Detection of Escherichia coli, Salmonella species, and Vibrio cholerae in tap water and bottled drinking water in Isfahan, Iran

Global and regional final point-of-drinking water prevalence of Vibrio pathogens: a systematic analysis with socioeconomic, global health security, and WASH indices-guided meta-regressions

The final point-of-drinking water (FPODW) exposure to Vibrio and waterborne pathogens remains a misaim surveillance target. Therefore, the current study purposed to estimate the global and regional prevalence of Vibrio pathogens in FPODW. Vibrio-FPODW data derived from integrated databases per PRISMA protocol were fitted to a random-intercept-logistic mixed-effects and meta-regression models. The global FPODW Vibrio prevalence was 5.13% (95%CI: 2.24-11.30) with 7.76% (6.84-8.78) cross-validated value. Vibrio prevalence in different FPODW varied with the highest in unclassified (13.98%, 3.98-38.95), household stored (6.42%, 1.16-28.69), municipal (4.39%, 1.54-11.90), and bottled (1.06%, 0.00-98.57) FPODW. Regionally, FPODW Vibrio prevalence varied significantly with highest in Africa (6.31%, 0.49-47.88), then Asia (4.83%, 2.01-11.18). Similarly, it varied significantly among income classification with the highest from low-income (8.77%, 0.91-50.05), then lower-middle-income (6.16%, 2.75-13.20), upper-middle-income (0.23%, 0.00-82.04), and 0.94% (0.19-2.72) in high-income economies. Among the WHO region, it varied significantly from 1.41% (0.17-10.45) in Eastern Mediterranean, 6.31% (0.49-47.88) in Africa to 8.86% (3.85-19.06) in South-East Asia and declining among SDI-quintiles from 11.64% (3.29-33.83) in Low-SDI, 10.59% (4.58-22.61) in High-middle-SDI to 0.26% (0.01-9.09) in Middle-SDI. FPODW Vibrio prevalence was 7.31% (2.94-17.03) in the low-GHSIG, followed by 4.55% (0.00-100.00) in the upper-GHSIG, and 2.21% (0.31-14.24) in middle-GHSIG; rural (4.18%, 0.06-76.17) and urban (5.28%, 2.35-11.44) settings. Also, sample size, SDI, SDI-quintiles, and nation significantly explained 14.12%, 10.91%, 30.35%, and 87.65% variance in FPODW Vibrio prevalence, respectively as a univariate influence. Additionally, 11.90% variance in FPODW Vibrio prevalence explained mortality rate attributed to unsafe WASH services. In conclusion, the study revealed a substantial high FPODW prevalence of Vibrio calling for initiative-taking and intentional surveillances of waterborne pathogens at the neglected stage across nations in order to achieve sustainably the SDG 3.

Multiple pathogen contamination of water, hands, and fomites in rural Nepal and the effect of WaSH interventions

Water, Sanitation, and Hygiene (WaSH) interventions are the most effective in reducing diarrheal disease severity and prevalence. However, very few studies have investigated the effectiveness of WaSH intervention in reducing pathogen presence and concentration. In this study, we employed a microfluidic PCR approach to quantify twenty bacterial pathogens in water (n = 360), hands (n = 180), and fomite (n = 540) samples collected in rural households of Nepal to assess the pathogen exposures and the effect of WaSH intervention on contamination and exposure rates. The pathogen load and the exposure pathways for each pathogen in intervention and control villages were compared to understand the effects of WaSH intervention. Pathogens were detected in higher frequency and concentration from fomites samples, toilet handle (21.42%; 5.4,0 95%CI: mean log10 of 4.69, 5.96), utensils (23.5%; 5.47, 95%CI: mean log10 of 4.77, 6.77), and water vessels (22.42%; 5.53, 95%CI: mean log10 of 4.79, 6.60) as compared to cleaning water (14.36%; 5.05, 95%CI: mean log10 of 4.36, 5.89), drinking water (14.26%; 4.37, 85%CI: mean log10 of 4.37, 5.87), and hand rinse samples (16.92%; 5.49, 95%CI: mean log10 of 4.77, 6.39). There was no clear evidence that WaSH intervention reduced overall pathogen contamination in any tested pathway. However, we observed a significant reduction (p < 0.05) in the prevalence, but not concentration, of some target pathogens, including Enterococcus spp. in the intervention village compared to the control village for water and hands rinse samples. Conversely, no significant reduction in target pathogen concentration was observed for water and hand rinse samples. In swab samples, there was a reduction mostly in pathogen concentration rather than pathogen prevalence, highlighting that a reduction in pathogen prevalence was not always accompanied by a reduction in pathogen concentration. This study provides an understanding of WaSH intervention on microbe concentrations. Such data could help with better planning of intervention activities in the future.

Microbiological quality of water samples obtained from water sources in Ishaka, Uganda

Objectives

This study aimed to evaluate the microbiological quality of water sources in Ishaka division, Bushenyi district.

Methods

Water from taps, wells and springs were sampled for the cross-sectional investigation. The enumeration and identification of microbes (Escherichia coli, Salmonella, Shigella, Proteus, Staphylococcus aureus and total coliforms) in water samples were carried out using a variety of methods. Escherichia coli was enumerated using the membrane filtration method; Salmonella, Shigella and Proteus using a two-step enrichment method; Staphylococcus aureus using the surface spread method and total coliforms using the most probable number technique. Mannitol salt agar was used for enumeration of Staphylococcus Aureus and violet red bile agar was used for enumeration of total coliforms and Escherichia coli; xylose lysine deoxycholate agar was used for both Salmonella spp. and Shigella spp. API-20E was used to phenotypically identify the Enterobacteriaceae contaminants in water. These included Escherichia coli, Proteus mirabilis, Proteus vulgaris, Salmonella spp. and Staphylococcus aureus.

Results

Escherichia coli counts in the water from springs and wells ranged from 0 to 314 cfu/mL (p = 0.173) and 0 to 3 cfu/mL (p = 0.269), respectively, while tap water had no incidence of Escherichia coli. Highest level of bacterial contamination in water sources, beyond acceptable WHO (0 cfu/100 mL) limits for drinking water, was reported: Proteus spp., 34 (54.8%), followed by total coliforms, 24 (38.7%), Shigella spp., 22 (35.5%) and least were Salmonella spp. (8.1%) and Staphylococcus aureus spp. (8.1%).

Conclusion

It is therefore concluded that spring and well community water sources in Ishaka division, Uganda, are significantly contaminated with pathogenic bacteria and thus unsafe for drinking without adequate water treatment (disinfection and filtration).

Detecting Enteric Pathogens in Low-Risk Drinking Water in Dhaka, Bangladesh: An Assessment of the WHO Water Safety Categories

The microbiological quality of water is usually assessed by fecal coliform bacteria, and the presence of E. coli as an indicator of fecal contamination is widely recommended by international guidelines. This study aimed to assess the prevalence of diarrheagenic pathogens, in both public and personal domain water sources and examine the reliance on the WHO drinking water risk assessment guidelines. This study was conducted in a low-income urban community in Dhaka, Bangladesh between September 2014 and October 2015. Polymerase chain reaction (PCR) was used to detect the marker and virulence genes of Escherichia coli, Vibrio cholerae, Salmonella species, and Campylobacter species, and the culture method was employed for the quantitative assessment of E. coli. According to the WHO guidelines, 48% of the public domain source water and 21% of the personal domain point-of-drinking water were classified in the low-risk group, i.e., 0 CFU of E. coli/100 mL. However, when using PCR, we detected pathogens in 39% (14/36) of the point-of-drinking water samples and 65% (74/114) of the public domain water source samples classified in the low-risk group. Our study showed that relying solely on E. coli detection as a measure of water quality may overlook the presence of other pathogens in the drinking water. In addition to the culture-based method, the detection of virulence genes by PCR should also be considered to add more scrutiny to the detection of diverse types of pathogens.

Caco-2 cell-derived biomimetic electrochemical biosensor for cholera toxin detection

Cholera is a highly contagious and lethal waterborne disease induced by an infection with Vibrio cholerae (V. cholerae) secreting cholera toxin (CTx). Cholera toxin subunit B (CTxB) from the CTx specifically binds with monosialo-tetra-hexosyl-ganglioside (GM1) found on the exterior cell membrane of an enterocyte. Bioinspired by the pathological process of CTx, we developed an electrochemical biosensor with GM1-expressing Caco-2 cell membrane (CCM) on the electrode surface. Briefly, the electrode surface was functionalized with CCM using the vesicle fusion method. We determined the CTxB detection performances of Caco-2 cell membrane-coated biosensor (CCB) using electrochemical impedance spectroscopy (EIS). the CCB had an excellent limit of detection of ∼11.46 nM and a detection range spanning 100 ng/mL - 1 mg/mL. In addition, the CCB showed high selectivity against various interfering molecules, including abundant constituents of intestinal fluid and various bacterial toxins. The long-term stability of the CCBs was also verified for 3 weeks using EIS. Overall, the CCB has excellent potential for practical use such as point-of-care and cost-effective testing for CTxB detection in developing countries.

A novel PCR-free and label-free cloth-based DNA sensor for sensitive and rapid detection of Escherichia coli

BACKGROUND

As is known to all, pathogenic bacteria have a serious impact on human health. The development of sensitive, simple, rapid and low-cost bacterial detection method is necessary. Nowadays, some conventional methods (such as plate count, polymerase chain reaction (PCR) and immunological techniques) can not meet the above needs. This work was aimed at providing a new method for addressing these unmet needs.

RESULT

This study proposed a novel PCR-free and label-free DNA sensor based on multiple linear hybridization chain reaction (ML-HCR) and cloth-based closed bipolar electrochemiluminescence for sensitive and rapid detection of Escherichia coli (E. coli). The target DNA can be obtained from the E. coli genomic DNA by using the restriction enzyme instead of PCR. The auxiliary probe-triggered ML-HCR is carried out with continuous hybridization of two hairpin DNA, and as a result the double stranded DNA is formed to provide a large number of binding sites for Ru(bpy)₃²⁺. The whole detection is PCR-free and label-free, and thus the detection procedure is easier and faster. Under optimized conditions, the linear detection range was from 10² to 10⁷ CFU/mL, and the detection limit was low to 38 CFU/mL. In addition, the proposed DNA sensor has an acceptable selectivity, stability and reproducibility, and is successfully applied to detect E. coli in milk samples with the recoveries from 96.24% to 105.98%.

SIGNIFICANCE

The proposed DNA sensor has broad application prospects in the fields of bacterial detection and gene diagnose. Further, this method has potential to be extended for establishing miniaturized, integrated, and automated detection system.

Multispecies biofilm architecture determines bacterial exposure to phages

Numerous ecological interactions among microbes-for example, competition for space and resources, or interaction among phages and their bacterial hosts-are likely to occur simultaneously in multispecies biofilm communities. While biofilms formed by just a single species occur, multispecies biofilms are thought to be more typical of microbial communities in the natural environment. Previous work has shown that multispecies biofilms can increase, decrease, or have no measurable impact on phage exposure of a host bacterium living alongside another species that the phages cannot target. The reasons underlying this variability are not well understood, and how phage-host encounters change within multispecies biofilms remains mostly unexplored at the cellular spatial scale. Here, we study how the cellular scale architecture of model 2-species biofilms impacts cell-cell and cell-phage interactions controlling larger scale population and community dynamics. Our system consists of dual culture biofilms of Escherichia coli and Vibrio cholerae under exposure to T7 phages, which we study using microfluidic culture, high-resolution confocal microscopy imaging, and detailed image analysis. As shown previously, sufficiently mature biofilms of E. coli can protect themselves from phage exposure via their curli matrix. Before this stage of biofilm structural maturity, E. coli is highly susceptible to phages; however, we show that these bacteria can gain lasting protection against phage exposure if they have become embedded in the bottom layers of highly packed groups of V. cholerae in co-culture. This protection, in turn, is dependent on the cell packing architecture controlled by V. cholerae biofilm matrix secretion. In this manner, E. coli cells that are otherwise susceptible to phage-mediated killing can survive phage exposure in the absence of de novo resistance evolution. While co-culture biofilm formation with V. cholerae can confer phage protection to E. coli, it comes at the cost of competing with V. cholerae and a disruption of normal curli-mediated protection for E. coli even in dual species biofilms grown over long time scales. This work highlights the critical importance of studying multispecies biofilm architecture and its influence on the community dynamics of bacteria and phages.

Microbial contamination and quantitative microbial risk assessment of high-density polyethylene (HDPE) film sachet drinking water in Ghana

The present research estimated the impact of storage on the microbial quality of high-density polyethylene drinking water. Samples were taken from two popular companies in Greater Accra using a two-sided exact test in SAS JMP to estimate the sample size. The samples were stored across three temperature profiles at 8 °C, 30 °C (average room temperature), and 40 °C (average outdoor temperature) for 28 days. The samples were examined using standard microbiological methods for heterotrophic plate counts (HPCs), faecal coliforms, and Escherichia coli. The data were described and regressed with Microsoft Excel, Argo 4.3.1, and SAS JMP software. The results demonstrated increasing deterioration of the water samples for all microbial indices at all temperatures with increasing storage duration. The highest HPC, faecal coliforms, and E. coli were 1,312; 622; and 252 cfu/100 mL, respectively, all at 40 °C. The daily risk of infection due to E. coli O157:H7 was 5.22 × 10^-5 infections per child per day for children under 5 years, and 1.6 × 10^-4 attacks per adult per day, compared to the upper limit of 1.0 × 10^-6. These results are higher than recommended exposures, and interventions along the sachet drinking water value chain are needed to protect public health.

Direct and Rapid Identification of Vibrio Cholerae Serogroup and Toxigenicity by a Novel Multiplex Real-Time Assay

Molecular diagnostic assays for cholera detection have superior sensitivity to conventional assays and are now being accepted as the new standard method, especially the real-time PCR/RT-PCR. However, limited throughput capacity and long detection duration prevent them from detecting more specimens and more targets in one turnaround time simultaneously. In this study, we utilized nucleic acid extraction-free, direct RT-PCR and high-speed amplification to develop a novel multiplex assay, a quadplex direct one-tube real-time RT-PCR assay, for rapid detection of the serogroup and cholera toxin toxigenicity of Vibrio cholerae targeting the epsM, ctxA, rfb-O1, and rfb-O139 genes. Performance of the multiplex assay was evaluated by comparison with the monoplex real-time PCR assay according to the China Cholera Prevention Manual. Detection data from clinical specimens showed that the new assay had good diagnostic sensitivities for epsM (100%, n = 301), ctxA (100%, n = 125), rfb-O1 (100%, n = 85), and rfb-O139 (97.87%, n = 49). Analysis of the analytical sensitivities with serial dilutions of positive standards showed that the detection limits of the new assay for Vibrio cholerae epsM,ctxA,rfb-O1, and rfb-O139 were up to 200, 590, 115, and 1052 copies per mL lower than the monoplex real-time PCR (910, 345, and 1616 copies/mL respectively, for ctxA,rfb-O1, and rfb-O139). The results indicate that the multiplex assay is a rapid, sensitive, specific, and easy-to-use detection tool for Vibrio cholerae, especially suitable for rapid identification and screening detection of mass specimens.

On-Farm Practices Associated with Multi-Drug-Resistant Escherichia coli and Vibrio parahaemolyticus Derived from Cultured Fish

Aquaculture activities have been implicated as responsible for the emergence of antimicrobial resistance (AMR), leading to broad dissemination and transference of antibiotic resistance to pathogens that affect humans and animals. The current study investigates the on-farm practices and environmental risk factors that can potentially drive the development and emergence of multi-drug-resistant (MDR) Escherichia coli and Vibrio parahaemolyticus in the aquaculture system. A cross-sectional study was conducted on 19 red hybrid tilapia (Oreochromis spp.) and 13 Asian seabass (Lates calcarifer, Bloch 1970) farms on the west coast of peninsular Malaysia. Data were collected using a structured questionnaire pertaining to farm demography, on-farm management practices and environmental characteristics. Multi-drug-resistant E. coli (n = 249) and V. parahaemolyticus (n = 162) isolates were analyzed using multi-level binary logistic regression to identify important drivers for the occurrence and proliferation of the MDR bacteria. On-farm practices such as manuring the pond (OR = 4.5; 95% CI = 1.21–16.57) were significantly associated with the occurrence of MDR E. coli, while earthen ponds (OR = 8.2; 95% CI = 1.47–45.2) and human activity adjacent to the farm (OR = 4.6; 95% CI = 0.75–27.98) were associated with an increased likelihood of MDR V. parahaemolyticus. Considering the paucity of information on the drivers of AMR in the aquaculture production in this region, these findings indicate the targeted interventions implementable at aquaculture farms to efficiently abate the risk of MDR amongst bacteria that affect fish that are of public health importance.

Cholera diagnosis in human stool and detection in water: A systematic review and meta-analysis

Background

Cholera continues to pose a problem for low-resource, fragile and humanitarian contexts. Evidence suggests that 2.86 million cholera cases and 95,000 deaths due to cholera are reported annually. Without quick and effective diagnosis and treatment, case-fatality may be 50%. In line with the priorities of the Global Task Force on Cholera Control, we undertook a systematic review and meta-analysis of diagnostic test accuracy and other test characteristics of current tests for cholera detection in stool and water.

Methods

We searched 11 bibliographic and grey literature databases. Data was extracted on test sensitivity, specificity and other product information. Meta-analyses of sensitivity and specificity were conducted for tests reported in three or more studies. Where fewer studies reported a test, estimates were summarised through narrative synthesis. Risk of Bias was assessed using QUADAS-2.

Results

Searches identified 6,637 records; 41 studies reporting on 28 tests were included. Twenty-two tests had both sensitivities and specificities reported above 95% by at least one study, but there was, overall, wide variation in reported diagnostic accuracy across studies. For the three tests where meta-analyses were possible the highest sensitivity meta-estimate was found in the Cholera Screen test (98.6%, CI: 94.7%-99.7%) and the highest specificity meta-estimate in the Crystal VC on enriched samples (98.3%, CI: 92.8%-99.6%). There was a general lack of evidence regarding field use of tests, but where presented this indicated trends for lower diagnostic accuracy in field settings, with lesser-trained staff, and without the additional process of sample enrichment. Where reported, mean test turnaround times ranged from over 50% to 130% longer than manufacturer’s specification. Most studies had a low to unclear risk of bias.

Conclusions

Currently available Rapid Diagnostic Tests can potentially provide high diagnostic and detection capability for cholera. However, stronger evidence is required regarding the conditions required to secure these levels of accuracy in field use, particularly in low-resource settings.

Registration

PROSPERO (CRD42016048428).

Potentially pathogenic Escherichia coli from household water in peri-urban Ibadan, Nigeria

Feco-orally transmitted infectious diseases are common in Nigeria where the potable water access is poor. In the south-western Nigerian Ibadan metropolis, supply of municipal water is meagre as residents depend on household wells and boreholes. The likelihood of fecal contamination of household water sources in Ibadan was examined longitudinally to quantify and understand its impact. Well and borehole water samples aseptically collected from 96 households in Ibadan were assessed for total heterotrophic counts (THCs), total coliform counts (TCCs) and total Escherichia coli counts (TECs) using a pour plate technique. E. coli were identified by uidA and whole-genome sequencing using Illumina technology, whereas virulence factors were predicted using VirulenceFinder. There was season-independent abundance of THC and TCC in the well and borehole with a significant recovery of E. coli in the wells during the wet season compared to the dry season (P = 0.0001). Virulence genes associated with pathogenic E. coli were identified in 13 (52%) strains with one E. coli each classified as extra-intestinal E. coli, avian pathogenic E. coli and enteroaggregative E. coli. High heterotrophic and coliform counts, with rainfall-driven E. coli contamination revealed that the water sources evaluated in this study are unfit for consumption.

Antimicrobial effects of Cynara scolymus essential oil: In vitro analysis

By benefits of using silicon and vermicompost based biofertilizers and also induction of drought stress for growing more efficient medicinal plants, we investigated such issues on growing Cynara scolymus (C. scolymus), as one of the most significant edible medicinal plants. In this regard, the antimicrobial effects of grown C. scolymus essential oil was investigated against some foodborne pathogens. Different concentrations of silicon and vermicompost with and without drought stress were considered for growing the plant and the extracted essential oils were extracted to examine their antimicrobial effects against different bacterial agents. Using vermicompost and silicon and 50% moisture discharge yielded significant increase in the mean diameter of growth inhibition zone and significant decrease in the minimum inhibitory concentration of tested bacteria (P <  0.05). The highest diameters of the inhibition zones of S. aureus, S. saprophyticus, P. aeruginosa, S. dysenteriae, and S. typhi were found for C. scolymus essential oil treated with 8 mmol silicon and conventional irrigation (14.92 mm), 4 mmol silicon and 50% moisture discharge (15.28 mm), 50% vermicompost and 50% moisture discharge (15.71 mm), 8 mmol silicon and conventional irrigation (17.34 mm) and 25% vermicompost, and 50% moisture discharge (15.48 mm), respectively. Antimicrobial effects of some treatments of C. scolymus were higher than some kinds of referenced antibiotics such as erythromycin. These findings could be used for the production of antibiotic drugs for specific purposes against certain bacteria.

Antimicrobial effects of Arctium lappa against infectious bacteria: Experimental in vitro analysis

Arctium lappa (A. lappa) is one of the most significant edible medicinal plants with high antibacterial effects, in which it could be supposed to grow with more beneficial effects under administration by salicylic acid and chitosan based biofertilizers. Accordingly, the effects of salicylic acid, chitosan, and 50% moisture discharge were investigated in this work to see the antimicrobial treatments of some foodborne pathogens effects by A. lappa. To this aim, plants were cultivated based on different concentrations of salicylic acid and chitosan with/without drought stress, in which their extracted essential oils were examined for showing the antimicrobial effect against different bacterial agents. The results indicated that the salicylic acid and chitosan administrated A. lappa could work with improved inhibitory functions. Comparing with referenced antibiotics showed even higher antimicrobial effects of A. lappa against the targeted bacterial agents, in which the species with 14 mmol of salicylic acid and 2 g/l of chitosan was a distinguished one for approaching the purpose. Consequently, the achievements of this work could be further investigated for producing novel antibiotic drug agents.

Prevalence and Antimicrobial Resistance of Escherichia coli, Salmonella and Vibrio Derived from Farm-Raised Red Hybrid Tilapia (Oreochromis spp.) and Asian Sea Bass (Lates calcarifer, Bloch 1970) on the West Coast of Peninsular Malaysia

Antibiotics are widely used in intensive fish farming, which in turn increases the emergence of antimicrobial-resistant (AMR) bacteria in the aquatic environment. The current study investigates the prevalence and determines the antimicrobial susceptibility of E. coli, Salmonella, and Vibrio in farmed fishes on the west coast of Peninsular Malaysia. Over a period of 12 months, 32 aquaculture farms from the Malaysian states of Selangor, Negeri Sembilan, Melaka, and Perak were sampled. Both E. coli and Salmonella were highly resistant to erythromycin, ampicillin, tetracycline, and trimethoprim, while Vibrio was highly resistant to ampicillin and streptomycin. Resistance to the antibiotics listed as the highest priority and critically important for human therapy, such as colistin in E. coli (18.1%) and Salmonella (20%) in fish, is a growing public health concern. The multi-drug resistance (MDR) levels of E. coli and Salmonella in tilapia were 46.5% and 77.8%, respectively. Meanwhile, the MDR levels of E. coli, Salmonella, V. parahaemolyticus, V. vulnificus and V. cholerae in Asian seabass were 34%, 100%, 21.6%, 8.3% and 16.7%, respectively. Our findings provide much-needed information on AMR in aquaculture settings that can be used to tailor better strategies for the use of antibiotics in aquaculture production at the local and regional levels.

Socio-Economic Inequalities in Access to Drinking Water among Inhabitants of Informal Settlements in South Africa

While evidence from several developing countries suggests the existence of socio-economic inequalities in the access to safe drinking water, a limited number of studies have been conducted on this topic in informal settlements. This study assessed socio-economic inequalities in the use of drinking water among inhabitants of informal settlements in South Africa. The study used data from “The baseline study for future impact evaluation for informal settlements targeted for upgrading in South Africa.” Households eligible for participation were living in informal settlements targeted for upgrading in all nine provinces of South Africa. Socio-economic inequalities were assessed by means of multinomial logistic regression analyses, concentration indices, and concentration curves. The results showed that the use of a piped tap on the property was disproportionately concentrated among households with higher socio-economic status (concentration index: +0.17), while households with lower socio-economic status were often limited to the use of other inferior (less safe or distant) sources of drinking water (concentration index for nearby public tap: −0.21; distant public tap: −0.17; no-tap water: −0.33). The use of inferior types of drinking water was significantly associated with the age, the marital status, the education status, and the employment status of the household head. Our results demonstrate that reducing these inequalities requires installing new tap water points in informal settlements to assure a more equitable distribution of water points among households. Besides, it is recommended to invest in educational interventions aimed at creating awareness about the potential health risks associated with using unsafe drinking water.

A method for correcting underestimation of enteric pathogen genome quantities in environmental samples

Exposure to enteric pathogens in the environment poses a serious risk for infection and disease. The accurate detection and quantification of enteric pathogens in environmental samples is critical for understanding pathogen transport and fate and developing risk assessment models. In this study, we successfully applied TaqMan real-time PCR assays to quantitatively detect five human-specific pathogens (Shigella/EIEC, Salmonella Typhi, Vibrio cholera, Norovirus, and Giardia) in samples from open drains, canals, floodwater, septic tanks, and anaerobic baffled reactors (ABR) collected in Mirpur, Dhaka, Bangladesh from April to October 2019. Overall, the grab and sediment samples showed low inhibition but the ultrafiltration samples collected from open drain had significantly higher (P = 0.0049) degree of PCR inhibition (median Ct = 31.06) compared to the extraction controls (Ct = 28.54). We developed a two-step method to adjust underestimation of pathogen quantities due to PCR inhibition and non-optimum PCR efficiency. Compared to other sample types, ultrafiltration samples demonstrated a wide range of concentration increase (1.0%-182.5%) by pathogens after adjusting for PCR inhibition and non-optimum efficiencies. These quantitative qPCR assays are successful in quantifying multiple enteric pathogens in environmental samples, and the adjustment method would be useful for correcting underestimates of pathogen quantities due to partial PCR inhibition and non-optimum efficiency.

Microbial contamination and its associations with major ions in shallow groundwater along coastal Tamil Nadu

Microbes in groundwater play a key role in determining the drinking water quality of the water. The study aims to interpret the sources of microbes in groundwater and its relationship to geochemistry. The study was carried out by collecting groundwater samples and analyzed to obtain various cations and anions, where HCO₃^-, Cl^- and NO₃^- found to be higher than permissible limits in few samples. Microbial analysis, like total coliform (TC), total viable counts (TVC), fecal coliforms (FC), Vibrio cholera (V. cholerae) and total Streptococci (T. streptococci) were analyzed, and the observations reveal that most of the samples were found to be above the permissible limits adopted by EU, BIS, WHO and USEPA standards. Correlation analysis shows good correlation between Mg²⁺-HCO₃^-, K⁺-NO₃^-, TVC- V. cholerae and T. streptococci-FC. Major ions like Mg⁺, K⁺, NO₃, Ca²⁺ and PO₄ along with TS and FC were identified to control the geochemical and microbial activities in the region. The magnesium hardness in the groundwater is inferred to influence the TVC and V. cholerae. The mixing of effluents from different sources reflected the association of Cl with TC. Population of microbes T. streptococci and FC was mainly associated with Ca and Cl content in groundwater, depicting the role of electron acceptors and donors. The sources of the microbial population were observed with respect to the land use pattern and the spatial distribution of hydrogeochemical factors in the region. The study inferred that highest microbial activity in the observed in the residential areas, cultivated regions and around the landfill sites due to the leaching of sewage water and fertilizers runoff into groundwater. The concentrations of ions and microbes were found to be above the permissible limits of drinking water quality standards. This may lead to the deterioration in the health of particular coastal region.

Assessment of Bacterial Load in Polyethylene Terephthalate (PET) Bottled Water Marketed in Kathmandu Valley, Nepal

In recent years, we are having mixed feelings regarding the use of polyethylene terephthalate (PET) bottles for storing water. The aim of this study is to determine any associations between bacterial load and the physical condition of the water bottle. For this study, bottled water was purchased, and parameters like pH, electrical conductivity (EC), total dissolved solids (TDS), heterotrophic plate count (HPC), total coliform count, and Pseudomonas spp. count were determined as per the American Public Health Association, 2005. The pH value of water samples tested ranged from 5.2 to 6.8. The majority of samples (96%) were found to contain pH values that were unacceptable as per the Department of Food Technology and Quality Control (DFTQC) guideline. Value of electrical conductivity (EC) ranged from 5 to 199 μS/cm. HPC revealed that, out of 100 samples, 48 (48%) samples were found to be acceptable as per the DFTQC guideline value (<25 cfu/mL). Among 100 samples, Pseudomonas spp. was found to be present in 23% of bottled water. Acidic pH and elevated concentrations of TDS and EC may lead to the survival of extremophiles present in HPC which may lead to degradation of PET. Extremophile bacteria that survive in bottled water for a long time rely on several survival mechanisms including evolutionary development (evo-devo) and solely survive on complex polymers like PET.

Bottled water brands are contaminated with multidrug resistant bacteria in Nairobi, Kenya

Background: The demand for drinking water has necessitated the proliferation of bottled water companies in Kenya. This study evaluated if retailed bottled water in Nairobi Kenya complies with both local and international reference criteria. Methods: A total of 42 different water brands (25 approved by Kenya Revenue Authority (KRA) and 17 banned brands) were analyzed for both physicochemical and bacteriological quality. The spread plate method was used to obtain the total plate count of bacteria, while the membrane filter method was used to obtain total coliform count (TCC) and fecal coliform count (FCC). Structured interviews were used to gather company-related information. Results: Overall, 16% of KRA-approved and 35.3% of banned bottled water were contaminated with heterotrophic bacteria. Of the approved water brands, 4% were positive for total coliforms, compared with 17% of the banned brands.  Similarly, 4% and 17% approved and banned water brands were positive for fecal coliforms, respectively. Escherichia coli (19.1%), Pseudomonas spp. (9.5%) and Klebsiella spp. (4.8%) were the most common bacterial types isolated from all water brands, most of which exhibited multidrug resistance. In multivariable analysis, water companies that cleaned pipework and bottles using chlorine-based disinfectants (OR 0.08, 95% CI 0.01 to 0.8), those that had food safety programs (OR 0.1, 95% CI 0.019 to 0.9), had standard operating procedures (SOP) for water sourcing (OR 0.1, 95% CI 0.012 to 0.9) and SOP for contamination protection (OR 0.1, 95% CI 0.02 to 0.9) remained independently associated with bottled water brands exceeding WHO TCC limits. Conclusions: A number of bottled water brands were contaminated with one or more types of indicator bacteria, some of which were multidrug-resistant. Water bottling companies' processes contribute to contamination. Rigorous regulation and monitoring will improve water quality and safety.

Bottled water brands are contaminated with multidrug resistant bacteria in Nairobi, Kenya

Background: The demand for drinking water has necessitated the proliferation of bottled water companies in Kenya. This study evaluated if retailed bottled water in Nairobi Kenya complies with both local and international reference criteria.

Methods: A total of 42 different water brands (25 approved by Kenya Revenue Authority (KRA) and 17 banned brands) were analyzed for both physicochemical and bacteriological quality. The spread plate method was used to obtain the total plate count of bacteria, while the membrane filter method was used to obtain total coliform count (TCC) and fecal coliform count (FCC). Structured interviews were used to gather company-related information.

Results: Overall, 16% of KRA-approved and 35.3% of banned bottled water were contaminated with heterotrophic bacteria. Of the approved water brands, 4% were positive for total coliforms, compared with 17% of the banned brands.  Similarly, 4% and 17% approved and banned water brands were positive for fecal coliforms, respectively. Escherichia coli (19.1%), Pseudomonas spp. (9.5%) and Klebsiella spp. (4.8%) were the most common bacterial types isolated from all water brands, most of which exhibited multidrug resistance. In multivariable analysis, water companies that cleaned pipework and bottles using chlorine-based disinfectants (OR 0.08, 95% CI 0.01 to 0.8), those that had food safety programs (OR 0.1, 95% CI 0.019 to 0.9), had standard operating procedures (SOP) for water sourcing (OR 0.1, 95% CI 0.012 to 0.9) and SOP for contamination protection (OR 0.1, 95% CI 0.02 to 0.9) remained independently associated with bottled water brands exceeding WHO TCC limits.

Conclusions: A number of bottled water brands were contaminated with one or more types of indicator bacteria, some of which were multidrug-resistant. Water bottling companies’ processes contribute to contamination. Rigorous regulation and monitoring will improve water quality and safety.

Assessing the Sustainability and Acceptance Rate of Cost-Effective Household Water Treatment Systems in Rural Communities of Makwane Village, South Africa

The current study investigated the acceptance rate and long-term effectiveness of cost-effective household water treatment systems deployed in Makwane Village. A structured questionnaire was used prior to implementation to collect information such as level of education, level of employment, and knowledge about point-of-use water treatment systems in the target area. The long-term effectiveness was determined by factors such as the Escherichia coli removal efficiency, turbidity reduction, silver leached, and flow rate of the household water treatment devices. The results of the survey prior to deployment revealed that only 4.3% of the community had a tertiary qualification. Moreover, 54.3% of the community were unemployed. The results further revealed that 65.9% of the community were knowledgeable about other point-of-use water treatment methods. The acceptance rate, which was found to be initially higher (100%), reduced after three months of implantation (biosand filter with zeolite-silver clay granular—82.9%; silver-impregnated porous pot filters—97.1%). Moreover, the long-term effectiveness was determined, taking into consideration the adoption rate, and it was found that silver-impregnated porous pot filters have a long life compared to biosand filter with zeolite-silver clay granular. Although household water treatment systems can effectively reduce the burden of waterborne diseases in impoverished communities, the success of adoption is dependent on the targeted group. This study highlights the significance of involving community members when making the decision to scale up household water treatment devices in rural areas for successful adoption.

Molecular characterization of antimicrobial resistance and virulence genes of Escherichia coli isolates from bovine mastitis

Background and Aim:

Mastitis is a common and economically important disease in dairy cattle. It remains one of the most common reasons for the extensive use of antimicrobials in dairy farms leading to the emergence of antimicrobial-resistant pathogens. The aim of this study was to determine the patterns of antimicrobial resistance of Escherichia coli isolates from bovine mastitis and to identify prominent antimicrobial resistance and virulence genes among isolated strains.

Materials and Methods:

Antimicrobial susceptibility testing against six antibiotic groups, including tetracyclines, aminoglycosides, beta-lactams, macrolides, sulfonamides, and fluoroquinolones was performed using the disk diffusion method. PCR was performed on resistant isolates to detect resistance and virulence genes using commercially available primers.

Results:

Out of 216 milk samples cultured, 14 samples yielded E. coli isolates. All isolates (100%) were resistant to ampicillin, amoxicillin, procaine penicillin, streptomycin, oxytetracycline, and sulfamethoxazole-trimethoprim. Only one isolate (7%) was sensitive to gentamicin, and all isolates (100%) were sensitive to enrofloxacin and ciprofloxacin. All isolates carried at least one resistance gene against one or more of the major antibiotic groups. All isolates carried the ereA, tetG, tetE, and tetB genes, followed by tetA (93%), ampC (86%), strA (86%), sul1 (78%), tetD (71%), tetC (57%), aadA (57%), and strB (36%). The lowest percentage of isolates carried bla1 (17%) and bla2 (12%) genes, and none of the isolates carried the qnrA gene. Most of the isolates (93%) carried the Shiga toxin 1 virulence gene, followed by complement resistance protein (79%), intimin (64%), Shiga toxin 2 (36%), cytotoxic necrotizing factor (35%), aerotaxis receptor (21%), and type 1 fimbriae (15%).

Conclusion:

Results of this study indicate that the high percentages of E. coli isolate from bovine mastitis are resistant to two or more of the major antibiotic groups, irrespective of the presence or absence of relevant resistance or virulence genes.

A novel filtration system based on ceramic silver-impregnated pot filter combined with adsorption processes to remove waterborne bacteria

Halving the proportion of the people without sustainable access to safe drinking water and basic sanitation is among the Sustainable Development Goals (SDG). Lack of access to safe drinking water has been associated with the prevalence of waterborne diseases. Due to this reported association, the development of household water treatment devices has been an alternative to improve the quality supply of domestic water. In this study, we aimed to evaluate the performance of a ceramic silver-impregnated pot filter (CSF) system coupled with an adsorption process, composed of silver-impregnated granular activated carbon and zeolite (CSF + GAC-Z), to remove waterborne bacteria Escherichia coli and Salmonella spp. from spiked water. The performance of this system was compared with the conventional CSF system. In this respect, we evaluated six CSF and six CSF + GAC-Z using spiked water with 10³ and 10² CFU/mL of E. coli and Salmonella spp. The mean percentage of removals ranged between 98% and 99.98%. The highest bacterial removal efficiency was recorded by the CSF + GAC-Z (99%) and CSF (99.98%) for E. coli and Salmonella spp., respectively, but no significant statistical differences were found between filtration systems. Our findings suggest that the CSF + GAC-Z system was effective in the removal of waterborne bacteria from spiked water.

Detection of Carbapenem-Resistant Genes in Escherichia coli Isolated from Drinking Water in Khartoum, Sudan

Waterborne Escherichia coli are a major reservoir of antimicrobial resistance (AMR). Carbapenem-resistance, especially when mediated by transferable carbapenemase-encoding genes, is spreading worldwide and causing dramatically limiting treatment options. In our country, studies for the detection of carbapenem resistance in drinking water do not exist; therefore, this work was carried out to determine the prevalence of carbapenem-resistant genes “bla_KPC, bla_IMP, bla_NDM, bla_SPM, bla_VIM, and bla_OXA-48” among Escherichia coli isolated from drinking water in Khartoum, Sudan. A total of forty-five E. coli bacteria were isolated from different sources of drinking water. Antimicrobial susceptibility testing was performed using imipenem (10 mg/disc), gentamicin (10 mg/disc), ceftriaxone (30 mg/disc), ciprofloxacin (5 mg/disc), chloramphenicol (30 mg/disc), and tetracycline (30 mg/disc). “Sensitive” or “resistant” patterns of E. coli were judged using antibiotic minimum inhibitory concentration (MIC). Bacterial genomic DNA was extracted by the boiling method, and then multiplex polymerase chain reaction was performed to detect the carbapenemase genes (bla_KPC, bla_IMP, bla_NDM, bla_SPM, bla_VIM, and bla_OXA-48). Multiplex PCR assays confirmed the presence of carbapenemase genes in 28% of all water isolates. OXA-48 gene was the most predominant gene, detected in 15.5% of the isolates. The bla_KPC and bla_SPM genes were also detected in 4.4% and 8.8% of the isolates, respectively. However, the isolates were negative for bla_NDM, bla_VIM, and bla_IMP genes. The isolates showed a high rate of tetracycline resistance (97.7%), followed by gentamicin (57.7%), ciprofloxacin (46.6%), ceftriaxone (35.5%), and chloramphenicol (31.1%). In conclusion, this study confirmed for the first time the presence of E. coli carried carbapenem-resistant genes in the drinking water of Khartoum state, Sudan. These isolates commonly carried OXA-48 (7/45), followed by SPM (4/45) and KPC (2/45).

SODIUM BICARBONATE REMEDIATION OF ANTHROPOGENIC CONTAMINATION OF WATER AT THE GBNERR IN MISSISSIPPI

Grand Bay National Estuarine Research Reserve (GBNERR) is an important ecosystem in the Mississippi Gulf Coast. The GBNERR may be a potential source for contamination with anthropogenic bacterial pathogens that may play a significant role in the causation of waterborne human diseases. The objective of this study was to evaluate the interaction of physicochemical and microbiological water quality parameters at the GBNERR, determine quantitative levels and establish the potential for remediation of post-contamination of water and seafood by human fecal pollution from anthropogenic sources at the reserve. Water samples were collected aseptically from Bayous Heron, Cumbest, Point Aux Chenes Bay and Bangs Lake (Pine-O-Pine). Physicochemical parameters were determined using standard protocols. Eight bacterial species including Campylobacter were concentrated from water samples by membrane filtration. Water samples were tested for the presence of traditional indicator microorganisms including: heterotrophic (HPC), total coliforms (TC), fecal coliforms (FC) and enterococcus (ENT) in CFU/ml concentrations. Mean values of temperature, specific conductivity, dissolved oxygen and pH were within acceptable levels in comparison to MDEQ, USEPA and the USGS standards during the time of investigation. However, the values of turbidity in Grand Bay water exceeded USEPA recommended levels in several occasions during the investigation. Data from this study indicates significant variability (p < 0.0001) in mean bacteria concentrations between sites. The data also indicates significant impact of Sodium bicarbonate treatment in the remediation of post contamination and survival of pathogens from the GBNERR Bayous Heron, Cumbest and Pine-O-Pine when compared with control findings. The interaction of physicochemical and microbiological parameters of water through external chemical manipulation by Sodium bicarbonate may provide utility in the remediation of post-contamination with anthropogenic pathogens such as E. coli, Enterococci, Campylobacter, Vibrio, Giardia and Cryptosporidium. Presence of high numbers of indicator bacteria suggest public health concerns for oyster and shellfish consumers as well as other water contact activities. Hence, control strategies should be developed and implemented to prevent or remediate any future contamination of the GBNERR waters citing the economic impact of such contamination on shell fish fishing activities at the reserve.

CALCIUM OXIDE REMEDIATION OF ANTHROPOGENIC CONTAMINATION OF WATER AT THE GBNERR IN MISSISSIPPI

Grand Bay National Estuarine Research Reserve (GBNERR) is an important ecosystem in the Mississippi Gulf Coast. The GBNERR may be a potential source for contamination with anthropogenic bacterial pathogens that may play a significant role in the causation of waterborne human diseases. The objective of this study was to evaluate the interaction of physicochemical and microbiological water quality parameters at the GBNERR, determine quantitative levels and establish the potential for remediation of post-contamination of water and seafood by human fecal pollution from anthropogenic sources at the reserve. Water samples were collected aseptically from Bayous Heron, Cumbest, Point Aux Chenes Bay and Bangs Lake (Pine-O-Pine). Physicochemical parameters were determined using standard protocols. Eight bacteria/parasitic species including Cryptosporidium were concentrated from water samples by membrane filtration. Water samples were tested for the presence of traditional indicator microorganisms including: heterotrophic (HPC), total coliforms (TC), fecal coliforms (FC) and enterococcus (ENT) in CFU/ml concentrations. Mean values of temperature, specific conductivity, dissolved oxygen and pH were within acceptable levels in comparison to MDEQ, USEPA and the USGS standards during the time of investigation. However, the values of turbidity in Grand Bay water exceeded USEPA recommended levels in several occasions during the investigation. Data from this study indicates significant variability (p < 0.0001) in mean bacteria concentrations between sites. The data also indicates significant impact of Calcium oxide treatment in the remediation of post contamination and survival of pathogens from the GBNERR Bayous Heron, Cumbest and Pine-O-Pine when compared with control findings. The interaction of physicochemical and microbiological parameters of water through external chemical manipulation by Calcium oxide may provide utility in the remediation of post-contamination with anthropogenic pathogens such as E. coli, Enterococci, Campylobacter, Vibrio, Giardia and Cryptosporidium. Presence of high numbers of indicator bacteria suggest public health concerns for oyster and shellfish consumers as well as other water contact activities. Hence, control strategies should be developed and implemented to prevent or remediate any future contamination of the GBNERR waters citing the economic impact of such contamination on shell fish fishing activities on the reserve.

Challenges to Sustainable Safe Drinking Water: A Case Study of Water Quality and Use across Seasons in Rural Communities in Limpopo Province, South Africa

Consumption of microbial-contaminated water can result in diarrheal illnesses and enteropathy with the heaviest impact upon children below the age of five. We aimed to provide a comprehensive analysis of water quality in a low-resource setting in Limpopo province, South Africa. Surveys were conducted in 405 households in rural communities of Limpopo province to determine their water-use practices, perceptions of water quality, and household water-treatment methods. Drinking water samples were tested from households for microbiological contamination. Water from potential natural sources were tested for physicochemical and microbiological quality in the dry and wet seasons. Most households had their primary water source piped into their yard or used an intermittent public tap. Approximately one third of caregivers perceived that they could get sick from drinking water. All natural water sources tested positive for fecal contamination at some point during each season. The treated municipal supply never tested positive for fecal contamination; however, the treated system does not reach all residents in the valley; furthermore, frequent shutdowns of the treatment systems and intermittent distribution make the treated water unreliable. The increased water quantity in the wet season correlates with increased treated water from municipal taps and a decrease in the average contaminant levels in household water. This research suggests that wet season increases in water quantity result in more treated water in the region and that is reflected in residents' water-use practices.

Uropathogenic Escherichia coli in the Urine Samples of Iranian Dogs: Antimicrobial Resistance Pattern and Distribution of Antibiotic Resistance Genes

Resistant uropathogenic Escherichia coli is the most common cause of urinary tract infections in dogs. The present research was done to study the prevalence rate and antimicrobial resistance properties of UPEC strains isolated from healthy dogs and those which suffered from UTIs. Four-hundred and fifty urine samples were collected and cultured. E. coli-positive strains were subjected to disk diffusion and PCR methods. Two-hundred out of 450 urine samples (44.4%) were positive for E. coli. Prevalence of E. coli in healthy and infected dogs was 28% and 65%, respectively. Female had the higher prevalence of E. coli (P = 0.039). Marked seasonality was also observed (P = 0.024). UPEC strains had the highest levels of resistance against gentamicin (95%), ampicillin (85%), amikacin (70%), amoxicillin (65%), and sulfamethoxazole-trimethoprim (65%). We found that 21.50% of UPEC strains had simultaneously resistance against more than 10 antibiotics. Aac(3)-IV (77%), CITM (52.5%), tetA (46.5%), and sul1 (40%) were the most commonly detected antibiotic resistance genes. Findings showed considerable levels of antimicrobial resistance among UPEC strains of Iranian dogs. Rapid identification of infected dogs and their treatment based on the results of disk diffusion can control the risk of UPEC strains.

Molecular characterization of Escherichia coli recovered from traditional milk products in Kashan, Iran

AIM

Shiga toxigenic Escherichia coli (STEC) strains as emerging groups of foodborne pathogens are responsible for most foodborne illnesses. The aim of this study was to determine the antibiotic resistance pattern in STEC isolated from traditional milk products and their molecular characterization.

MATERIALS AND METHODS

A total of 116 samples were randomly purchased from local markets in Kashan, Iran, and evaluated for the occurrence of STEC by culturing and molecular methods. The antibiotic resistance of obtained isolates was determined by Kirby Bauer method. Furthermore, isolates were assayed for the presence of Shiga toxins (stx1 and stx2) and intimin gene (eae).

RESULTS

The incidence of E. coli in 60 ice cream, 30 yoghurt, and 26 cheese samples was 8.33%, 10%, and 11.54%, respectively. The findings showed that 11 out of 11 (100%) E. coli had both stx1 and stx2 while eae gene was not found in E. coli isolated of traditional milk products. For E. coli strains carrying stx1 and stx2, highest antibiotic sensitive levels were related to trimethoprim/sulfamethoxazole, norfloxacin, chloramphenicol, and ciprofloxacin, respectively.

CONCLUSION

The results showed relationship between the presence of virulence factors and antimicrobial resistance. These results can be used for further studies on STEC as an emerging foodborne pathogen.

Helicobacter pylori in bottled mineral water: genotyping and antimicrobial resistance properties

BACKGROUND

Up to now, fecal-oral and oral-oral are the most commonly known routes for transmission of H. pylori, therefore, contaminated water can play an important role in transmission of H. pylori to humans. Genotyping using virulence markers of H. pylori is one of the best approaches to study the correlations between H. pylori isolates from different samples. The present research was carried out to study the vacA, cagA, cagE, oipA, iceA and babA2 genotyping and antimicrobial resistance properties of H. pylori isolated from the bottled mineral water samples of Iran.

RESULTS

Of 450 samples studied, 8 samples (1.77%) were contaminated with H. pylori. Brand C of bottled mineral water had the highest prevalence of H. pylori (3.63%). The bottled mineral water samples of July month had the highest levels of H. pylori-contamination (50%). H. pylori strains had the highest levels of resistance against metronidazole (62.5%), erythromycin (62.5%), clarithromycin (62.5%), amoxicillin (62.5%) and trimethoprim (62.5%). Totally, 12.5% of strains were resistant to more than 6 antibiotics. VvacAs1a (100%), vacAm1a (87.5%), cagA (62.5%), iceA1 (62.5%), oipA (25%), babA2 (25%) and cagE (37.5%) were the most commonly detected genotypes. M1as1a (62.5%), m1as2 (37.5%), m2s2 (37.5%) and S1a/cagA+/IceA2/oipA-/babA2-/cagE- (50%) were the most commonly detected combined genotypes.

CONCLUSIONS

Contaminated bottled mineral water maybe the sources of virulent and resistant strains H. pylori. Careful monitoring of bottled mineral water production may reduce the risk of H. pylori transmission into the human population.

Pathotypic and Phylogenetic Study of Diarrheagenic Escherichia coli and Uropathogenic E. coli Using Multiplex Polymerase Chain Reaction

BACKGROUND

Acute diarrheal disease and urinary tract infection are leading causes of childhood morbidity and mortality in the developing world. Diarrheagenic Escherichia coli (DEC) has been identified as a major etiologic agent of diarrhea worldwide, and urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) is one of the most common bacterial infections among human beings. Quick and precise detection of these bacteria help provide more effective intervention and management of infection.

OBJECTIVES

In this study we present a precise and sensitive typing and phylogenetic study of UPEC and DEC using multiplex PCR in order to simplify and improve the intervention and management of diarrheal and UT infections.

MATERIALS AND METHODS

In total, 100 urinary tract infection samples (UTI) and 200 specimens from children with diarrhea, which had been diagnosed with E. coli as the underlying agent by differential diagnosis using MacConkey's agar and biochemical study, were submitted for molecular detection. Pathotyping of E. coli pathotypes causing urinary tract infection and diarrhea were examined using a two set multiplex PCR, targeting six specific genes. Phylogenetic typing was done by targeting three genes, including ChuA, YjaA and TspE4C2.

RESULTS

Overall, 88% of DEC and 54% of UTI isolates were positive for one or more of the six genes encoding virulence factors. Prevalence of the genes encoding virulence factors for DEC were 62%, 25%, 24%, 13%, 7% and 5% for ST (ETEC), LT (ETEC), aggR (EAggEC), daaD (DAEC), invE (EIEC) and eae (EPEC), respectively; whereas, the prevalence rates for the UTI samples were 23%, 14%, 6%, 6% and 4% for aggR (EAggEC), LT (ETEC), daaD (DAEC), invE (EIEC) and ST (ETEC), respectively. No coding virulence factors were detected for eae (EPEC). Group B2 was the most prevalent phylogroup and ST was the most frequently detected pathotype in all phylogroups.

CONCLUSIONS

ETEC and EAggEC were the most detected E. coli among stool and UTI samples, emphasizing the need to dedicate more health care attention to this group. In addition, our phylogenetic study may be helpful in figuring out the infection origin and for epidemiological studies. Nonetheless, more research studies with larger sample sizes are suggested for confirming our results.

A Systematic Review and Meta-Analysis of Fecal Contamination and Inadequate Treatment of Packaged Water

BACKGROUND

Packaged water products provide an increasingly important source of water for consumption. However, recent studies raise concerns over their safety.

OBJECTIVES

To assess the microbial safety of packaged water, examine differences between regions, country incomes, packaged water types, and compare packaged water with other water sources.

METHODS

We performed a systematic review and meta-analysis. Articles published in English, French, Portuguese, Spanish and Turkish, with no date restrictions were identified from online databases and two previous reviews. Studies published before April 2014 that assessed packaged water for the presence of Escherichia coli, thermotolerant or total coliforms were included provided they tested at least ten samples or brands.

RESULTS

A total of 170 studies were included in the review. The majority of studies did not detect fecal indicator bacteria in packaged water (78/141). Compared to packaged water from upper-middle and high-income countries, packaged water from low and lower-middle-income countries was 4.6 (95% CI: 2.6-8.1) and 13.6 (95% CI: 6.9-26.7) times more likely to contain fecal indicator bacteria and total coliforms, respectively. Compared to all other packaged water types, water from small bottles was less likely to be contaminated with fecal indicator bacteria (OR = 0.32, 95%CI: 0.17-0.58) and total coliforms (OR = 0.10, 95%CI: 0.05, 0.22). Packaged water was less likely to contain fecal indicator bacteria (OR = 0.35, 95%CI: 0.20, 0.62) compared to other water sources used for consumption.

CONCLUSIONS

Policymakers and regulators should recognize the potential benefits of packaged water in providing safer water for consumption at and away from home, especially for those who are otherwise unlikely to gain access to a reliable, safe water supply in the near future. To improve the quality of packaged water products they should be integrated into regulatory and monitoring frameworks.

Optomagnetic read-out enables easy, rapid, and cost-efficient qualitative biplex detection of bacterial DNA sequences

There is an increasing need to develop novel bioassay methods for low-cost, rapid, and easy-to-use multiplex detection of pathogens in various fields ranging from human infectious disease diagnosis, drinking water quality control, to food safety applications. Due to their unique advantages, magnetic and optomagnetic bioassay principles are particularly promising for biodetection platforms that will be used in developing countries. In this paper, an optomagnetic method for rapid and cost-efficient qualitative biplex detection of bacterial DNA sequences is demonstrated. Within less than two hours, the assay gives an answer to whether none, both, or only one of the bacterial DNA sequences is present in the sample. The assay relies on hybridization of oligonucleotide-functionalized magnetic nanobeads of two different sizes to rolling circle amplification (RCA) products originating from two different bacterial targets. The different bead sizes are equipped with different oligonucleotide probes, complementary to only one of the RCA products, and the read-out is carried out in the same sample volume. In an optomagnetic setup, the frequency modulation of transmitted laser light in response to an applied AC magnetic field is measured. The presented methodology is potentially interesting for low-cost screening of pathogens relating to both human and veterinary medicine in resource-poor regions of the world.

Exposure to synthetic gray water inhibits amoeba encystation and alters expression of Legionella pneumophila virulence genes

Water conservation efforts have focused on gray water (GW) usage, especially for applications that do not require potable water quality. However, there is a need to better understand environmental pathogens and their free-living amoeba (FLA) hosts within GW, given their growth potential in stored gray water. Using synthetic gray water (sGW) we examined three strains of the water-based pathogen Legionella pneumophila and its FLA hosts Acanthamoeba polyphaga, A. castellanii, and Vermamoeba vermiformis. Exposure to sGW for 72 h resulted in significant inhibition (P < 0.0001) of amoebal encystation versus control-treated cells, with the following percentages of cysts in sGW versus controls: A. polyphaga (0.6 versus 6%), A. castellanii (2 versus 62%), and V. vermiformis (1 versus 92%), suggesting sGW induced maintenance of the actively feeding trophozoite form. During sGW exposure, L. pneumophila culturability decreased as early as 5 h (1.3 to 2.9 log10 CFU, P < 0.001) compared to controls (Δ0 to 0.1 log10 CFU) with flow cytometric analysis revealing immediate changes in membrane permeability. Furthermore, reverse transcription-quantitative PCR was performed on total RNA isolated from L. pneumophila cells at 0 to 48 h after sGW incubation, and genes associated with virulence (gacA, lirR, csrA, pla, and sidF), the type IV secretion system (lvrB and lvrE), and metabolism (ccmF and lolA) were all shown to be differentially expressed. These results suggest that conditions within GW may promote interactions between water-based pathogens and FLA hosts, through amoebal encystment inhibition and alteration of bacterial gene expression, thus warranting further exploration into FLA and L. pneumophila behavior in GW systems.

Virulence factors and o-serogroups profiles of uropathogenic Escherichia coli isolated from Iranian pediatric patients

Background:

Uropathogenic Escherichia coli O- Serogroups with their virulence factors are the most prevalent causes of UTIs.

Objectives:

The present investigation was performed to study the virulence factors and O-Serogroups profiles of UPEC isolated from Iranian pediatric patients.

Patients and Methods:

This cross sectional investigation was performed on 100 urine samples collected from hospitalized pediatrics of Baqiyatallah Hospital, Tehran, Iran. Midstream urine was collected to decrease potential bacterial, cellular and artifactual contamination. All samples were cultured and those with positive results were subjected to polymerase chain reactions to detect pap, cnf1, afa, sfa and hlyA genes and various O- Serogroups.

Results:

We found that 37.5% of boys and 75% of girls had positive results for Escherichia coli. We also found that O1 (19.33%), O2 (13.33%), O6 (13.33%), O4 (11.66%), and O18 (11.66 %) were the most commonly detected Serogroups. Totally, the serogroup of 5% of all strains were not detected. In addition, all of these O- Serogroups were pap+, cnf1+, hlyA+, and afa+. Totally, pap (70 %), cnf1 (56.66 %), and hlyA (43.33 %) were the most commonly detected virulence genes in the both studied groups of children. The sfa (30 %) and afa (26.66 %) genes had the lowest incidence rates.

Conclusions:

Special health care should be performed on UTIs management in Iranian pediatric patients. Extended researches should be performed to evaluate relation between other O-Serogroups and virulent genes.