ORCID Profile
0000-0002-2236-7589
Current Organisation
University of Oxford
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Publisher: MDPI AG
Date: 07-09-2022
DOI: 10.3390/PH15091116
Abstract: The emergence of virulent extended spectrum β-lactamase producing Klebsiella pneumoniae (ESBL-KP) including carbapenem-resistant Klebsiella pneumoniae (CRKP) in hospital-acquired infections has resulted in significant morbidity and mortality worldwide. We investigated the antibiotic resistance and virulence factors associated with ESBL-KP and CRKP in tertiary care hospitals in Bangladesh and explored their ability to form biofilm. A total of 67 ESBL-KP were isolated from 285 Klebsiella pneumoniae isolates from environmental and patient s les from January 2019 to April 2019. For ESBL-KP isolates, molecular typing was carried out using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR), antibiotic susceptibility testing, PCR for virulence and drug-resistant genes, and biofilm assays were also performed. All 67 isolates were multidrug-resistant (MDR) to different antibiotics at high levels and 42 isolates were also carbapenem-resistant. The most common β-lactam resistance gene was blaCTX-M-1 (91%), followed by blaTEM (76.1%), blaSHV (68.7%), blaOXA-1 (29.9%), blaGES (14.9%), blaCTX-M-9 (11.9%), and blaCTX-M-2 (4.5%). The carbapenemase genes blaKPC (55.2%), blaIMP (28.4%), blaVIM (14.9%), blaNDM-1 (13.4%), and blaOXA-48 (10.4%) and virulence-associated genes such as fimH (71.6%), ugeF (58.2%), wabG (56.7%), ureA (47.8%) and kfuBC (28.4%) were also detected. About 96.2% of the environmental and 100% of the patient isolates were able to form biofilms. ERIC-PCR-based genotyping and hierarchical clustering of K. pneumoniae isolates revealed an association between environmental and patient s les, indicating clonal association with possible transmission of antimicrobial resistance genes. Our findings can help in improving patient care and infection control, and the development of public health policies related to hospital-acquired infections.
Publisher: Elsevier BV
Date: 10-2014
Publisher: Informa UK Limited
Date: 04-02-2021
Publisher: Springer Science and Business Media LLC
Date: 20-04-2020
DOI: 10.1038/S41545-020-0062-X
Abstract: The need to increase drinking water quality monitoring in rural sub-Saharan Africa is widely recognised. Rural water service providers (RWSPs) may be positioned to include water quality monitoring in their activities however, it is important that water safety activities do not compromise cooperation between the RWSP, bureaucracy, and communities. Using dilemma analysis, drawing on an institutional experiment engaging 76 stakeholders, we find that conceptualising water quality versus quantity as a dichotomy delays progress on safe water. This false dichotomy makes it more difficult to deliver water safety improvements due to contrasting assumptions about the importance of quality risks associated with not being able to act and unclear isions of responsibility. Monitoring water quality can be a threat to stakeholders and stakeholder cooperation however, this may be mitigated by including supported water safety planning in the technical and institutional design of rural water projects at their conception.
Publisher: MDPI AG
Date: 05-01-2022
Abstract: Reducing disease from unsafe drinking-water is a key environmental health objective in rural Sub-Saharan Africa, where water management is largely community-based. The effectiveness of environmental health risk reporting to motivate sustained behaviour change is contested but as efforts to increase rural drinking-water monitoring proceed, it is timely to ask how water quality information feedback can improve water safety management. Using cross-sectional (1457 households) and longitudinal (167 participants) surveys, semi-structured interviews (73 participants), and water quality monitoring (79 sites), we assess water safety perceptions and evaluate an information intervention through which Escherichia coli monitoring results were shared with water managers over a 1.5-year period in rural Kitui County, Kenya. We integrate the extended parallel process model and the precaution adoption process model to frame risk information processing and stages of behaviour change. We highlight that responses to risk communications are determined by the specificity, framing, and repetition of messaging and the self-efficacy of information recipients. Poverty threatscapes and gender norms hinder behaviour change, particularly at the household-level however, test results can motivate supply-level managers to implement hazard control measures—with effectiveness and sustainability dependent on infrastructure, training, and ongoing resourcing. Our results have implications for rural development efforts and environmental risk reporting in low-income settings.
Publisher: American Chemical Society (ACS)
Date: 30-08-2005
DOI: 10.1021/ES050427B
Abstract: To define protection zones around groundwater abstraction wells and safe setback distances for artificial recharge systems in watertreatment, quantitative information is needed about the removal of microorganisms during soil passage. Column experiments were conducted using natural soil and water from an infiltration site with fine sandy soil and a river bank infiltration site with gravel soil. The removal of phages, bacteria, bacterial spores, and protozoan (oo)-cysts was determined at two velocities and compared with field data from the same sites. The microbial elimination rate (MER) in both soils was generally >2 log, but MER in the gravel soil was higher than that in the fine sandy soil. This was attributed to enhanced attachment, related to higher metal-hydroxides content. From the high sticking efficiencies (>1) and the low influence of flow rate on MER it was deduced that straining played a significant role in the removal of Escherichia coli and Cryptosporidium parvum oocysts in the gravel soil. Lower removal of oocysts than the 4-5 times smaller E. coli and spores in the fine sand indicates that the contribution of straining is variable and needs further attention in transport models. Thus, simple extrapolation of grain size and particle size to the extent of microbial transport underground is inappropriate. Finally, the low MER of indigenous E. coli and Clostridium perfringens observed in the soil columns as well as under field conditions and the second breakthrough peak found for Cryptosporidium and spores in the fine sandy soil upon a change in the feedwater pH indicate a significant role of detachment and retardation to microbial transport and the difficulty of extrapolation of quantitative column test results to field conditions.
Publisher: Informa UK Limited
Date: 13-03-2014
DOI: 10.1080/09603123.2014.893570
Abstract: Sanitation improvement is crucial in saving lives that are lost due to water contamination. Progress towards achieving full sanitation coverage is still slow in low-income informal settlements in most developing countries. Furthermore, resources are being wasted on installing facilities that are later misused or never used because they do not meet the local demand. Understanding demand for improved sanitation in the local context is critical if facilities are to be continually used. Various approaches that attempt to change peoples' behaviours or create demand have been reviewed to identify what they are designed to address. A multi-disciplinary research team using mixed methods is re-emphasised as a comprehensive approach for assessing demand for improved sanitation in low-income informal settlements, where the sanitation situation is more challenging than in other areas. Further research involving a multi-disciplinary research team and use of mixed methods to assess sanitation demand in informal settlements is needed.
Publisher: Oxford University Press (OUP)
Date: 06-2009
DOI: 10.1111/J.1365-2672.2009.04150.X
Abstract: To investigate the potential health hazard from infectious viruses where coliphages, or viruses by polymerase chain reaction (PCR), have been detected in groundwater. Two aspects were investigated: the relationship between infectivity and detection by PCR and the stability of coliphage compared to human viruses. Virus decay (1 year) and detection (2 years) studies were undertaken on groundwater at 12 degrees C. The order of virus stability from most to least stable in groundwater, based on first-order inactivation, was: coliphage PhiX174 (0.5 d(-1)) > adenovirus 2 > coliphage PRD1 > poliovirus 3 > coxsackie virus B1 (0.13 d(-1)). The order for PCR results was: norovirus genotype II > adenovirus > norovirus genotype I > enterovirus. Enterovirus and adenovirus detection by PCR and the duration of infectivity in groundwater followed similar trends over the time period studied. Adenovirus might be a better method for assessing groundwater contamination than using enterovirus norovirus detection would provide information on a significant human health hazard. Bacteriophage is a good alternative indicator. PCR is a useful tool for identifying the health hazard from faecal contamination in groundwater where conditions are conducive to the survival of viruses and their nucleic acid.
Publisher: IWA Publishing
Date: 12-09-2012
DOI: 10.2166/WH.2012.205
Abstract: The Millennium Development Goals (MDGs) set out to halve the proportion of the population without access to basic sanitation between 1990 and 2015. The slow pace of progress has lead to a search for innovative responses, including social motivation approaches. One ex le of this type of approach is ‘Community-led Total Sanitation’ (CLTS). CLTS represents a major shift for sanitation projects and programmes in recognising the value of stopping open-defecation across the whole community, even when the in idual toilets built are not necessarily wholly hygienic. However, recent publications on CLTS document a number of ex les of practices which fail to meet basic ethical criteria and infringe human rights. There is a general theme in the CLTS literature encouraging the use of ‘shame’ or ‘social stigma’ as a tool for promoting behaviours. There are reported cases where monetary benefits to which in iduals are otherwise entitled or the means to practice a livelihood are withheld to create pressures to conform. At the very extreme end of the scale, the investigation and punishment of violence has reportedly been denied if the crime occurred while defecating in the open, violating rights to a remedy and related access to justice. While social mobilisation in general, and CLTS in particular, have drastically and positively changed the way we think about sanitation, they neither need nor benefit from an association with any infringements of human rights.
Publisher: Informa UK Limited
Date: 31-12-2008
Publisher: Springer Science and Business Media LLC
Date: 18-08-2020
DOI: 10.1038/S41545-020-00083-1
Abstract: The sustainable developments goals (SDGs) introduced monitoring of drinking water quality to the international development agenda. At present, Escherichia coli are the primary measure by which we evaluate the safety of drinking water from an infectious disease perspective. Here, we propose and apply a framework to reflect on the purposes of and approaches to monitoring drinking water safety. To deliver SDG 6.1, universal access to safe drinking water, a new approach to monitoring is needed. At present, we rely heavily on single measures of E. coli contamination to meet a normative definition of safety. Achieving and sustaining universal access to safe drinking water will require monitoring that can inform decision making on whether services are managed to ensure safety and security of access.
Publisher: IWA Publishing
Date: 18-12-2014
Abstract: Throughout Africa, the population in urban areas is increasing rapidly, often exceeding the capacity and the resources of the cities and towns to accommodate the people. In sub-Saharan Africa, the majority of urban dwellers live in informal settlements served by inadequate sanitation facilities. These settlements present unique challenges to the provision of sustainable and hygienic sanitation, and there is insufficient information on access to improved facilities. This paper reports findings of a study undertaken in low-income informal settlements using a mixed methods approach to assess access to sanitation and identify the barriers to household uptake of improved sanitation facilities. More than half of the respondents (59.7%) reported using sanitation facilities that are included in the WHO/UNICEF Joint Monitoring Programme definition of improved sanitation. However, a high proportion of these facilities did not provide access to basic sanitation. Less than 5% of all the respondents did not report problems related to sustainable access to basic sanitation. The findings highlight the urgent need to develop specific and strategic interventions for each low-income informal settlement, to upscale the sustainable access and use of improved sanitation in urban centres.
Publisher: Elsevier BV
Date: 05-2023
Publisher: Elsevier BV
Date: 10-2018
Publisher: Informa UK Limited
Date: 09-06-2020
Publisher: Oxford University Press (OUP)
Date: 02-2006
DOI: 10.1111/J.1365-2672.2005.02777.X
Abstract: To generate field-relevant inactivation data for incorporation into models to predict the likelihood of viral contamination of surface waters by septic seepage. Inactivation rates were determined for PRD1 bacteriophage and Adenovirus 2 in two catchment soils under a range of temperature, moisture and biotic status regimes. Inactivation rates presented for both viruses were significantly different at different temperatures and in different soil types (alpha = 0.05). Soil moisture generally did not significantly affect virus inactivation rate. Biotic status significantly affected inactivation rates of PRD1 in the loam soil but not the clay-loam soil. Adenovirus 2 was inactivated more rapidly in the loam soil than PRD1 bacteriophage. Virus inactivation rates incorporated into models should be appropriate for the climate/catchment in question with particular regard to soil type and temperature. Given that PRD1 is similar in size to adenoviruses, yet more conservative with regard to inactivation in soil, it may be a useful surrogate in studies of Adenovirus fate and transport. A better understanding of the factors that govern virus fate and transport in catchments would facilitate the design of barrier measures to prevent viral contamination of surface waters by septic seepage.
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.SCITOTENV.2018.07.274
Abstract: Microbial water quality is frequently assessed with a risk indicator approach that relies on Escherichia coli. Relying exclusively on E. coli is limiting, particularly in low-resource settings, and we argue that risk assessments could be improved by a complementary parameter, tryptophan-like fluorescence (TLF). Over two c aigns (June 2016 and March 2017) we s led 37 water points in rural Kwale County, Kenya for TLF, E. coli and thermotolerant coliforms (total n = 1082). Using three World Health Organization defined classes (very high, high, and low/intermediate), risk indicated by TLF was not significantly different from risk indicated by E. coli (p = 0.85). However, the TLF and E. coli risk classifications did show disagreement, with TLF indicating higher risk for 14% of s les and lower risk for 13% of s les. Comparisons of duplicate/replicate results demonstrated that precision is higher for TLF (average relative percent difference of duplicates = 14%) compared to culture-based methods (average RPD of duplicates ≥ 26%). Additionally, TLF s ling is more practical because it requires less time and resources. Precision and practicality make TLF well-suited to high-frequency s ling in low resource contexts. Interpretation and interference challenges are minimised when TLF is measured in groundwaters, which typically have low dissolved organic carbon, relatively consistent temperature, negligible turbidity and pH between 5 and 8. TLF cannot be used as a proxy for E. coli on an in idual s le basis, but it can add value to groundwater risk assessments by improving prioritization of s ling and by increasing understanding of spatiotemporal variability.
Publisher: Elsevier BV
Date: 11-2016
Publisher: Elsevier BV
Date: 06-2022
Publisher: Springer Science and Business Media LLC
Date: 29-09-2023
DOI: 10.1007/S12403-022-00505-0
Abstract: The occurrence of major water contamination events across the world have been met with varying levels of policy responses. Arsenic—a priority water contaminant globally, occurring naturally in groundwater, causing adverse health effects—is widespread in Bangladesh. However, the policy response has been slow, and marked by ineffectiveness and a lack of accountability. We explore the delayed policy response to the arsenic crisis in Bangladesh through comparison with water contamination crises in other contexts, using the Multiple Streams Framework to compare policy processes. These included Escherichia coli O157:H7 and C ylobacter in Walkerton, Canada lead and Legionella in Flint, Michigan, USA and chromium-6 contamination in Hinkley, California, USA. We find that, while water contamination issues are solvable, a range of complex conditions have to be met in order to reach a successful solution. These include aspects of the temporal nature of the event and the outcomes, the social and political context, the extent of the public or media attention regarding the crisis, the politics of visibility, and accountability and blame. In particular, contaminants with chronic health outcomes, and longer periods of subclinical disease, lead to smaller policy windows with less effective policy changes. Emerging evidence on health threats from drinking water contamination raise the risk of new crises and the need for new approaches to deliver policy change.
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.WATRES.2008.02.032
Abstract: Studies undertaken to assess the performance of filter materials to remove phosphorus in decentralised sewage systems have not reported on the broader performance of these systems. This study aimed to identify virus fate and transport mechanisms at the laboratory scale for comparison with field experiments on a mound system amended with blast furnace slag. Inactivation was a significant removal mechanism for MS2 bacteriophage, but not for PRD1 bacteriophage. Column studies identified rapid transport of PRD1. Laboratory studies predicted lower removal of PRD1 in a full scale system than was experienced in the field study, highlighting the importance of considering pH and flow rate in pathogen removal estimates. The results highlight the necessity for studying a range of organisms when assessing the potential for pathogen transport.
Publisher: Springer Science and Business Media LLC
Date: 05-08-2021
Publisher: MDPI AG
Date: 25-01-2021
DOI: 10.3390/SU13031254
Abstract: Assessing the impact of climate change and population growth on river water quality is a key issue for many developing countries, where multiple and often conflicting river water uses (water supply, irrigation, wastewater disposal) are placing increasing pressure on limited water resources. However, comprehensive water quality datasets are often lacking, thus impeding a full-scale data-based river water quality assessment. Here we propose a model-based approach, using both global datasets and local data to build an evaluation of the potential impact of climate changes and population growth, as well as to verify the efficiency of mitigation measures to curb river water pollution. The upper Awash River catchment in Ethiopia, which drains the city of Addis Ababa as well as many agricultural areas, is used as a case-study. The results show that while decreases in runoff and increases in temperature due to climate change are expected to result in slightly decreased nutrient concentrations, the largest threat to the water quality of the Awash River is population growth, which is expected to increase nutrient loads by 15 to 20% (nitrate) and 30 to 40% (phosphorus) in the river by the second half of the 21st century. Even larger increases are to be expected downstream of large urban areas, such as Addis Ababa. However, improved wastewater treatment options are shown to be efficient in counteracting the negative impact of population growth and returning water pollution to acceptable levels.
Publisher: American Chemical Society (ACS)
Date: 11-01-2006
DOI: 10.1021/ES0580237
Publisher: MDPI AG
Date: 10-12-2013
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 09-2016
Publisher: Public Library of Science (PLoS)
Date: 14-06-2023
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Katrina Charles.