Occurrence Of Antibiotic Resistance Genes Research Articles

Occurrence and human exposure risk of antibiotic resistance genes in tillage soils of dryland regions: A case study of northern Ningxia Plain, China

Agricultural soils are important source and sink of antibiotic resistance genes (ARGs). However, little is known about the fate of ARGs in dryland soils, while its human exposure risks were seriously overlooked. Taking the northern Ningxia Plain as a case, this study explored the occurrence of ARGs and its relationship with mobile genetic elements (MGEs), pathogens, and environmental factors. Furthermore, the concentrations of airborne ARGs by soil wind erosion and the human exposure doses of soil ARGs were evaluated. The results showed the abundances of different regions ranged from 4.0 × 105 to 1.6 × 106 copies/g. Soil ARGs are driven by MGEs, but multiply impacted by soil properties, nutrition, and bacterial community. Vibrio metschnikovii, Acinetobacter schindleri, and Serratia marcescens are potential pathogenic hosts for ARGs. Further exploration revealed the concentration of ARGs loaded in dust by soil wind erosion reached more than 105 copies/m3, which were even higher than those found in sewage treatment plants and hospitals. Skin contact is the primary route of ARGs exposure, with a maximum dose of 24071.33 copies/kg/d, which is largely attributed to ARGs loaded in dust. This study bridged the gap on ARGs in dryland soils, and provided reference for human exposure risk assessment of soil ARGs.

Sewerage surveillance tracking characteristics of human antibiotic resistance genes in sewer system

Sewage surveillance is widely applied to track valid human excretion information and identify public health conditions during corona virus disease 2019 (COVID-19) pandemic. This approach can be applied to monitor the antibiotic resistance level in sewers and to assess the risk of spreading antibiotic resistance in municipal wastewater systems. However, there is still little information about human antibiotic resistance occurrence characteristics in sewer system. This study conducted a field trial for whole year to advance understanding on spatial and temporal occurrence of antibiotic resistance genes (ARGs) in gravity sewerage. The spatial distribution of ARGs along the drainage pipe line (from human settlements to wastewater treatement pant (WWTP)) was insignificant, which may be affected by irregular human emission alongside the pipeline. The correlation between ARGs and antibiotics in sewage was insignificant. The temporal distribution showed that the effect of temperature on ARGs abundance was evident, the ARGs abundance in sewage was generally higher during the cold season. Metagenomic analysis revealed that the detected ARGs were mainly distributed in Proteobacteria (47.51 %) and Antinobacteria (20.11 %). Potential hosts of ARGs in sewage were mainly identified as human gut microorganisms, including human pathogenic bacteria, such as Prevotella, Kocuria, and Propionibacterium, etc. This study provides a new insight into the sewerage surveillance tracking characteristics of human ARGs in sewer system, and suggesting that the sewage-carried ARGs surveillance is a promising method for assessment and management of antibiotic resistance level on population size.

Graphene oxide inhibits the transfer of ARGs in rice by reducing the root endophytic bacterial complexity

Antibiotic resistance genes (ARGs) as an emerging contaminant have attracted much attention for their transfer in agricultural ecosystems. Meanwhile, graphene oxide (GO), due to its high adsorption capacity and antibacterial properties, poses potential environmental ecological risks to the occurrence of ARGs, bacteria, and plant physiological ecology. However, the impact and mechanism of GO on the transfer of ARGs in host plants remain unclear. Therefore, this study selected rice as the research object and inoculated Bacillus subtilis carrying ARGs to investigate the influence of GO on the migration of ARGs into rice and its microbiological mechanism. The study found that GO had a certain inhibitory effect on the transfer of ARGs in rice. Although GO reduced the rhizosphere pH in rice, leading to a transition in endophytic bacteria from dominance by Burkholderia to dominance by Gordonia, this process did not directly affect the transfer of ARGs in rice. Further analysis of bacterial interactions revealed that GO could inhibit the transfer of ARGs in rice by reducing the network complexity of endophytic bacteria. Additionally, GO inhibited the formation of endophytic bacterial biofilms and mobile elements, which might affect ARGs’ migration in rice. This study elucidated the key microbiological ecological processes of GO on the transfer of ARGs in rice, providing fundamental information for the ecological risk assessment of GO.

A metagenomics-based approach to decipher the resistome and mobilome of two seahorse species, Hippocampus barbouri and Hippocampus comes

ObjectiveThis study aimed to explore the abundance and diversity of antibiotic resistance genes (ARGs) in seahorses (Hippocampus barbouri and Hippocampus comes) and their surrounding environment. MethodsA combination of shotgun metagenomics and bioinformatics was used to investigate the resistome of both seahorse species. ResultsThe analyses demonstrated a higher abundance of ARGs in seahorse-associated microbiomes, particularly in skin and gut samples, compared to those from water and sediment. Interestingly, genes conferring multidrug resistance (e.g., acrB, acrF, cpxA, msbA, and oqxB) were highly prevalent in all samples, especially in skin and gut samples. High levels of genes conferring resistance to fluoroquinolones (e.g., mfd and emrB), β-lactam (e.g., blaCMY-71, blaOXA-55, and penA), aminocoumarin (e.g., mdtB and mdtC), and peptide antibiotics (arnA, pmrE, and rosA) were also observed in skin and gut samples. An enrichment of mobile genetic elements (MGEs) was also observed in the analysed samples, highlighting their potential role in facilitating the acquisition and spread of ARGs. In fact, the abundance of mobilisation (MOB) relaxases (e.g., MOBF, MOBP, MOBT, and MOBV) in gut and skin samples suggests a high potential for conjugation events. ConclusionsThe occurrence of ARGs and MGEs in seahorses and the surrounding environment raises concerns about their transmission to humans, either through direct contact or the consumption of contaminated seafood. To the best of our knowledge, this study represents the first comprehensive analysis of ARGs in seahorse-associated microbiomes, and its results emphasise the need for monitoring and controlling the spread of ARGs in environmental settings.

Differential drivers on the occurrence of antibiotic resistance genes in agricultural soils and crops: Evidence from the different fertilization regimes

Organic fertilizer application caused bacterial resistance contamination in farming systems has been widely documented, and long-term fertilization will exacerbate the migration of antibiotic resistance genes (ARGs) to crops and humans. However, it remains unclear whether a combined pattern of chemical and organic fertilizer application can arrest the high prevalence of ARGs in soil-crop. Here we investigated the ARGs occurrence under different fertilization regimes, and explored the mechanisms by which micro-ecological shifts and geochemical factors in modulating the ARGs fate in soil and crop. The results showed that the soil ARGs abundance was highest under 100% organic fertilizer, while the highest ARGs abundance in crops was observed at 100% chemical fertilizer. Application of organic fertilizers with more than 50% ration intensified the soil accumulation and migration of tetA, sul1, sul2 and macA genes. And, multidrug_transporter, macA and sul1 were co-shared in soil and crop, where ARGs potential hosts differed complete in the two, suggesting that these ARGs may be transferred across media by horizontal transfer. Procrustes analysis revealed that soil microbial community was significantly correlated with ARG hosts, and soil microbial evolutionary pathway was congruent with antibiotic resistance, suggesting that fertilizers affect soil ARGs abundance mainly by altering soil microbial composition and their ecological evolutionary trajectories. While, no significant correlation was observed between endophytes and crop ARG host. Structural equations demonstrated that soil nutrients and crop growth characteristics contributed largely to the prevalence of crop ARGs. This outcome will provide new insights into the high prevalence of ARGs in soil and crop, and offer fertilizer recommendations for effectively curbing antibiotic-resistance contamination in farming systems.

Multiple antibiotic resistance and herbicide catabolic profiles of bacteria isolated from Lake Villarrica surface sediments (Chile)

Antibiotics and herbicides are contaminants of emerging concern in aquatic environments. Lake Villarrica is a relevant freshwater body in Chile and was recently designated a ‘saturated nutrient zone’. Here, we investigated the occurrence of multiple antibiotic resistance (MAR) and herbicide catabolic profiles among bacteria present in the surface sediments of Lake Villarrica. The occurrence of antibiotic-resistant genes (ARGs; blaTEM, catA and tetM) and herbicide-catabolic genes (HCGs; phnJ and atzA) was investigated by qPCR. Subsequently, the presence of culturable bacteria with multiple resistance to amoxicillin (AMX), chloramphenicol (CHL) and oxytetracycline (OXT) was studied. Forty-six culturable MAR (AMX + CHL + OXT) strains were isolated and characterized with respect to their resistance to 11 antibiotics by using a disc diffusion assay and testing their ability to use herbicides as a nutrient source. qPCR analyses revealed that ARGs and HCGs were present in all sediment samples (101 to 103 gene copies g−1), with significant (P ≤ 0.05) higher values in sites near Villarrica city and cattle pastures. The plate method was used to recover MAR isolates from sediment (103–106 CFU g−1), and most of the 46 isolates also showed resistance to oxacillin (100%), cefotaxime (83%), erythromycin (96%) and vancomycin (93%). Additionally, 54 and 57% of the MAR isolates were able to grow on agar supplemented (50 mg L−1) with atrazine and glyphosate as nutrient sources, respectively. Most of the MAR isolates were taxonomically close to Pseudomonas (76.1%) and Pantoea (17.4%), particularly those isolated from urbanized sites (Pucón city). This study shows the presence of MAR bacteria with herbicide catabolic activity in sediments, which is valuable for conservation strategies and risk assessments of Lake Villarrica. However, major integrative studies on sediments as reservoirs or on the fate of MAR strains and traces of antibiotics and herbicides as a result of anthropic pressure are still needed.

Fertilizing drug resistance: Dissemination of antibiotic resistance genes in soil and plant bacteria under bovine and swine slurry fertilization

The increasing global demand for food production emphasizes the use of organic animal fertilizers, such as manure and slurry, to support sustainable agricultural practices. However, recent studies highlight concerns about antibiotic resistance determinants in animal excrements, posing a potential risk of spreading antibiotic resistance genes (ARGs) in agricultural soil and, consequently, in food products.This study examines the dissemination of ARGs within the soil and plant-associated microbiomes in cherry radish following the application of swine and bovine slurry. In a 45-day pot experiment, slurry-amended soil, rhizospheric bacteria, and endophytic bacteria in radish roots and leaves were sampled and analyzed for 21 ARGs belonging to 7 Antibiotic Resistance Phenotypes (ARPs). The study also assessed slurry's impact on soil microbiome functional diversity, enzymatic activity, physicochemical soil parameters, and the concentration of 22 selected antimicrobials in soil and plant tissues.Tetracyclines and β-lactams were the most frequently identified ARGs in bovine and swine slurry, aligning with similar studies worldwide. Swine slurry showed a higher prevalence of ARGs in soil and plant-associated bacteria, particularly TET genes, reflecting pig antibiotic treatments. The persistent dominance of TET genes across slurry, soil, and plant microbiomes highlights significant influence of slurry application on gene occurrence in plant bacteria. The presence of ARGs in edible plant parts underscores health risks associated with raw vegetable consumption. Time-dependent dynamics of ARG occurrence highlighted their persistent presence throughout the experiment duration, influenced by the environmental factors and antibiotic residuals. Notably, ciprofloxacin, which was the only one antimicrobial detected in fertilized soil, significantly impacted bovine-amended variants. Soil salinity modifications induced by slurry application correlated with changes in ARG occurrence. Overall, the research underscores the complex relationships between agricultural practices, microbial activity, and antibiotic resistance dissemination, emphasizing the need for a more sustainable and health-conscious farming approaches.

Visual and photoelectrochemical analysis of antibiotic resistance genes enabled by surface-engineered ZIF-8@Au cascade nanozymes

The aggravation of antibiotic resistance genes (ARGs) in the environment has posed a significant global health crisis. Accurate evaluation of ARGs levels in a facile manner is a pressing issue for environmental surveillance. Here, we demonstrate a unique dumbbell-shaped cascade nanozyme for visual/photoelectrochemical (PEC) dual-mode detection of ARGs. Gold nanoparticles (AuNPs) with tunable exposed facets are controllably anchored onto ZIF-8 dodecahedrons, exhibiting glucose oxidase (GOx)-like (ZIF-8@Au/G) and peroxidase (POD)-like (ZIF-8@Au/P) activities. Upon the occurrence of ARGs, an asymmetric cascade-amplified “dumbbell” configuration is spontaneously generated via target-induced DNA hybridization, comprising GOx-like ZIF-8@Au/G with capture DNA on one side and POD-like ZIF-8@Au/P with signal DNA on the opposite side. Such a cascade nano-system can efficiently oxidize colorless 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) into its green oxidation state and synergistically decompose H2O2, realizing colorimetric/PEC dual-mode ARGs detection with a detection limit of 0.112 nM. The applicability of the present bioassay is validated through measuring ARGs in real sludge samples. This work suggests the possibility to rationally design task-specific nanozymes and develop target-responsive nano-cascade assays for environmental monitoring.

Removal of antibiotics, bacterial toxicity, and occurrence of antibiotic resistance genes in secondary hospital effluents treated with granular activated carbon and the impact of preceding chlorination

This comprehensive investigation highlighted the complex adsorption behaviors of antibiotics onto granular activated carbon (GAC), the effectiveness of this adsorption in reducing bacterial toxicity, and the reduction of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) in hospital wastewater (HWW) effluents. Six GACs were characterized for their physicochemical properties, and their ability to adsorb six antibiotics in the background matrix of actual HWW was evaluated. Coconut shell-derived GAC (Co-U), which had the highest hydrophobicity and lowest content of oxygen-containing acidic functional groups, demonstrated the highest adsorption capacities for the tested antibiotics. Bacterial toxicity tests revealed that GACs could eliminate the bacterial toxicity from antibiotic intermediates present in chlorinated HWW. By contrast, the bacterial toxicity could not be removed by GACs in non-chlorinated HWW due to the greater presence of intermediate components identified by LC-MS/MS. The intraparticle diffusion coefficient of antibiotics adsorbed onto Co-U could be calculated by adsorption kinetics derived from the linear driving force model and the homogenous intraparticle diffusion model associated with the linear adsorption isotherms (0–150 μg/L). Meropenem and sulfamethoxazole exhibited the highest adsorption capacities in a single-solute solution compared to penicillin G, ampicillin, cetazidime, and ciprofloxacin. However, the greater adsorption capacities of meropenem and sulfamethoxazole disappeared in mixed-solute solutions, indicating the lowest adsorption competition. GAC can eliminate most ARGs while also promoting the growth of some ARB. Chlorination (free chlorine residues at 0.5 mg Cl2/L) did not significantly affect the overall composition of ARGs and ARB in HWW. However, the accumulation of ARGs and ARB on GAC in fixed bed columns was lower in chlorinated HWW than in non-chlorinated HWW due to an increase in the adsorption of intermediates.

Food waste compost and digestate as novel fertilizers: Impacts on antibiotic resistome and potential risks in a soil-vegetable system

As a novel agricultural practice, the reuse of food waste compost and digestate as fertilizers leads to a circular economy, but inevitably introduces bio-contaminants such as antibiotic resistance genes (ARGs) into the agroecosystem. Moreover, heavy metal and antibiotic contamination in farmland soil may exert selective pressures on the evolution of ARGs, posing threats to human health. This study investigated the fate, influencing mechanisms and potential risks of ARGs in a soil-vegetable system under different food waste fertilization and remediation treatments and soil contamination conditions. Application of food waste fertilizers significantly promoted the pakchoi growth, but resulted in the spread of ARGs from fertilizers to pakchoi. A total of 56, 80, 84, 41, and 73 ARGs, mobile genetic elements (MGEs) and metal resistance genes (MRGs) were detected in the rhizosphere soil (RS), bulk soil (BS), control soil (CS), root endophytes (RE), and leaf endophytes (LE), respectively. Notably, 7 genes were shared in the above five subgroups, indicating a specific soil-root-endophytes transmission pathway. 36 genes were uniquely detected in the LE, which may originate from airborne ARGs. The combined application of biochar and fertilizers reduced the occurrence of ARGs and MGEs to some extent, showing the remediation effect of biochar. The average abundance of ARGs in the RS, BS and CS was 3.15 × 10−2, 1.31 × 10−2 and 2.35 × 10−1, respectively. Rhizosphere effects may reduce the abundance of ARGs in soil. The distribution pattern of ARGs was influenced by the types of soil, endophyte and contaminant. MGEs is the key driver shaping ARGs dynamics. Soil properties and pakchoi growth status may affect the bacterial composition, and consequently regulate ARGs fate, while endophytic ARGs were more impacted by biotic factors. Moreover, the average daily doses of ARGs from pakchoi consumption is 107–109 copies/d/kg, and its potential health risks should be emphasized.

A database on the abundance of environmental antibiotic resistance genes

Antimicrobial resistance (AMR) poses a severe threat to global health. The wide distribution of environmental antibiotic resistance genes (ARGs), which can be transferred between microbiota, especially clinical pathogens and human commensals, contributed significantly to AMR. However, few databases on the spatiotemporal distribution, abundance, and health risk of ARGs from multiple environments have been developed, especially on the absolute level. In this study, we compiled the ARG occurrence data generated by a high-throughput quantitative PCR platform from 1,403 samples in 653 sampling sites across 18 provinces in China. The database possessed 291,870 records from five types of habitats on the abundance of 290 ARGs, as well as 8,057 records on the abundance of 30 mobile genetic elements (MGEs) from 2013 to 2020. These ARGs conferred resistance to major common types of antibiotics (a total of 15 types) and represented five major resistance mechanisms, as well as four risk ranks. The database can provide information for studies on the dynamics of ARGs and is useful for the health risk assessment of AMR.

Wastewater surveillance for antibiotics and resistance genes in a river catchment: Spatiotemporal variations and the main drivers

Wastewater-based epidemiology (WBE) is used for mining information about public health such as antibiotics resistance. This study investigated the distribution profiles of six types of antibiotic resistance genes (ARGs) in wastewater and rivers in Wuhu City, China. The levels of ARGs found in the Qingyijiang River were significantly higher than other rivers, and were comparable to effluent levels. Among the ARGs, sulfonamides ARGs and intI1 were the predominant in both wastewaters and rivers. Additionally, the concentrations of ARGs were higher on weekends as opposed to weekdays. Their distribution patterns remained consistent inter-week and inter-season using linear regression analysis (p < 0.001). Interestingly, the occurrence levels of ARGs in wastewaters during spring were significantly higher than in autumn, although insignificant in rivers. The apparent removal rate of ARGs in domestic wastewater sources ranged from 61.52–99.29%, except for qepA (-1.91% to 81.09%), whereas the removal rates in mixed domestic and industrial wastewaters showed a marked decrease (-92.94% to 76.67%). A correlation network analysis revealed that azithromycin and erythromycin were key antibiotics, while blaNDM-1, tetM, tetB, and ermB were identified as key ARGs. Sulfonamide and fluoroquinolone antibiotics, and tetracycline and macrolide ARGs were the primary contributors. Linear mixed models demonstrated that socio-economic variables positively impacted the occurrence levels of ARGs, whereas wastewater flow and river runoff were the negative drivers for their concentrations in wastewaters and surface waters, respectively. Overall, this WBE study contributes to the understanding of spatiotemporal profiles and main drivers of the occurrence of ARGs in wastewater and receiving water.

Concentrations, distribution, and key influencing factors of antibiotic resistance genes and bacterial community in water and reared fish tissues in a typical tilapia farm in South China

Although previous studies have investigated the occurrence of antibiotic resistance genes (ARGs) in aquaculture, few have monitored the concentrations and propagation of ARGs in biological tissues or investigated the key factors influencing their spread in aquaculture. This study investigated the concentration, propagation, and distribution of ARGs and bacterial communities in water sources, pond water, and tilapia tissues, and their key influencing factors, in a typical tilapia farm. ErmF, sul1, and sul2 were the dominant ARGs with high concentrations. The total concentrations of ARGs (TCAs) in tilapia tissues decreased in the following order: stomach > scales > intestine > gills (P < 0.05). Redundancy analysis and multiple linear regression revealed that suspended solids (SS) and chemical oxygen demand (COD) were positively correlated with the dominant ARGs ermF sul2, and the TCAs (P < 0.05); additionally, Chloroflexi and Bacteroidetes in tilapia aquaculture water were positively correlated with the dominant ARGs ermF and sul2, as well as the TCAs (P < 0.05). This study suggests that SS and COD were the key factors driving the distribution and spread of ARGs in tilapia aquaculture water. Additionally, Chloroflexi and Bacteroidetes were the key bacterial flora affecting the propagation of ARGs in tilapia aquaculture systems.

Microbial-influenced pesticide removal co-occurs with antibiotic resistance gene variation in soil-earthworm-maize system

Within human-influenced landscapes, pesticides cooccur with a variety of antibiotic stressors. However, the relationship between pesticides removal process and antibiotic resistance gene variation are not well understood. This study explored pesticide (topramezone, TPZ) and antibiotic (polymyxin E, PME) co-contamination using liquid chromatography-tandem mass spectrometry (LC-MS/MS), bacterial-16 S rRNA sequencing and high-throughput quantitative polymerase chain reaction (HT-qPCR) in a soil-earthworm-maize system. After incubating soil for 28 days with TPZ and PME (10 mg kg−1 dry weight), earthworm weight-gain, mortality rates, and maize plant weight-gain only differed slightly, but height-gain significantly decreased. PME significantly increased TPZ-removal in the soil. Accumulation of TPZ in earthworm's tissues may pose potential risks in the food chain. Combined pollution altered the microbial community structure and increased the abundance of functional microorganisms involved in aromatic compound degradation. Furthermore, maize rhizosphere can raise resistance genes, however earthworms can reduce resistance genes. Co-contamination increased absolute abundance of mobile genetic elements (MGEs) in bulk-soil samples, antibiotic resistance genes (ARGs) in skin samples and number of ARGs in bulk-soil samples, while decreased absolute abundance of transposase gene in bulk-soil samples and number of ARGs in rhizosphere-soil samples. Potential hosts harbouring ARGs may be associated with the antagonistic effect during resistance and detoxification of TPZ and PMB co-occurrence. These findings provide insights into the mechanism underlining pesticide removal regarding occurrence of ARGs in maize agroecosystem.

Antimicrobial Susceptibility and Resistance Genes in Streptococcus uberis Isolated from Bovine Mastitis in the Czech Republic.

Streptococcus uberis is one of the most important causative agents of mastitis and is a common reason for the use of antimicrobials in dairy cows. In this study, we assessed the antimicrobial susceptibility of 667 S. uberis isolates originating from 216 Czech dairy farms collected between 2019 and 2023 using the broth microdilution method. We tested 140 of the isolates for the presence of antimicrobial genes using whole-genome sequencing and evaluated their relationship with phenotypic resistance. Streptococcus uberis isolates showed high levels of resistance to tetracycline (59%), followed by streptomycin (38%) and clindamycin (29%). Although all of the isolates were susceptible to beta-lactams, a relatively high percentage of intermediately susceptible isolates was recorded for ampicillin (44%) and penicillin (18%). The isolates were mainly resistant to tetracycline alone (31.3%); the second most frequent occurrence of the phenotypic profile was simultaneous resistance to tetracycline, streptomycin, and clindamycin (16.6%). The occurrence of antibiotic resistance genes did not always match the phenotypic results; in total, 36.8% of isolates that possessed the ant(6)-Ia gene did not show phenotypic resistance to streptomycin. To a lesser extent, silent genes were also detected in clindamycin and tetracycline. This study confirmed the high susceptibility of S. uberis to penicillins used as first-line antimicrobials for S. uberis mastitis treatment.

Unraveling the antibiotic resistome in backwater zones of large cascade reservoirs: Co-occurrence patterns, horizontal transfer directions and health risks

The widespread occurrence of antibiotic resistant genes (ARGs) throughout aquatic environments has raised global concerns for public health. However, the profiles and patterns of antibiotic resistome in backwater zone of cascade reservoirs, where water flow is slowed down, are still poorly understood. Here, we proposed a metagenomic analysis framework to comprehensively reveal the diversity, abundance, co-occurrence patterns and transfer direction of ARGs in cascade reservoirs system and evaluated their health risks through a procedure based on contigs. A total of 364 ARGs subtypes conferring resistance to different antibiotics classes were detected in our water samples, and the dominant ARGs (macB, bacA, vanRA, bcrA) were similar in different reservoirs. Meanwhile, the distribution of ARGs was influenced by the presence of biotic factors such as metal resistant genes (MRGs) and mobile genetic elements (MGEs), as well as abiotic factors such as dissolved oxygen (DO) and pH. Remarkably, ARGs (vanR, rosB, MexT) co-occurred with plasmids and virulence factor genes (VFGs), which can lead to the emergence and spread of highly virulent and antibiotic resistant bacteria in microbial communities. Overall, this study helps administrators to better understand the complex patterns of ARGs in backwater zones of large cascade reservoirs and provides a proper procedure for detecting the presence of high-risk of ARGs.

Removal of oxytetracycline and sulfamethoxazole in vertical down-up flow constructed wetlands: Efficiency, removal pathways, and occurrence of antibiotic resistance genes

The extensive use of antibiotics leads to their frequent detection in the environment, posing potential threats to public health. Constructed wetlands (CWs) have been widely applied in wastewater treatment and can efficiently remove antibiotics. However, the removal of antibiotics in the CWs is still in a “black box”, and the information about the potential risks of antibiotic resistance genes (ARGs) occurrence in CWs is limited. In the present study, the removal of oxytetracycline (OTC) and sulfamethoxazole (SMZ), as well ARGs occurrence in vertical down-up flow constructed wetlands (VDUF-CWs) were assessed. The results indicated that VDUF-CWs exhibited great removal efficiency for OTC (84.3 ± 3.5 %) and SMZ (77.7 ± 3.9 %). Based on conservation of mass, the contributions of different removal pathways (i.e., microbial degradation, plant absorption, photodegradation, and substrate adsorption) to antibiotic removal were calculated. Of which, microbial degradation was found to be the dominant route in removing OTC and SMZ with the contribution of 58.52 ± 2.34 % and 65.13 ± 3.72 % respectively, followed by photodegradation (18.47 ± 3.04 % and 8.22 ± 3.94 %), plant absorption (9.01 ± 1.28 % and 7.75 ± 4.07 %) and substrate adsorption (2.08 ± 0.03 % and 1.73 ± 0.02 %). Notably, tetA, tetC, tetW, sulI, and sulII genes were detected in layer samples, and the relative abundances of the sul and tet genes were boosted with the extension of operation days, indicating that VDUF-CWs allow a risk of ARGs spread and threatening public health. The present study provided a deeper insight into the mechanism of antibiotic removal in CWs, but further explorations are required to develop the effective control strategies for eliminating ARGs from CWs.

Lactiplantibacillus plantarum, lactiplantibacillus pentosus and inulin meal inclusion boost the metagenomic function of broiler chickens

BackgroundThe inclusion of alternative ingredients in poultry feed is foreseen to impact poultry gut microbiota. New feeding strategies (probiotics/prebiotics) must be adopted to allow sustainable productions. Therefore, the current study aimed to use metagenomics approaches to determine how dietary inclusion of prebiotic (inulin) plus a multi-strain probiotic mixture of Lactiplantibacillus plantarum and Lactiplantibacillus pentosus affected microbiota composition and functions of the gastro-intestinal tract of the broilers during production. Fecal samples were collected at the beginning of the trial and after 5, 11 and 32 days for metataxonomic analysis. At the end of the trial, broilers were submitted to anatomo-pathological investigations and caecal content was subjected to volatilome analysis and DNAseq.ResultsProbiotic plus prebiotic inclusion did not significantly influence bird performance and did not produce histopathological alterations or changes in blood measurements, which indicates that the probiotic did not impair the overall health status of the birds. The multi-strain probiotic plus inulin inclusion in broilers increased the abundance of Blautia, Faecalibacterium and Lachnospiraceae and as a consequence an increased level of butyric acid was observed. In addition, the administration of probiotics plus inulin modified the gut microbiota composition also at strain level since probiotics alone or in combination with inulin select specific Faecalibacterium prausnitzi strain populations. The metagenomic analysis showed in probiotic plus prebiotic fed broilers a higher number of genes required for branched-chain amino acid biosynthesis belonging to selected F. prausnitzi strains, which are crucial in increasing immune function resistance to pathogens. In the presence of the probiotic/prebiotic a reduction in the occurrence of antibiotic resistance genes belonging to aminoglycoside, beta-lactamase and lincosamide family was observed.ConclusionsThe positive microbiome modulation observed is particularly relevant, since the use of these alternative ingredients could promote a healthier status of the broiler’s gut.

The occurrence and abundance of antibiotic resistance genes in rivers of tropical islands: a case of Hainan Island, China.

In this study, the occurrence and distribution of 49 antibiotic resistance genes (ARGs) and two integrase genes (intl1, intl2) in three major rivers of Hainan Island, China, were investigated in July 2021, and to explore the spatial distribution of the target genes in the three rivers with the potential influencing factors such as regional characteristics and environmental factors. The results showed that a total of 46 ARGs and two integrase genes were detected in water and sediment, and the absolute abundance of ARGs ranged from 1.16 × 103 to 2.97 × 107 copies/L and 3.34 × 103-1.55 × 107 copies/g. ARGs of macrolides, aminoglycosides, and sulfonamides were this study's main types of ARGs. The aadA2, tetE, ermF, tetX, aac(6')-Ib, tetW, and qnrS genes are predominant ARGs in the water and sediment of the three rivers. The relative abundance of ARGs shows higher abundance in the midstream and downstream and lower abundance in the upstream and estuarine. After conducting a correlation analysis, it was found that there was a significant positive correlation between the ARGs detected in the water of the three main rivers. However, in sediment, tetC was negatively correlated with tetQ, macB was negatively correlated with ermF and ereA (p < 0.05), while the remaining ARGs showed positive correlations. Specifically, there was no significant positive correlation between tetQ and tetC, macB and ereA, and ermF in the sediments. Among the nine environmental factors studied, pH was found to be the main factor associated with the occurrence of ARGs in the aquatic environment, but it was also significantly associated with only nine ARGs. Among the detected heavy metals, only Cd and Zn showed significant correlations with the two ARGs in the water bodies of the three main rivers. It indicated that the pollution of ARGs in the three major rivers was in the initial stage, the detection abundance was low, the influence of environmental factors was small, and the interaction between ARGs seemed to be the main driving force. This study provides a scientific basis for further understanding the occurrence of ARGs and their influencing factors in a tropical island environment, and lays a foundation for subsequent management.

Prevalence of Antibiotic-Resistant Pathogenic Bacteria and Level of Antibiotic Residues in Hospital Effluents in Selangor, Malaysia: Protocol for a Cross-sectional Study.

Antimicrobial resistance (AMR) has emerged as a major global public health challenge due to the overuse and misuse of antibiotics for humans and animals. Hospitals are among the major users of antibiotics, thereby having a large contribution to AMR. The aim of this study is to determine the prevalence of antibiotic-resistant pathogenic bacteria and the level of antibiotic residues in the hospital effluents in Selangor, Malaysia. A cross-sectional study will be performed in the state of Selangor, Malaysia. Tertiary hospitals will be identified based on the inclusion and exclusion criteria. The methods are divided into three phases: sample collection, microbiological analysis, and chemical analysis. Microbiological analyses will include the isolation of bacteria from hospital effluents by culturing on selective media. Antibiotic sensitivity testing will be performed on the isolated bacteria against ceftriaxone, ciprofloxacin, meropenem, vancomycin, colistin, and piperacillin/tazobactam. The identification of bacteria will be confirmed using 16S RNA polymerase chain reaction (PCR) and multiplex PCR will be performed to detect resistance genes (ermB, mecA, blaNDM-L, blaCTX-M, blaOXA-48, blaSHV, VanA, VanB, VanC1, mcr-1, mcr-2, mcr-3, Intl1, Intl2, and qnrA). Finally, the level of antibiotic residues will be measured using ultrahigh-performance liquid chromatography. The expected outcomes will be the prevalence of antibiotic-resistant Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter (ESKAPE) bacterial species from the hospital effluents, the occurrence of antibiotic resistance genes (ARGs) from the isolated ESKAPE bacteria, and the level of antibiotic residues that may be detected from the effluent. Sampling has been conducted in three hospitals. Data analysis from one hospital showed that as of July 2022, 80% (8/10) of E. faecium isolates were resistant to vancomycin and 10% (1/10) were resistant to ciprofloxacin. Further analysis will be conducted to determine if the isolates harbor any ARGs and effluent samples are being analyzed to detect antibiotic residues. Sampling activities will be resumed after being suspended due to the COVID-19 pandemic and are scheduled to end by December 2022. This study will provide the first baseline information to elucidate the current status of AMR of highly pathogenic bacteria present in hospital effluents in Malaysia. DERR1-10.2196/39022.