Emerging water-borne pathogens

Nanoplasmonic biosensors for environmental sustainability and human health

Monitoring the health conditions of the environment and humans is essential for ensuring human well-being, promoting global health, and achieving sustainability. Innovative biosensors are crucial in accurately monitoring health conditions, uncovering the hidden connections between the environment and human well-being, and understanding how environmental factors trigger autoimmune diseases, neurodegenerative diseases, and infectious diseases. This review evaluates the use of nanoplasmonic biosensors that can monitor environmental health and human diseases according to target analytes of different sizes and scales, providing valuable insights for preventive medicine. We begin by explaining the fundamental principles and mechanisms of nanoplasmonic biosensors. We investigate the potential of nanoplasmonic techniques for detecting various biological molecules, extracellular vesicles (EVs), pathogens, and cells. We also explore the possibility of wearable nanoplasmonic biosensors to monitor the physiological network and healthy connectivity of humans, animals, plants, and organisms. This review will guide the design of next-generation nanoplasmonic biosensors to advance sustainable global healthcare for humans, the environment, and the planet.

The impact of anthropogenic climate change on pediatric viral diseases

The adverse effects of climate change on human health are unfolding in real time. Environmental fragmentation is amplifying spillover of viruses from wildlife to humans. Increasing temperatures are expanding mosquito and tick habitats, introducing vector-borne viruses into immunologically susceptible populations. More frequent flooding is spreading water-borne viral pathogens, while prolonged droughts reduce regional capacity to prevent and respond to disease outbreaks with adequate water, sanitation, and hygiene resources. Worsening air quality and altered transmission seasons due to an increasingly volatile climate may exacerbate the impacts of respiratory viruses. Furthermore, both extreme weather events and long-term climate variation are causing the destruction of health systems and large-scale migrations, reshaping health care delivery in the face of an evolving global burden of viral disease. Because of their immunological immaturity, differences in physiology (e.g., size), dependence on caregivers, and behavioral traits, children are particularly vulnerable to climate change. This investigation into the unique pediatric viral threats posed by an increasingly inhospitable world elucidates potential avenues of targeted programming and uncovers future research questions to effect equitable, actionable change. IMPACT: A review of the effects of climate change on viral threats to pediatric health, including zoonotic, vector-borne, water-borne, and respiratory viruses, as well as distal threats related to climate-induced migration and health systems. A unique focus on viruses offers a more in-depth look at the effect of climate change on vector competence, viral particle survival, co-morbidities, and host behavior. An examination of children as a particularly vulnerable population provokes programming tailored to their unique set of vulnerabilities and encourages reflection on equitable climate adaptation frameworks.

Vertical flow constructed wetlands as green facades and gardens for on-site greywater treatment in buildings: Two-year mesocosm study on removal performance

This study focuses on the performance and clogging of vertical flow constructed wetlands (VFCWs) planted with climbing ornamentals and ornamental plants for greywater treatment, after two years of operation at mesocosm level. Different substrate (sand, vermiculite) and vegetation (Trachelospermum jasminoides, Lonicera japonica, Callistemon laevis) types were evaluated to determine the optimal removal of pollutants. Results revealed that, during the second year of operation, removal efficiencies of turbidity and COD were significantly higher (1st year: 54-94 %; 71-89 %, 2nd year: 82-98 %; 86-95 %, respectively) for both studied planted substrates, compared to the first year. Moreover, it was found that sand systems from each studied plant as well as from the unplanted systems, were more effective compared to vermiculite for most of the studied parameters (turbidity, TSS, COD, anionic surfactants, pathogens). Sand systems were also quite effective in removing total coliforms (5 log reduction) and Escherichia coli (4 log reduction). At the end of the two-year experiment, all planted systems with sand had significantly higher hydraulic conductivity than the unplanted ones. With reference to evapotranspiration, even though planted systems had significantly higher losses, C. laevis systems demonstrated less water losses than the other vegetated systems. According to the findings, the studied plants managed to continue growing without facing added stress. Therefore, the application of climbing and ornamental plants in VFCWs for greywater treatment in buildings seems a promising option for developing green infrastructures in urban areas and enhancing the removal efficiency of such systems.

Inhibition of microbial pathogens in farmed fish

Aquaculture, also known as aqua farming, is defined as farming fish, crustaceans, mollusks, aquatic plants, algae, and other marine organisms. It includes cultivating fresh- and saltwater populations under controlled conditions compared to commercial fishing or wild fish harvesting. Worldwide, carp, salmon, tilapia, and catfish are the most common fish species used in fish farming in descending order. Disinfectants prevent and/or treat different infections in aquatic animals. The current review indicates the uses of different disinfectants against some important pathogens in aquaculture, with particular reference to tilapia (Oreochromis niloticus) farming. A single review cannot cover all aspects of disinfection throughout aquaculture, so the procedures and principles of disinfection in tilapia farming/aquaculture have been chosen for illustration purposes.

Biogeographic patterns of potential pathogenic bacteria in the middle and lower reaches of the Yangtze River as well as its two adjoining lakes, China

Understanding the distribution patterns and shaping factors of bacterial pathogens in aquatic ecosystems, especially in natural waters, are critical to the control of pathogen transmission. In this study, using 16S rRNA gene amplicon sequencing, we explored the composition and biogeographic dynamics of potential bacterial pathogens in the middle and lower reaches of the Yangtze River, as well as its two vast adjoining lakes (Dongting Lake and Poyang Lake). The pathogen community belonged to 12 potential pathogenic groups, with “intracellular parasites,” “animal parasites or symbionts” and “human pathogens all” occupying 97.5% in total. The potential pathogen community covered seven phyla with Proteobacteria (69.8%) and Bacteroidetes (13.5%) the most predominant. In addition, 53 genera were identified with Legionella (15.2%) and Roseomonas (14.2%) the most dominant. The average relative abundance, alpha diversity and microbial composition of the potential bacterial pathogens exhibited significant biogeographical variations among the different sections. An in-depth analysis reflected that environmental variables significantly structured the potential bacterial pathogens, including water physiochemical properties (i.e., chlorophyll-a, total nitrogen and transparency), heavy metals (i.e., As and Ni), climate (i.e., air temperature) and land use type (i.e., waters). Compared to the overall bacterial community which was composed of both pathogenic and non-pathogenic bacteria, the pathogen community exhibited distinct microbial diversity patterns and shaping factors. This signifies the importance of different variables for shaping the pathogen community. This study represents one attempt to explore pathogen diversity patterns and their underlying drivers in the Yangtze River, which provides a foundation for the management of pathogenic bacteria.

The association between E. coli exceedances in drinking water supplies and healthcare utilisation of older people

Evidence concerning the effects of indicators of waterborne pathogens on healthcare systems is of importance for policymaking, future infrastructure considerations and healthcare planning. This paper examines the association between the detection of E. coli in water tests associated with drinking water supplies and the use of healthcare services by older people in Ireland. Uniquely, three sources of data are linked to conduct the analysis. Administrative records of E. coli exceedances recorded from routine water quality tests carried out by Ireland’s Environmental Protection Agency are first linked to maps of water systems infrastructure in Ireland. Then, residential addresses of participants of The Irish Longitudinal Study of Ageing (TILDA), a nationally representative survey of over 50-year-olds in Ireland, are linked to the water systems dataset which has the associated water quality monitoring information. Multivariate regression analysis estimates a greater incident rate ratio (IRR) of General Practitioner (GP) visits in the previous year where E. coli is detected in the water supply associated with an older person’s residence (Incidence Rate Ratio (IRR) 1.118; [95% Confidence interval (CI): 1.019–1.227]), controlling for demographic and socio-economic factors, health insurance coverage, health, and health behaviours. Where E. coli is detected in water, a higher IRR is also estimated for visits to an Emergency Department (IRR: 1.292; [95% CI: 0.995–1.679]) and nights spent in hospital (IRR: 1.351 [95% CI: 1.004–1.818]).

Prevalence and predictors of water-borne diseases among elderly people in India: evidence from Longitudinal Ageing Study in India, 2017-18

BACKGROUND

India suffers from a high burden of diarrhoea and other water-borne diseases due to unsafe water, inadequate sanitation and poor hygiene practices among human population. With age the immune system becomes complex and antibody alone does not determine susceptibility to diseases which increases the chances of waterborne disease among elderly population. Therefore the study examines the prevalence and predictors of water-borne diseases among elderly in India.

METHOD

Data for this study was collected from the Longitudinal Ageing Study in India (LASI), 2017-18. Descriptive statistics along with bivariate analysis was used in the present study to reveal the initial results. Proportion test was applied to check the significance level of prevalence of water borne diseases between urban and rural place of residence. Additionally, binary logistic regression analysis was used to estimate the association between the outcome variable (water borne diseases) and the explanatory variables.

RESULTS

The study finds the prevalence of water borne disease among the elderly is more in the rural (22.5%) areas compared to the urban counterparts (12.2%) due to the use of unimproved water sources. The percentage of population aged 60 years and above with waterborne disease is more in the central Indian states like Chhattisgarh and Madhya Pradesh followed by the North Indian states. Sex of the participate, educational status, work status, BMI, place of residence, type of toilet facility and water source are important determinants of water borne disease among elderly in India.

CONCLUSION

Elderly people living in the rural areas are more prone to waterborne diseases. The study also finds state wise variation in prevalence of waterborne diseases. The elderly people might not be aware of the hygiene practices which further adhere to the disease risk. Therefore, there is a need to create awareness on basic hygiene among this population for preventing such bacterial diseases.

Transition metal dichalcogenide-based Janus micromotors for on-the-fly Salmonella detection

Janus micromotors encapsulating transition metal dichalcogenides (TMDs) and modified with a rhodamine (RhO)-labeled affinity peptide (RhO-NFMESLPRLGMH) are used here for Salmonella enterica endotoxin detection. The OFF–ON strategy relies on the specific binding of the peptide with the TMDs to induce fluorescence quenching (OFF state); which is next recovered due to selectively binding to the endotoxin (ON state). The increase in the fluorescence of the micromotors can be quantified as a function of the concentration of endotoxin in the sample. The developed strategy was applied to the determination of Salmonella enterica serovar Typhimurium endotoxin with high sensitivity (limits of detection (LODs) of 2.0 µg/mL using MoS₂, and 1.2 µg/mL using WS₂), with quantitative recoveries (ranging from 93.7 ± 4.6 % to 94.3 ± 6.6%) in bacteria cultures in just 5 min. No fluorescence recovery is observed in the presence of endotoxins with a similar structure, illustrating the high selectivity of the protocol, even against endotoxins of Salmonella enterica serovar Enteritidis with great similarity in its structure, demonstrating the high bacterial specificity of the developed method. These results revealed the analytical potential of the reported strategy in multiplexed assays using different receptors or in the design of portable detection devices.

Nanotechnology in food and water security: on-site detection of agricultural pollutants through surface-enhanced Raman spectroscopy

Agricultural pollutants are harmful components threatening human health, wildlife, the environment, and the ecosystem. To avoid their exposure, developing prevention and detection systems with high sensitivity and selectivity is required. Most conventional methods, including molecular and chromatographic techniques, cannot be adopted for outdoor on-site detection even though they can provide sensitive and selective detection. Thus, detection platforms that can provide on-site detection via miniaturized and high throughput systems should be developed. As an alternative method, surface-enhanced Raman scattering (SERS) provides unique information about the substances in the presence of plasmonic nanostructures, and it can be portable with the use of portable detection systems and spectrometers. In this study, on-site detection of agricultural pollutants through SERS is reviewed. Three different types of agricultural pollutants were pointed out. On-site detection of biological pollutants, including bacteria and viruses, is reviewed as the first type of pollutant. As a second type, the detection of pesticides, antibiotics, and additives are focused on as chemical pollutants. The third group includes the detection of microplastics and also nanoparticles from the environment.

Field and Laboratory Evaluation of the Microsporidian Parasite Heterosporis sutherlandae: Prevalence, Severity, and Transmission

Heterosporis sutherlandae is an invasive microsporidian parasite in the Great Lakes region of North America that infects the skeletal muscle of numerous fish species, rendering the fillet unfit for human consumption. Although H. sutherlandae has been identified as a pathogen of concern by state management agencies, there is little information to inform regulation and intervention. We sampled fishes over 1 year from three lakes in northern Minnesota with known infected populations to determine the importance of host demographic and environmental variables for influencing H. sutherlandae infection prevalence. Heterosporis sutherlandae was present during all sampling periods, ranging in prevalence from 1% to 11%. The prevalence of H. sutherlandae among Yellow Perch Perca flavescens varied significantly according to season, with winter having the lowest prevalence (1%) and summer having the highest prevalence (11%). For other fish species, the prevalence of H. sutherlandae also varied significantly with season: the lowest prevalence occurred during spring (1%) and the highest prevalence occurred in fall (9%). Rates of pathogen transmission were estimated by exposing Fathead Minnows Pimephales promelas in the laboratory. Transmission rates were 23% when naïve fish were fed infected tissues and only 2% when naïve fish were held in cohabitation with tissue-fed fish. Exposure method and exposure duration (d) increased the probability that a fish was infected with H. sutherlandae. These findings suggest that H. sutherlandae transmission is greater when a susceptible host consumes infected tissue than when the fish is exposed to spores present in the water column. The current rates of infection in wild fishes are in stark contrast to the prevalence documented in 2004 (28%), suggesting a reduction in H. sutherlandae prevalence within at least one Yellow Perch population in the Laurentian Great Lakes region since the early 2000s.

Extreme storms cause rapid but short-lived shifts in nearshore subtropical bacterial communities

Climate change scenarios predict tropical cyclones will increase in both frequency and intensity, which will escalate the amount of terrestrial run-off and mechanical disruption affecting coastal ecosystems. Bacteria are key contributors to ecosystem functioning, but relatively little is known about how they respond to extreme storm events, particularly in nearshore subtropical regions. In this study, we combine field observations and mesocosm experiments to assess bacterial community dynamics and changes in physicochemical properties during early- and late-season tropical cyclones affecting Okinawa, Japan. Storms caused large and fast influxes of freshwater and terrestrial sediment - locally known as red soil pollution - and caused moderate increases of macronutrients, especially SiO₂ and PO₄ ^3-, with up to 25 and 0.5 μM respectively. We detected shifts in relative abundances of marine and terrestrially derived bacteria, including putative coral and human pathogens, during storm events. Soil input alone did not substantially affect marine bacterial communities in mesocosms, indicating that other components of run-off or other storm effects likely exert a larger influence on bacterial communities. The storm effects were short-lived and bacterial communities quickly recovered following both storm events. The early- and late-season storms caused different physicochemical and bacterial community changes, demonstrating the context-dependency of extreme storm responses in a subtropical coastal ecosystem.

Assessment of spring water microbiology and role of Typha angustata as biosorbent

More than 2.1 billion people worldwide are deprived of safe drinking water at homes. The situation is strikingly worse in a developing country like Pakistan where over 69% of the population does not have access to safe drinking water. The present study evaluated a perenial herb, Typha angustata (TA), to purify the spring water. For this purpose, 25 water samples were collected. Majority of samples (20/25) were highly contaminated with microbes ranging colony forming units (CFU) per millileter per Petri dish ranged from 85 to 279 with an average of 136.4. Microbial inhibition of water samples treated with the nonmodified plant extract was observed to be better with the average of 55.5% compared to the treatment with NaOH chemically modified plant where average 46.4% inhibition of microbial load was observed. Four species of microbes such as Bacillus cereus, Pseudomonas aeruginosa, Pseudomonas otitidis, and Streptococcus agalactiae were identified after sequencing. We concluded that T. angustata extract may be used as an antibacterial agent/biosorbent for the purification of drinking water to provide safe drinking water to billions of humans. PRACTITIONER POINTS: Spring water samples were collected from 25 different springs. Spring water samples were analyzed for physiochemical parameters. Spring water samples were found to be contaminated with pathogenic bacteria, that is, Bacillus cereus, Pseudomonas aeruginosa, Pseudomonas otitidis, and Streptococcus agalactiae. Pathogenic bacteria in spring water samples were treated with extract of Typha angustata. Extract of Typha angustata was found as a potential antibacterial agent against pathogenic bacteria.

Global Comparison of the Bacterial Communities of Bilge Water, Boat Surfaces, and External Port Water

In the past, ballast water has been a key vector in the ship-mediated dispersal of invasive species. Here, we evaluate the potential for port microorganisms to enter and colonize the hull and bilge water of ships. Due to the small size and ubiquitous nature of bacteria, they also have the potential to be spread through hull fouling and bilge water discharge. The goal of this study was to identify the extent to which the boat microbial community is shaped by the microbial community in the port water where the boat spends most of its time. Here, we compared the microbial communities of the hull and bilge compartments of 20 boats to those of the port water in 20 different ports in five regions around the world. We found that there was a significant difference in microbial diversity between boat and port microbial communities. Despite these differences, we found that Cyanobacteria were present at high abundances in the bilge water of most vessels. Due to the limited light in the bilge, the presence of Cyanobacteria suggests that port microorganisms can enter the bilge. Using source-tracking software, we found that, on average, 40% of the bilge and 52% of the hull microbial communities were derived from water. These findings suggest that the bilge of a vessel contains a diverse microbial community that is influenced by the port microbial community and has the potential to serve as an underappreciated vector for dispersal of life.IMPORTANCE Invasive species have been a worldwide problem for many years. However, the potential for microorganisms to become invasive is relatively underexplored. As the tools to study bacterial communities become more affordable, we are able to perform large-scale studies and examine bacterial communities in higher resolution than was previously practical. This study looked at the potential for bacteria to colonize both boat surfaces and bilge water. We describe the bacterial communities on boats in 20 shipping ports in five regions around the world, describing how these microorganisms were similar to microorganisms found in port water. This suggests that the water influences the bacterial community of a boat and that microorganisms living on a boat could be moved from place to place when the boat travels.

Broad-spectrum antimicrobial activity of secondary metabolites produced by Serratia marcescens strains

The genus Serratia is a predominantly unexplored source of antimicrobial secondary metabolites. The aim of the current study was thus to isolate and evaluate the antimicrobial properties of biosurfactants produced by Serratia species. Forty-nine (n = 34 pigmented; n = 15 non-pigmented) biosurfactant producing Serratia strains were isolated from environmental sources and selected isolates (n = 11 pigmented; n = 11 non-pigmented) were identified as Serratia marcescens using molecular typing. The swrW gene (serrawettin W1 synthetase) was detected in all the screened pigmented strains and one non-pigmented strain and primers were designed for the detection of the swrA gene (non-ribosomal serrawettin W2 synthetase), which was detected in nine non-pigmented strains. Crude extracts obtained from S. marcescens P1, NP1 and NP2 were chemically characterised using ultra-performance liquid chromatography coupled to electrospray ionisation mass spectrometry (UPLC-ESI-MS), which revealed that P1 produced serrawettin W1 homologues and prodigiosin, while NP1 produced serrawettin W1 homologues and glucosamine derivative A. In contrast, serrawettin W2 analogues were predominantly identified in the crude extract obtained from S. marcescens NP2. Both P1 and NP1 crude extracts displayed broad-spectrum antimicrobial activity against clinical, food and environmental pathogens, such as multidrug-resistant Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and Cryptococcus neoformans. In contrast, the NP2 crude extract displayed antibacterial activity against a limited range of pathogenic and opportunistic pathogens. The serrawettin W1 homologues, in combination with prodigiosin and glucosamine derivatives, produced by pigmented and non-pigmented S. marcescens strains, could thus potentially be employed as broad-spectrum therapeutic agents against multidrug-resistant bacterial and fungal pathogens.

F. A review on the development of urease inhibitors as antimicrobial agents against pathogenic bacteria

Ureases are enzymes that hydrolyze urea into ammonium and carbon dioxide. They have received considerable attention due to their impacts on living organism health, since the urease activity in microorganisms, particularly in bacteria, are potential causes and/or factors contributing to the persistence of some pathogen infections. This review compiles examples of the most potent antiurease organic substances. Emphasis was given to systematic screening studies on the inhibitory activity of rationally designed series of compounds with the corresponding SAR considerations. Ureases of Canavalia ensiformis, the usual model in antiureolytic studies, are emphasized. Although the active site of this class of hydrolases is conserved among bacteria and vegetal ureases, the same is not observerd for allosteric site. Therefore, inhibitors acting by participating in interactions with the allosteric site are more susceptible to a potential lack of association among their inhibitory profile for different ureases. The information about the inhibitory activity of different classes of compounds can be usefull to guide the development of new urease inhibitors that may be used in future in small molecular therapy against pathogenic bacteria.

Nanostructured Electrochemical Biosensors for Label-Free Detection of Water- and Food-Borne Pathogens

The emergence of nanostructured materials has opened new horizons in the development of next generation biosensors. Being able to control the design of the electrode interface at the nanoscale combined with the intrinsic characteristics of the nanomaterials engenders novel biosensing platforms with improved capabilities. The purpose of this review is to provide a comprehensive and critical overview of the latest trends in emerging nanostructured electrochemical biosensors. A detailed description and discussion of recent approaches to construct label-free electrochemical nanostructured electrodes is given with special focus on pathogen detection for environmental monitoring and food safety. This includes the use of nanoscale materials such as nanotubes, nanowires, nanoparticles, and nanosheets as well as porous nanostructured materials including nanoporous anodic alumina, mesoporous silica, porous silicon, and polystyrene nanochannels. These platforms may pave the way toward the development of point-of-care portable electronic devices for applications ranging from environmental analysis to biomedical diagnostics.

Phylogenetic Analysis and Antimicrobial Profiles of Cultured Emerging Opportunistic Pathogens (Phyla Actinobacteria and Proteobacteria) Identified in Hot Springs

Hot spring water may harbour emerging waterborne opportunistic pathogens that can cause infections in humans. We have investigated the diversity and antimicrobial resistance of culturable emerging and opportunistic bacterial pathogens, in water and sediment of hot springs located in Limpopo, South Africa. Aerobic bacteria were cultured and identified using 16S ribosomal DNA (rDNA) gene sequencing. The presence of Legionella spp. was investigated using real-time polymerase chain reaction. Isolates were tested for resistance to ten antibiotics representing six different classes: β-lactam (carbenicillin), aminoglycosides (gentamycin, kanamycin, streptomycin), tetracycline, amphenicols (chloramphenicol, ceftriaxone), sulphonamides (co-trimoxazole) and quinolones (nalidixic acid, norfloxacin). Gram-positive Kocuria sp. and Arthrobacter sp. and gram-negative Cupriavidus sp., Ralstonia sp., Cronobacter sp., Tepidimonas sp., Hafnia sp. and Sphingomonas sp. were isolated, all recognised as emerging food-borne pathogens. Legionella spp. was not detected throughout the study. Isolates of Kocuria, Arthrobacter and Hafnia and an unknown species of the class Gammaproteobacteria were resistant to two antibiotics in different combinations of carbenicillin, ceftriaxone, nalidixic acid and chloramphenicol. Cronobacter sp. was sensitive to all ten antibiotics. This study suggests that hot springs are potential reservoirs for emerging opportunistic pathogens, including multiple antibiotic resistant strains, and highlights the presence of unknown populations of emerging and potential waterborne opportunistic pathogens in the environment.

Identification of opportunistic enteric parasites among immunocompetent patients with diarrhoea from Northern India and genetic characterisation of Cryptosporidium and Microsporidia

PURPOSE

Enteric parasitic infestation is a major public health problem in developing countries. Parasites such as Cryptosporidium spp., Cyclospora spp., Cystoisospora spp. and Microsporidia may cause severe diarrhoea among immunocompromised patients. There is scanty data on their frequency among immunocompetent patients. Accordingly, we studied the frequency of enteric opportunistic parasites among immunocompetent patients with diarrhoea from northern India; we also performed genetic characterisation of Cryptosporidia and Microsporidia among them.

PATIENTS AND METHODS

Stool samples from 80 immunocompetent patients with diarrhoea, and 110 healthy controls were examined. Parasites were detected by direct microscopy, modified acid-fast (Kinyoun's) and modified trichrome stain. Polymerase chain reaction--restriction fragment length polymorphism was used for genetic characterisation of selected species such as Cryptosporidia and Microsporidia.

RESULTS

Enteric parasites were detected in 16/80 (20%) patients (mean age 28.8±20 years, 45, 56% males) and in 2/110 (1.8%) healthy controls (P=0.00007). Parasites detected were Cryptosporidium spp. (8/16, 50.0%), Cystoisospora spp. (4/16, 25%), Microsporidia (1/16, 6.25%), Cyclospora spp. (1/16, 6.25%) and Giardia spp. (1/16, 6.25%). One patient had mixed infection with Cystoisospora spp. and Giardia spp. The species of Cryptosporidia and Microsporidia detected were Cryptosporidium hominis and Enterocytozoon bieneusi, respectively. Parasites were more often detected in younger patients (≤20 years of age) than in older. Most of the parasite infected patients presented with chronic diarrhoea.

CONCLUSION

Opportunistic enteric parasitic infestation was more common among immunocompetent patients with diarrhoea than healthy subjects. Special staining as well as molecular methods are essential for appropriate diagnosis of these parasites.

Magnetic removal of Entamoeba cysts from water using chitosan oligosaccharide-coated iron oxide nanoparticles

Amebiasis, a major health problem in developing countries, is the second most common cause of death due to parasitic infection. Amebiasis is usually transmitted by the ingestion of Entamoeba histolytica cysts through oral–fecal route. Herein, we report on the use of chitosan oligosaccharide-functionalized iron oxide nanoparticles for efficient capture and removal of pathogenic protozoan cysts under the influence of an external magnetic field. These nanoparticles were synthesized through a chemical synthesis process. The synthesized particles were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and zeta potential analysis. The particles were found to be well dispersed and uniform in size. The capture and removal of pathogenic cysts were demonstrated by fluorescent microscopy, transmission electron microscopy, and scanning electron microscopy (SEM). Three-dimensional modeling of various biochemical components of cyst walls, and thereafter, flexible docking studies demonstrate the probable interaction mechanism of nanoparticles with various components of E. histolytica cyst walls. Results of the present study suggest that E. histolytica cysts can be efficiently captured and removed from contaminated aqueous systems through the application of synthesized nanoparticles.

Microbial indicators, pathogens and methods for their monitoring in water environment

Water is critical for life, but many people do not have access to clean and safe drinking water and die because of waterborne diseases. The analysis of drinking water for the presence of indicator microorganisms is key to determining microbiological quality and public health safety. However, drinking water-related illness outbreaks are still occurring worldwide. Moreover, different indicator microorganisms are being used in different countries as a tool for the microbiological examination of drinking water. Therefore, it becomes very important to understand the potentials and limitations of indicator microorganisms before implementing the guidelines and regulations designed by various regulatory agencies. This review provides updated information on traditional and alternative indicator microorganisms with merits and demerits in view of their role in managing the waterborne health risks as well as conventional and molecular methods proposed for monitoring of indicator and pathogenic microorganisms in the water environment. Further, the World Health Organization (WHO) water safety plan is emphasized in order to develop the better approaches designed to meet the requirements of safe drinking water supply for all mankind, which is one of the major challenges of the 21st century.

Goharshadi E. Effects of pH and Temperature on Antibacterial Activity of Zinc Oxide Nanofluid Against Escherichia coli O157: H7 and Staphylococcus aureus

Background:

Zinc oxide nanoparticles (ZnO NPs) are known as one of the important inorganic materials used in research and health-related applications with effective antibacterial activities. Although the toxic effects of ZnO NPs have already been evaluated, more information is required to understand the possible mechanisms.

Objectives:

The aim of the present study was to determine the influences of pH and temperature on antibacterial activity of ZnO NPs against some strains of pathogenic bacteria. Identifying the interrelationship between toxicity and cultural conditions helps us to have a better understanding of the optimum reaction conditions for maximum antimicrobial activity.

Materials and Methods:

ZnO NPs were prepared and characterized and then dispersed in glycerol with the help of ammonium citrate as the dispersant. The antibacterial tests were performed by measuring the growth of Escherichia coli O157:H7 and Staphylococcus aureus with different concentrations of ZnO NPs in glycerol. All the experiments were conducted at different incubation temperatures (25-42^°C) and pH levels (4-10 for E. coli O157:H7 and 5-10 for S. aureus).

Results:

The results showed that ZnO nanofluid have antibacterial activity against E. coli O157:H7 and S. aureus and the inhibitory effect increases with increasing the nanofluid concentration. The experiments showed that the antibacterial activity of ZnO NPs was influenced by temperature and pH. Higher antibacterial activity was observed at acidic pH levels with the maximum toxicity at pH = 4 and pH = 5 for E. coli O157: H7 and S. aureus, respectively. By raising the temperature, the toxicity of ZnO nanofluid increased, with the highest antibacterial activity at 42°C for both bacterial types in comparison with positive controls under the same conditions.

Conclusions:

Analysis of the results demonstrated that exposure media of ZnO NPs and cultural factors play a role in their cytotoxic effects. It could be attributed to the principal mechanism at different reaction conditions.

Detection of Yersinia enterocolitica in food: an overview

Yersinia enterocolitica is a gastrointestinal pathogen which causes yersiniosis, an illness characterized by diarrhea, ileitis, and mesenteric lymphadenitis. Y. enterocolitica is transmitted via the feco-oral route by the consumption of contaminated food or water. Several phenotypic and genotypic methods have been developed to reliably detect Y. enterocolitica in food. However, the source of infection of many recently reported foodborne outbreaks remains obscure. The detection of this pathogen in food is a challenging task, since it shares similarities with other enteric bacteria. The presence of other microorganisms in the food samples makes it even more difficult to identify this slow-growing pathogen. Therefore, the present-day emphasis is on the development of sensitive, easily automated methods suitable for in-situ detection, allowing quick and cost-effective characterization of food samples. This review summarizes and compares the currently available cultural, immunological, and molecular methods, particularly in relation to their specific merits or demerits when implemented for the detection of Y. enterocolitica in food.

Biofilm formation and persistence on abiotic surfaces in the context of food and medical environments

The biofilm formation on abiotic surfaces in food and medical sectors constitutes a great public health concerns. In fact, biofilms present a persistent source for pathogens, such as Pseudomonas aeruginosa and Staphylococcus aureus, which lead to severe infections such as foodborne and nosocomial infections. Such biofilms are also a source of material deterioration and failure. The environmental conditions, commonly met in food and medical area, seem also to enhance the biofilm formation and their resistance to disinfectant agents. In this regard, this review highlights the effect of environmental conditions on bacterial adhesion and biofilm formation on abiotic surfaces in the context of food and medical environment. It also describes the current and emergent strategies used to study the biofilm formation and its eradication. The mechanisms of biofilm resistance to commercialized disinfectants are also discussed, since this phenomenon remains unclear to date.

[Intestinal parasitoses in Argentina: major causal agents found in the population and in the environment]

Intestinal parasitic diseases are widely spread in the world, with the highest prevalence in developing countries. Children are mainly affected, showing a decrease in physical and mental development, as well as the expected manifestations of the disease. This situation can be greatly enhanced in children with poor nutritional status. The World Health Organization considers intestinal parasitic diseases a major cause of morbidity, closely linked to poverty and poor personal hygiene, inappropriate handling of raw food, lack of sanitation, lack of potable water supply, and environmental fecal contamination. Some parasitic diseases are cosmopolitan while others have variable geographic distribution, due to different factors such as the presence of exclusive intermediate hosts. In the past few years, globalization allowed the spread of certain parasites from endemic to non-endemic regions. Even though people's customs influence on the frequency of certain parasites, environmental conditions are a determinant factor for parasite survival. In our country, due to the variety of soils and climatic conditions, several causative agents of these parasitoses can be found. The aim of this work was to review the literature on the intestinal parasitic agents found in Argentina in human fecal samples and its environment, as parasitic contamination constitutes a direct indicator of the infection risk by intestinal parasites.

Identification of antimicrobial resistant bacteria in rivers: insights into the cultivation bias

In the present study, the antimicrobial resistant (AR) bacteria were quantified and identified in different river samples using in parallel a culture-based approach and a culture-independent one. The objective was to evaluate the importance of the cultivation bias when studying antimicrobial resistance among environmental bacteria. Three different river samples covering a gradient of anthropic influence were tested and three different antimicrobial compounds were used as selective agents: amoxicillin, tetracycline and sulfamethoxazole. From a quantitative point of view, our results highlight the importance of the culture media used, as for the same sample and the same selective agent significant differences were observed in the counts of culturable AR bacteria depending on the culture media used. The identification of AR bacteria through culture or culture-independent methods put on evidence AR bacterial communities that differ dramatically: γ-proteobacteria and more specifically Aeromonadaceae dominated among the isolates while β-proteobacteria (Comamonadaceae), dominated among the sequences obtained without culture. Altogether these results highlight the necessity to develop a methodological consensus preferably without culture, to approach this important topic in the coming years.

Molecular characterization of human-pathogenic microsporidia and Cyclospora cayetanensis isolated from various water sources in Spain: a year-long longitudinal study

Recent studies suggest the involvement of water in the epidemiology of Cyclospora cayetanensis and some microsporidia. A total of 223 samples from four drinking water treatment plants (DWTPs), seven wastewater treatment plants (WWTPs), and six locations of influence (LI) on four river basins from Madrid, Spain, were analyzed from spring 2008 to winter 2009. Microsporidia were detected in 49% of samples (109/223), Cyclospora spp. were detected in 9% (20/223), and both parasites were found in 5.4% (12/223) of samples. Human-pathogenic microsporidia were detected, including Enterocytozoon bieneusi (C, D, and D-like genotypes), Encephalitozoon intestinalis, Encephalitozoon cuniculi (genotypes I and III), and Anncaliia algerae. C. cayetanensis was identified in 17 of 20 samples. To our knowledge, this is the first study that shows a year-long longitudinal study of C. cayetanensis in drinking water treatment plants. Additionally, data about the presence and molecular characterization of the human-pathogenic microsporidia in drinking water, wastewater, and locations of influence during 1 year in Spain are shown. It is noteworthy that although the DWTPs and WWTPs studied meet European and national regulations on water sanitary quality, both parasites were found in water samples from these plants, supporting the idea that new and appropriate controls and regulations for drinking water, wastewater, and recreational waters should be proposed to avoid health risks from these pathogens.

Modeling the combined influence of host dispersal and waterborne fate and transport on pathogen spread in complex landscapes

Environmental models, often applied to questions on the fate and transport of chemical hazards, have recently become important in tracing certain environmental pathogens to their upstream sources of contamination. These tools, such as first order decay models applied to contaminants in surface waters, offer promise for quantifying the fate and transport of pathogens with multiple environmental stages and/or multiple hosts, in addition to those pathogens whose environmental stages are entirely waterborne. Here we consider the fate and transport capabilities of the human schistosome Schistosoma japonicum, which exhibits two waterborne stages and is carried by an amphibious intermediate snail host. We present experimentally-derived dispersal estimates for the intermediate snail host and fate and transport estimates for the passive downstream diffusion of cercariae, the waterborne, human-infective parasite stage. Using a one dimensional advective transport model exhibiting first-order decay, we simulate the added spatial reach and relative increase in cercarial concentrations that dispersing snail hosts contribute to downstream sites. Simulation results suggest that snail dispersal can substantially increase the concentrations of cercariae reaching downstream locations, relative to no snail dispersal, effectively putting otherwise isolated downstream sites at increased risk of exposure to cercariae from upstream sources. The models developed here can be applied to other infectious diseases with multiple life-stages and hosts, and have important implications for targeted ecological control of disease spread.

Critical issues in sensor science to aid food and water safety

The stability of food and water supplies is widely recognized as a global issue of fundamental importance. Sensor development for food and water safety by nonconventional assays continues to overcome technological challenges. The delicate balance between attaining adequate limits of detection, chemical fingerprinting of the target species, dealing with the complex food matrix, and operating in difficult environments are still the focus of current efforts. While the traditional pursuit of robust recognition methods remains important, emerging engineered nanomaterials and nanotechnology promise better sensor performance but also bring about new challenges. Both advanced receptor-based sensors and emerging non-receptor-based physical sensors are evaluated for their critical challenges toward out-of-laboratory applications.

Prevalence of multiple antibiotics resistant (MAR) Pseudomonas species in the final effluents of three municipal wastewater treatment facilities in South Africa

The final effluents of three (Alice, Dimbaza, and East London) wastewater treatment plants (WWTPs) were evaluated to determine their physicochemical quality and prevalence of multiple antibiotics resistant (MAR) Pseudomonas species, between August 2007 and July 2008. The annual mean total Pseudomonas count (TPC) was 1.20 × 10⁴ (cfu/100 mL), 1.08 × 10⁴ (cfu/100 mL), and 2.66 × 10⁴ (cfu/100 mL), for the Alice, Dimbaza, and East London WWTPs respectively. The effluents were generally compliant with recommended limits for pH, temperature, TDS, DO, nitrite and nitrate; but fell short of target standards for turbidity, COD, and phosphate. The tested isolates were highly sensitive to gentamicin (100%), ofloxacin (100%), clindamycin (90%), erythromycin (90%) and nitrofurantoin (80%); whereas high resistance was observed against the penicillins (90–100%), rifampin (90%), sulphamethoxazole (90%) and the cephems (70%). MAR index ranged between 0.26 and 0.58. The study demonstrated that MAR Pseudomonas species were quite prevalent in the final effluents of WWTPs in South Africa; and this can lead to serious health risk for communities that depend on the effluent-receiving waters for sundry purposes.

A blinded, randomized, palatability study comparing variations of 2 popular field water disinfection tablets

OBJECTIVE

Halogen-based water disinfection tablets may render an unpleasant taste to treated water. Proposed safe additives such as ascorbic acid may reduce this objectionable taste. We compared the palatability of 2 field water disinfectants: iodine-based tetraglycine hydroperiodide (TGHP) and chlorine-based chlorine dioxide (CD) both with and without the concomitant use of an ascorbic acid taste neutralizer.

METHODS

Blinded participants randomly sampled 5 different distilled water samples containing combinations of disinfectant tablets and ascorbic acid: 1) water; 2) water with TGHP; 3) water with CD; 4) water with TGHP plus ascorbic acid; and 5) water with CD plus ascorbic acid. Participants rated beverage taste via a 100 mm visual analogue scale (VAS) and ranked the samples from "most pleasant" to "least pleasant."

RESULTS

Sixty participants evaluated the samples. On the VAS, water with TGHP tasted worst and water with CD tasted second worst. Water with TGHP plus ascorbic acid, water alone, and water with CD plus ascorbic acid measured similarly as significantly best tasting. Water with TGHP was ranked by 58% as "least pleasant" tasting, while water with TGHP and ascorbic acid was ranked by 40% as "most pleasant" tasting.

CONCLUSIONS

Participants found halogen-based disinfected water significantly less palatable prior to the addition of ascorbic acid. Addition of ascorbic acid to treated water created a beverage of similar preference to distilled water. These results may increase compliance with the use of disinfecting tablets by increasing the palatability of drinking water made potable via addition of ascorbic acid to halogen-based chemical disinfection.

Yersinia enterocolitica and Yersinia pseudotuberculosis Detection in Foods

Yersinia enterocolitica and Y. pseudotuberculosis which can cause yersiniosis in humans and animals are thought to be significant food-borne pathogens and be important as hygiene indicator in food safety. The pathogenic Y. enterocolitica serotypes/biotypes are O:3/4 and 3 variant VP negative, O:5, 27/2, O:8/1b, and O:9/2, have been reported worldwide. Y. pseudotuberculosis is distributed less widely than Y. enterocolitica. Isolation methods usually involve selective and recovery enrichment of the food sample followed by plating onto selective media, confirmation of typical colonies and testing for virulence properties of isolated strains. Recently, DNA-based methods, such as PCR assays, have been developed to detect pathogenic Y. enterocolitica and Y. pseudotuberculosis in foods more rapidly, and sensitivity than can be achieved by conventional culture methods. This paper reviews commercially available conventional and PCR-based procedures for the detection of pathogenic Yersinia in food. These methods are effective as the isolation and detection methods to target pathogenic Y. enterocolitica and Y. pseudotuberculosis in foods.

Herd factors associated with the serological Yersinia prevalence in fattening pig herds

Recent epidemiological evidence has demonstrated that pork is an important source of yersiniosis in humans. Identifying risk factors and potential interventions in swine production that may decrease the risk of pork production contamination during harvest and processing is an important step before controlling Yersinia spp. Therefore, management strategies and production processes that might be associated with fattening pigs testing seropositive for pathogenic Yersinia spp. were investigated in 80 fattening pig farms. Although >70 farm characteristics were included in the risk assessment, there were only a few that seemed to be connected with serological prevalence: housing on a fully slatted floor and the use of municipal water were observed more often in herds with low serological Yersinia prevalence, whereas recurring health problems and a low daily weight gain compared with the mean of the herds included in the study were found in herds with a high prevalence. Besides, the Yersinia prevalence seemed to be inversely proportional to the herds' serological Salmonella status collected in accordance with German legislation. Additionally, the development of the serological Yersinia status of selected herds was assessed over a period of a year to gain knowledge of the dynamics of Yersinia infections in fattening pig herds. Three out of four serological negative herds maintained a low level of Yersinia prevalence, whereas one herd shifted between negative status and a prevalence of 100%. The reason for these considerable fluctuations could not be explained, and there was no direct association with the analyzed risk factors. Further research should be carried out to prove the given risk factors, especially the possible relation to the Salmonella prevalence before implementing a combined zoonoses surveillance and control program.

Factors related to the prevalence of pathogenicYersinia enterocoliticaon pig farms

A survey of 788 pigs from 120 farms was conducted to determine the within-farm prevalence of pathogenicYersinia enterocoliticaand a questionnaire of management conditions was mailed to the farms afterwards. A univariate statistical analysis with carriage and shedding as outcomes was conducted with random-effects logistic regression with farm as a clustering factor. Variables with aPvalue <0·15 were included into the respective multivariate random-effects logistic regression model. The use of municipal water was discovered to be a protective factor against carriage and faecal shedding of the pathogen. Organic production and buying feed from a certain feed manufacturer were also protective against total carriage. Tonsillar carriage, a different feed manufacturer, fasting pigs before transport to the slaughterhouse, higher-level farm health classification, and snout contacts between pigs were risk factors for faecal shedding. We concluded that differences in management can explain different prevalences ofY. enterocoliticabetween farms.

Antimicrobial resistance of heterotrophic bacteria in sewage-contaminated rivers

Sewage-contaminated rivers are ecosystems deeply disturbed by human activity due to the release of heavy metals, organic pollutants and pharmaceuticals as well as faecal and pathogenic micro-organisms, which coexist with the autochthonous microbial population. In this study, we compared the percentage of resistance in faecal and heterotrophic bacteria in rivers with different degrees of sewage pollution. As a matter of fact, no correlation was found neither between the degree of sewage pollution and the percentage of antimicrobial resistant heterotrophic bacteria nor between the number of resistant faecal bacteria and that of resistant heterotrophic bacteria. Most of the resistant isolates from the Zenne river downstream Brussels were multi-resistant and the resistance patterns were similar among the strains of each phylogenetic group. The total microbial community in this polluted river (as evaluated through a 16S rRNA gene clone library analysis) appeared to be dominated by the phyla Proteobacteria and Bacteroidetes while the phylum TM7 was the third most represented.

Probiotic Lactobacillus reuteri ameliorates disease due to enterohemorrhagic Escherichia coli in germfree mice

Strains of enterohemorrhagic Escherichia coli (EHEC) are a group of Shiga toxin-producing food-borne pathogens that cause severe hemorrhagic colitis and can lead to hemolytic-uremic syndrome (HUS), a life-threatening condition that principally affects children and for which there is no effective treatment. We used a germfree mouse model of renal and enteric disease due to EHEC to determine if probiotic Lactobacillus reuteri ATCC PTA 6475 is effective in suppressing disease symptoms caused by EHEC. When germfree Swiss Webster mice are monocolonized with EHEC, they develop disease characterized by weight loss, cecal luminal fluid accumulation, and renal tubular necrosis. When L. reuteri was administered 1 day prior to EHEC challenge and every other day thereafter, EHEC colonization was suppressed and mice were significantly protected from the manifestations of disease. Protection from disease did not require the induction of the antimicrobial compound reuterin in L. reuteri prior to treatment. The twice-daily administration of L. reuteri appeared more effective than every-other-day administration. These data indicated that L. reuteri partially protects mice from disease manifestations of EHEC.

10% Povidone-iodine may be a practical field water disinfectant

OBJECTIVE

A paucity of data exists regarding the use of iodophores such as povidone-iodine (PVI) to disinfect water. We sought to determine a practical minimal disinfecting concentration of 10% PVI over different contact times and temperatures when added to water inoculated with E. coli.

METHODS

1:100, 1:1,000, and 1:10,000 dilutions of 10% PVI were created. Escherichia coli was exposed to these dilutions for 5, 15, and 30 minutes at 10, 20, and 30°C. Bactericidal activity was neutralized with 0.5% sodium thiosulfate. Mean viable colony forming units (CFUs) was determined after triplicate plating on Luria-bertani agar and 24 hours of incubation at 37°C. Effective bactericidal activity was defined as a 5-log reduction.

RESULTS

Of the 200,000 E. coli plated, no CFUs were observed after exposure to the 1:100 dilution. After 5 minutes of contact time with the 1:1,000 dilution, at 10°C CFUs were too numerous to count (TNTC), at 20°C the mean CFU count was 92 (standard error ±11), and at 30°C the mean CFU count was 25 (standard error ±8). No CFUs were observed after 15 minutes of exposure to the 1:1,000 dilution across experimental temperatures. The 1:10,000 dilution always yielded CFU growth that was TNTC.

CONCLUSIONS

The lowest disinfecting concentration of 10% PVI was the 1:1,000 dilution at 15 minutes of contact time. This supports the use of PVI for water disinfection against E. coli, the organism most commonly responsible for traveler's diarrhea. Further studies may assess its effectiveness against more virulent water borne pathogens.

Evaluation of the removal of indicator bacteria from domestic sludge processed by Autothermal Thermophilic Aerobic Digestion (ATAD)

The degradation of sludge solids in an insulated reactor during Autothermal Thermophilic Aerobic Digestion (ATAD) processing results in auto-heating, thermal treatment and total solids reduction, however, the ability to eliminate pathogenic organisms has not been analysed under large scale process conditions. We evaluated the ATAD process over a period of one year in a two stage, full scale Irish ATAD plant established in Killarney and treating mixed primary and secondary sludge, by examining the sludge microbiologically at various stages during and following ATAD processing to determine its ability to eliminate indicator organisms. Salmonella spp. (pathogen) and fecal-coliform (indicator) densities were well below the limits used to validate class A biosolids in the final product. Enteric pathogens present at inlet were deactivated during the ATAD process and were not detected in the final product using both traditional microbial culture and molecular phylogenetic techniques. A high DNase activity was detected in the bulk sludge during the thermophilic digestion stage which may be responsible for the rapid turn over of DNA from lysed cells and the removal of mobile DNA. These results offer assurance for the safe use of ATAD sludge as a soil supplement following processing.

Molecular detection of pathogens in water--the pros and cons of molecular techniques

Pollution of water by sewage and run-off from farms produces a serious public health problem in many countries. Viruses, along with bacteria and protozoa in the intestine or in urine are shed and transported through the sewer system. Even in highly industrialized countries, pathogens, including viruses, are prevalent throughout the environment. Molecular methods are used to monitor viral, bacterial, and protozoan pathogens, and to track pathogen- and source-specific markers in the environment. Molecular techniques, specifically polymerase chain reaction-based methods, provide sensitive, rapid, and quantitative analytical tools with which to study such pathogens, including new or emerging strains. These techniques are used to evaluate the microbiological quality of food and water, and to assess the efficiency of virus removal in drinking and wastewater treatment plants. The range of methods available for the application of molecular techniques has increased, and the costs involved have fallen. These developments have allowed the potential standardization and automation of certain techniques. In some cases they facilitate the identification, genotyping, enumeration, viability assessment, and source-tracking of human and animal contamination. Additionally, recent improvements in detection technologies have allowed the simultaneous detection of multiple targets in a single assay. However, the molecular techniques available today and those under development require further refinement in order to be standardized and applicable to a diversity of matrices. Water disinfection treatments may have an effect on the viability of pathogens and the numbers obtained by molecular techniques may overestimate the quantification of infectious microorganisms. The pros and cons of molecular techniques for the detection and quantification of pathogens in water are discussed.