Evaluation of an Inexpensive Growth Medium for Direct Detection of Escherichia coli in Temperate and Sub-Tropical Waters.

The cost and complexity of traditional methods for the detection of faecal indicator bacteria, including E. coli, hinder widespread monitoring of drinking water quality, especially in low-income countries and outside controlled laboratory settings. In these settings the problem is exacerbated by the lack of inexpensive media for the detection of E. coli in drinking water. We developed a new low-cost growth medium, aquatest (AT), and validated its use for the direct detection of E. coli in temperate and sub-tropical drinking waters using IDEXX Quanti-Tray®. AT was compared with IDEXX Colilert-18® and either EC-MUG or MLSB for detecting low levels of E. coli from water samples from temperate (n = 140; Bristol, UK) and subtropical regions (n = 50, Pretoria/Tshwane, South Africa). Confirmatory testing (n = 418 and 588, respectively) and the comparison of quantitative results were used to assess performance. Sensitivity of AT was higher than Colilert-18® for water samples in the UK [98.0% vs. 86.9%; p<0.0001] and South Africa [99.5% vs. 93.2%; p = 0.0030]. There was no significant difference in specificity, which was high for both media (>95% in both settings). Quantitative results were comparable and within expected limits. AT is reliable and accurate for the detection of E. coli in temperate and subtropical drinking water. The composition of the new medium is reported herein and can be used freely.

Diagnostic imaging of cervical intraepithelial neoplasia based on hematoxylin and eosin fluorescence.

BACKGROUND: Pathological classification of cervical intraepithelial neoplasia (CIN) is problematic as it relies on subjective criteria. We developed an imaging method that uses spectroscopy to assess the fluorescent intensity of cervical biopsies derived directly from hematoxylin and eosin (H&E) stained tissues. METHODS: Archived H&E slides were identified containing normal cervical tissue, CIN I, and CIN III cases, from a Community Hospital and an Academic Medical Center. Cases were obtained by consensus review of at least 2 senior pathologists. Images from H&E slides were captured first with bright field illumination and then with fluorescent illumination. We used a Zeiss Axio Observer Z1 microscope and an AxioVision 4.6.3-AP1 camera at excitation wavelength of 450-490 nm with emission captured at 515-565 nm. The 32-bit grayscale fluorescence images were used for image analysis. RESULTS: We reviewed 108 slides: 46 normal, 33 CIN I and 29 CIN III. Fluorescent intensity increased progressively in normal epithelial tissue as cells matured and advanced from the basal to superficial regions of the epithelium. In CIN I cases this change was less prominent as compared to normal. In high grade CIN lesions, there was a slight or no increase in fluorescent intensity. All groups examined were statistically different. CONCLUSION: Presently, there are no markers to help in classification of CIN I-III lesions. Our imaging method may complement standard H&E pathological review and provide objective criteria to support the CIN diagnosis.

Mathematical models of tumor growth using Voronoi tessellations in pathology slides of kidney cancer.

The impact of patient-specific spatial distribution features of cell nuclei on tumor growth characteristics was analyzed. Tumor tissues from kidney cancer patients were allowed to grow in mice to apply H&E staining and to measure tumor volume during preclinical phase of our study. Imaging the H&E stained slides under a digital light microscope, the morphological characteristics of nuclei positions were determined. Using artificial intelligence based techniques, Voronoi features were derived from diagrams, where cell nuclei were considered as distinct nodes. By identifying the effect of each Voronoi feature, tumor growth was expressed mathematically. Consistency between the computed growth curves and preclinical measurements indicates that the information obtained from the H&E slides can be used as biomarkers to build personalized mathematical models for tumor growth.

Synthesis and application of resorufin ß-D-glucuronide, a low-cost chromogenic substrate for detecting Escherichia coli in drinking water.

The development of low-cost tests for Escherichia coli is hampered by the expense and limited choice of enzyme substrates. Most chromogenic substrates are required in costly amounts, while fluorogenic substrates require an additional apparatus (e.g., an ultraviolet lamp) to be detected. Herein, we propose an alternative chromogenic substrate, resorufin ß-d-glucuronide (REG), which is exceptionally sensitive and may be employed in very small amounts. We show that REG can be produced similarly to other simple glucuronides and should therefore be no more expensive. The compound is used by both healthy and injured E. coli, resulting in a pronounced color change from orange to a bright pink. Because the released dye (resorufin) has a high extinction coefficient, substantially lower amounts are needed than for commercially available substrates. The potential of this substrate is demonstrated by a presence/absence test requiring just 0.1 mg of REG/100 mL of water sample, one hundredth of the quantity needed for common chromogenic substrates, with an estimated bulk cost of ≤0.1 U.S. cents/test. REG shows promise as a chromogenic substrate for E. coli detection and should be considered in the development of new water tests, especially for low-income settings.

Water quality laboratories in Colombia: a GIS-based study of urban and rural accessibility.

The objective of this study was to quantify sample transportation times associated with mandated microbiological monitoring of drinking-water in Colombia. World Health Organization Guidelines for Drinking-Water Quality recommend that samples spend no more than 6h between collection and analysis in a laboratory. Census data were used to estimate the minimum number of operational and surveillance samples required from piped water supplies under national regulations. Drive-times were then computed from each supply system to the nearest accredited laboratory and translated into sample holding times based on likely daily monitoring patterns. Of 62,502 surveillance samples required annually, 5694 (9.1%) were found to be more than 6 h from the nearest of 278 accredited laboratories. 612 samples (1.0%) were more than 24 hours' drive from the nearest accredited laboratory, the maximum sample holding time recommended by the World Health Organization. An estimated 30% of required rural samples would have to be stored for more than 6 h before reaching a laboratory. The analysis demonstrates the difficulty of undertaking microbiological monitoring in rural areas and small towns from a fixed laboratory network. Our GIS-based approach could be adapted to optimise monitoring strategies and support planning of testing and transportation infra-structure development. It could also be used to estimate sample transport and holding times in other countries.

Na(+) /H(+) exchanger 1 (NHE1) function is necessary for maintaining mammary tissue architecture.

BACKGROUND: The mammary gland is an ideal model to study the link between form and function in normal tissue. Perhaps as interesting as the cues necessary to generate this structure are the signals required to maintain its branched architecture over the lifetime of the organism, since likely these pathways are de-regulated in malignancies. Previously, we have shown that the Na(+) /H(+) exchanger 1 (NHE1), a critical regulator of intracellular pH, was necessary for mammary branching morphogenesis. Here we provide strong evidence that NHE1 function is also necessary for maintaining mammary branched architecture. RESULTS: Inhibition of NHE1 with 5-N-Methy-N-isobutyl amiloride (MIA) on branched structures resulted in a rapid (within 24 hr) and reversible loss of branched architecture that was not accompanied by any overt changes in cell proliferation or cell death. NHE1 inhibition led to a significant acidification of intracellular pH in the branched end buds that preceded a number of events, including altered tissue polarity of myoepithelial cells, loss of NHE1 basal polarity, F-actin rearrangements, and decreased E-cadherin expression. CONCLUSIONS: Our results implicate NHE1 function and intracellular pH homeostasis as key factors that maintain mammary tissue architecture, thus, indirectly allowing for mammary function as a milk-providing (form) and -producing (function) gland.

Mathematical models for absorption and efficacy of ovarian cancer treatments.

The creation of personal and individualized anti-cancer treatments has been a major goal in the progression of cancer discovery as evident by the continuous research efforts in genetics and population based PK/PD studies. In this paper we use our clinical decision support tool, called ChemoDSS, to evaluate the effectiveness of three treatments recommended by the NCCN guidelines for ovarian cancer using pre-clinical data from the literature. In particular, we analyze the treatments of PC (i.e., Paclitaxel and Cispaltin), DC (i.e., Docetaxel and Carboplatin), and PBC (i.e., Paclitaxel, Bevacizumab, and Carboplatin). Our in silico analysis of the ovarian cancer treatments shows that PC was the most effective regimen for treating ovarian cancer compared to DC and PBC, which is consistent with literature findings. We demonstrate that we can successfully evaluate the effectiveness of the selected ovarian cancer treatment regimens using ChemoDSS.

Accuracy of the H2S test: a systematic review of the influence of bacterial density and sample volume.

The presence/absence hydrogen sulphide test (P/A H2S) is widely used as a low-cost alternative faecal indicator test in remote and resource-poor settings. The aim of the paper is to assess how bacterial density and sample volume affect its accuracy. Based on a systematic search, we identified studies that tested water samples (n = 2,034) using both the P/A H2S test and recognised tests for thermotolerant coliforms (TTC) or Escherichia coli. We calculated P/A H2S test specificity and sensitivity against a range of TTC and E. coli densities. For two studies, we compared this with sensitivity and specificity estimates for simulated 100 and 20 ml presence/absence tests. For most of the 19 included studies, as the threshold used to define contamination increased from 1 to 100 cfu/100 ml, P/A H2S test sensitivity increased but specificity decreased. Similarly, the simulation indicated that increasing test volumes from 20 to 100 ml increased sensitivity but reduced specificity. There was potential for bias, for example from lack of blinding during test interpretation, in most of the studies reviewed. In assessing the P/A H2S test as an alternative to standard methods, careful consideration of likely indicator bacteria levels and sample volume is required.

Water safety and inequality in access to drinking-water between rich and poor households.

While water and sanitation are now recognized as a human right by the United Nations, monitoring inequality in safe water access poses challenges. This study uses survey data to calculate household socio-economic-status (SES) indices in seven countries where national drinking-water quality surveys are available. These are used to assess inequalities in access as indicated by type of improved water source, use of safe water, and a combination of these. In Bangladesh, arsenic exposure through drinking-water is not significantly related to SES (p = 0.06) among households using tubewells, whereas in Peru, chlorine residual in piped systems varies significantly with SES (p < 0.0001). In Ethiopia, Nicaragua, and Nigeria, many poor households access nonpiped improved sources, which may provide unsafe water, resulting in greater inequality of access to "safe" water compared to "improved" water sources. Concentration indices increased from 0.08 to 0.15, 0.10 to 0.14, and 0.24 to 0.26, respectively, in these countries. There was minimal difference in Jordan and Tajikistan. Although the results are likely to be underestimates as they exclude individual-level inequalities, they show that use of a binary "improved"/"unimproved" categorization masks substantial inequalities. Future international monitoring programmes should take account of inequality in access and safety.

A spatial analysis of pit latrine density and groundwater source contamination.

This study aims to assess the relationship between chemical and microbial contamination of groundwater sources and a range of potential hazards in two peri-urban areas of Kisumu, Kenya where shallow wells and pit latrines are widely used. From 1998 to 2004, 263 samples were taken from 61 groundwater sources and tested for thermotolerant coliforms. Eighteen of these sources were also tested for chemical contaminants, including nitrate, chloride and fluoride. The locations of all water sources, buildings and pit latrines in the study area were surveyed. Local pit latrine densities were calculated using a geographic information system. Ten out 18 samples were above the World Health Organization guideline values for nitrate, 236 out of 263 were positive for thermotolerant coliforms, and all were above the guideline values for fluoride. There was neither a relationship between thermotolerant coliform levels and daily rainfall patterns nor with sanitary risk inspection scores for samples from shallow wells (r = 0.01, p = 0.91, n = 191). The density of pit latrines within a 100-m radius was significantly correlated with nitrate and chloride levels (r = 0.64, p = 0.004 and r = 0.46, p = 0.05, respectively) but not with thermotolerant coliforms (r = 0.22, p = 0.11). These results illustrate both the public health risks associated with shallow groundwater sources, on-site sanitation and high population density. These findings have implications for current policies that promote latrine construction, especially in peri-urban areas of high population density. More comprehensive studies of larger communities should be commissioned to extend this analysis of the links between latrine density and groundwater contamination and so identify the contingent policy risks.

Public perception of drinking water safety in South Africa 2002-2009: a repeated cross-sectional study.

BACKGROUND: In low and middle income countries, public perceptions of drinking water safety are relevant to promotion of household water treatment and to household choices over drinking water sources. However, most studies of this topic have been cross-sectional and not considered temporal variation in drinking water safety perceptions. The objective of this study is to explore trends in perceived drinking water safety in South Africa and its association with disease outbreaks, water supply and household characteristics. METHODS: This repeated cross-sectional study draws on General Household Surveys from 2002-2009, a series of annual nationally representative surveys of South African households, which include a question about perceived drinking water safety. Trends in responses to this question were examined from 2002-2009 in relation to reported cholera cases. The relationship between perceived drinking water safety and organoleptic qualities of drinking water, supply characteristics, and socio-economic and demographic household characteristics was explored in 2002 and 2008 using hierarchical stepwise logistic regression. RESULTS: The results suggest that perceived drinking water safety has remained relatively stable over time in South Africa, once the expansion of improved supplies is controlled for. A large cholera outbreak in 2000-02 had no apparent effect on public perception of drinking water safety in 2002. Perceived drinking water safety is primarily related to water taste, odour, and clarity rather than socio-economic or demographic characteristics. CONCLUSION: This suggests that household perceptions of drinking water safety in South Africa follow similar patterns to those observed in studies in developed countries. The stability over time in public perception of drinking water safety is particularly surprising, given the large cholera outbreak that took place at the start of this period.

A summary catalogue of microbial drinking water tests for low and medium resource settings.

Microbial drinking-water quality testing plays an essential role in measures to protect public health. However, such testing remains a significant challenge where resources are limited. With a wide variety of tests available, researchers and practitioners have expressed difficulties in selecting the most appropriate test(s) for a particular budget, application and setting. To assist the selection process we identified the characteristics associated with low and medium resource settings and we specified the basic information that is needed for different forms of water quality monitoring. We then searched for available faecal indicator bacteria tests and collated this information. In total 44 tests have been identified, 18 of which yield a presence/absence result and 26 of which provide enumeration of bacterial concentration. The suitability of each test is assessed for use in the three settings. The cost per test was found to vary from $0.60 to $5.00 for a presence/absence test and from $0.50 to $7.50 for a quantitative format, though it is likely to be only a small component of the overall costs of testing. This article presents the first comprehensive catalogue of the characteristics of available and emerging low-cost tests for faecal indicator bacteria. It will be of value to organizations responsible for monitoring national water quality, water service providers, researchers and policy makers in selecting water quality tests appropriate for a given setting and application.

Accounting for water quality in monitoring access to safe drinking-water as part of the Millennium Development Goals: lessons from five countries.

OBJECTIVE: To determine how data on water source quality affect assessments of progress towards the 2015 Millennium Development Goal (MDG) target on access to safe drinking-water. METHODS: Data from five countries on whether drinking-water sources complied with World Health Organization water quality guidelines on contamination with thermotolerant coliform bacteria, arsenic, fluoride and nitrates in 2004 and 2005 were obtained from the Rapid Assessment of Drinking-Water Quality project. These data were used to adjust estimates of the proportion of the population with access to safe drinking-water at the MDG baseline in 1990 and in 2008 made by the Joint Monitoring Programme for Water Supply and Sanitation, which classified all improved sources as safe. FINDINGS: Taking account of data on water source quality resulted in substantially lower estimates of the percentage of the population with access to safe drinking-water in 2008 in four of the five study countries: the absolute reduction was 11% in Ethiopia, 16% in Nicaragua, 15% in Nigeria and 7% in Tajikistan. There was only a slight reduction in Jordan. Microbial contamination was more common than chemical contamination. CONCLUSION: The criterion used by the MDG indicator to determine whether a water source is safe can lead to substantial overestimates of the population with access to safe drinking-water and, consequently, also overestimates the progress made towards the 2015 MDG target. Monitoring drinking-water supplies by recording both access to water sources and their safety would be a substantial improvement.

Intracellular pH regulation by Na⁺/H⁺ exchanger-1 (NHE1) is required for growth factor-induced mammary branching morphogenesis.

Regulation of intracellular pH (pHi) and protection against cytosolic acidification is primarily a function of the ubiquitous plasma membrane Na+/H+exchanger-1 (NHE1), which uses a highly conserved process to transfer cytosolic hydrogen ions (H+) across plasma membranes in exchange for extracellular sodium ions (Na+). Growth factors, which are essential regulators of morphogenesis, have also been found to be key activators of NHE1 exchanger activity; however, the crosstalk between both has not been fully evaluated during organ development. Here we report that mammary branching morphogenesis induced by transforming growth factor-alpha (TGFα) requires PI3K-dependent NHE1-activation and subsequent pHi alkalization. Inhibiting NHE1 activity after TGFα stimulation with 10 µM of the NHE1-specific inhibitor N-Methyl-N-isobutyl Amiloride (MIA) dramatically disrupted branching morphogenesis, induced extensive proliferation, ectopic expression of the epithelial hyper-proliferative marker Keratin-6 and sustained activation of MAPK. Together these findings indicate a novel developmental signaling cascade involving TGFα>PI3K>NHE1>pHi alkalization, which leads to a permissible environment for MAPK negative feedback inhibition and thus regulated mammary branching morphogenesis.

The H(2)S test versus standard indicator bacteria tests for faecal contamination of water: systematic review and meta-analysis.

OBJECTIVES: To assess the diagnostic accuracy of the H(2)S test for microbiological contamination of domestic water across different settings, as a basis for providing guidance on its use. METHODS: We searched a range of bibliographic and 'grey' literature databases to identify studies that had processed domestic water samples using both the H(2)S test and recognized tests for thermotolerant coliforms or Escherichia coli. We screened 661 study abstracts and identified 51 relevant studies based on 13 853 water samples. For each relevant study, we recorded the level of correspondence between the H(2)S and recognized tests, microbial testing procedures, details of the samples processed and study quality indicators. We conducted a meta-analysis to investigate the impact of testing procedures, study quality and sample characteristics on the diagnostic accuracy of the H(2)S test. RESULTS: H(2)S test implementation varied between studies, and the test's diagnostic accuracy varied significantly and substantially between studies. Little of this variation was explained by testing procedures, study quality or the nature of the samples processed. CONCLUSIONS: Although in widespread use, our findings suggest that the diagnostic accuracy, particularly specificity, of the H(2)S test is variable. Optimal conditions for conducting the test remain unclear. As H(2)S test accuracy is low in a minority of these studies, we recommend that its performance be evaluated relative to standard methods, prior to its operational deployment in a new setting.

Child dysentery in the Limpopo Valley: a cohort study of water, sanitation and hygiene risk factors.

The objective of this cohort study was to assess risk factors for child dysentery and watery diarrhoea. The study participants consisted of 254 children aged 12-24 months in rural South Africa and Zimbabwe in households where drinking water was collected from communal sources. The main outcome measure was the most severe diarrhoea episode: dysentery, watery diarrhoea or none. For dysentery, drinking water from sources other than standpipes had a relative risk ratio of 3.8 (95% CI 1.5-9.8). Poor source water quality, as indicated by Escherichia coli counts of 10 or more cfu 100 ml(-1), increased risk by 2.9 (1.5-5.7). There were no other significant risk factors for dysentery and none for watery diarrhoea. In this study, endemic dysentery is associated only with faecal contamination of source water. Sources other than standpipes, including improved groundwater, are of greater risk. Remediation of water quality by treatment at source or in the household will be required to achieve access to safe drinking water in accordance with the 7th Millennium Development Goal.