Fecal indicators, pathogens, antibiotic resistance genes, and ecotoxicity in Galveston Bay after Hurricane Harvey. - Related Documents




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354201.0000Fecal indicators, pathogens, antibiotic resistance genes, and ecotoxicity in Galveston Bay after Hurricane Harvey. Unprecedented rainfall after Hurricane Harvey caused a catastrophic flood in the southern coast of Texas, and flushed significant floodwater and sediments into Galveston Bay, the largest estuary along the Texas Gulf Coast. This study investigated the immediate and long-term (6 months post-Harvey) fecal indicators, pathogenic bacteria, antibiotic resistance genes (ARGs), and ecotoxicity in the Galveston Bay. Dramatic decrease of salinity profile to zero, increased levels of fecal indicator bacteria and pathogenic bacteria, and detection of various ARGs were observed in the water and sediment samples collected 2 weeks post-Harvey. High levels of Bla(TEM) and cytotoxicity measured by yeast bioluminescent assay (BLYR) were also observed especially near the river mouths. While Vibrio spp. was dominant in water, much higher abundance of fecal indicator bacteria and pathogen were detected in the sediments. A decreasing trend of Bla(TEM) and cytotoxicity was observed in March 2018 samples, suggesting the Bay has returned to its pre-hurricane conditions 6 months post-Harvey. Interestingly, the abundance of fecal indicator bacteria and pathogens were shifted dramatically according to high-streamflow and low-streamflow seasons in the Bay. The data are useful to construct the model of risk assessment in coastal estuaries system and predict the effects of extreme flooding events in the future.202133445049
712910.9995Impact of flooding on urban soils: Changes in antibiotic resistance and bacterial community after Hurricane Harvey. Major perturbations in soil and water quality are factors that can negatively impact human health. In soil environments of urban areas, changes in antibiotic-resistance profiles may represent an increased risk of exposure to antibiotic-resistant bacteria via oral, dermal, or inhalation routes. We studied the perturbation of antibiotic-resistance profiles and microbial communities in soils following a major flooding event in Houston, Texas, caused by Hurricane Harvey. The main objective of this study was to examine the presence of targeted antibiotic-resistance genes and changes in the diversity of microbial communities in soils a short time (3-5 months) and a long time (18 months) after the catastrophic flooding event. Using polymerase chain reaction, we surveyed fourteen antibiotic-resistance elements: intI1, intI2, sul1, sul2, tet(A) to (E), tet(M), tet(O), tet(W), tet(X), and bla(CMY-2). The number of antibiotic-resistance genes detected were higher in short-time samples compared to samples taken a long time after flooding. From all the genes surveyed, only tet(E), bla(CMY-2), and intI1 were prevalent in short-time samples but not observed in long-time samples; thus, we propose these genes as indicators of exogenous antibiotic resistance in the soils. Sequencing of the V3-V4 region of the bacterial 16S rRNA gene was used to find that flooding may have affected bacterial community diversity, enhanced differences among bacterial lineages profiles, and affected the relative abundance of Actinobacteria, Verrucomicrobia, and Gemmatimonadetes. A major conclusion of this study is that antibiotic resistance profiles of soil bacteria are impacted by urban flooding events such that they may pose an enhanced risk of exposure for up to three to five months following the hurricane. The occurrence of targeted antibiotic-resistance elements decreased eighteen months after the hurricane indicating a reduction of the risk of exposure long time after Harvey.202133077230
709820.9993Antibiotic resistance along an urban river impacted by treated wastewaters. Urban rivers are impacted ecosystems which may play an important role as reservoirs for antibiotic-resistant (AR) bacteria. The main objective of this study was to describe the prevalence of antibiotic resistance along a sewage-polluted urban river. Seven sites along the Zenne River (Belgium) were selected to study the prevalence of AR Escherichia coli and freshwater bacteria over a 1-year period. Culture-dependent methods were used to estimate E. coli and heterotrophic bacteria resistant to amoxicillin, sulfamethoxazole, nalidixic acid and tetracycline. The concentrations of these four antibiotics have been quantified in the studied river. The antibiotic resistance genes (ARGs), sul1, sul2, tetW, tetO, blaTEM and qnrS were also quantified in both particle-attached (PAB) and free-living (FLB) bacteria. Our results showed an effect of treated wastewaters release on the spread of antibiotic resistance along the river. Although an increase in the abundance of both AR E. coli and resistant heterotrophic bacteria was observed from upstream to downstream sites, the differences were only significant for AR E. coli. A significant positive regression was also found between AR E. coli and resistant heterotrophic bacteria. The concentration of ARGs increased from upstream to downstream sites for both particle-attached (PAB) and free-living bacteria (FLB). Particularly, a significant increase in the abundance of four among six ARGs analyzed was observed after crossing urban area. Although concentrations of tetracycline significantly correlated with tetracycline resistance genes, the antibiotic levels were likely too low to explain this correlation. The analysis of ARGs in different fractions revealed a significantly higher abundance in PAB compared to FLB for tetO and sul2 genes. This study demonstrated that urban activities may increase the spread of antibiotic resistance even in an already impacted river.201829453174
711730.9992Persistence of antibiotic resistance genes in beef cattle backgrounding environment over two years after cessation of operation. Confined animal feeding operations can facilitate the spread of genes associated with antibiotic resistance. It is not known how cattle removal from beef cattle backgrounding operation affects the persistence of antibiotic resistance genes (ARGs) in the environment. We investigated the effect of cessation of beef cattle backgrounding operation on the persistence and distribution of ARGs in the beef cattle backgrounding environment. The study was conducted at a pasture-feedlot type beef cattle backgrounding operation which consisted of feeding and grazing areas that were separated by a fence with an access gate. Backgrounding occurred for seven years before cattle were removed from the facility. Soil samples (n = 78) from 26 georeferenced locations were collected at the baseline before cattle were removed, and then one year and two years after cattle were removed. Metagenomic DNA was extracted from the soil samples and total bacterial population (16S rRNA), total Enterococcus species and class 1 integrons (intI1), and erythromycin (ermB and ermF), sulfonamide (sul1 and sul2) and tetracycline (tetO, tetW and tetQ) resistance genes were quantified. Concentrations of total bacteria, Enterococcus spp., class 1 integrons, and ARGs were higher in the feeding area and its immediate vicinity (around the fence and the gate) followed by a gradient decline along the grazing area. Although the concentrations of total bacteria, Enterococcus spp., class 1 integrons and ARGs in the feeding area significantly decreased two years after cattle removal, their concentrations were still higher than that observed in the grazing area. Higher concentrations over two years in the feeding area when compared to the grazing area suggest a lasting effect of confined beef cattle production system on the persistence of bacteria and ARGs in the soil.201930768641
727640.9992Antibiotic resistance in urban and hospital wastewaters and their impact on a receiving freshwater ecosystem. The main objective of this study was to investigate the antibiotic resistance (AR) levels in wastewater (WW) and the impact on the receiving river. Samples were collected once per season over one year in the WW of a hospital, in the raw and treated WW of two wastewater treatment plants (WWTPs), as well as upstream and downstream from the release of WWTPs effluents into the Zenne River (Belgium). Culture-dependent methods were used to quantify Escherichia coli and heterotrophic bacteria resistant to amoxicillin, sulfamethoxazole, nalidixic acid and tetracycline. Six antibiotic resistance genes (ARGs) were quantified in both particle-attached (PAB) and free-living (FLB) bacteria. Our results showed that WWTPs efficiently removed antibiotic resistant bacteria (ARB) regardless of its AR profile. The ARGs levels were the highest in the hospital WW and were significantly reduced in both WWTPs. However, ARB and ARGs abundances significantly increased into the Zenne River downstream from the WWTPs outfalls. The variation in the relative abundance of ARGs through WW treatment differed depending on the WWTP, fraction, and gene considered. The sul1 and sul2 genes in PAB fraction showed significantly higher relative abundances in the effluent compared to the influent of both WWTPs. This study demonstrated that WWTPs could be hotspots for AR spread with significant impacts on receiving freshwater ecosystems. This was the first comprehensive study investigating at the same time antibiotics occurrence, fecal bacteria indicators, heterotrophic bacterial communities, and ARGs (distinguishing PAB and FLB) to assess AR levels in WW and impacts on the receiving river.201829730567
725850.9992Occurrence of antibiotics and antibiotic resistances in soils from wastewater irrigation areas in Beijing and Tianjin, China. Non-irrigated and wastewater-irrigated soils were collected from five wastewater irrigation areas in Beijing and Tianjin, China. The concentrations of sulfadiazine, sulfamethoxazole, oxytetracycline and chlortetracycline in the soils were determined. Abundances of antibiotic resistant bacteria and corresponding resistance genes were also measured to examine the impact of wastewater irrigation. No significant difference in antibiotic resistance bacteria was observed between irrigated and non-irrigated soils. However, the concentrations of antibiotics and abundances of resistance genes were significantly greater in irrigated soils, indicating that agricultural activities enhanced the occurrence of antibiotics and resistance genes in the soils. In addition, no significant difference was observed between previously and currently wastewater-irrigated soils. Therefore, cessation of wastewater irrigation did not significantly reduce the levels of antibiotic concentrations and resistance gene abundances. Other factors, e.g., manure application, may explain the lack of significant difference in the occurrence of antibiotics and resistance genes between previously and currently wastewater-irrigated soils.201425016103
708260.9992Catchment-scale export of antibiotic resistance genes and bacteria from an agricultural watershed in central Iowa. Antibiotics are administered to livestock in animal feeding operations (AFOs) for the control, prevention, and treatment of disease. Manure from antibiotic treated livestock contains unmetabolized antibiotics that provide selective pressure on bacteria, facilitating the expression of anti-microbial resistance (AMR). Manure application on row crops is an agronomic practice used by growers to meet crop nutrient needs; however, it can be a source of AMR to the soil and water environment. This study in central Iowa aims to directly compare AMR indicators in outlet runoff from two adjacent (221 to 229 ha) manured and non-manured catchments (manure comparison), and among three catchments (600 to 804 ha) with manure influence, no known manure application (control), and urban influences (mixed land use comparison). Monitored AMR indicators included antibiotic resistance genes (ARGs) ermB, ermF (macrolide), tetA, tetM, tetO, tetW (tetracycline), sul1, sul2 (sulfonamide), aadA2 (aminoglycoside), vgaA, and vgaB (pleuromutilin), and tylosin and tetracycline resistant enterococci bacteria. Results of the manure comparison showed significantly higher (p<0.05) tetracycline and tylosin resistant bacteria from the catchment with manure application in 2017, but no differences in 2018, possibly due to changes in antibiotic use resulting from the Veterinary Feed Directive. Moreover, the ARG analysis indicated a larger diversity of ARGs at the manure amended catchment. The mixed land use comparison showed the manure amended catchment had significantly higher (p<0.05) tetracycline resistant bacteria in 2017 and significantly higher tylosin resistant bacteria in 2017 and 2018 than the urban influenced catchment. The urban influenced catchment had significantly higher ermB concentrations in both sampling years, however the manure applied catchment runoff consisted of higher relative abundance of total ARGs. Additionally, both catchments showed higher AMR indicators compared to the control catchment. This study identifies four ARGs that might be specific to AMR as a result of agricultural sources (tetM, tetW, sul1, sul2) and optimal for use in watershed scale monitoring studies for tracking resistance in the environment.202031923233
723470.9992Urban and agriculturally influenced water contribute differently to the spread of antibiotic resistance genes in a mega-city river network. The widespread of water borne antibiotic resistance genes (ARGs) represents a growing threat to the health of millions of people. Our study detected the relative abundances of 10 ARG subtypes in the Shanghai river network, where the major ARG components were strB, sul1, and ermB. These ARGs were significantly enriched by the combined sewage, tail water from urban wastewater treatment plant and runoff from agricultural areas, which reached the Suzhou (SZ), Dianpu (DP), and Huangpu (HP) River, respectively (one-way ANOVA, P < 0.01). The target ARGs were distributed in varying patterns across different rivers. bla(CTX-M) and bla(TEM) contributed to the increase of total ARGs in the rivers influenced by urban sources, particularly in the SZ River, whose distribution of ARGs was significantly related to that of the confluence of the whole river network (Mantel test, P < 0.01). The bacterial community was closely structured with ARGs and potential pathogenic bacteria's association with target ARGs became significant in downstream samples (Procrustes test, P = 0.03). Water near urban wastewater fallouts was observed to have the highest content of intl1 in the DP River, whose downstream samples' intl -ARG relationship fitted the same regression model as that of the network confluence (R = 0.84, P < 0.001). The amelioration of river water quality does not reduce ARGs, but may affect their distributional patterns in the river network in Shanghai.201931009830
709180.9992Abundance of Class 1 Integron-Integrase and Sulfonamide Resistance Genes in River Water and Sediment Is Affected by Anthropogenic Pressure and Environmental Factors. In this study, we determined the presence of class 1 integron-integrase gene in culturable heterotrophic bacteria isolated from river water and sediment sampled upstream and downstream of a wastewater treatment plant effluent discharge. Moreover, we quantified intI1 and sulfonamide resistance genes (sul1 and sul2) in the water and sediment using qPCR. There was no correlation between the results from water and sediment samples, which suggests integron-containing bacteria are differentially retained in these two environmental compartments. The discharge of treated wastewater significantly increased the frequency of intI1 among culturable bacteria and the gene copy number in river water, and increased the number of sul1 genes in the sediment. We also observed seasonal differences in the frequency of the class 1 integron-integrase gene among culturable heterotrophs as well as intI1 copy number in water, but not in sediment. The results suggest that the abundance of class 1 integrons in aquatic habitat depends on anthropogenic pressure and environmental factors.201627599709
706790.9992Impact of the antibiotic doxycycline on the D. magna reproduction, associated microbiome and antibiotic resistance genes in treated wastewater conditions. Wastewater Treatment Plant (WWTP) effluents are important sources of antibiotics, antibiotic resistance genes (ARGs) and resistant bacteria that threaten aquatic biota and human heath. Antibiotic effects on host-associated microbiomes, spread of ARGs and the consequences for host health are still poorly described. This study investigated changes of the Daphnia magna associated microbiome exposed to the recalcitrant antibiotic doxycycline under artificial reconstituted lab water media (lab water) and treated wastewater media. D. magna individual juveniles were exposed for 10 days to treated wastewater with and without doxycycline, and similarly in lab water. We analysed 16 S rRNA gene sequences to assess changes in community structure, monitored Daphnia offspring production and quantified ARGs abundances by qPCR from both Daphnia and water (before and after the exposure). Results showed that doxycycline and media (lab water or wastewater) had a significant effect modulating Daphnia-associated microbiome composition and one of the most discriminant taxa was Enterococcus spp. Moreover, in lab water, doxycycline reduced the presence of Limnohabitans sp., which are dominant bacteria of the D. magna-associated microbiome and impaired Daphnia reproduction. Contrarily, treated wastewater increased diversity and richness of Daphnia-associated microbiome and promoted fecundity. In addition, the detected ARG genes in both lab water and treated wastewater medium included the qnrS1, sul1, and bla(TEM,) and the integron-related intI1 gene. The treated wastewater contained about 10 times more ARGs than lab water alone. Furthermore, there was an increase of sul1 in Daphnia cultured in treated wastewater compared to lab water. In addition, there were signs of a higher biodegradation of doxycycline by microbiomes of treated wastewater in comparison to lab water. Thus, results suggest that Daphnia-associated microbiomes are influenced by their environment, and that bacterial communities present in treated wastewater are better suited to cope with the effects of antibiotics.202337442322
7274100.9992Neighbor urban wastewater treatment plants display distinct profiles of bacterial community and antibiotic resistance genes. Urban wastewater treatment plants (UWTPs) are among the major recipients of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and antibiotic residues in urban environments. Although during treatment, bacteria of human and animal origin are removed, some are able to survive, persisting in the final effluent. The occurrence of these bacteria, especially those harboring ARGs, may have a direct impact on the quality of the treated wastewater that is returned to the environment. In this study, we aimed to assess if the final effluent bacterial communities of three UWTPs (PT1, PT2, and PT3) located next to each other were distinct and if such differences were related with the antibiotic resistance profiles.It was observed that the bacterial community (16S rRNA gene Illumina sequencing) and load of selected ARGs of final effluent differed among the three UWTPs, irrespective of sampling time. Members of the families Aeromonadaceae, Campylobacteraceae, Veillonellaceae, [Weeksellaceae], and Porphyromonadaceae were observed to be positively correlated with some ARGs (bla(CTX-M), bla(OXA-A), bla(SHV)) and intI1 (p < 0.05), while Intrasporangiaceae were observed to be negatively correlated. While Aeromonadaceae are recognized relevant ARG harbors, the other bacterial families may represent bacteria that co-exist with the ARG hosts, which may belong to minor bacterial groups omitted in the analyses. These findings suggest the importance of bacterial dynamics during treatment to the ARB&ARGs removal, a rationale that may contribute to design new strategies to apply in the UWTPs to prevent the spread of antibiotic resistance.201930796660
7114110.9991Antibiotic Resistance Genes in Freshwater Trout Farms in a Watershed in Chile. Point sources such as wastewater treatment plants, terrestrial agriculture, and aquaculture may release antibiotic residues, antibiotic resistant bacteria, and antibiotic resistance genes (ARGs) into aquatic ecosystems. However, there is a lack of quantitative studies attributing environmental ARG abundance to specific sources. The goal of this study was to evaluate the role of freshwater trout farms in the release and dissemination of ARGs into the environment. Sediment samples upstream and downstream from five rainbow trout farms were collected over time in southern Chile. A microfluidic quantitative polymerase chain reaction approach was used to quantify an ARG array covering different mechanisms of resistance, and data were analyzed using principal component analysis (PCA) and linear mixed regression models. Surveys were also conducted to obtain information about management practices, including antibiotic use, at the farms. Florfenicol and oxytetracycline were used at these farms, although at different rates. A total of 93 samples were analyzed. In the PCA, , , , , (A), (B), (C), (W), and grouped together. A statistically significant increase in abundance of , , , and several genes was found downstream from the farms compared with upstream sites, and retention ponds had the highest ARG abundance at each site. Antibiotic resistance gene levels returned to baseline at an average distance of 132.7 m downstream from the farms. Although results from this study indicate an influence of trout farms on the presence of ARGs in the immediate environment, the extent of their contribution to ARG dissemination is unknown and deserves further investigation.201931589726
7156120.9991Effect of antibiotics, antibiotic-resistant bacteria, and extracellular antibiotic resistance genes on the fate of ARGs in marine sediments. Surface runoff is a prevalent source via which emerging pollutants (i.e., antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs)) enter marine sediments. However, few studies have investigated the effect of emerging pollutants on the fate of ARGs in marine sediments. Therefore, three systems were established to measure the relative abundances of four common ARGs (i.e., bla(TEM), tetA, tetC, and aphA) and the integron-integrase gene (intI1) after exposure to emerging pollutants in marine sediments from the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea in China. The results revealed that antibiotic exposure could decrease the relative abundance of most ARGs (including bla(TEM), tetA, and tetC) in these marine sediment samples. The exceptions were the relative abundance of bla(TEM) in the Bohai Sea marine sediments under ampicillin exposure and tetC in the Yellow Sea marine sediments under tetracycline exposure, which increased significantly. Among marine sediments challenged with ARB, the relative abundance of aphA in all four marine sediments displayed a decreasing trend, whereas the abundances of bla(TEM) and tetA in the marine sediments from the Bohai Sea and the South China Sea showed an increasing trend. The relative abundance of tetA in the marine sediments from the Yellow Sea and the East China Sea dropped markedly when exposed to extracellular ARG (eARG). Significant changes in bla(TEM) abundance were observed in the four marine sediments under eARG exposure. Gene aphA abundance showed the same trend as the intI1 abundance. IntI1 showed a decreasing trend under the exposure of antibiotic, ARB, or eARG, apart from the East and the South China Sea marine sediments under ampicillin conditions and the South China Sea marine sediments under RP4 plasmid condition. These findings suggest that dosing with emerging pollutants does not increase ARG abundance in marine sediments.202337245825
7113130.9991Stormwater loadings of antibiotic resistance genes in an urban stream. Antibiotic resistance presents a critical public health challenge and the transmission of antibiotic resistance via environmental pathways continues to gain attention. Factors driving the spread of antibiotic resistance genes (ARGs) in surface water and sources of ARGs in urban stormwater have not been well-characterized. In this study, five ARGs (sul1, sul2, tet(O), tet(W), and erm(F)) were quantified throughout the duration of three storm runoff events in an urban inland stream. Storm loads of all five ARGs were significantly greater than during equivalent background periods. Neither fecal indicator bacteria measured (E. coli or enterococci) was significantly correlated with sul1, sul2, or erm(F), regardless of whether ARG concentration was absolute or normalized to 16S rRNA levels. Both E. coli and enterococci were correlated with the tetracycline resistance genes, tet(O) and tet(W). Next-generation shotgun metagenomic sequencing was conducted to more thoroughly characterize the resistome (i.e., full complement of ARGs) and profile the occurrence of all ARGs described in current databases in storm runoff in order to inform future watershed monitoring and management. Between 37 and 121 different ARGs were detected in each stream sample, though the ARG profiles differed among storms. This study establishes that storm-driven transport of ARGs comprises a considerable fraction of overall downstream loadings and broadly characterizes the urban stormwater resistome to identify potential marker ARGs indicative of impact.201728662396
7291140.9991Accumulation of clinically relevant antibiotic-resistance genes, bacterial load, and metals in freshwater lake sediments in Central Europe. Wastewater treatment plants (WWTP) receive the effluents from various sources (communities, industrial, and hospital effluents) and are recognized as reservoir for antibiotic-resistance genes (ARGs) that are associated with clinical pathogens. The aquatic environment is considered a hot-spot for horizontal gene transfer, and lake sediments offer the opportunity for reconstructing the pollution history and evaluating the impacts. In this context, variation with depth and time of the total bacterial load, the abundance of faecal indicator bacteria (FIB; E. coli and Enterococcus spp. (ENT)), Pseudomonas spp., and ARGs (blaTEM, blaSHV, blaCTX-M, blaNDM, and aadA) were quantified in sediment profiles of different parts of Lake Geneva using quantitative PCR. The abundance of bacterial marker genes was identified in sediments contaminated by WWTP following eutrophication of the lake. Additionally, ARGs, including the extended-spectrum ß-lactam- and aminoglycoside-resistance genes, were identified in the surface sediments. The ARG and FIB abundance strongly correlated (r ≥ 0.403, p < 0.05, n = 34) with organic matter and metal concentrations in the sediments, indicating a common and contemporary source of contamination. The contamination of sediments by untreated or partially treated effluent water can affect the quality of ecosystem. Therefore, the reduction of contaminants from the source is recommended for further improvement of water quality.201525933054
3507150.9991Temporal variation of antibiotic resistance genes carried by culturable bacteria in the shrimp hepatopancreas and shrimp culture pond water. The increasing prevalence of antibiotic resistance genes (ARGs) is a challenge to the health of humans, animals and the environments. Human activities and aquatic environments can increase ARGs. Few studies have focused on the temporal variation of aquatic bacteria with multiple ARGs in aquatic environments affected by human production activity. We studied culturable bacteria (CB) carrying ARGs, including sul1, sul2, floR, strA and gyrA in the shrimp hepatopancreas (HP) and in pond water during shrimp culture. The relative abundance of ARGs carried by CB in HP was higher than that in water (P < 0.05). However, CB carrying ARGs generally varied in random pattern. The correlation of sul2 abundance was significantly positive in HP, while that of strA abundance was significantly negative in water (P < 0.05) during shrimp culture. Among all of the CB, 33.59% carried multiple ARGs. Temporal distance-decay analysis indicated that CB carrying ARGs in water were more resistant to the effects of human activity. CB carrying ARGs varied temporally in HP and pond water during shrimp culture. These results demonstrate that multiple ARGs are carried by CB, and these varied with the phase of aquatic culture.202032447139
7278160.9991Effects of snowmelt runoff on bacterial communities and antimicrobial resistance gene concentrations in an urban river in a cold climate region. Urban rivers are essential for human activities and ecosystems. Urban runoff is a major source of various pollutants in urban rivers. In this study, we investigated the effect of rainfall and snowmelt subsequently causing urban runoff in a cold climate region on bacterial community structures and antimicrobial resistance gene concentrations in an urban river in Sapporo city, Japan, which has an average snowfall of 4.8 m. Bacterial community structures of the river water were analyzed by next generation sequencing of bacterial 16S rRNA genes. The antimicrobial resistance genes, mphA and bla(IMP), were determined using quantitative polymerase chain reaction. Rainfall and snowmelt increased the effluent discharge rate of treated wastewater, and river water depth. Rainfall and snowmelt also increased Escherichia coli concentrations by 4-20 folds in the river, probably because of combined sewer overflows, urban runoff, or increased effluent discharge rate of treated wastewater to the river. Urban runoff and the subsequent discharge of treated wastewater decreased the bacterial alpha diversity and increased the species evenness of bacteria. Bacterial beta diversity analysis showed that the discharge of treated wastewater caused by rainfall and snowmelt changed the structure and diversity of the bacterial community in the river. The concentrations of the antimicrobial resistance gene mphA were related to the discharge of treated wastewater. In contrast, the antimicrobial resistance gene bla(IMP) appeared to be present in the upstream pristine environment. Results of this study should be informative for challenge to reduce the antimicrobial resistance bacteria due to combined sewer overflows by wastewater management authorities.202540042701
5347170.9991High-quality treated wastewater causes remarkable changes in natural microbial communities and intI1 gene abundance. We carry out a mesocosms experiment to assess the impact of high-quality treated wastewater intended for agricultural reuse (HQWR) on freshwater bacteria seldom exposed to anthropogenic pollution. Effects were assessed by comparing the abundance and composition of bacterial communities as well as their resistance profile under control (source water from an unpolluted lake) and treatment conditions (source water mixed 1:1 with HQWR, with and without 5 μg L(-1) of cefotaxime). We investigated the effect of the different conditions on the abundance of genes encoding resistance to β-lactams and carbapenems (bla(TEM), bla(CTX-M), bla(OXA,) and bla(KPC)), fluoroquinolones (qnrS), tetracyclines (tetA), sulfonamides (sul2), macrolides (ermB), arsenic and cadmium (arsB and czcA, respectively), and on the gene encoding the Class 1 integron integrase (intI1). Bacterial communities exposed to HQWR showed a significant higher abundance of tetA, arsB, czcA, and intI1 genes, whereas those exposed to Cefotaxime-amended HQWR did not. Genes conferring resistance to carbapenems, β-lactams, fluoroquinolones, and macrolides were below detection limit in all treatments. Besides, the higher availability of nutrients under treatment conditions favored bacterial growth in comparison to those exposed to control conditions. Particularly, Acinetobacter spp. and Pseudomonas spp. were significantly enriched after 22 days of treatment exposure. The presence of cefotaxime (a third generation cephalosporine) in the feeding medium caused an enrichment of bacterial communities in sequences affiliated to Acinetobacter thus suggesting that these resistant forms may possess resistance genes other than those studied here (bla(CTX-M), bla(OXA,) and bla(KPC)). Although derived from a mesocosm experiment in continuous cultures, our results call attention to the need of refined regulations regarding the use of reclaimed water in agriculture since even high-quality treated wastewater may lead to undesired effects on receiving bacterial communities in terms of composition and dissemination of antibiotic resistance genes.201931553931
3508180.9991Prevalence and distribution of antibiotic resistance in marine fish farming areas in Hainan, China. Antibiotic resistance represents a global health crisis for humans, animals, and for the environment. Transmission of antibiotic resistance through environmental pathways is a cause of concern. In this study, quantitative PCR and culture-dependent bacteriological methods were used to detect the abundance of antibiotic resistance genes (ARGs) and the quantity of culturable heterotrophic antibiotic-resistant bacteria (ARB) in marine fish farming areas. The results indicated that sul and tet family genes were widely distributed in marine fish farming areas of Hainan during both rearing and harvesting periods. Specifically, sul1 and tetB were the most dominant ARGs. The total abundance of ARGs increased significantly from the rearing to the harvesting period. A total of 715 ARB strains were classified into 24 genera, within these genera Vibrio, Acinetobacter, Pseudoalteromonas, and Alteromonas are opportunistic pathogens. High bacterial resistance rate to oxytetracycline (OT) was observed. The numbers of OT- and enrofloxacin-resistant bacteria dropped significantly from rearing the period to the harvesting. The co-occurrence pattern showed that Ruegeria and tetB could be indicators of ARB and ARGs, respectively, which were found in the same module. Redundancy analysis indicated that salinity was positively correlated with the most dominant ARB, and was negatively correlated with the most dominant ARGs. These findings demonstrated the prevalence and persistence of ARGs and ARB in marine fish farming areas in China.201930414589
5323190.9991Monitoring and assessing the impact of wastewater treatment on release of both antibiotic-resistant bacteria and their typical genes in a Chinese municipal wastewater treatment plant. Wastewater treatment plants (WWTPs) are important hotspots for the spread of antibiotic resistance. However, the release and impact factors of both antibiotic resistant bacteria and the relevant genes over long periods in WWTPs have rarely been investigated. In this study, the fate of bacteria and genes resistant to six commonly used antibiotics was assessed over a whole year. In WWTP effluent and biosolids, a high prevalence of heterotrophic bacteria resistant to vancomycin, cephalexin, sulfadiazine and erythromycin were detected, each with a proportion of over 30%. The corresponding genes (vanA, ampC, sulI and ereA) were all detected in proportions of (2.2 ± 0.8) × 10(-10), (6.2 ± 3.2) × 10(-9), (1.2 ± 0.8) × 10(-7) and (7.6 ± 4.8) × 10(-8), respectively, in the effluent. The sampling season imposed considerable influence on the release of all ARB. High release loads of most ARB were detected in the spring, while low release loads were generally found in the winter. In comparison, the ARG loads changed only slightly over various seasons. No statistical relevance was found between all ARB abundances and their corresponding genes over the long-term investigation period. This inconsistent behavior indicates that bacteria and genes should both be considered when exploring resistance characteristics in wastewater. A redundancy analysis was adopted to assess the impact of wastewater quality and operational conditions on antibiotic resistance. The results indicated that most ARB and ARG proportions were positively related to the COD and turbidity of the raw sewage, while negatively related to those of the effluent. DO and temperature exhibited strong negative relevance to most ARB prevalence.201424927359