Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 47
Filter
1.
Materials (Basel) ; 14(11)2021 May 25.
Article in English | MEDLINE | ID: mdl-34070704

ABSTRACT

The authors wish to make the following corrections to this paper [1]:Throughout the paper's text and in the table, "HCoV-299E" is referred to a few times [...].

2.
Materials (Basel) ; 13(22)2020 Nov 18.
Article in English | MEDLINE | ID: mdl-33218120

ABSTRACT

The unwavering spread of COVID-19 has taken the world by storm. Preventive measures like social distancing and mask usage have been taken all around the globe but still, as of September 2020, the number of cases continues to rise in many countries. Evidently, these measures are insufficient. Although decreases in population density and surges in the public's usage of personal protective equipment can mitigate direct transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), indirect transmission of the virus is still probable. By summarizing the current state of knowledge on the stability of coronaviruses on dry materials, this review uncovers the high potential for SARS-CoV-2 transmission through contaminated surfaces (i.e., fomites) and prompts future research. Fully contextualized data on coronavirus persistence are presented. The methods and limitations to testing the stability of coronaviruses are explored, and the SARS-CoV-2 representativeness of different coronaviruses is analyzed. The factors which dictate the persistence of coronaviruses on surfaces (media, environmental conditions, and material-type) are investigated, and the review is concluded by encouraging material innovation to combat the current pandemic. To summarize, SARS-CoV-2 remains viable on the timescale of days on hard surfaces under ambient indoor conditions. Similarly, the virus is stable on human skin, signifying the necessity of hand hygiene amidst the current pandemic. There is an inverse relationship between SARS-CoV-2 surface persistence and temperature/humidity, and the virus is well suited to air-conditioned environments (room temperature, ~ 40% relative humidity). Sunlight may rapidly inactivate the virus, suggesting that indirect transmission predominantly occurs indoors. The development of antiviral materials and surface coatings would be an extremely effective method to mitigate the spread of COVID-19. To obtain applicable data on the persistence of coronaviruses and the efficiency of virucidal materials, future researchers should understand the common experimental limitations outlined in this review and plan their studies accordingly.

3.
Mar Pollut Bull ; 133: 289-293, 2018 Aug.
Article in English | MEDLINE | ID: mdl-30041316

ABSTRACT

In the present research, we aimed to investigate organochlorine toxins accumulated in both Rutilus frisii kutum and Liza aurata captured at the southern Caspian Sea. At six sampling stations, organochlorine toxins were measured in fish tissues by the gas chromatography-electron capture detector (GC-ECD) method. Total organochlorine toxins ranged from 2.102 ppb to 9.033 ppb in L. aurata at the study area. The highest content of total organochlorine toxins was obtained at station 5, whereas the lowest content was achieved at station 4. In L. aurata, lindane showed the highest level among the measured components (1.642 ppb), whereas α-lindane showed the highest mean level of the measured components (0.57 ppb). In this investigation, the total amount of organochlorine compounds in R. frisii kutum was more than that in L. aurata, but these compounds indicated no significant difference between the two types of fishes (p > 0.05). Moreover, the measured components in both types of fishes were lesser than the allowable limit.


Subject(s)
Fishes , Hydrocarbons, Chlorinated/analysis , Pesticides/analysis , Water Pollutants, Chemical/analysis , Animals , Cyprinidae , Environmental Monitoring , Hexachlorocyclohexane/analysis , Oceans and Seas
4.
Mar Pollut Bull ; 130: 1-5, 2018 May.
Article in English | MEDLINE | ID: mdl-29866535

ABSTRACT

We aimed to investigate mercury level in three species of fish such as Sander lucioperca, Liza aurata, and Rutilus frisii kutum. Sampling was done in the southern coasts of the Caspian Sea. The ranges of mercury level in S. lucioperca, L. aurata, and R. frisii kutum were 104.67-675.33 ppb, 60.66-175.33 ppb, and 123.33-170.33 ppb, respectively. Results revealed that the mercury level in S. lucioperca was more than the allowable limit at several sites, while it was less than the allowable limit in R. frisii kutum and L. aurata at all sampling sites. Further, the target hazard quotient (THQ) index for S. lucioperca was >1 at some sites and <1 for other species at all sites. The maximum allowable consumption for each species at the study area was measured daily and monthly.


Subject(s)
Fishes , Food Contamination/analysis , Mercury/toxicity , Animals , Humans , Mercury/analysis , Perches , Risk
5.
Sci Total Environ ; 621: 1601-1614, 2018 Apr 15.
Article in English | MEDLINE | ID: mdl-29054671

ABSTRACT

Rapid urbanization in China has dramatically deteriorated the water quality of streams and threatening aquatic ecosystem health. This study aims to 1) assess the impacts of urbanization on water quality and macroinvertebrate composition and 2) address the question of how urbanization affects macroinvertebrate distribution patterns. Environmental variables over multispatial scales and macroinvertebrate community data were collected on April (dry season) and September (wet season) of 2014 and 2015 at 19 sampling sites, of which nine had a high urbanization level (HUL), six had moderate urbanization level (MUL) and four had low urbanization level (LUL), in the Liangjiang New Area. The results of this study showed that macroinvertebrate assemblages significantly varied across the three urbanization levels. The sensitive species (e.g., EPT taxa) were mainly centralized at LUL sites, whereas tolerant species, such as Tubificidae (17.3%), Chironomidae (12.1%), and Physidae (4.61%), reached highest relative abundance at LUL sites. The values of family biotic index (FBI) and biological monitoring working party (BMWP) indicated the deterioration of water quality along urbanization gradient. Seasonal and inter - annual changes in macroinvertebrate communities were not observed. The results of variation partitioning analyses (CCAs) showed that habitat scale variables explained the major variation in macroinvertebrate community composition. Specifically, the increased nutrient concentrations favored tolerant species, whereas high water flow and substrate coarseness benefitted community taxa richness, diversity and EPT richness. Considering the interactions between scale-related processes, the results of this study suggested that urbanization resulted in less diverse and more tolerant stream macroinvertebrate assemblages mainly via increased nutrient concentrations and reduced substrate coarseness.


Subject(s)
Environmental Monitoring , Invertebrates , Urbanization , Water Quality , Animals , China , Ecosystem , Rivers
6.
Environ Monit Assess ; 189(4): 174, 2017 Apr.
Article in English | MEDLINE | ID: mdl-28324277

ABSTRACT

Rapid urbanization in China has been causing dramatic deterioration in the water quality of rivers and threatening aquatic ecosystem health. In this paper, multivariate techniques, such as factor analysis (FA) and cluster analysis (CA), were applied to analyze the water quality datasets for 19 rivers in Liangjiang New Area (LJNA), China, collected in April (dry season) and September (wet season) of 2014 and 2015. In most sampling rivers, total phosphorus, total nitrogen, and fecal coliform exceeded the Class V guideline (GB3838-2002), which could thereby threaten the water quality in Yangtze and Jialing Rivers. FA clearly identified the five groups of water quality variables, which explain majority of the experimental data. Nutritious pollution, seasonal changes, and construction activities were three key factors influencing rivers' water quality in LJNA. CA grouped 19 sampling sites into two clusters, which located at sub-catchments with high- and low-level urbanization, respectively. One-way ANOVA showed the nutrients (total phosphorus, soluble reactive phosphorus, total nitrogen, ammonium nitrogen, and nitrite), fecal coliform, and conductivity in cluster 1 were significantly greater than in cluster 2. Thus, catchment urbanization degraded rivers' water quality in Liangjiang New Area. Identifying effective buffer zones at riparian scale to weaken the negative impacts of catchment urbanization was recommended.


Subject(s)
Environmental Monitoring/methods , Water Pollutants, Chemical/analysis , China , Cluster Analysis , Ecosystem , Factor Analysis, Statistical , Nitrogen/analysis , Phosphorus/analysis , Rivers , Seasons , Urbanization , Water Quality
7.
J Environ Qual ; 45(6): 1933-1940, 2016 Nov.
Article in English | MEDLINE | ID: mdl-27898784

ABSTRACT

Catechol, nitrite, and dissolved metals are ubiquitous in source drinking water. Catechol and nitrite have been identified as precursors for halonitromethanes (HNMs), but the effect of metal ions on HNM formation during chlorination remains unclear. The main objective of this study was to investigate the effect of metal ions (Fe, Ti, Al) on the formation of trichloronitromethane (TCNM) (the most representative HNM species in disinfected water) on chlorinating catechol and nitrite. Trichloronitromethane was extracted by methyl tert-butyl ether and detected by gas chromatography. The results show that metal ions promoted the formation of TCNM and that the enhancement efficiency followed the order of Fe > Ti > Al. Trichloronitromethane formation increased greatly within 2 h, and a basic condition (pH 8-9) favored TCNM formation more than acidic or neutral conditions. The conjoint effect of the metal-ion mixtures was shown to be similar to that of the single metal ion having the highest promoting effect on TCNM formation. Our results strongly suggest that metal ions play a significant role in enhancing TCNM formation.


Subject(s)
Catechols/chemistry , Hydrocarbons, Chlorinated/chemistry , Nitrites/chemistry , Water Pollutants, Chemical/chemistry , Disinfection , Halogenation , Ions , Metals , Water Purification
8.
Genome Announc ; 4(4)2016 Aug 04.
Article in English | MEDLINE | ID: mdl-27491986

ABSTRACT

We present here the draft genome sequence of Pseudoalteromonas tetraodonis strain MQS005, a bacterium possessing potential quorum-sensing regulatory activity. This strain was isolated from water from the South China Sea, People's Republic of China. The assembly consists of 4,252,538 bp and contains 144 contigs, with a G+C content of 41.85%.

9.
J Anim Ecol ; 85(3): 681-91, 2016 05.
Article in English | MEDLINE | ID: mdl-26880007

ABSTRACT

Ontogenetic niche shifts are widely prevalent in nature and are important in shaping the structure and dynamics of ecosystems. Stable isotope analysis is a powerful tool to assess these shifts, with δ(15) N providing a measure of trophic level and δ(13) C a measure of energy source. Previous applications of stable isotopes to study ontogenetic niche shifts have not considered the appreciable time lag between diet and consumer tissue associated with isotopic turnover. These time lags introduce significant complexity into field studies of ontogenetic niche shifts. Juvenile Chinook salmon (Oncorhynchus tshawytscha) migrate from freshwater to marine ecosystems and shift their diet from feeding primarily on invertebrates to feeding primarily on fish. This dual ontogenetic habitat and diet shift, in addition to the long time lag associated with isotopic turnover, suggests that there is potential for a disconnect between the prey sources that juvenile salmon are consuming, and the inferred prey sources from stable isotopes. We developed a model that considered ontogenetic niche shifts and time lags associated with isotopic turnover, and compared this 'ontogeny' model to one that considered only isotopic turnover. We used a Bayesian framework to explicitly account for parameter uncertainty. Data showed overwhelming support for the ontogeny model relative to the isotopic turnover model. Estimated variables from best model fits indicate that the ontogeny model predicts a much greater reliance on fish prey than does the stomach content data. Overall, we found that this method of quantifying ontogenetic niche shifts effectively accounted for both isotopic turnover and ontogenetic diet shifts; a finding that could be widely applicable to a variety of systems.


Subject(s)
Carbon Isotopes/metabolism , Diet , Models, Theoretical , Nitrogen Isotopes/metabolism , Salmon/growth & development , Salmon/metabolism , Animals , Bayes Theorem , Ecosystem , Fishes , Fresh Water , Gastrointestinal Contents/chemistry , Invertebrates , Seawater , Time Factors
10.
Environ Geochem Health ; 38(6): 1303-1312, 2016 Dec.
Article in English | MEDLINE | ID: mdl-26803297

ABSTRACT

The purpose of this study was to develop the multiple regression models to evaluate the formation of trihalomethanes (THMs) and haloacetonitriles (HANs) during chlorination of source water with low specific ultraviolet absorbance (SUVA) in Yangtze River Delta, China. The results showed that the regression models of THMs exhibited good accuracy and precision, and 86-97 % of the calculated values fell within ±25 % of the measured values. While the HANs models showed relatively weak evaluation ability, as only 75-83 % of the calculated values were within ±25 % of the measured values. The organic matter [dissolved organic carbon (DOC) or UV absorbance at 254 nm] and bromide exerted the most important influence on the formation of HANs. While for THMs, besides the organic matter and bromide, reaction time was also a key factor. Comparing the models for total THMs (T-THMs) in this study with others revealed that the regression models from the low SUVA waters may have low DOC coefficients, but high bromide coefficients as compared with those from the high SUVA waters.


Subject(s)
Fresh Water/chemistry , Halogenation , Hydrocarbons, Halogenated/chemistry , Acetonitriles/analysis , Acetonitriles/chemistry , China , Drinking Water/analysis , Models, Theoretical , Organic Chemicals/chemistry , Trihalomethanes/analysis , Trihalomethanes/chemistry , Water Pollutants, Chemical/analysis , Water Purification/methods , Water Supply
12.
Environ Toxicol Chem ; 35(4): 919-29, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26363402

ABSTRACT

Pharmaceuticals and personal care products (PPCPs) are emerging chemicals of concern detected in surface waters globally. Recent reviews advocate that PPCP occurrence, fate, and exposure need to be better predicted and characterized. The use of pharmaceutical prescription rates to estimate PPCP concentrations in the environment has been suggested. Concentrations of 7 pharmaceuticals (acetylsalicylic acid, diclofenac, fenoprofen, gemfibrozil, ibuprofen, ketoprofen, and naproxen) were measured in municipal wastewater using gas chromatography/ion trap-tandem mass spectroscopy (GC/IT-MS/MS). Subregional pharmaceutical prescription data were investigated to determine whether they could predict measured effluent concentrations (MECs) in wastewaters. Predicted effluent concentrations (PECs) for 5 of the 7 pharmaceuticals were within 2-fold agreement of the MECs when the fraction of parent pharmaceutical excreted was not considered. When the fraction of parent pharmaceutical excreted was considered, the respective PECs decreased, and most were within an order of magnitude of the MECs. Regression relationships of monthly PECs versus MECs were statistically significant (p < 0.05) but weak (R(2) = 0.18-0.56) for all pharmaceuticals except ketoprofen. This suggests high variability in the data and may be the result of factors influencing MECs such as the analytical methods used, wastewater sampling frequency, and methodology. The PECs were based solely on prescription rates and did not account for inputs of pharmaceuticals that had a significant over-the-counter component or were from other sources (e.g., hospitals).


Subject(s)
Cities , Drug Prescriptions , Pharmaceutical Preparations/analysis , Wastewater/chemistry , Water Pollutants, Chemical/analysis , Adolescent , Adult , Aged , British Columbia , Child , Child, Preschool , Female , Geography , Humans , Infant , Infant, Newborn , Male , Middle Aged , Quality Control , Regression Analysis , Uncertainty , Waste Disposal, Fluid , Young Adult
13.
Ecol Evol ; 5(21): 4829-39, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26640663

ABSTRACT

Many organisms experience fasting in their life time, and this physiological process has the potential to alter stable isotope values of organisms, and confound interpretation of food web studies. However, previous studies on the effects of fasting and starvation on stable isotopes show disparate results, and have never been quantitatively synthesized. We performed a laboratory experiment and meta-analysis to determine how stable isotopes of δ (15)N and δ (13)C change with fasting, and we tested whether moderators such as taxa and tissue explain residual variation. We collected literature data from a wide variety of taxa and tissues. We surveyed over 2000 papers, and of these, 26 met our selection criteria, resulting in 51 data points for δ (15)N, and 43 data points for δ (13)C. We determine that fasting causes an average increase in the isotopic value of organisms of 0.5‰ for δ (15)N and that the only significant moderator is tissue type. We find that the overall effect size for δ (13)C is not significant, but when the significant moderator of tissue is considered, significant increases in blood and whole organisms are seen with fasting. Our results show that across tissues and taxa, the nutritional status of an organism must be considered when interpreting stable isotope data, as fasting can cause large differences in stable isotope values that would be otherwise attributed to other factors.

14.
Environ Pollut ; 206: 64-72, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26142752

ABSTRACT

Owing to the growing public awareness on the safety and aesthetics in water sources, more attention has been given to the adverse effects of volatile organic compounds (VOCs) on aquatic organisms and human beings. In this study, 77 target VOCs (including 54 common VOCs, 13 carbonyl compounds, and 10 taste and odor compounds) were detected in typical drinking water sources from 5 major river basins (the Yangtze, the Huaihe, the Yellow, the Haihe and the Liaohe River basins) and their occurrences were characterized. The ecological, human health, and olfactory assessments were performed to assess the major hazards in source water. The investigation showed that there existed potential ecological risks (1.30 × 10 ≤ RQtotals ≤ 8.99 × 10) but little human health risks (6.84 × 10(-7) ≤ RQtotals ≤ 4.24 × 10(-4)) by VOCs, while that odor problems occurred extensively. The priority contaminants in drinking water sources of China were also listed based on the present assessment criteria.


Subject(s)
Drinking Water/chemistry , Rivers/chemistry , Volatile Organic Compounds/chemistry , Water Pollutants, Chemical/chemistry , China , Drinking Water/standards , Environmental Monitoring , Health , Humans , Odorants/analysis , Water Supply
15.
Isotopes Environ Health Stud ; 51(2): 332-43, 2015.
Article in English | MEDLINE | ID: mdl-25560176

ABSTRACT

The use of nitrogen stable isotopes to discriminate between conventionally and organically grown crops has been further developed in this study. Soil and irrigation water from different regions, as well as nitrogen fertilizers used, have been examined in detail to determine their effects on nitrogen isotope composition of spinach, lettuce, broccoli and tomatoes. Over 1000 samples of various types of organically and conventionally grown produce of known origin, along with the samples of nitrogen fertilizers used for their growth, have been analysed in order to assemble the datasets of crop/fertilizer correlations. The results demonstrate that the developed approach can be used as a valuable component in the verification of agricultural practices for more than 25 different types of commercially grown green produce, either organic or conventional. Over a period of two years, various organic and non-organic greens, from different stores in Seattle (WA, USA) and Victoria (BC, Canada), were collected and analysed using this methodology with the objective of determining any pattern of misrepresentation.


Subject(s)
Fertilizers/analysis , Food, Organic/analysis , Mass Spectrometry/methods , Agricultural Irrigation , British Columbia , Nitrogen Isotopes/analysis , Soil/chemistry , Washington , Water/analysis
16.
Appl Environ Microbiol ; 81(5): 1788-98, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25548059

ABSTRACT

Escherichia coli isolates (n = 658) obtained from drinking water intakes of Comox Lake (2011 to 2013) were screened for the following virulence genes (VGs): stx1 and stx2 (Shiga toxin-producing E. coli [STEC]), eae and the adherence factor (EAF) gene (enteropathogenic E. coli [EPEC]), heat-stable (ST) enterotoxin (variants STh and STp) and heat-labile enterotoxin (LT) genes (enterotoxigenic E. coli [ETEC]), and ipaH (enteroinvasive E. coli [EIEC]). The only genes detected were eae and stx2, which were carried by 37.69% (n = 248) of the isolates. Only eae was harbored by 26.74% (n = 176) of the isolates, representing potential atypical EPEC strains, while only stx2 was detected in 10.33% (n = 68) of the isolates, indicating potential STEC strains. Moreover, four isolates were positive for both the stx2 and eae genes, representing potential EHEC strains. The prevalence of VGs (eae or stx2) was significantly (P < 0.0001) higher in the fall season, and multiple genes (eae plus stx2) were detected only in fall. Repetitive element palindromic PCR (rep-PCR) fingerprint analysis of 658 E. coli isolates identified 335 unique fingerprints, with an overall Shannon diversity (H') index of 3.653. Diversity varied among seasons over the years, with relatively higher diversity during fall. Multivariate analysis of variance (MANOVA) revealed that the majority of the fingerprints showed a tendency to cluster according to year, season, and month. Taken together, the results indicated that the diversity and population structure of E. coli fluctuate on a temporal scale, reflecting the presence of diverse host sources and their behavior over time in the watershed. Furthermore, the occurrence of potentially pathogenic E. coli strains in the drinking water intakes highlights the risk to human health associated with direct and indirect consumption of untreated surface water.


Subject(s)
Escherichia coli Proteins/genetics , Escherichia coli/classification , Escherichia coli/isolation & purification , Genetic Variation , Lakes/microbiology , Virulence Factors/genetics , British Columbia , Cluster Analysis , DNA Fingerprinting , Escherichia coli/genetics , Forests , Molecular Typing , Seasons
17.
Appl Environ Microbiol ; 80(6): 1933-40, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24441159

ABSTRACT

Contamination of surface water by fecal microorganisms originating from human and nonhuman sources is a public health concern. In the present study, Escherichia coli isolates (n = 412) from the feces of various avian host sources were screened for various virulence genes: stx1 and stx2 (Shiga toxin-producing E. coli [STEC]), eae (enteropathogenic E. coli [EPEC]), est-h, est-p, and elt (encoding heat-stable toxin [ST] variants STh and STp and heat-labile toxin [LT], respectively) (enterotoxigenic E. coli [ETEC]), and ipaH (enteroinvasive E. coli [EIEC]). None of the isolates were found to be positive for stx1, while 23% (n = 93) were positive for only stx2, representing STEC, and 15% (n = 63) were positive for only eae, representing EPEC. In addition, five strains obtained from pheasant were positive for both stx2 and eae and were confirmed as non-O157 by using an E. coli O157 rfb (rfbO157) TaqMan assay. Isolates positive for the virulence genes associated with ETEC and EIEC were not detected in any of the hosts. The repetitive element palindromic PCR (rep-PCR) fingerprint analysis identified 143 unique fingerprints, with an overall Shannon diversity index of 2.36. Multivariate analysis of variance (MANOVA) showed that the majority of the STEC and EPEC isolates were genotypically distinct from nonpathogenic E. coli and clustered independently. MANOVA analysis also revealed spatial variation among the E. coli isolates, since the majority of the isolates clustered according to the sampling locations. Although the presence of virulence genes alone cannot be used to determine the pathogenicity of strains, results from this study show that potentially pathogenic STEC and EPEC strains can be found in some of the avian hosts studied and may contaminate surface water and potentially impact human health.


Subject(s)
Birds/microbiology , Escherichia coli/classification , Escherichia coli/isolation & purification , Feces/microbiology , Genetic Variation , Virulence Factors/genetics , Animals , British Columbia , Cluster Analysis , DNA Fingerprinting , Escherichia coli/genetics , Escherichia coli Proteins/genetics , Genotype , Humans , Polymerase Chain Reaction
18.
Water Res ; 48: 170-8, 2014 Jan 01.
Article in English | MEDLINE | ID: mdl-24095594

ABSTRACT

Quantifying the influence of hydro-meteorological variability on surface source water fecal contamination is critical to the maintenance of safe drinking water. Historically, this has not been possible due to the scarcity of data on fecal indicator bacteria (FIB). We examined the relationship between hydro-meteorological variability and the most commonly measured FIB, fecal coliform (FC), concentration for 43 surface water sites within the hydro-climatologically complex region of British Columbia. The strength of relationship was highly variable among sites, but tended to be stronger in catchments with nival (snowmelt-dominated) hydro-meteorological regimes and greater land-use impacts. We observed positive relationships between inter-annual FC concentration and hydro-meteorological variability for around 50% of the 19 sites examined. These sites are likely to experience increased fecal contamination due to the projected intensification of the hydrological cycle. Seasonal FC concentration variability appeared to be driven by snowmelt and rainfall-induced runoff for around 30% of the 43 sites examined. Earlier snowmelt in nival catchments may advance the timing of peak contamination, and the projected decrease in annual snow-to-precipitation ratio is likely to increase fecal contamination levels during summer, fall, and winter among these sites. Safeguarding drinking water quality in the face of such impacts will require increased monitoring of FIB and waterborne pathogens, especially during periods of high hydro-meteorological variability. This data can then be used to develop predictive models, inform source water protection measures, and improve drinking water treatment.


Subject(s)
Enterobacteriaceae/isolation & purification , Feces/microbiology , Hydrology , Meteorology , Seasons , Water Microbiology , British Columbia , Colony Count, Microbial
19.
Appl Environ Microbiol ; 79(23): 7371-80, 2013 Dec.
Article in English | MEDLINE | ID: mdl-24056456

ABSTRACT

In order to assess the health risk associated with a given source of fecal contamination using bacterial source tracking (BST), it is important to know the occurrence of potential pathogens as a function of host. Escherichia coli isolates (n=593) from the feces of diverse animals were screened for various virulence genes: stx1 and stx2 (Shiga toxin-producing E. coli [STEC]), eae and EAF (enteropathogenic E. coli [EPEC]), STh, STp, and LT (enterotoxigenic E. coli [ETEC]), and ipaH (enteroinvasive E. coli [EIEC]). Eleven hosts were positive for only the eae (10.11%) gene, representing atypical EPEC, while two hosts were positive for both eae and EAF (1.3%), representing typical EPEC. stx1, stx2, or both stx1 and stx2 were present in 1 (0.1%,) 10 (5.56%), and 2 (1.51%) hosts, respectively, and confirmed as non-O157 by using a E. coli O157 rfb (rfbO157) TaqMan assay. STh and STp were carried by 2 hosts (2.33%) and 1 host (0.33%), respectively, while none of the hosts were positive for LT and ipaH. The repetitive element palindromic PCR (rep-PCR) fingerprint analysis identified 221 unique fingerprints with a Shannon diversity index of 2.67. Multivariate analysis of variance revealed that majority of the isolates clustered according to the year of sampling. The higher prevalence of atypical EPEC and non-O157 STEC observed in different animal hosts indicates that they can be a reservoir of these pathogens with the potential to contaminate surface water and impact human health. Therefore, we suggest that E. coli from these sources must be included while constructing known source fingerprint libraries for tracking purposes. However, the observed genetic diversity and temporal variation need to be considered since these factors can influence the accuracy of BST results.


Subject(s)
Diarrhea/microbiology , Escherichia coli Infections/microbiology , Escherichia coli Infections/veterinary , Escherichia coli/classification , Feces/microbiology , Genetic Variation , Virulence Factors/genetics , Animals , Cluster Analysis , Escherichia coli/genetics , Escherichia coli/isolation & purification , Escherichia coli Proteins/genetics , Genotype , Humans , Molecular Typing
20.
J Water Health ; 11(2): 324-32, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23708579

ABSTRACT

The objective of the study was to evaluate the survival response of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi to the salinity fluctuations induced by a saltwater barrier constructed in Vembanadu lake, which separates the lake into a freshwater dominated southern and brackish water dominated northern part. Therefore, microcosms containing freshwater, brackish water and microcosms with different saline concentrations (5, 10, 15, 20, 25 ppt) inoculated with E. coli/S. paratyphi were monitored up to 34 days at 20 and 30 °C. E. coli and S. paratyphi exhibited significantly higher (p < 0.05) survival at 20 °C compared to 30 °C in all microcosms. Despite fresh/brackish water, E. coli and S. paratyphi showed prolonged survival up to 34 days at both temperatures. They also demonstrated better survival potential at all tested saline concentrations except 25 ppt where a significantly higher (p < 0.0001) decay was observed. Therefore, enhanced survival exhibited by the multi-drug resistant enteropathogenic E. coli and S. paratyphi over a wide range of salinity levels suggest that they are able to remain viable for a very long time at higher densities in all seasons of the year in Vembanadu lake irrespective of saline concentrations, and may pose potential public health risks during recreational activities.


Subject(s)
Drug Resistance, Multiple, Bacterial , Enteropathogenic Escherichia coli/drug effects , Salmonella paratyphi A/drug effects , Seawater/microbiology , Enteropathogenic Escherichia coli/isolation & purification , India , Indian Ocean , Lakes , Salmonella paratyphi A/isolation & purification , Time Factors
SELECTION OF CITATIONS
SEARCH DETAIL
...