracterização fenotipica e genotipica das propriedades de virulencia; Escherichia coli isolated from drinking water: fenotypic and genotypic characterization of virulence factors

Daniela Alves Ribeiro
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/02/2006 PT
Relevância na Pesquisa
66.04%
Estudos de infecções causadas pela ingestão de águas contaminadas, em especial por Escherichia coli, são importantes para definir o papel dessas bactérias em casos de gastroenterites. Devido à ocorrência freqüente da diarréia infantil na cidade de Ouro Preto-MG, análises microbiológicas da sua água de consumo determinaram a presença de E. coli. No presente trabalho, propriedades fenotípicas e genotípicas de virulência foram estudadas em 97 amostras de E. coli isoladas da água de consumo desse município. Os resultados obtidos para padrões de adesão mostraram que 79 (81,4%) amostras aderiram a células HEp-2 em diferentes padrões de adesão, sendo que 49 (62%) amostras aderiram de forma agregativa, 16 (20,3%) apresentaram o padrão difuso, 12 (15,2%) aderiram de forma não característica e 2 (2,5%) apresentaram o perfil de adesão localizada ?like?. Por ensaios de hemaglutinação verificou-se que 70 (72%) amostras hemaglutinaram hemácias de cobaia, 64 (65,9%) aglutinaram hemácias eqüinas, 5 (5,2%) foram positivas com hemácias humanas do grupo A e 10 (10,3%) aglutinaram hemácias bovinas. Todas essas amostras evidenciaram um perfil de hemaglutinação manose sensível, o que está associado à presença da fímbria tipo 1. Outro fator de virulência detectado foi a produção de aerobactina em 11 (11...

Water safety plans : methodologies for risk assessment and risk management in drinking-water systems

Vieira, J. M. Pereira
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2005 ENG
Relevância na Pesquisa
66.18%
Providing good and safe drinking-water is world-wide considered to be a fundamental political issue for public health protection, and must be the primary objective of water supply systems. Drinking-water quality control has currently been based on detection of pathogens and toxic concentrations of chemicals by means of monitoring programs and compliance with national or international guidelines and standards, relying mainly on indicator bacteria and chemicals maximum concentration levels. However, this methodology is often slow, complex and costly. Even for sophisticated and well-operated systems these monitoring schemes have proved to be inefficient in preventing waterborne diseases like, for instance, Giardia or Cryptosporidium outbreaks. From this evidence we can conclude that end-product testing is a reactive rather than preventive way to demonstrate confidence in good and safe drinking-water. This justifies the need for the formulation of a new approach in drinking-water quality control based on understanding of system vulnerability for contamination and on preventive means and actions necessary to guarantee the safety of the water supplied to the consumer. Water safety plan is a concept for risk assessment and risk management throughout the water cycle from the catchments to the point of consumption. This approach includes the identification of the hazards and introduction of control points that serve to minimize these potential hazards...

Drinking water biofilm assessment of total and culturable bacteria under different operating conditions

Simões, Lúcia C.; Azevedo, N. F.; Pacheco, A. P.; Keevil, C. W.; Vieira, M. J.
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
Relevância na Pesquisa
66.19%
Monitoring of biofilms subjected to different operating conditions was performed using a flow cell system. The system was fed by chlorine-free tap water, with and without added nutrients (0.5 mg l ˉ¹carbon, 0.1 mg l ˉ¹nitrogen and 0.01 mg lˉ¹ phosphorus), and biofilms were grown on polyvinyl chloride (PVC) and stainless steel (SS) coupons, both in laminar and turbulent flow. The parameters analysed were culturable cells, using R2A, and total bacteria, which was assessed using the 4,6-diamino-2-phenylindole (DAPI) staining method. The impact of the different operating conditions in the studied parameters was established using Multivariate Analysis of Variance (MANOVA). From the most relevant to the least relevant factor, the total and culturable bacteria in biofilms increased due to the addition of nutrients to water (F=20.005; p<0.001); the use of turbulent (Re=11000) instead of laminar (Re=2000) hydrodynamic flows (F=9.173; p<0.001); and the use of PVC instead of SS as the support material (F=2.848; p=0.060). Interactions between these conditions, namely between surface and flow (F=8.235; p<0.001) and also flow and nutrients (F=5.498; p<0.05) have also proved to significantly influence biofilm formation. This work highlights the need for a deeper understanding of how the large spectrum of conditions interact and affect biofilm formation potential and accumulation with the final purpose of predicting the total and culturable bacteria attached to real drinking water distribution pipes based on the system characteristics.; Fundação para a Ciência e a Tecnologia (FCT); European Commission Research Project SAFER.

Potential of the adhesion of bacteria isolated from drinking water to materials

Simões, Lúcia C.; Simões, M.; Oliveira, Rosário; Vieira, M. J.
Fonte: WILEY-VCH Verlag Publicador: WILEY-VCH Verlag
Tipo: Artigo de Revista Científica
Publicado em /04/2007 ENG
Relevância na Pesquisa
66.12%
Heterotrophic bacteria (11 genera, 14 species, 25 putative strains) were isolated from drinking water, identified either biochemically or by partial 16s rDNA gene sequencing and their adherence characteristics were determined by two methods: i. thermodynamic prediction of adhesion potential by measuring hydrophobicity (contact angle measurements) and ii. by measuring adherence to eight different substrata (ASI 304 and 316 stainless steel, copper, polyvinyl chloride, polypropylene, polyethylene, silicone and glass). All the test organisms were hydrophilic and inter-species variation in hydrophobicity occurred only for Comamonas acidovorans. Stainless steel 304 (SS 304), copper, polypropylene (PP), polyethylene (PE) and silicone thermodynamically favoured adhesion for the majority of test strains (>18/25), whilst adhesion was generally less thermodynamically favorable for stainless steel 316 (SS 316), polyvinyl chloride (PVC) and glass. The predictability of thermodynamic adhesion test methods was validated by comparison with 24-well microtiter plate assays using nine reference strains and three adhesion surfaces (SS 316, PVC and PE). Results for Acinetobacter calcoaceticus, Burkolderia cepacia and Stenotrophomonas maltophilia sp. 2 were congruent between both methods whilst they differed for the other bacteria to at least one material. Only A. calcoaceticus had strongly adherent properties to the three tested surfaces. Strain variation in adhesion ability was detected only for Sphingomonas capsulata. Analysis of adhesion demonstrated that in addition to physicochemical surface properties of bacterium and substratum...

The relationship between initial adhesion and biofilm formation by drinking water bacteria

Simões, Lúcia C.; Simões, M.; Vieira, M. J.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 28/11/2007 ENG
Relevância na Pesquisa
65.98%

Acinetobacter calcoaceticus plays a bridging function in drinking water biofilms

Simões, Lúcia C.; Simões, M.; Vieira, M. J.
Fonte: Escola de Engenharia, Universidade do Minho Publicador: Escola de Engenharia, Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
Relevância na Pesquisa
66.12%
Intergeneric coaggregation of six drinking water autochthonous heterotrophic bacteria isolated from a model laboratory system were tested for their ability to coaggregate by a visual assay and by two microscopic techniques (epifluorescence and scanning electron microscopies). One isolate, identified as Acinetobacter calcoacticus, was found not only to autoaggregate, but also to coaggregate with four of the five other isolates (Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp.) to different degrees as assessed by the visual assay, highlighting a possible bridging function in a biofilm consortium. In its absence, no coaggregation was found. Microscopic observations revealed a higher degree of interaction for all the aggregates than did the visual assay. Heat and protease reversed autoaggregation and coaggregation, suggesting that interactions were lectin-saccharide mediated. The increase/decrease in the level of extracellular proteins and polysaccharides produced during intergeneric bacteria association was not correlated with coaggregation occurrence, but probably with coaggregation strength. The bridging function of A. calcoaceticus was evidenced by multispecies biofilm studies through a strain exclusion process.; Este trabalho investiga a co-agregação intergenérica de seis bactérias heterotróficas autóctones de água potável isoladas de um sistema laboratorial modelo...

Adhesion and biofilm formation on polystyrene by drinking water-isolated bacteria

Simões, Lúcia C.; Simões, M.; Vieira, M. J.
Fonte: Springer Science+Business Media Publicador: Springer Science+Business Media
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
Relevância na Pesquisa
86.31%
This study was performed in order to characterize the relationship between adhesion and biofilm formation abilities of drinking water-isolated bacteria (Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp.). Adhesion was assessed by two distinct methods: thermodynamic prediction of adhesion potential by quantifying hydrophobicity and the free energy of adhesion; and by microtiter plate assays. Biofilms were developed in microtiter plates for 24, 48 and 72 h. Polystyrene (PS) was used as adhesion substratum. The tested bacteria had negative surface charge and were hydrophilic. PS had negative surface charge and was hydrophobic. The free energy of adhesion between the bacteria and PS was[0 mJ/m2 (thermodynamic unfavorable adhesion). The thermodynamic approach was inappropriate for modelling adhesion of the tested drinking water bacteria, underestimating adhesion to PS. Only three (B. cepacia, Sph. capsulata and Staphylococcus sp.) of the six bacteria were non-adherent to PS. A. calcoaceticus, Methylobacterium sp. and M. mucogenicum were weakly adherent. This adhesion ability was correlated with the biofilm formation ability when comparing with the results of 24 h aged biofilms. Methylobacterium sp. and M. mucogenicum formed large biofilm amounts...

Impact of biofilms in simulated drinking water and urban heat supply systems

Lopes, F. A.; Morin, P.; Oliveira, Rosário; Melo, L. F.
Fonte: Inderscience Enterprises Limited Publicador: Inderscience Enterprises Limited
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
Relevância na Pesquisa
66.16%
Biofouling and biocorrosion were studied in drinking water and heating water systems by forming biofilms on steel and on polymethylmetacrylate. In the drinking water system, biofilm development was more significant on corroded surfaces, suggesting that in these conditions they were largely protected from disinfection, probably because of sheltering and chlorine demand by corrosion products. In the urban heat supply system, results suggest a higher biofilm activity at lower pH. Sulphate-reducing bacteria were detected in the urban heating biofilms, but little corrosion was observed on steel coupons. Results indicate that surface and bulk medium properties, as well as bacterial diversity are determinant parameters when studying biofouling and biocorrosion.; Cirius – Danish Centre for International Cooperation and Mobility in Education and Training

Arsenic removal from drinking water by advanced filtration processes

Duarte, António A. L. Sampaio; Oliveira, Sara L. C.; Amorim, M. T. Pessoa de
Fonte: IWRA - CD Rom Publicador: IWRA - CD Rom
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2011 ENG
Relevância na Pesquisa
66.05%
All over the world the presence of arsenic in water sources for human consumption has been raising great concern in terms of public health since many epidemiologic studies confirm the potential carcinogenic effect of arsenic. Because arsenic removal is the most frequent option for safe drinking water, the development of more efficient and sustainable technologies is extremely important. Membrane separation processes are suitable for water treatment because they can provide an absolute barrier for bacteria and viruses, besides removing turbidity and colour. Their application is a promising technology in arsenic removal since it does not require the addition of chemical reagents nor the preliminary oxidation of arsenite required in conventional treatment options. However, since membrane technologies such as reverse osmosis can be a very expensive and unsustainable treatment option for small water supply systems, it becomes crucial that alternative methods are developed. This work presents a few conclusions based on a laboratorial study performed to evaluate the efficiency of arsenic removal using ultrafiltration, microfiltration and solar oxidation processes under different experimental conditions for relevant parameters. The results showed removal efficiencies higher than 90%.

The effects of metabolite molecules produced by drinking water-isolated bacteria on their single and multispecies biofilms

Simões, Lúcia C.; Simões, M.; Vieira, M. J.
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2011 ENG
Relevância na Pesquisa
76.24%
The elucidation of the mechanisms by which diverse species survive and interact in drinking water (DW) biofilm communities may allow the identification of new biofilm control strategies. The purpose of the present study was to investigate the effects of metabolite molecules produced by bacteria isolated from DW on biofilm formation. Six opportunistic bacteria, viz. Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp. isolated from a drinking water distribution systems (DWDS) were used to form single and multispecies biofilms in the presence and absence of crude cell-free supernatants produced by the partner bacteria. Biofilms were characterized in terms of mass and metabolic activity. Additionally, several physiological aspects regulating interspecies interactions (sessile growth rates, antimicrobial activity of cell-free supernatants, and production of iron chelators) were studied to identify bacterial species with biocontrol potential in DWDS. Biofilms of Methylobacterium sp. had the highest growth rate and M. mucogenicum biofilms the lowest. Only B. cepacia was able to produce extracellular iron-chelating molecules. A. calcoaceticus, B. cepacia...

A comparative study of drinking water biofilm monitoring with flow cell and Propella™ bioreactors

Simões, Lúcia C.; Simões, M.; Vieira, M. J.
Fonte: International Water Association Publishing Publicador: International Water Association Publishing
Tipo: Artigo de Revista Científica
Publicado em //2012 ENG
Relevância na Pesquisa
76.19%
Monitoring of drinking water (DW) biofilm formation under different process conditions was performed using two distinct bioreactors: a Propella™ and a flow cell system. Biofilms were grown on polyvinyl chloride (PVC) and stainless steel (SS) coupons under laminar (Reynolds number: 2000) and turbulent (Reynolds number: 11000) flow. The parameters analysed were the numbers of total and cultivable bacteria. The impact of different process conditions was assessed after the biofilms reached steady-state. The number of total bacteria was mostly higher than those cultivable. Biofilm steady-state was achieved in 3 days in both bioreactors with adhesion surfaces under turbulent flow. Under laminar flow it was only achieved in 6 days. The numbers of total and cultivable bacteria in turbulent flow-generated biofilms were similar in both bioreactors, regardless of the adhesion surface tested. Under laminar flow, the Propella™ bioreactor allowed the formation of steady-state biofilms with a higher number of total and cultivable bacteria than the flow cell system. Comparing the effects of the flow regime on biofilm accumulation, only turbulent flow-generated biofilms formed on the flow cell system had a higher amount of total and cultivable bacteria than those formed under laminar flow. In terms of adhesion surface effects...

Comparison of methods to assess biofilm disinfection and recovery by drinking water-isolated bacteria

Simões, Lúcia C.; Simões, M.; Vieira, M. J.
Fonte: ICAR 2012 Publicador: ICAR 2012
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 ENG
Relevância na Pesquisa
76.17%
Drinking water (DW) distribution systems are known to harbour biofilms even in the presence of disinfectants. DW biofilms are constituted by microbial communities adapted to low nutrient concentrations and high chlorine levels. Biofilm formation and resistance to disinfection have been recognized as important factors that contribute to the survival and persistence of microbial contamination in DW. The purpose of this work was the comparison of diverse methods to assess the disinfection of biofilms formed by six DW-isolated opportunistic bacteria (Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp.) by sodium hypochlorite (SHC). Single and multi-species biofilms (composed of combinations of 6 and 5 bacteria) were developed in 96- wells microtiter plates for 3 days, afterwards, were exposed to several independent SHC concentrations (0.1, 0.5, 1 and 10 mg/L) during 1 h. The potential of biofilms to recover was assessed 24 h after disinfection. The disinfection efficacy and recovery were assessed in terms of variation in: biofilm mass (crystal violet staining); metabolic activity (XTT staining); cultivability (CFUs) and viability (Live/Dead staining). The results indicated that biomass removal increased with increasing SHC concentration...

The influence of microbial ecology of drinking water biofilms on their resistance to disinfection

Simões, Lúcia C.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2010 ENG
Relevância na Pesquisa
76.18%
The knowledge of the role of microbial ecology of drinking water (DW) biofilms on disinfection might help to improve our understanding of their resistance mechanisms and allow the development of effective strategies to apply in drinking water distribution systems (DWDS). In this study six opportunistic bacteria (Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp.) isolated from a DWDS were used to form single and multispecies biofilms. Those biofilms were exposed to sodium hypochlorite (SHC) at different oncentrations for 1 h and biofilm control was assessed in terms of mass removal and metabolic activity, cultivability and viability reduction. Biofilm recovery was also assessed 24 h after SHC treatment. The results demonstrate that total biofilm mass removal (single and multispecies biofilms) was not achieved for the SHC concentrations tested. Total biofilm inactivation was only achieved for A. calcoaceticus and Staphylococcus sp. single species biofilms and for multispecies biofilms without A. calcoaceticus, when exposed to high SHC concentrations. From the single species biofilms, Methylobacterium sp. and M. mucogenicum had the highest resistance to SHC...

Aeromonas spp. and microbial indicators in raw drinking water source

Di Bari,Marisa; Hachich,Elayse M.; Melo,Adalgisa M.J.; Sato,Maria I. Z.
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2007 EN
Relevância na Pesquisa
66.19%
Aeromonas species are autochtonous in the aquatic environment and some of them have been associated with health effects like wound infections, septicemia and diarrhoeal illness. In this study, the occurrence of Aeromonas spp. and microbial indicators in raw drinking water from wells, springs, fountains and mineral waters was evaluated. A total of 126 water samples was analyzed for Aeromonas spp. by the membrane filtration technique using ADA media and by P/A test. Typical colonies of Aeromonas spp. were submitted to biochemical tests for species differentiation. Toxin production was tested using Y-1 mouse adrenal cells. Coliforms and heterotrophic bacteria were enumerated by membrane filtration and pour plate techniques, respectively. P. aeruginosa, C. perfringens and fecal streptococci were determined by P/A method. Aeromonas spp. were isolated in 36.5% of the samples, whereas total and thermotolerant coliforms were detected in 51.2% and in 23.8% of the samples, respectively. C. perfringens, fecal streptococci and P. aeruginosa were present in 16.5%, 20.4% and 3.8% of the samples, respectively. The concentrations of heterotrophic bacteria were higher than 1,0x10³ CFU/mL in 52.5% of the samples. A. hydrophila was the most frequent species...

Putative new heat-stable cytotoxic and enterotoxic factors in culture supernatant of Escherichia coli isolated from drinking water

Ribeiro,DA; Niemann,FS; Gatti,MSV; Lanna,MCS; Tsuji,T; Yano,T
Fonte: Centro de Estudos de Venenos e Animais Peçonhentos - CEVAP, Universidade Estadual Paulista - UNESP Publicador: Centro de Estudos de Venenos e Animais Peçonhentos - CEVAP, Universidade Estadual Paulista - UNESP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
66.07%
Enteric infections caused by the ingestion of contaminated water, especially by Escherichia coli, are important to define the virulence properties of these bacteria. Due to frequent infantile diarrhea in the city of Ouro Preto, Minas Gerais state, Brazil, the phenotypic and genotypic diarrheagenic properties of E. coli isolated from drinking water were studied. The culture supernatants of 39 (40%) among a total of 97 E. coli isolates from drinking water were positive by suckling mouse assay and induced cytotoxic effects on Vero cells. The enterotoxic and cytotoxic activities were present in the fraction with less than 10 kDa and were not lost when heated up to 60°C and 100°C for 30 minutes. PCR assays showed that among these 39 Vero cytotoxigenic E. coli, four (10.2%) were positive for ST II (estB) and two (5%) positive for αHly (hlyA). Gene amplification of SLT (stx 1, stx 2), ST I (estA), LT (eltI, eltII), EAST1 (astA), EHly (enhly) and plasmid-encoded enterotoxin (pet) were not observed. This heat-stable cytotoxic enterotoxin of E. coli is probably a new putative diarrheagenic virulence factor, as a toxin presenting these characteristics has not yet been described.

Removal of geosmin and 2-methylisoborneol from drinking water through biologically active sand filters.

McDowall, Bridget
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008
Relevância na Pesquisa
66.17%
This thesis outlines results of a series of studies investigating the removal of two common taste and odour compounds, 2-methylisoborneol (MIB) and geosmin, from drinking water using biologically active sand filtration. A combination of full-, pilot- and laboratory-scale studies were carried out. A review of long term water quality data from a South Australian water treatment plant indicated that the conventional plant was capable of removing MIB and geosmin to below detection limit without the need for additional treatment. A series of laboratory studies were carried out, validating the theory that the geosmin removal was occurring through biological activity in the rapid gravity filters of the water treatment plant. Microorganisms capable of geosmin removal were found to be present in the settled water of two South Australian water treatment plants, Morgan and Happy Valley. Laboratory sand column experiments were conducted with these waters and a range of sand media, investigating the effect of biofilm development on MIB and geosmin biodegradation. It was found that the process could produce effective removals, however long start-up periods were often required. A laboratory-scale column utilising new sand fed with Happy Valley settled water took in excess of 300 days before it was capable of removing MIB and geosmin by greater than 80%. Studies on sands with inactivated pre-existing biofilms required much shorter biofilm development periods...

Biofilm formation in surface and drinking water distribution systems in Mafikeng, South Africa

Mulamattathil,Suma George; Bezuidenhout,Carlos; Mbewe,Moses
Fonte: South African Journal of Science Publicador: South African Journal of Science
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 EN
Relevância na Pesquisa
66.21%
Poor quality source water and poorly treated reused wastewater may result in poor quality drinking water that has a higher potential to form biofilms. A biofilm is a group of microorganisms which adhere to a surface. We investigated biofilm growth in the drinking water distribution systems in the Mafikeng area, in the NorthWest Province of South Africa. Analysis was conducted to determine the presence of faecal coliforms, total coliforms, Pseudomonas spp. and Aeromonas spp. in the biofilms. Biofilms were grown on a device that contained copper and galvanised steel coupons. A mini tap filter - a point-of-use treatment device which can be used at a single faucet - was also used to collect samples. Scanning electron microscopy demonstrated that multi-species biofilms developed on all the coupons as well as on the point-of-use filters. Galvanised steel and carbon filters had the highest density of biofilm. Total coliforms, faecal coliforms and Pseudomonas spp. were isolated from raw water biofilm coupons only. Aeromonas spp. and Pseudomonas spp. were isolated from filters. The susceptibility of selected isolates was tested against 11 antibiotics of clinical interest. The most prevalent antibiotic resistance phenotype observed was KF-AP-C-E-OT-K-TM-A. The presence of virulence genes was determined using the polymerase chain reaction. These results indicate that bacteria present in the water have the ability to colonise as biofilms and drinking water biofilms may be a reservoir for opportunistic bacteria including Pseudomonas and Aeromonas species.

Removal of waterborne bacteria from surface water and groundwater by cost-effective household water treatment systems (HWTS): A sustainable solution for improving water quality in rural communities of Africa

Mwabi,Jocelyne K; Mamba,Bhekie B; Momba,Maggy NB
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
66.1%
In this study 5 household water-treatment devices/systems (HWTS) were constructed using inexpensive local materials (sand, gravel, zeolites and clays). They included the silver-impregnated porous pot filter (SIPP), the ceramic candle filter (CCF), the conventional biosand filter (BSF-S), a modified biosand filter with zeolites (BSF-Z), and a bucket filter (BF). Their ability to remove turbidity and pathogenic bacteria (Vibrio cholerae, Salmonella typhimurium and Shigella dysenteriae) from synthetic sterile water, groundwater and surface-water sources was evaluated. The flow rates ranged from 0.05ℓ∙h-1 to 2.49ℓ∙h-1 for SIPP; 1ℓ∙h-1 to 4ℓ∙h-1 for CCF; 0.81ℓ∙h-1 to 6.84ℓ∙h-1 for BSF-S; 1.74ℓ∙h-1 to 19.2ℓ∙h-1 for BSF-Z; and from 106.5ℓ∙h-1 to 160.5ℓ∙h-1 for BF. The highest (64% to 98% (0.74 to 1.08 NTU)) and lowest (14% to 76% (2.91 to 7.19 NTU)) average percentage turbidity removals were noted for SIPP and BF, respectively. The SIPP was the only device that consistently removed 100% of all target pathogens throughout the study. Its performance was found to be significantly superior (p<0.05) compared to that of the other four devices. Sixty (60%) to 100% bacterial removals were observed for BSF-S; 90% to 100% for BSF-Z; 90% to 100% for CCF; and 40% to 99.9% for BF. Based on the findings of this study the SIPP can be recommended for use by rural communities as it consistently produced high-quality water that complied with the SANS 241 turbidity and microbiological limits for drinking water.

Microbial quality of drinking water from groundtanks and tankers at source and point-of-use in eThekwini Municipality, South Africa, and its relationship to health outcomes

Singh,U; Lutchmanariyan,R; Wright,J; Knight,S; Jackson,S; Langmark,J; Vosloo,D; Rodda,N
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
76.2%
Drinking water quality was investigated at source and corresponding point-of-use in 2 peri-urban areas receiving drinking water either by communal water tanker or by delivery directly from the distribution system to household-based groundtanks with taps. Water quality variables measured were heterotrophic bacteria, total coliforms, E. coli, conductivity, turbidity, pH, and total and residual chlorine. Water quality data were analysed together with an existing epidemiological database to investigate links between microbial quality of drinking water, household demographics, health outcomes, socio-economic status, hygiene and sanitation practices. Groundtank households had better quality drinking water than households using storage containers filled from communal tankers. Uncovered storage containers had the poorest microbial water quality among all storage containers. All stored water did not meet drinking water standards, although mains water did. Households with children under 5 years and using open-topped containers had the poorest water quality overall. Households with groundtanks had the best water quality at point-of-use, but did not have the lowest occurrence of health effects. Although groundtanks were supplied together with urine diversion (UD) toilets and hygiene education...

Low prevalence of antibiotic-resistant gram-negative bacteria isolated from rural south-western Ugandan groundwater

Soge,Olusegun O; Giardino,Michael A; Ivanova,Iana C; Pearson,Amber L; Meschke,John S; Roberts,Marilyn C
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2009 EN
Relevância na Pesquisa
66.09%
The objective of this study was to determine antibiotic resistance patterns and specific resistance genes in Gram-negative enteric bacteria recovered from 42 different drinking water sources servicing 2 rural villages in south-western Uganda. These water sites were prone to contamination by both human and cattle activity. Of the 52 isolates examined, 26 carried antibiotic resistance genes with 25 being ampicillin resistant, 21 carrying the blaTEM gene, and no isolate carrying genes coding for extended-spectrum β−lactamases. Twelve isolates were tetracycline resistant and these bacteria carried between 1 and 3 different tet genes, with the tet(A) gene the most common. Six isolates carried the macrolide resistance mef(A) and/or the macrolide-lincosamide-streptogramin B resistance erm(B) genes. Four isolates carried the sul1 gene, and 4 isolates carried the sul1 and int1 genes indicating the presence of Class 1 integrons. The Ugandan isolates in this study had lower than expected carriage rates of antibiotic and multi-drug resistance genes, carriage of Class 1 integrons and lacked genes coding for extended-spectrum β−lactamases as compared to antibiotic resistance carriage in clinical African isolates.