Exposure Levels of Airborne Fungi, Bacteria, and Antibiotic Resistance Genes in Cotton Farms during Cotton Harvesting and Evaluations of N95 Respirators against These Bioaerosols. - Related Documents




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353901.0000Exposure Levels of Airborne Fungi, Bacteria, and Antibiotic Resistance Genes in Cotton Farms during Cotton Harvesting and Evaluations of N95 Respirators against These Bioaerosols. The USA is the third-leading cotton-producing country worldwide and cotton farming is common in the state of Georgia. Cotton harvest can be a significant contributor to airborne microbial exposures to farmers and nearby rural communities. The use of respirators or masks is one of the viable options for reducing organic dust and bioaerosol exposures among farmers. Unfortunately, the OSHA Respiratory Protection Standard (29 CFR Part 1910.134) does not apply to agricultural workplaces and the filtration efficiency of N95 respirators was never field-tested against airborne microorganisms and antibiotic resistance genes (ARGs) during cotton harvesting. This study addressed these two information gaps. Airborne culturable microorganisms were sampled using an SAS Super 100 Air Sampler in three cotton farms during cotton harvesting, and colonies were counted and converted to airborne concentrations. Genomic DNA was extracted from air samples using a PowerSoil(®) DNA Isolation Kit. A series of comparative critical threshold (2(-ΔΔCT)) real-time PCR was used to quantify targeted bacterial (16S rRNA) genes and major ARGs. Two N95 facepiece respirator models (cup-shaped and pleated) were evaluated for their protection against culturable bacteria and fungi, total microbial load in terms of surface ATP levels, and ARGs using a field experimental setup. Overall, culturable microbial exposure levels ranged between 10(3) and 10(4) CFU/m(3) during cotton harvesting, which was lower when compared with bioaerosol loads reported earlier during other types of grain harvesting. The findings suggested that cotton harvesting works can release antibiotic resistance genes in farm air and the highest abundance was observed for phenicol. Field experimental data suggested that tested N95 respirators did not provide desirable >95% protections against culturable microorganisms, the total microbial load, and ARGs during cotton harvesting.202337375063
711810.9991Detection of pathogens, indicators, and antibiotic resistance genes after land application of poultry litter. Poultry litter (PL) is a by-product of broiler production. Most PL is land applied. Land-applied PL is a valuable nutrient source for crop production but can also be a route of environmental contamination with manure-borne bacteria. The objective of this study was to characterize the fate of pathogens, fecal indicator bacteria (FIB), and bacteria containing antibiotic resistance genes (ARGs) after application of PL to soils under conventional till or no-till management. This 2-yr study was conducted in accordance with normal agricultural practices, and microbial populations were quantified using a combination of culture and quantitative, real-time polymerase chain reaction analysis. Initial concentrations of in PL were 5.4 ± 3.2 × 10 cells g PL; sp. was not detected in the PL but was enriched periodically from PL-amended soils. was detected in PL (1.5 ± 1.3 × 10 culturable or 1.5 ± 0.3 × 10 genes g) but was rarely detected in field soils, whereas enterococci (1.5 ± 0.5 × 10 cells g PL) were detected throughout the study. These results suggest that enterococci may be better FIB for field-applied PL. Concentrations of ARGs for sulfonamide, streptomycin, and tetracycline resistance increased up to 3.0 orders of magnitude after PL application and remained above background for up to 148 d. These data provide new knowledge about important microbial FIB, pathogens, and ARGs associated with PL application under realistic field-based conditions.201425603240
728020.9990Microbial communities of biofilms developed in a chlorinated drinking water distribution system: A field study of antibiotic resistance and biodiversity. Antibiotic resistance and biodiversity were investigated in microbial communities attached to inner surfaces of water supply fittings in a chlorinated drinking water distribution system (DWDS) supplied by two independent water treatment plants (WTPs) drawing the same source water. The investigation of the effect of the season, the applied water treatment technology, and type, material, and age of water supply fittings on both antibiotic resistance and biodiversity in biofilms involved collection of tubercles during summer and winter seasons throughout the DWDS. A total of 16 samples were collected (8 per season) from areas supplied by two independent WTPs. Culturable aerobic antibiotic resistant bacteria (ARB) proved more prevalent in summer. Various antibiotic resistance genes (ARGs) were detected, confirming the role of biofilms as ARGs reservoirs, but the abundances of quantified genes (sulI, ermB, qacEΔ1, intI1) were low (a range of 202133610999
534430.9990Seasonal dynamics of tetracycline resistance gene transport in the Sumas River agricultural watershed of British Columbia, Canada. Environmental transport of contaminants that can influence the development of antibiotic resistance in bacteria is an important concern in the management of ecological and human health risks. Agricultural regions are locales where practices linked to food crop and livestock production can introduce contaminants that could alter the selective pressures for the development of antibiotic resistance in microbiota. This is important in regions where the use of animal manure or municipal biosolids as waste and/or fertilizer could influence selection for antibiotic resistance in pathogenic bacterial species. To investigate the environmental transport of contaminants that could lead to the development of antibiotic resistance in bacteria, a watershed with one of the highest levels of intensity of agricultural activity in Canada was studied; the Sumas River located 60 km east of Vancouver, British Columbia. This two-year assessment monitored four selected tetracycline resistance genes (tet(O), tet(M), tet(Q), tet(W)) and water quality parameters (temperature, specific conductivity, turbidity, suspended solids, nitrate, phosphate and chloride) at eight locations across the watershed. The tetracycline resistance genes (Tc(r)) abundances in the Sumas River network ranged between 1.47 × 10(2) and 3.49 × 10(4) copies/mL and ranged between 2.3 and 6.9 copies/mL in a control stream (located far from agricultural activities) for the duration of the study. Further, Tc(r) abundances that were detected in the wet season months ranged between 1.3 × 10(3) and 2.29 × 10(4) copies/mL compared with dry season months (ranging between 0.6 and 31.2 copies/mL). Highest transport rates between 1.67 × 10(11) and 1.16 × 10(12) copies/s were observed in November 2005 during periods of high rainfall. The study showed that elevated concentrations of antibiotic resistance genes in the order of 10(2)-10(4) copies/mL can move through stream networks in an agricultural watershed but seasonal variations strongly influenced specific transport patterns of these genes.201829453178
528840.9990Microbial source tracking in a small southern California urban watershed indicates wild animals and growth as the source of fecal bacteria. Three independent microbial source tracking (MST) methods were applied to a small urban subwatershed in Orange County, California. Fifty-seven water samples collected over summer 2002 were analyzed for human adenovirus and enterovirus. Enterococci and E. coli were isolated for antibiotic resistance analysis (ARA) and for PCR identification of human- and animal-specific toxin genes, respectively. All water samples were PCR negative for human enteroviruses and E. coli human-specific toxin gene. E. coli toxin markers revealed the presence of toxin genes specific to bird, rabbit, and cow. Enterococci ARA results supported this conclusion and indicated that fecal bacteria from bird and wild animal feces as well as soil were the predominant source found in the watershed. An E. coli, isolated from the watershed and inoculated back into the heat-sterilized storm drain water, increased 4 log units within 6 days. Collectively, these results suggest that bird and wild animal feces, soil amendments, and/or fecal coliform growth in the storm drain are the major contributors to the fecal bacterial pollution in downstream areas. However, human adenoviruses were detected on two occasions. Fecal bacterial concentrations were not elevated on these two occasions, suggesting that the elevated levels of fecal indicator bacteria in this small watershed could be unrelated to the source of human adenovirus.200717589839
707650.9990Indoor Air Quality and Potential Health Risk Impacts of Exposure to Antibiotic Resistant Bacteria in an Office Rooms in Southern Poland. The aims of this article are to characterize: the quantity of culturable bacterial aerosol (QCBA) and the quality of culturable bacterial aerosol (QlCBA) in an office building in Southern Poland during the spring. The average concentration of culturable bacterial aerosol (CCBA) in this building ranged from 424 CFU m(-3) to 821 CFU m(-3), below Polish proposals for threshold limit values. Size distributions were unimodal, with a peak of particle bacterial aerodynamic diameters less than 3.3 μm, increasing potentially adverse health effects due to their inhalation. The spring office exposure dose (SPED) of bacterial aerosol was estimated. The highest value of SPED was in April (218 CFU kg(-1)), whereas the lowest was in June (113 CFU kg(-1)). Analysis was undertaken to determine the antibiotic resistance of isolated strains and their ability to form biofilms, which may facilitate the spread of antibiotic resistance genes. In the course of the study, it was found that Staphylococcus xylosus had the greatest ability to form biofilms, while the strains with the highest antibiotic resistance were Micrococcus luteus D and Macrococcus equipercicus. Given that mainly antibiotic-sensitive bacteria from bioaerosol were isolated, which transfers resistance genes to their plasmids, this shows the need for increased monitoring of indoor air quality in workplaces.201830469413
710360.9990Microbial ecology, bacterial pathogens, and antibiotic resistant genes in swine manure wastewater as influenced by three swine management systems. The environmental influence of farm management in concentrated animal feeding operations (CAFO) can yield vast changes to the microbial biota and ecological structure of both the pig and waste manure lagoon wastewater. While some of these changes may not be negative, it is possible that CAFOs can enrich antibiotic resistant bacteria or pathogens based on farm type, thereby influencing the impact imparted by the land application of its respective wastewater. The purpose of this study was to measure the microbial constituents of swine-sow, -nursery, and -finisher farm manure lagoon wastewater and determine the changes induced by farm management. A total of 37 farms were visited in the Mid-South USA and analyzed for the genes 16S rRNA, spaQ (Salmonella spp.), Camp-16S (Campylobacter spp.), tetA, tetB, ermF, ermA, mecA, and intI using quantitative PCR. Additionally, 16S rRNA sequence libraries were created. Overall, it appeared that finisher farms were significantly different from nursery and sow farms in nearly all genes measured and in 16S rRNA clone libraries. Nearly all antibiotic resistance genes were detected in all farms. Interestingly, the mecA resistance gene (e.g. methicillin resistant Staphylococcus aureus) was below detection limits on most farms, and decreased as the pigs aged. Finisher farms generally had fewer antibiotic resistance genes, which corroborated previous phenotypic data; additionally, finisher farms produced a less diverse 16S rRNA sequence library. Comparisons of Camp-16S and spaQ GU (genomic unit) values to previous culture data demonstrated ratios from 10 to 10,000:1 depending on farm type, indicating viable but not cultivatable bacteria were dominant. The current study indicated that swine farm management schemes positively and negatively affect microbial and antibiotic resistant populations in CAFO wastewater which has future "downstream" implications from both an environmental and public health perspective.201424704907
353870.9989Amoxicillin Increased Functional Pathway Genes and Beta-Lactam Resistance Genes by Pathogens Bloomed in Intestinal Microbiota Using a Simulator of the Human Intestinal Microbial Ecosystem. Antibiotics are frequently used to treat bacterial infections; however, they affect not only the target pathogen but also commensal gut bacteria. They may cause the dysbiosis of human intestinal microbiota and consequent metabolic alterations, as well as the spreading of antibiotic resistant bacteria and antibiotic resistance genes (ARGs). In vitro experiments by simulator of the human intestinal microbial ecosystem (SHIME) can clarify the direct effects of antibiotics on different regions of the human intestinal microbiota, allowing complex human microbiota to be stably maintained in the absence of host cells. However, there are very few articles added the antibiotics into this in vitro model to observe the effects of antibiotics on the human intestinal microbiota. To date, no studies have focused on the correlations between the bloomed pathogens caused by amoxicillin (AMX) exposure and increased functional pathway genes as well as ARGs. This study investigated the influence of 600 mg day(-1) AMX on human intestinal microbiota using SHIME. The impact of AMX on the composition and function of the human intestinal microbiota was revealed by 16S rRNA gene sequencing and high-throughput quantitative PCR. The results suggested that: (i) AMX treatment has tremendous influence on the overall taxonomic composition of the gut microbiota by increasing the relative abundance of Klebsiella [linear discriminant analysis (LDA) score = 5.26] and Bacteroides uniformis (LDA score = 4.75), as well as taxonomic diversity (Simpson, P = 0.067, T-test; Shannon, P = 0.061, T-test), and decreasing the members of Parabacteroides (LDA score = 4.18), Bifidobacterium (LDA score = 4.06), and Phascolarctobacterium (LDA score = 3.95); (ii) AMX exposure significantly enhanced the functional pathway genes and beta-lactam resistance genes, and the bloomed pathogens were strongly correlated with the metabolic and immune system diseases gene numbers (R = 0.98, P < 0.001) or bl2_len and bl2be_shv2 abundance (R = 0.94, P < 0.001); (iii) the changes caused by AMX were "SHIME-compartment" different with more significant alteration in ascending colon, and the effects were permanent, which could not be restored after 2-week AMX discontinuance. Overall results demonstrated negative side-effects of AMX, which should be considered for AMX prescription.202032582117
712080.9989Impact of liquid hog manure applications on antibiotic resistance genes concentration in soil and drainage water in field crops. Agricultural practices such as manure applications could contribute to the spread of antibiotic resistance genes (ARGs) within the environment. Our objective was to assess the impact of certain fertilization methods (mineral or manure) and tillage practices (reduced or conventional) on the presence of ARGs and bacteria in soil and drainage water under wheat and grain corn crops. Targeted ARGs tet(T), sul1, and bla(CTX-M-1) in liquid hog manure, soil, and water samples were quantified by qPCR. Conventional PCR was used to detect mcr-1 and mcr-2. ARGs in control plots were detected despite the absence of manure, representing an environmental reservoir of resistant microorganisms. The manure application rate higher than 39 m(3)/ha increased tet(T) and sul1 gene concentrations in soil for more than 180 days. Tillage practices had no impact on ARG concentrations in soil and water samples. The bla(CTX-M-1) gene was only detected in seven water samples in 2016, but no link was established with the treatments. The mcr-1 and mcr-2 genes were not detected in all tested samples. This study demonstrated that tet(T) and sul1 gene concentrations increased in soil after liquid hog manure application as well as in drainage water in the next weeks.202032330390
776490.9989Air-drying beds reduce the quantities of antibiotic resistance genes and class 1 integrons in residual municipal wastewater solids. This study investigated whether air-drying beds reduce antibiotic resistance gene (ARG) concentrations in residual municipal wastewater solids. Three laboratory-scale drying beds were operated for a period of nearly 100 days. Real-time PCR was used to quantify 16S rRNA genes, 16S rRNA genes specific to fecal bacteria (AllBac) and human fecal bacteria (HF183), the integrase gene of class 1 integrons (intI1), and five ARGs representing a cross-section of antibiotic classes and resistance mechanisms (erm(B), sul1, tet(A), tet(W), and tet(X)). Air-drying beds were capable of reducing all gene target concentrations by 1 to 5 orders of magnitude, and the nature of this reduction was consistent with both a net decrease in the number of bacterial cells and a lack of selection within the microbial community. Half-lives varied between 1.5 d (HF183) and 5.4 d (tet(X)) during the first 20 d of treatment. After the first 20 d of treatment, however, half-lives varied between 8.6 d (tet(X)) and 19.3 d (AllBac), and 16S rRNA gene, intI1, and sul1 concentrations did not change (P > 0.05). These results demonstrate that air-drying beds can reduce ARG and intI1 concentrations in residual municipal wastewater solids within timeframes typical of operating practices.201323909386
3545100.9989Fecal indicators and antibiotic resistance genes exhibit diurnal trends in the Chattahoochee River: Implications for water quality monitoring. Water bodies that serve as sources of drinking or recreational water are routinely monitored for fecal indicator bacteria (FIB) by state and local agencies. Exceedances of monitoring thresholds set by those agencies signal likely elevated human health risk from exposure, but FIB give little information about the potential source of contamination. To improve our understanding of how within-day variation could impact monitoring data interpretation, we conducted a study at two sites along the Chattahoochee River that varied in their recreational usage and adjacent land-use (natural versus urban), collecting samples every 30 min over one 24-h period. We assayed for three types of microbial indicators: FIB (total coliforms and Escherichia coli); human fecal-associated microbial source tracking (MST) markers (crAssphage and HF183/BacR287); and a suite of clinically relevant antibiotic resistance genes (ARGs; blaCTX-M, blaCMY, MCR, KPC, VIM, NDM) and a gene associated with antibiotic resistance (intl1). Mean levels of FIB and clinically relevant ARGs (blaCMY and KPC) were similar across sites, while MST markers and intI1 occurred at higher mean levels at the natural site. The human-associated MST markers positively correlated with antibiotic resistant-associated genes at both sites, but no consistent associations were detected between culturable FIB and any molecular markers. For all microbial indicators, generalized additive mixed models were used to examine diurnal variability and whether this variability was associated with environmental factors (water temperature, turbidity, pH, and sunlight). We found that FIB peaked during morning and early afternoon hours and were not associated with environmental factors. With the exception of HF183/BacR287 at the urban site, molecular MST markers and intI1 exhibited diurnal variability, and water temperature, pH, and turbidity were significantly associated with this variability. For blaCMY and KPC, diurnal variability was present but was not correlated with environmental factors. These results suggest that differences in land use (natural or urban) both adjacent and upstream may impact overall levels of microbial contamination. Monitoring agencies should consider matching sample collection times with peak levels of target microbial indicators, which would be in the morning or early afternoon for the fecal associated indicators. Measuring multiple microbial indicators can lead to clearer interpretations of human health risk associated with exposure to contaminated water.202236439800
7109110.9989Explore the Contamination of Antibiotic Resistance Genes (ARGs) and Antibiotic-Resistant Bacteria (ARB) of the Processing Lines at Typical Broiler Slaughterhouse in China. Farms are a major source of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB), and previous research mainly focuses on polluted soils and breeding environments. However, slaughtering is an important link in the transmission of ARGs and ARB from farmland to dining table. In this study, we aim to reveal the pollution of ARGs and ARB in the slaughter process of broilers. First, by qualitative and quantitative analysis of ARGs in samples collected from the broiler slaughtering and processing production chain, the contamination level of ARGs was reflected; secondly, potential hosts for ARGs and microbial community were analyzed to reflect the possible transmission rules; thirdly, through the antibiotic susceptibility spectrum analysis of four typical food-borne pathogens, the distribution of ARB was revealed. The results showed that 24 types of ARGs were detected positive on the broiler slaughter production line, and tetracycline-resistance genes (20.45%) were the most frequently detected. The types of ARGs vary with sampling process, and all sampling links contain high levels of sul2 and intI1. The most abundant ARGs were detected in chicken surface in the scalding stage and entrails surface in the evisceration stage. There was a significant correlation between intI1 and tetM, suggesting that tetM might be able to enter the human food chain through class-1 integrons. The host range of the oqxB gene is the most extensive, including Sphingobacterium, Bacteroidia unclassified, Rothia, Microbacterium, Algoriella, etc. In the relevant links of the slaughter production line, the microbial community structure is similar. Removing viscera may cause diffusion of ARGs carried by intestinal microorganisms and contaminate chicken and following processing production. The four food-borne pathogens we tested are widely present in all aspects of the slaughter process, and most of them have multi-drug resistance and even have a high degree of resistance to some veterinary drugs banned by the Ministry of Agriculture. Our study preliminarily revealed the pollution of ARGs and ARB in the slaughter process of broilers, and these results are helpful to carry out food safety risk assessment and formulate corresponding control measures.202540232101
5323120.9989Monitoring 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
7651130.9989Antibiotic resistance gene profile changes in cropland soil after manure application and rainfall. Land application of manure introduces gastrointestinal microbes into the environment, including bacteria carrying antibiotic resistance genes (ARGs). Measuring soil ARGs is important for active stewardship efforts to minimize gene flow from agricultural production systems; however, the variety of sampling protocols and target genes makes it difficult to compare ARG results between studies. We used polymerase chain reaction (PCR) methods to characterize and/or quantify 27 ARG targets in soils from 20 replicate, long-term no-till plots, before and after swine manure application and simulated rainfall and runoff. All samples were negative for the 10 b-lactamase genes assayed. For tetracycline resistance, only source manure and post-application soil samples were positive. The mean number of macrolide, sulfonamide, and integrase genes increased in post-application soils when compared with source manure, but at plot level only, 1/20, 5/20, and 11/20 plots post-application showed an increase in erm(B), sulI, and intI1, respectively. Results confirmed the potential for temporary blooms of ARGs after manure application, likely linked to soil moisture levels. Results highlight uneven distribution of ARG targets, even within the same soil type and at the farm plot level. This heterogeneity presents a challenge for separating effects of manure application from background ARG noise under field conditions and needs to be considered when designing studies to evaluate the impact of best management practices to reduce ARG or for surveillance. We propose expressing normalized quantitative PCR (qPCR) ARG values as the number of ARG targets per 100,000 16S ribosomal RNA genes for ease of interpretation and to align with incidence rate data.202033016404
7248140.9989Fate and transport of tylosin-resistant bacteria and macrolide resistance genes in artificially drained agricultural fields receiving swine manure. Application of manure from swine treated with antibiotics introduces antibiotics and antibiotic resistance genes to soil with the potential for further movement in drainage water, which may contribute to the increase in antibiotic resistance in non-agricultural settings. We compared losses of antibiotic-resistant Enterococcus and macrolide-resistance (erm and msrA) genes in water draining from plots with or without swine manure application under chisel plow and no till conditions. Concentrations of ermB, ermC and ermF were all >10(9)copies g(-1) in manure from tylosin-treated swine, and application of this manure resulted in short-term increases in the abundance of these genes in soil. Abundances of ermB, ermC and ermF in manured soil returned to levels identified in non-manured control plots by the spring following manure application. Tillage practices yielded no significant differences (p>0.10) in enterococci or erm gene concentrations in drainage water and were therefore combined for further analysis. While enterococci and tylosin-resistant enterococci concentrations in drainage water showed no effects of manure application, ermB and ermF concentrations in drainage water from manured plots were significantly higher (p<0.01) than concentrations coming from non-manured plots. ErmB and ermF were detected in 78% and 44%, respectively, of water samples draining from plots receiving manure. Although ermC had the highest concentrations of the three genes in drainage water, there was no effect of manure application on ermC abundance. MsrA was not detected in manure, soil or water. This study is the first to report significant increases in abundance of resistance genes in waters draining from agricultural land due to manure application.201626874610
7113150.9989Stormwater 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
7121160.9989Fate of fluoroquinolones in field soil environment after incorporation of poultry litter from a farm with enrofloxacin administration via drinking water. The practice of incorporating animal manure into soil is supported within the European Circular economy as a possible substitute for mineral fertilizers and will become crucial for the sustainability of agriculture. However, this practice may indirectly contribute to the dissemination of antibiotics, resistance bacteria, and resistance genes. In this study, medicated drinking water and poultry litter samples were obtained from a broiler-chick farm. The obtained poultry litter was incorporated into the soil at the experimental field site. The objectives of this research project were first to develop analytical methods able to quantify fluoroquinolones (FQs) in medicated drinking water, poultry litter, and soil samples by LC-MS; second to study the fate of these FQs in the soil environment after incorporation of poultry litter from flock medicated by enrofloxacin (ENR); and third to screen the occurrence of selected fluoroquinolone resistance encoding genes in poultry litter and soil samples (PCR analysis). FQs were quantified in the broiler farm's medicated drinking water (41.0 ± 0.3 mg∙L(-1) of ENR) and poultry litter (up to 70 mg∙kg(-1) of FQs). The persistence of FQs in the soil environment over 112 days was monitored and evaluated (ENR concentrations ranged from 36 μg∙kg(-1) to 9 μg∙kg(-1) after 100 days). The presence of resistance genes was confirmed in both poultry litter and soil samples, in agreement with the risk assessment for the selection of AMR in soil based on ENR concentrations. This work provides a new, comprehensive perspective on the entry and long-term fate of antimicrobials in the terrestrial environment and their consequences after the incorporation of poultry litter into agricultural fields.202438367114
7082170.9989Catchment-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
7126180.9989Longitudinal characterization of antimicrobial resistance genes in feces shed from cattle fed different subtherapeutic antibiotics. BACKGROUND: Environmental transmission of antimicrobial-resistant bacteria and resistance gene determinants originating from livestock is affected by their persistence in agricultural-related matrices. This study investigated the effects of administering subtherapeutic concentrations of antimicrobials to beef cattle on the abundance and persistence of resistance genes within the microbial community of fecal deposits. Cattle (three pens per treatment, 10 steers per pen) were administered chlortetracycline, chlortetracycline plus sulfamethazine, tylosin, or no antimicrobials (control). Model fecal deposits (n = 3) were prepared by mixing fresh feces from each pen into a single composite sample. Real-time PCR was used to measure concentrations of tet, sul and erm resistance genes in DNA extracted from composites over 175 days of environmental exposure in the field. The microbial communities were analyzed by quantification and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S-rRNA. RESULTS: The concentrations of 16S-rRNA in feces were similar across treatments and increased by day 56, declining thereafter. DGGE profiles of 16S-rRNA differed amongst treatments and with time, illustrating temporal shifts in microbial communities. All measured resistance gene determinants were quantifiable in feces after 175 days. Antimicrobial treatment differentially affected the abundance of certain resistance genes but generally not their persistence. In the first 56 days, concentrations of tet(B), tet(C), sul1, sul2, erm(A) tended to increase, and decline thereafter, whereas tet(M) and tet(W) gradually declined over 175 days. At day 7, the concentration of erm(X) was greatest in feces from cattle fed tylosin, compared to all other treatments. CONCLUSION: The abundance of genes coding for antimicrobial resistance in bovine feces can be affected by inclusion of antibiotics in the feed. Resistance genes can persist in feces from cattle beyond 175 days with concentrations of some genes increasing with time. Management practices that accelerate DNA degradation such as frequent land application or composting of manure may reduce the extent to which bovine feces serves as a reservoir of antimicrobial resistance.201121261985
7125190.9989Persistence of resistance to erythromycin and tetracycline in swine manure during simulated composting and lagoon treatments. The use of antimicrobials in food animal production leads to the development of antimicrobial resistance (AMR), and animal manure constitutes the largest reservoir of such AMR. In previous studies, composted swine manure was found to contain substantially lower abundance of AMR genes that encode resistance to tetracyclines (tet genes) and macrolide-lincosamide-streptogramin B (MLS(B)) superfamily (erm genes), than manures that were treated by lagoons or biofilters. In this study, temporal changes in AMR carried by both cultivated and uncultivated bacteria present in swine manure during simulated composting and lagoon storage were analyzed. Treatments were designed to simulate the environmental conditions of composting (55°C with modest aeration) and lagoon storage (ambient temperature with modest aeration). As determined by selective plate counting, over a 48-day period, cultivated aerobic heterotrophic erythromycin-resistant bacteria and tetracycline-resistant bacteria decreased by more than 4 and 7 logs, respectively, in the simulated composting treatment while only 1 to 2 logs for both resistant bacterial groups in the simulated lagoon treatment. Among six classes each of erm and tet genes quantified by class-specific real-time PCR assays, the abundance of erm(A), erm(C), erm(F), erm(T), erm(X), tet(G), tet(M), tet(O), tet(T), and tet(W) declined marginally during the first 17 days, but dramatically thereafter within 31 days of the composting treatment. No appreciable reduction of any of the erm or tet genes analyzed was observed during the simulated lagoon treatment. Correlation analysis showed that most of the AMR gene classes had similar persistence pattern over the course of the treatments, though not all AMR genes were destructed at the same rate during the treatments.201221811793