Review of antibiotic resistance in China and its environment

Simultaneous removal of tetracycline and sulfamethoxazole by laccase-mediated oxidation and ferrate(VI) oxidation: the impact of mediators and metal ions

This study explores the impact of mediators and metal ions of laccase-mediated oxidation and ferrate(VI) oxidation for the simultaneous removal of tetracycline antibiotics (TCs) and sulfonamide antibiotics (SAs) and to effectively remove their antimicrobial activity. The results showed that the antimicrobial activity of tetracycline against Bacillus altitudinis and Escherichia coli was significantly reduced, and the antimicrobial activity of sulfamethoxazole against B. altitudinis disappeared completely after treatment with the laccase-ABTS system. The combination of 6.0 U/mL of laccase and 0.2 mmol/L of ABTS removed 100% of 20.0 mg/L of tetracycline after 1.0 min at pH 6.0 and 25.0 °C, whereas the removal ratio of 20.0 mg/L of sulfamethoxazole was only 6.7%. The Al3+ and Cu2+ ions promoted the oxidation, and the Mn2+ ion decelerated the oxidation of tetracycline and sulfamethoxazole by the laccase-mediator systems. In contrast, the antimicrobial activity of tetracycline against B. altitudinis and E. coli was shown to be significantly reduced, and the sulfamethoxazole still retained high antimicrobial activity against B. altitudinis after treatment with Fe(VI) oxidation. The removal ratio of 20.0 mg/L of tetracycline was 100% after 1.0 min of treatment with 982.0 mg/L of K2FeO4 at pH 6.0 and 25.0 °C, whereas the removal ratio of 20.0 mg/L of sulfamethoxazole was only 49.5%. The Al3+, Cu2+, and Mn2+ ions both decelerated the oxidation of tetracycline and sulfamethoxazole by Fe(VI) oxidation. In general, the combination of the laccase-ABTS system and Fe(VI) was proposed for the simultaneous treatment of TCs and SAs in wastewater and to effectively remove their antimicrobial activity.

Deciphering the antibiotic resistome and microbial community in municipal wastewater treatment plants at different elevations in eastern and western China

Antibiotic resistance genes (ARGs) as emerging environmental contaminants pose severe global risks to public health and ecosystems. Municipal wastewater treatment plants (WWTPs) are crucial transmitters for the dissemination and propagation of ARGs into receiving water bodies via mobile genetic elements (MGEs). However, the comprehensive and deep deciphering of the diversity, abundance, and potential hosts of ARGs in two distinct altitudinal WWTPs is scarce. In this work, we revealed the elevational distribution characteristics of the resistance genes and microbial community of six WWTPs from two distinct geographical zones: a low-elevation (LE) region (Shandong, 10-22 m above sea level) and a high-elevation (HE) region (Gansu, 1,520-1,708 m above sea level). Significant elevational variations in the diversity and relative abundance of resistance genes were observed. Wastewater treatment could significantly reduce the concentrations of ARGs and MGEs by about 1-2 and 2-3 orders of magnitude, respectively. However, above 69.95% of resistance genes were enriched in effluent. In particular, 24 ARG subtype, 3 MGE subtypes, and 59 bacterial genera were persistent in all samples. More potential hosts for ARGs in LE region and more abundant human gut microbiota in HE region were identified. This work provides helpful information for controlling the spread of ARGs for their management and assessment, thereby mitigating the risks of ARGs in WWTPs.

Effect of graphene and graphene oxide on antibiotic resistance genes during copper-contained swine manure anaerobic digestion

Copper is an important selectors for antibiotic resistance genes (ARGs) transfer because of metal-antibiotic cross-resistance and/or coresistance. Due to carbon-based materials' good adsorption capacity for heavy metals, graphene and graphene oxide have great potential to reduce ARGs abundance in the environment with copper pollution. To figure out the mechanics, this study investigated the effects of graphene and graphene oxide on the succession of ARGs, mobile genetic elements (MGEs), heavy metal resistance genes (HMRGs), and bacterial communities during copper-contained swine manure anaerobic digestion. Results showed that graphene and graphene oxide could reduce ARGs abundance in varying degrees with the anaerobic reactors that contained a higher concentration of copper. Nevertheless, graphene decreased the abundance of ARGs more effectively than graphene oxide. Phylum-level bacteria such as Firmicutes, Bacteroidetes, Spirochaetes, and Verrucomicrobiaat were significantly positively correlated with most ARGs. Network and redundancy analyses demonstrated that alterations in the bacterial community are one of the main factors leading to the changes in ARGs. Firmicutes, Bacteroidetes, and Spirochaetes were enriched lower in graphene reactor than graphene oxide in anaerobic digestion products, which may be the main reason that graphene is superior to graphene oxide in reduced ARGs abundance. Additionally, ARGs were close to HMRGs than MGEs in the treatments with graphene, the opposite in graphene oxide reactors. Therefore, we speculate that the reduction of HMRGs in graphene may contribute to the result that graphene is superior to graphene oxide in reduced ARGs abundance in anaerobic digestion.

Recent advances in cellulose supported photocatalysis for pollutant mitigation: A review

In recent times, green chemistry or "green world" is a new and effective approach for sustainable environmental remediation. Among all biomaterials, cellulose is a vital material in research and green chemistry. Cellulose is the most commonly used natural biopolymer because of its distinctive and exceptional properties such as reproducibility, cost-effectiveness, biocompatibility, biodegradability, and universality. Generally, coupling cellulose with other nanocomposite materials enhances the properties like porosity and specific surface area. The polymer is environment-friendly, bioresorbable, and sustainable which not only justifies the requirements of a good photocatalyst but boosts the adsorption ability and degradation efficiency of the nanocomposite. Hence, knowing the role of cellulose to enhance photocatalytic activity, the present review is focused on the properties of cellulose and its application in antibiotics, textile dyes, phenol and Cr(VI) reduction, and degradation. The work also highlighted the degradation mechanism of cellulose-based photocatalysts, confirming cellulose's role as a support material to act as a sink and electron mediator, suppressing the charge carrier's recombination rate and enhancing the charge migration ability. The review also covers the latest progressions, leanings, and challenges of cellulose biomaterials-based nanocomposites in the photocatalysis field.

Diversity, antibacterial and phytotoxic activities of culturable endophytic fungi from Pinellia pedatisecta and Pinellia ternata

BACKGROUND

Endophytic fungi of medicinal plants, as special microorganisms, are important sources of antibacterial compounds. However, the diversity and antibacterial activity of endophytic fungi from Pinellia Tenore have not been systematically studied.

RESULTS

A total of 77 fungi were isolated from roots, stems, leaves, and tubers of Pinellia ternata and P. pedatisecta. All fungi were belonged to five classes and twenty-five different genera. Biological activities tests indicated that 21 extracts of endophytic fungi exhibited antibacterial activities against at least one of the tested bacteria, and 22 fermentation broth of endophytic fungi showed strong phytotoxic activity against Echinochloa crusgalli with the inhibition rate of 100%. Furthermore, four compounds, including alternariol monomethyl ether (1), alternariol (2), dehydroaltenusin (3) and altertoxin II (4), and three compounds, including terreic acid (5), terremutin (6), citrinin (7), were isolated from Alternaria angustiovoidea PT09 of P. ternata and Aspergillus floccosus PP39 of P. pedatisecta, respectively. Compound 5 exhibited strong antibacterial activities against Escherichia coli, Micrococcus tetragenus, Staphylococcus aureus, and Pseudomonas syringae pv. actinidiae with the inhibition zone diameter (IZD) of 36.0, 31.0, 33.7, 40.2 mm and minimum inhibitory concentration (MIC) values of 1.56, 3.13, 1.56, 1.56 μg/mL respectively, which were better than or equal to those of positive gentamicin sulfate. The metabolite 7 also exhibited strong antibacterial activity against P. syringae pv. actinidiae with the IZD of 26.0 mm and MIC value of 6.25 μg/mL. In addition, the compound 7 had potent phytotoxic activity against E. crusgalli with the inhibition rate of 73.4% at the concentration of 100 μg/mL.

CONCLUSIONS

Hence, this study showed that endophytic fungi of P. ternata and P. pedatisecta held promise for the development of new antibiotic and herbicide resources.

Biochar Facilitated Direct Interspecies Electron Transfer in Anaerobic Digestion to Alleviate Antibiotics Inhibition and Enhance Methanogenesis: A Review

Efficient conversion of organic waste into low-carbon biofuels such as methane through anaerobic digestion (AD) is a promising technology to alleviate energy shortages. However, issues such as inefficient methane production and poor system stability remain for AD technology. Biochar-facilitated direct interspecies electron transfer (DIET) has recently been recognized as an important strategy to improve AD performance. Nonetheless, the underlying mechanisms of biochar-facilitated DIET are still largely unknown. For this reason, this review evaluated the role of biochar-facilitated DIET mechanism in enhancing AD performance. First, the evolution of DIET was introduced. Then, applications of biochar-facilitated DIET for alleviating antibiotic inhibition and enhancing methanogenesis were summarized. Next, the electrochemical mechanism of biochar-facilitated DIET including electrical conductivity, redox-active characteristics, and electron transfer system activity was discussed. It can be concluded that biochar increased the abundance of potential DIET microorganisms, facilitated microbial aggregation, and regulated DIET-associated gene expression as a microbial mechanism. Finally, we also discussed the challenges of biochar in practical application. This review elucidated the role of DIET facilitated by biochar in the AD system, which would advance our understanding of the DIET mechanism underpinning the interaction of biochar and anaerobic microorganisms. However, direct evidence for the occurrence of biochar-facilitated DIET still requires further investigation.

Transmission of antibiotic resistance genes through mobile genetic elements in Acinetobacter baumannii and gene-transfer prevention

Antibiotic resistance is a major global public health concern. Acinetobacter baumannii is a nosocomial pathogen that has emerged as a global threat because of its high levels of resistance to many antibiotics, particularly those considered as last-resort antibiotics, such as carbapenems. Mobile genetic elements (MGEs) play an important role in the dissemination and expression of antibiotic resistance genes (ARGs), including the mobilization of ARGs within and between species. We conducted an in-depth, systematic investigation of the occurrence and dissemination of ARGs associated with MGEs in A. baumannii. We focused on a cross-sectoral approach that integrates humans, animals, and environments. Four strategies for the prevention of ARG dissemination through MGEs have been discussed: prevention of airborne transmission of ARGs using semi-permeable membrane-covered thermophilic composting; application of nanomaterials for the removal of emerging pollutants (antibiotics) and pathogens; tertiary treatment technologies for controlling ARGs and MGEs in wastewater treatment plants; and the removal of ARGs by advanced oxidation techniques. This review contemplates and evaluates the major drivers involved in the transmission of ARGs from the cross-sectoral perspective and ARG-transfer prevention processes.

Ultrafast degradation of SMX and TC by CoSiO x activated peroxymonosulfate: efficiency and mechanism

To address the concern about residual antibiotics in effluent of sewage treatment plants, cobalt silicate (CoSiO x ) was prepared by hydrothermal method and employed as an activator of peroxymonosulfate (PMS) for the rapid degradation of antibiotics. Taking sulfamethoxazole (SMX) and tetracycline (TC) as representatives of antibiotics, the effects of operation parameters (CoSiO x and PMS dosage) and water quality parameters (temperature, solution pH, bicarbonate, chloride, and natural organic matter) on degradation of target pollutants by a CoSiO x activated PMS process (CoSiO x /PMS) were investigated. The mechanism involved in the interaction of CoSiO x and PMS was also elucidated. The results indicated that CoSiO x /PMS can degrade SMX and TC at fast pseudo-first-order rate constants (0.47 and 0.56 min-1 respectively) under optimal conditions. Increasing the dosage of PMS and CoSiO x appropriately was beneficial to the degradation of antibiotics. Chloride, bicarbonate, and HA showed negative effects on the degradation process due to their free radical-scavenging ability and were ranked as chloride < bicarbonate < HA. Abundant [triple bond, length as m-dash]Co-OHs and oxygen vacancies on the surface of CoSiO x contributed to its excellent activation capability towards PMS. The radical scavenging experiments indicated that target pollutant degradation mainly resulted from the attack of sulfate radicals (43.0% contribution) and hydroxyl radicals (52.9% contribution). The practicality of CoSiO x /PMS was verified by continuous flow test. This study provides a cheap, highly efficient, and feasible advanced depollution method based on CoSiO x .

Deterministic Effect of pH on Shaping Soil Resistome Revealed by Metagenomic Analysis

Soil is recognized as the major reservoir of antibiotic resistance genes (ARGs), harboring the most diverse naturally evolved ARGs on the planet. Multidrug resistance genes are a class of ARGs, and their high prevalence in natural soil ecosystems has recently raised concerns. Since most of these genes express proton motive force (PMF) driven efflux pumps, studying whether soil pH is a determinant for the selection of multidrug efflux pump genes and thus shaping the soil resistome are of great interest. In this study, we collected 108 soils with pH values ranging from 4.37 to 9.69 from multiple ecosystems and profiled the composition of ARGs for metagenomes and metagenome-assembled genomes. We observed the multidrug efflux pump genes enriched in the acidic soil resistome, and their abundances have significant soil pH dependence. This reflects the benefits of high soil proton activity on the multidrug efflux pump genes, especially for the PMF-driven inner membrane transferase. In addition, we preliminary indicate the putative microbial participants in pH shaping the soil resistome by applying ecological analyzing tools such as stepwise regression and random forest model fitting. The decisive influence of proton activity on shaping the resistome is more impactful than any other examined factors, and as the consequence, we revisited the influence of edaphic factors on the soil resistome; i.e., the deterministic selection of resistance mechanisms by edaphic factors could lead to the bottom-up shaping of the ARG composition. Such natural developing mechanisms of the resistome are herein suggested to be considered in assessing human-driven ARG transmissions.

Evolution and implementation of One Health to control the dissemination of antibiotic-resistant bacteria and resistance genes: A review

Antibiotic resistance is a serious threat to humanity and its environment. Aberrant usage of antibiotics in the human, animal, and environmental sectors, as well as the dissemination of resistant bacteria and resistance genes among these sectors and globally, are all contributing factors. In humans, antibiotics are generally used to treat infections and prevent illnesses. Antibiotic usage in food-producing animals has lately emerged as a major public health concern. These medicines are currently being utilized to prevent and treat infectious diseases and also for its growth-promoting qualities. These methods have resulted in the induction and spread of antibiotic resistant infections from animals to humans. Antibiotics can be introduced into the environment from a variety of sources, including human wastes, veterinary wastes, and livestock husbandry waste. The soil has been recognized as a reservoir of ABR genes, not only because of the presence of a wide and varied range of bacteria capable of producing natural antibiotics but also for the usage of natural manure on crop fields, which may contain ABR genes or antibiotics. Fears about the human health hazards of ABR related to environmental antibiotic residues include the possible threat of modifying the human microbiota and promoting the rise and selection of resistant bacteria, and the possible danger of generating a selection pressure on the environmental microflora resulting in environmental antibiotic resistance. Because of the connectivity of these sectors, antibiotic use, antibiotic residue persistence, and the existence of antibiotic-resistant bacteria in human-animal-environment habitats are all linked to the One Health triangle. The pillars of support including rigorous ABR surveillance among different sectors individually and in combination, and at national and international level, overcoming laboratory resource challenges, and core plan and action execution should be strictly implemented to combat and contain ABR under one health approach. Implementing One Health could help to avoid the emergence and dissemination of antibiotic resistance while also promoting a healthier One World. This review aims to emphasize antibiotic resistance and its regulatory approaches from the perspective of One Health by highlighting the interconnectedness and multi-sectoral nature of the human, animal, and environmental health or ill-health facets.

A Comprehensive Contamination Investigation of Bohai Bay Seawater: Antibiotics Occurrence, Distribution, Ecological Risks and Their Interactive Factors

A comprehensive, large-scale coastal investigation of antibiotics in seawater from Bohai Bay is lacking. Therefore, in this study, we investigated the occurrence and ecological risks of 45 antibiotics belonging to 5 classes in seawater from Bohai Bay, as well as their inter-relation with trace elements and other contaminants. The results show that tetracyclines (TCs) were detected in the highest concentration among the five classes (in the range of 0.6−2.0 μg/L). The total concentrations of the five classes of antibiotics were detected in the following order: tetracyclines (TCs) > quinolones (QAs) > sulfonamides (SAs) > macrolides (MAs) > lactams (LAs). Higher antibiotic concentrations were detected at the sampling sites closest to the coast or the shipping port. Among seven trace elements, four were quantitatively detected, with Zn representing the highest concentration. Antibiotic residuals were found to be positively correlated with total organic carbon (TOC), conductivity (Ec) and suspended solids (SS); pH and NH4+-N usually showed a negative correlation with antibiotics; TN and TP also exhibited relationships with antibiotics. The risk quotient (RQ) was calculated for different antibiotics at different sites. It was found that antibiotics pose higher risks to algae than to invertebrates or fish; sulfamethoxazole, enrofloxacin and ofloxacin were all found to pose high risk to algae at some of the sampling sites. Structural equation model (SEM) results show that trace elements, antibiotic levels and EC50 are the main factors affecting the ecological risks of antibiotics.

Spread and driving factors of antibiotic resistance genes in soil-plant system in long-term manured greenhouse under lead (Pb) stress

Livestock manure is often used as fertilizer in greenhouses, resulting in simultaneous enrichment of heavy metals and antibiotic resistance genes (ARGs) in soils. The soil-plant system is a non-negligible way to spread ARGs; however, the effects of lead (Pb) on the spread of ARGs and their driving factors in the greenhouse soil-plant system remain unclear. In this present study, the occurrence of ARGs in greenhouse soils and their spread into plants under Pb stress were studied. Overall, Pb promoted the accumulation of ARGs in root endophytes at 10, 50, and 100 mg/kg as well as in soils at 10 and 200 mg/kg, but reduced the total relative abundance of ARGs in leaf endophytes. Particularly, Pb increased the mobile genetic elements (MGEs) relative abundance and endophytic bacterial community diversity in roots, consistent with the change in the total relative abundance of ARGs. Network analysis revealed that bacterial community and MGEs may jointly affect the migration of ARGs in the soil-plant system of greenhouses. Overall, this study extended our knowledge of how Pb can promote the transmission of ARGs to plant roots from greenhouse soils receiving long-term manure applications, which must be considered when assessing the risk of ARGs to public health.

Responses of soil microbial communities to concentration gradients of antibiotic residues in typical greenhouse vegetable soils

To explore the responses of soil microbial communities to concentration gradients of antibiotic residues in soil, 32 soil samples were collected from a typical greenhouse vegetable production base in Northern China in 2019. The total concentrations of 26 antibiotic residues in these soil samples was 83.24-4237.93 μg·kg^-1, of which metabolites of tetracyclines were 23.34-1798.80 μg·kg^-1. The total concentrations in 32 samples were clustered into three levels (L: <100 μg·kg^-1, M: 100-300 μg·kg^-1, H: >300 μg·kg^-1) to elucidate the impacts of antibiotic residues on the diversity, structure, composition, function and antibiotic resistome of soil microbial community. Results showed that higher concentration of antibiotic residues in soil was prone to decrease the diversity and shift the structure and composition of soil microbial community. Antibiotic resistome occurred in soils with antibiotic residues exceeding 300 μg·kg^-1. Interactions among soil bacteria followed the order of H > L > M, consistent with the relative abundances of mobile genetic elements. Bacteroidetes and Firmicutes were the top attributors impacting the profile of antibiotics in soil. According to weighted comprehensive pollution index of risk quotient, in 28.1 % of soil samples the residual antibiotics presented high ecological risk, whereas in the rest of soil samples the ecological risk is medium. The results will enrich the database and provide references for antibiotic contamination control in soils of the region and alike.

Distribution of antibiotic resistance genes in the sediments of Erhai Lake, Yunnan-Kweichow Plateau, China: Their linear relations with nonpoint source pollution discharges from 26 tributaries

Erhai Lake, a typical plateau deep water lake, experienced long-term nonpoint source (NPS) pollution discharge from 26 tributaries, which significantly affected the abundance and spread of resistance genes. In this study, 25 antibiotic resistance genes (ARGs), classified into six types, and NPS pollution discharges were investigated throughout around the Erhai basin. FCA (mexF) and sulfonamide resistance genes (sul1, sul2 and sul3) were the most common. Although the absolute overall abundance of ARGs there was low so far, the individual gene like sulfonamide resistance gene was high. Regression analysis using an ordinary least squares model (OLS) showed that the discharge of NPS pollution into Erhai Lake would have an obvious effect on the distribution of ARGs. And the relations between them were linear. Concretely speaking, the total nitrogen (TN) pollution input from tributaries could significantly correlated with the increasing of ARG abundance, while the total phosphorus (TP) pollution input showed the opposite correlation, and ultimately affect the distribution of ARGs. Moreover, the effect of TP on ARG distribution was more significant than TN. This study provides a geographical profile of ARG distribution in a subtropical deep lake on Yunnan-Kweichow Plateau. The results are beneficial for predicting the distribution characteristics of ARGs and controlling their pollution in plateau lakes.

Distribution and migration of antibiotic resistance genes, as well as their correlation with microbial communities in swine farm and its surrounding environments

The prevalence and correlation of antibiotic resistance genes (ARGs) in pig farm wastewater treatment plants (WWTPs) and surrounding environment were investigated using metagenomics and real time quantitative PCR (q-PCR). The hosts of ARGs were also studied in this study. The abundance of ARGs decreased significantly in the anoxic/oxic (A/O) process and disinfection tank of WWTPs. New ARGs emerged in wastewater that passed though the anaerobic reactor. The abundances of ARGs in the soils and water near pig farm were 10- and 35-fold higher than those in the control, respectively. The abundance of ARGs in wells near pig farm were an order of magnitude higher than that in the control. Similarly, a high abundance of ARGs was detected in swine manure. After composting, most of the ARGs were eliminated, but sul1 increased 10.5-fold. A high-throughput analysis revealed that the pig farm altered the microbial community structure in the surrounding environment, with 52% and 37% of the operational taxonomic units (OTUs) endemic to the soil and water samples near pig farm in comparison with these data in the control, respectively. The phyla Proteobacteria, Choroflexi, and Actinobacteriota dominated the water and soil samples. In addition, three pathogenic genera were found in the surrounding soil and water samples. A metagenomic analysis identified 14 types of ARGs (>1%), with the highest proportion of multidrug ARGs at 47%. A total of 28 subtypes of ARGs were detected (>1%), with macB the most prevalent. The correlation analysis revealed that several key phyla, including Proteobacteria, Actinobacteria and Acidobacteria, were the main potential hosts and posed a positive correlation with the ARGs. Efflux pumps (60-66%) were the primary resistance mechanism, and each resistance mechanism was distributed in similar proportions in the microbial community.

Industrial effluents boosted antibiotic resistome risk in coastal environments

Wastewater treatment plants (WWTPs) have been regarded as an important source of antibiotic resistance genes (ARGs) in environment, but out of municipal domestic WWTPs, few evidences show how environment is affected by industrial WWTPs. Here we chose Hangzhou Bay (HZB), China as our study area, where land-based municipal and industrial WWTPs discharged their effluent into the bay for decades. We adopted high-throughput metagenomic sequencing to examine the antibiotic resistome of the WWTP effluent and coastal sediment samples. And we proposed a conceptual framework for the assessment of antibiotic resistome risk, and a new bioinformatic pipeline for the evaluation of the potential horizontal gene transfer (HGT) frequency. Our results revealed that the diversity and abundance of ARGs in the WWTP's effluent were significantly higher than those in the sediment. Furthermore, the antibiotic resistome in the effluent-receiving area (ERA) showed significant difference from that in HZB. For the first time, we identified that industrial WWTP effluent boosted antibiotic resistome risk in coastal sediment. The crucial evidences included: 1) the proportion of ARGs derived from WWTP activated sludge (WA) was higher (14.3 %) and two high-risky polymyxin resistance genes (mcr-4 and mcr-5) were enriched in the industrial effluent receiving area; 2) the HGT potential was higher between resistant microbiome of the industrial effluent and its ERA sediment; and 3) the highest resistome risk was determined in the industrial effluent, and some biocide resistance genes located on high-risky contigs were related to long-term stress of industrial chemicals. These findings highlight the important effects of industrial activities on the development of environmental antimicrobial resistance.

Effect of minute amounts of arsenic on the sulfamethoxazole removal and microbial community structure via the SBR system

In this study, the effect of arsenic on the sulfamethoxazole (SMX) removal efficiency and microbial community structure was investigated over 60 days using the SBR process. The results showed that the presence of arsenic had no significant impact on the system performance, the removal efficiencies of two reactors, R1 (the control test) and R2 (with the addition of arsenic), were 13.36 ± 5.71 and 14.20 ± 5.27%, which were attributed to the adsorption of SMX by fulvic acid-like substances and tryptophan-like proteins of extracellular polymeric substances. Compared to the seed sludge, the species number indicated that R2 possessed the richer diversity, while R1 possessed the lower diversity on day 60, which might be relative to the transferring of antibiotic resistance genes (ARGs) in sludge bacterial communities; the minute amounts of arsenic could make the relative levels of Sul1 and Sul2 genes which encode ARGs of sulfonamides in R2 (2.07 and 2.47%) be higher than that in R1 (1.65 and 1.27%), which made the bacterial community of the R2 system more adaptable to SMX stress. Therefore, the minute amounts of arsenic weakened the effect of SMX on the system and enhanced the stability of the microbial community structure.

Tracking antibiotic resistance genes in microplastic-contaminated soil

Agricultural soils and microplastics (MPs) are hotspots for antibiotic resistance genes (ARGs). Plastic mulch is the most important source of MPs in agricultural soil. ARGs, mobile genetic elements (MGEs), and their host profiles in long-term mulch MP-exposed soils remain unclear. In the present study, metagenomics was used to investigate the distribution patterns of ARGs and MGEs in eight Chinese provinces with a long history of plastic mulch use. A total of 204 subtypes of ARGs and thousands of MGEs (14 integrons, 28 insertions, and 2993 plasmids) were identified. A similar diversity of ARGs was found among MPs film-contaminated sites. The types of ARGs with a high abundance were more concentrated, and multidrug resistance genes were the dominant ARGs. Soils from regions with a longer history of plastic film use (such as Xinjiang province) had a higher abundance of ARGs and MGEs. The distribution of ARGs and MGEs exhibited a modular network distribution pattern. A total of 27 ARG subtypes and 29 MGEs showed co-occurrence network relationships. More than 10 common hosts of ARGs and MGEs, such as Pseudomonas, were found, and their abundances were highest in three provinces, including Xinjiang. This study may help elucidate the impact mechanism of long-term MP residues on the occurrence and spread of ARGs in soil.

Insights into antibiotic stewardship of lake-rivers-basin complex systems for resistance risk control

Antibiotic stewardship is hindered by a lack of consideration for complicated environmental fate of antibiotics and their role in resistance development, while the current methodology of eco-toxicological risk assessment has not been fully protective against their potential to select for antibiotic resistance. To address this problem, we established a novel methodologic framework to perform comprehensive environmental risk assessment of antibiotics in terms of resistance development, which was based on selection effect, phenotype resistance level, heteroresistance frequency, as well as prevalence and stability of antibiotic resistance genes. We tracked the contribution of antibiotic load reduction to the mitigation of environmental risk of resistance development by fate and transport modeling. The method was instantiated in a lake-river network-basin complex system, taking the Taihu Basin as a case study. Overall, antibiotic load posed no eco-toxicological risk but an average medium-level environmental risk for resistance development in Taihu Lake. The effect of antibiotic load on resistance risk was both seasonal-dependent and category-dependent, while quinolones posed the greatest environmental risk for resistance development. Mass-flow analysis indicated that temporal-spatial variation in hydrological regime and antibiotic fate together exerted a significant effect on antibiotic load in the system. By apportioning antibiotic load to riverine influx, we identified the hotspots for load reduction and predicted the beneficial response of resistance risk under load-reduction scenarios. Our study proposed a risk-oriented strategy of basin-scaled antibiotic load reduction for environmental risk control of resistance development.

Antibiotics degradation by advanced oxidation process (AOPs): Recent advances in ecotoxicity and antibiotic-resistance genes induction of degradation products

Antibiotic contamination could cause serious risks of ecotoxicity and resistance gene induction. Advanced oxidation processes (AOPs) such as Fenton, photocatalysis, activated persulfate, electrochemistry and other AOPs technologies have been proven effective in the degradation of high-risk, refractory organic pollutants such as antibiotics. However, due to the limited mineralization ability, a large number of degradation intermediates will be produced in the oxidation process. The residual or undiscovered ecological risks of degradation products are potential safety hazards and problems necessitating comprehensive studies. In-depth investigations especially on the full assessments of ecotoxicity and resistance genes induction capability of antibiotic degradation products are important issues in reducing the environmental problems of antibiotics. Therefore, this review presents an overview of the current knowledge on the efficiency of different AOPs systems in reducing antibiotics toxicity and antibiotic resistance.

The impact of early-life antibiotics and probiotics on gut microbial ecology and infant health outcomes: a Pregnancy and Birth Cohort in Northwest China (PBCC) study protocol

BACKGROUND

Unreasonable use of antibiotics and probiotics can alter the gut ecology, leading to antibiotic resistance and suboptimal health outcomes during early life. Our study aims are to clarify the association among antibiotic and probiotic exposure in early life, the microecology of the gut microbiota, and the development of antibiotic resistance; to investigate the long-term impact of antibiotics and probiotics on the health outcomes of infants and young children; and to provide a theoretical basis for the rational use of antibiotics and probiotics from a life course perspective.

METHODS

The study is a prospective, longitudinal birth cohort study conducted in Shaanxi Province, China from 2018 to 2024. A total of 3,000 eligible mother-child pairs will be enrolled from rural, suburban, and urban areas. The recruitment of the participants begins at pregnancy, and the newborns will be followed up for 2 years at successive timepoints: within 3 days after birth, 42 days after birth, and at 3, 6, 12, 18, and 24 months of age. Sociodemographic data, environmental exposures, dietary patterns, psychological conditions, and medical and drug histories are collected. Cognitive and behavioural development among infants and young children and questionnaires on antibiotic knowledge and behaviour among caregivers will be collected at 12 and 24 months of age. The faecal samples are collected and analysed by 16S rRNA high-throughput sequencing and quantitative PCR (qPCR) for antibiotic resistance genes.

DISCUSSION

The findings will inform antibiotic and probiotic use for pregnant women and infants and contribute to establishing rational use strategies of antibiotics and probiotics for paediatricians, health practitioners, and drug administration policy-makers.

TRIAL REGISTRATION

The study was registered on the Chinese Clinical Trial Registry (ChiCTR) platform, http://www.chictr.org.cn (Record ID: ChiCTR2100047531, June 20, 2021).

Multiplexed Target Enrichment Enables Efficient and In-Depth Analysis of Antimicrobial Resistome in Metagenomes

Antibiotic resistance genes (ARGs) pose a serious threat to public health and ecological security in the 21st century. However, the resistome only accounts for a tiny fraction of metagenomic content, which makes it difficult to investigate low-abundance ARGs in various environmental settings. Thus, a highly sensitive, accurate, and comprehensive method is needed to describe ARG profiles in complex metagenomic samples. In this study, we established a high-throughput sequencing method based on targeted amplification, which could simultaneously detect ARGs (n = 251), mobile genetic element genes (n = 8), and metal resistance genes (n = 19) in metagenomes. The performance of amplicon sequencing was compared with traditional metagenomic shotgun sequencing (MetaSeq). A total of 1421 primer pairs were designed, achieving extremely high coverage of target genes. The amplicon sequencing significantly improved the recovery of target ARGs (~9 × 104-fold), with higher sensitivity and diversity, less cost, and computation burden. Furthermore, targeted enrichment allows deep scanning of single nucleotide polymorphisms (SNPs), and elevated SNPs detection was shown in this study. We further performed this approach for 48 environmental samples (37 feces, 20 soils, and 7 sewage) and 16 clinical samples. All samples tested in this study showed high diversity and recovery of targeted genes. Our results demonstrated that the approach could be applied to various metagenomic samples and served as an efficient tool in the surveillance and evolution assessment of ARGs. Access to the resistome using the enrichment method validated in this study enabled the capture of low-abundance resistomes while being less costly and time-consuming, which can greatly advance our understanding of local and global resistome dynamics. IMPORTANCE ARGs, an increasing global threat to human health, can be transferred into health-related microorganisms in the environment by horizontal gene transfer, posing a serious threat to public health. Advancing profiling methods are needed for monitoring and predicting the potential risks of ARGs in metagenomes. Our study described a customized amplicon sequencing assay that could enable a high-throughput, targeted, in-depth analysis of ARGs and detect a low-abundance portion of resistomes. This method could serve as an efficient tool to assess the variation and evolution of specific ARGs in the clinical and natural environment.

Antibiotic resistance genes in landfill leachates from seven municipal solid waste landfills: Seasonal variations, hosts, and risk assessment

Landfills are reservoir of antibiotics and antibiotic resistance. Antibiotic resistance would transport to the environment through landfill leachate, posing threaten to the environment. However, long term monitoring on antibiotic resistance genes in landfill leachate transportation is limited. Furthermore, antibiotic resistance gene hosts and their risk assessment are lacking. In this study, we investigated the seasonal variation of ARGs sulI, tetO and tetW in seven Chinese municipal solid waste landfill leachates over two years (2017-2018) by quantitative polymerase chain reaction. We also evaluated the associated bacterial hosts and their risk levels based on metagenomics and omics-based framework for assessing the health risk of antimicrobial resistance genes, respectively. Because sulI, tetO and tetW are abundant and the most frequently detected ARGs in global landfill system, they are selected as target ARGs. Results showed that the relative content of target ARGs in 2017 was 100 times higher than that in 2018, suggesting ARGs attenuation. The hosts of sulI were phyla of Lentisphaerae and Proteobacteria, whereas the hosts of tetO and tetW were Bacteroidetes and Firmicutes. Remarkably, the host species include pathogenic bacterium (Salmonella enterica, Labilibaculum filiforme, Bacteroidales bacterium, Anaeromassilibacillus senegalensis, and Pseudochrobactrum sp. B5). ARGs tetO and tetW belong to the Rank II level with characters of enrichment in the human-associated environment and gene mobility, and sulI ranked as Rank VI. In addition, among 1210 known ARGs in the landfill leachate, 78 ARGs belonged to risk Rank I (enrichment in human-associated environment, gene mobility and pathogenicity), demonstrating high health risk of landfill system. These results demonstrate that antibiotic resistance in landfill and landfill leachate have high health risk and the kind of ARGs with high abundance in human-associated environment, gene mobility and pathogenicity should be paid more attention.

Protective effect and mechanism of baicalin on lung inflammatory injury in BALB/cJ mice induced by PM2.5

The public health harms caused by fine particulate matter (PM2.5) have become a global focus, with PM2.5 exposure recognized as a critical risk factor for global morbidity and mortality. Chronic inflammation is the common pathophysiological feature of respiratory diseases induced by PM2.5 and is the most critical cause of all these diseases. However, presently there is a lack of effective preventive and therapeutic approaches for inflammatory lung injuries caused by PM2.5 exposure. Baicalin is a herb-derived effective flavonoid compound with multiple health benefits. This study established a murine lung inflammatory injury model via inhalation of PM2.5 aerosols. The data showed that after baicalin intervention, lung injury pathological score of baicalin (4.16 ± 0.54, 3.33 ± 0.76, 4.00 ± 0.45) and claricid (3.00 ± 0.78) treatments were markedly lower than PM2.5-treated mice (6.17 ± 0.31), and pathological damage was alleviated. Compared to the PM2.5 group, the spleen and lung indexes in the baicalin and claricid groups were significantly reduced. The inflammatory cytokines of TNF-α, IL-18, and IL-1β in serum, alveolar lavage fluid, and lung tissue were significantly decreased in the baicalin and claricid groups. The expressions of inflammatory pathway-related genes and proteins HMGB1, NLRP3, ASC, and caspase-1 were up-regulated in the PM2.5 group. The expressions of these genes and proteins were significantly decreased following baicalin treatment. The lung function indicators showed that the MV (65.94 ± 8.19 mL), sRaw (1.79 ± 0.08 cm H2O^.s), and FRC (0.52 ± 0.01 mL) in the PM2.5 group were higher than in the control and baicalin groups, and respiratory function was improved by baicalin. PM2.5 exposure markedly altered the bacterial composition at the genus level. The dominant flora relative abundances of uncultured_bacterium_f_Muribaculaceae, Streptococcus, and Lactobacillus, were decreased from the control group (9.20%, 8.53%, 6.21%) to PM2.5 group (6.26%, 5.49%, 4.77%), respectively. Following baicalin intervention, the relative abundances were 9.72%, 6.65%, and 3.57%, respectively. Therefore, baicalin could potentially prevent and improve mice lung inflammatory injury induced by PM2.5 exposure. Baicalin might provide a protective role by balancing oropharyngeal microbiota and affecting the expression of the HMGB1/Caspase1 pathway.

The antibiotic resistance and risk heterogeneity between urban and rural rivers in a pharmaceutical industry dominated city in China: The importance of social-economic factors

Rivers are important environmental sources of human exposure to antibiotic resistance. Many factors can change antibiotic resistance in rivers, including bacterial communities, human activities, and environmental factors. However, the systematic comparison of the differences in antibiotics resistance and risks between urban rivers (URs) and rural rivers (RRs) in a pharmaceutical industry dominated city is still rare. In this study, Shijiazhuang City (China) was selected as an example to compare the differences in antibiotics resistance and risks between URs and RRs. The results showed higher concentrations of total quinolones (QNs) antibiotics in both water and sediment samples collected from URs than those from RRs. The subtypes and abundances of antibiotic resistance genes (ARGs) in URs were significantly higher than those in RRs, and most emerging ARGs (including OXA-type, GES-type, MCR-type, and tet(X)) were only detected in URs. The ARGs were mainly influenced by QNs in URs and social-economic factors (SEs) in RRs. The composition of the bacterial community was significantly different between URs and RRs. The abundance of antibiotic-resistant pathogenic bacteria (ARPBs) and virulence factors (VFs) were higher in URs than those in RRs. Therein, 371 and 326 pathogen types were detected in URs and RRs, respectively. Most emerging ARGs showed a significantly positive correlation with priority ARPBs. Variance partitioning analysis revealed that SEs were the main driving factors of ARGs (80 %) and microbial communities (92 %) both in URs and RRs. Structural equation models indicated that antibiotics (QNs) and microbial communities were the most direct influence of ARGs in URs and RRs, respectively. The cumulative resistance risk of QNs was high in URs, but relatively low in RRs. Enrofloxacin and flumequine posed the highest risk in water and sediment, respectively. This study could help us to better manage and control the risk of antibiotic resistance in different rivers.

Statistical modeling optimization for antibiotics decomposition by ultrasound/electro-Fenton integrated process: Non-carcinogenic risk assessment of drinking water

The present work proposes an ultrasound (US) assisted electro-Fenton (EF) process for eliminating penicillin G (PNG) and ciprofloxacin (CIP) from aqueous solutions and the process was further optimized by response surface methodology (RSM)- Box-Behnken design (BBD). The impact of pH, hydrogen peroxide (H₂O₂) concentration, applied voltage, initial pollutant concentration, and operating time were studied. The capability application of the electro-Fenton (EF) and US processes was compared separately and in combination under the optimum conditions of pH of 4, a voltage of 15 V, the initial antibiotic concentration of 20.7 mg/L, H₂O₂ concentration of 0.8 mg/L, and the operating time of 75 min. The removal efficiency of PNG and CIP using the sono-electro-Fenton (SEF) process, as the results revealed, was approximately 96% and 98%, respectively. The experiments on two scavengers demonstrated that ^⦁OH contributes significantly to the CIP and PNG degradation by SEF, whereas ^⦁O^-₂ corresponds to only a negligible amount. The total organic carbon (TOC) and chemical oxygen demand (COD) analyses were used to assess the mineralization of CIP and PNG. The efficiency of COD and TOC removal was reached at 73.25% and 62.5% for CIP under optimized operating circumstances, and at 61.52% and 72% for PNG, respectively. These findings indicate that a sufficient rate of mineralization was obtained by SEF treatment for the mentioned pollutants. The reaction kinetics of CIP and PNG degradation by the SEF process were found to follow a pseudo-first-order kinetic model. In addition, the human health risk assessment of natural water containing CIP and PNG that was purified by US, EF, and SEF processes was done for the first time. According to the findings, the non-carcinogenic risk (HQ) caused by drinking purified water by all three systems was calculated in the acceptable range. Thus, SEF is a proper system to remove various antibiotics in potable water and reduces their human health risks.

Biochar application for remediation of organic toxic pollutants in contaminated soils; An update

Bioremediation of organic contaminants has become a major environmental concern in the last few years, due to its bio-resistance and potential to accumulate in the environment. The use of diverse technologies, involving chemical and physical principles, and passive uptake utilizing sorption using ecofriendly substrates have drawn a lot of interest. Biochar has got attention mainly due to its simplicity of manufacturing, treatment, and disposal, as it is a less expensive and more efficient material, and has a lot of potential for the remediation of organic contaminants. This review highlighted the adverse impact of persistent organic pollutants on the environment and soil biota. The utilization of biochar to remediate soil and contaminated compounds i.e., pesticides, polycyclic aromatic hydrocarbons, antibiotics, and organic dyes has also been discussed. The soil application of biochar has a significant impact on the biodegradation, leaching, and sorption/desorption of organic contaminants. The sorption/desorption of organic contaminants is influenced by chemical composition and structure, porosity, surface area, pH, and elemental ratios, and surface functional groups of biochar. All the above biochar characteristics depend on the type of feedstock and pyrolysis conditions. However, the concentration and nature of organic pollutants significantly alters the sorption capability of biochar. Therefore, the physicochemical properties of biochar and soils/wastewater, and the nature of organic contaminants, should be evaluated before biochar application to soil and wastewater. Future initiatives, however, are needed to develop biochars with better adsorption capacity, and long-term sustainability for use in the xenobiotic/organic contaminant remediation strategy.

Mineral contents, antimicrobial profile, acute and chronic toxicity of the aqueous extract of Moroccan Thymus vulgaris in rodents

Moroccan flora is rich in plants used in traditional medicine, but the further scientific investigation is necessary. The aim of the research was to evaluate the nutritional content and antimicrobial activity of Moroccan Thymus vulgaris, as well as its possible acute and chronic toxicological effects on rodents. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine the mineral content. The antimicrobial activity was determined using a well-diffusion test, a minimum inhibitory concentration (MIC), and a minimum bactericidal/fungicidal concentration (MBC/MFC) assay. Acute and chronic toxicity studies were conducted in vivo on mice and rats, respectively. Following that, haematological, serum-biochemistry, and histological investigations were performed. Moroccan Thyme was shown to be a source of numerous minerals which are necessary for health promotion. All antimicrobial testing, disc diffusion, MIC, and MBC tests revealed that thyme had potent antibacterial activity against all microorganisms tested. Staphylococcus aureus was the most susceptible bacterium, followed by Salmonella enterica and Escherichia coli. Additionally, thyme exhibited great antifungal efficacy against Candida albicans. The acute toxicity results indicated that the aqueous extract of T. vulgaris is almost non-toxic when taken orally. According to the chronic toxicity study, the extract is generally safe when taken orally over an extended period of time. The biochemical and haematological characteristics of the serum and blood were within acceptable limits, and histological examination revealed no abnormalities. In conclusion, the findings of this investigation, confirm the antimicrobial efficacy of the aqueous extract of Moroccan T. vulgaris and its safety for experimental animals.

A Review on Electrospinning as Versatile Supports for Diverse Nanofibers and Their Applications in Environmental Sensing

Rapid industrialization is accompanied by the deterioration of the natural environment. The deepening crisis associated with the ecological environment has garnered widespread attention toward strengthening environmental monitoring and protection. Environmental sensors are one of the key technologies for environmental monitoring, ultimately enabling environmental protection. In recent decades, micro/nanomaterials have been widely studied and applied in environmental sensing owing to their unique dimensional properties. Electrospinning has been developed and adopted as a facile, quick, and effective technology to produce continuous micro- and nanofiber materials. The technology has advanced rapidly and become one of the hotspots in the field of nanomaterials research. Environmental sensors made from electrospun nanofibers possess many advantages, such as having a porous structure and high specific surface area, which effectively improve their performance in environmental sensing. Furthermore, by introducing functional nanomaterials (carbon nanotubes, metal oxides, conjugated polymers, etc.) into electrospun fibers, synergistic effects between different materials can be utilized to improve the catalytic activity and sensitivity of the sensors. In this review, we aimed to outline the progress of research over the past decade on electrospinning nanofibers with different morphologies and functional characteristics in environmental sensors.

Provincial clustering and related factors analysis of clinic antimicrobial resistance in China

OBJECTIVE

Antimicrobial resistance (AMR) is among the biggest and most pressing risks facing healthcare in China and globally. We aimed to describe the current status regarding the distribution of clinic AMR in China through provincial clustering and analyse the related factors.

METHODS

Based on the detection rates of 13 major drug-resistant bacteria in 31 provinces across the country, as reported by the National Bacterial Resistance Surveillance Network in 2019, we carried out a provincial clustering by dividing the conditions of provincial clinical AMR into different groups, and we then examined the potentially related factors, such as the use of antibiotics, economic development status, health service utilization, and health resource allocation.

RESULTS

According to the different levels of bacterial resistance, the provinces were clustered into three categories: low, medium, and high detection rates of AMR. The three categories had notable geographic clustering and associations. Economic development status, health service utilization, such as the number of the types of antibacterial drugs (P = 0.025), health resource allocations, such as low licensed pharmacist per 1000 patient visits (P = 0.004) were related to AMR in China.

CONCLUSIONS

The levels of AMR in public hospitals within the coastal areas of North China and East China were higher than those in other areas. The regions with higher levels of clinical bacterial resistance also had higher levels of health costs, health services volume and utilization, insufficient health resources per time, and higher probability of overuse of antimicrobials. Targeted measures should be taken in these areas to curb the resistance trends.

Identification and characterization of Fe3O4/peroxodisulfate advanced oxidation products from sulfameter

Sulfonamides (SAs) are one of the most widely used antibiotics and their residuals in the environment could cause some negative environmental issues. Advanced oxidation such as Fenton-like reaction has been widely applied in the treatment of SAs polluted water. Degradation rates of 95%-99.7% were achieved in this work for the tested 8 SAs, including sulfisomidine, sulfameter (SME), phthalylsulfathiazole, sulfamethoxypyridazine, sulfamonomethoxine, sulfisoxazole, sulfachloropyridazine, and sulfadimethoxine, in the Fe₃O₄/peroxodisulfate (PDS) oxidation system after the optimization of PDS concentration and pH. Meanwhile, it was found that a lot of unknown oxidation products were formed, which brought up the uncertainty of health risks to the environment, and the identification of these unknown products was critical. Therefore, SME was selected as the model compound, from which the oxidation products were never elucidated, to identify these intermediates/products. With liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS), 10 new products were identified, in which 2-amino-5-methoxypyrimidine (AMP) was confirmed by its standard. The investigation of the oxidation process of SME indicated that most of the products were not stable and the degradation pathways were very complicated as multiple reactions, such as oxidation of the amino group, SO₂ extrusion, and potential cross-reaction occurred simultaneously. Though most of the products were not verified due to the lack of standards, our results could be helpful in the evaluation of the treatment performance of SAs containing wastewater.

Plant Lectins: A Review on their Biotechnological Potential Toward Human Pathogens

The indiscriminate use of antibiotics is associated with the appearance of bacterial resistance. In light of this, plant-based products treating infections are considered potential alternatives. Lectins are a group of proteins widely distributed in nature, capable of reversibly binding carbohydrates. Lectins can bind to the surface of pathogens and cause damage to their structure, thus preventing host infection. The antimicrobial activity of plant lectins results from their interaction with carbohydrates present in the bacterial cell wall and fungal membrane. The data about lectins as modulating agents of antibiotic activity, potentiates the effect of antibiotics without triggering microbial resistance. In addition, lectins play an essential role in the defense against fungi, reducing their infectivity and pathogenicity. Little is known about the antiviral activity of plant lectins. However, their effectiveness against retroviruses and parainfluenza is reported in the literature. Some authors still consider mannose/ glucose/N-Acetylglucosamine binding lectins as potent antiviral agents against coronavirus, suggesting that these lectins may have inhibitory activity against SARS-CoV-2. Thus, it was found that plant lectins are an alternative for producing new antimicrobial drugs, but further studies still need to decipher some mechanisms of action.

Source prevention of halogenated antibiotic resistance genes proliferation: UV/sulfite advanced reduction process achieved accurate and efficient elimination of florfenicol antibacterial activity

The production and consumption of halogenated antibiotics, such as florfenicol (FLO), remain high, accompanied by a large amount of antibiotic-containing wastewater, which would induce the potential proliferation and transmission of antibiotic resistance genes (ARGs) in conventional biological systems. This study revealed that the introduction of reductive species (mainly H) by adding sulfite during UV irradiation process accelerated the decomposition rate of FLO, increasing from 0.1379 min^-1 in the single UV photolytic system to 0.3375 min^-1 in the UV/sulfite system. The enhanced photodecomposition in UV/sulfite system was attributed to the improved dehalogenation performance and additional removal of sulfomethyl group at the site of the benzene ring, which were the representative structures consisting of FLO antibacterial activity. Compared with single UV photolysis, UV/sulfite advanced reduction process saved the light energy requirement by 40 % for the evolutionary suppression of floR, and its corresponding class of ARGs in subsequent biotreatment system was controlled at the level of the negative group. Compared with UV/H₂O₂ and UV/persulfate systems, the decomposition rate of FLO in the UV/S system was the highest and preserved the corresponding carbon source of the coexisting organic compounds for the potential utilization of microbial metabolism in subsequent biotreatment process. These results demonstrated that UV/sulfite advanced reduction process could be adopted as a promising pretreatment option for the source prevention of representative ARGs proliferation of halogenated antibiotics in subsequent biotreatment process.

Ti/PbO2 Electrode Efficiency in Catalytic Chloramphenicol Degradation and Its Effect on Antibiotic Resistance Genes

Livestock farming has led to the rapid accumulation of antibiotic resistance genes in the environment. Chloramphenicol (CAP) was chosen as a model compound to investigate its degradation during electrochemical treatment. Ti/PbO₂ electrodes were prepared using electrodeposition. The prepared Ti/PbO₂-La electrodes had a denser surface and a more complete PbO₂ crystal structure. Ti/PbO₂-Co electrodes exhibited improved electrochemical catalytic activity and lifetime in practice. The impact of different conditions on the effectiveness of CAP electrochemical degradation was investigated, and the most favorable conditions were identified (current density: I = 15.0 mA/cm, electrolyte concentration: c = 0.125 mol/L, solution pH = 5). Most importantly, we investigated the effects of the different stages of treatment with CAP solutions on the abundance of resistance genes in natural river substrates (intI1, cmlA, cmle3, and cata2). When CAP was completely degraded (100% TOC removal), no effect on resistance gene abundance was observed in the river substrate; incomplete CAP degradation significantly increased the absolute abundance of resistance genes. This suggests that when treating solutions with antibiotics, they must be completely degraded (100% TOC removal) before discharge into the environment to reduce secondary pollution. This study provides insights into the deep treatment of wastewater containing antibiotics and assesses the environmental impact of the resulting treated wastewater.

Antibiotics in the Basque coast (N Spain): Occurrence in waste and receiving waters, and risk assessment (2017-2020)

The study of the presence of antibiotics in the aquatic environment is a preliminary step to analyse their possible harmful effects on aquatic ecosystems. In order to monitor their occurrence in the aquatic environment, the European Commission established in 2015, 2018, and 2020 three Watch Lists of substances for Union-wide monitoring (Decisions (EU) 2015/495, 2018/840, and 2020/1161), where some antibiotics within the classes of macrolides, fluoroquinolones and penicillins were included. In the Basque coast, northern Spain, three macrolide antibiotics (erythromycin, clarithromycin, azithromycin) and ciprofloxacin were monitored quarterly from 2017 to 2020 (covering a period before and after the COVID19 outbreak), in water samples collected from two Waste Water Treatment Plants (WWTPs), and three control points associated with receiving waters (transitional and coastal water bodies). This work was undertaken for the Basque Water Agency (URA). The three macrolide antibiotics in water showed a frequency of quantification >65 % in the Basque coast, with higher concentrations in the WWTP emission stations than in receiving waters. Their frequency of quantification decreased from 2017 to 2020, as did the consumption of antibiotics in Spanish primary care since 2015. Ciprofloxacin showed higher frequencies of quantification in receiving waters than in wastewaters, but the highest concentrations were observed in the WWTP emission stations. Although consumption of fluoroquinolones (among which is ciprofloxacin) in primary care in the Basque Country has decreased in recent years, this trend was not observed in the waters sampled in the present study. On the other hand, concentrations of clarithromycin, azithromycin, and ciprofloxacin in receiving waters exceeded their respective Predicted No-Effect Concentrations, so they could pose an environmental risk. These substances are widely used in human and animal medicine, so, although only ciprofloxacin is included in the third Watch List, it would be advisable to continue monitoring macrolides in the Basque coast as well.

Efficient degradation of tylosin by Klebsiella oxytoca TYL-T1

Tylosin is widely used in livestock; however, the release of tylosin through animal manure can cause serious environmental problems. In this study, a new tylosin-degrading strain, TYL-T1, was isolated. Its phylogenetic similarity to Klebsiella oxytoca was found to be 99.17 %. TYL-T1 maintained good growth at 40 °C over a broad pH range (4.0-10). TYL-T1 degraded 99.34 % of tylosin in 36 h under optimal conditions (tylosin initial concentration: 25 mg/L, pH: 7.0, and temperature: 35 °C). After LC-MS-MS analysis, a new degradation pathway for tylosin was proposed, including ester bond breaking of the macrolide lactone ring, redox reaction, and loss of mycinose and mycarose. Based on a transcriptome analysis, 164 genes essential for degradation were upregulated through hydrolysis and redox of tylosin. Among various transferases, lipopolysaccharide methyltransferase, glycogen glucosyltransferase, and fructotransferase were responsible for tylosin degradation. The present study revealed the degradation mechanism of tylosin and highlighted the potential of Klebsiella oxytoca TYL-T1 to remove tylosin from the environment.

Antibiotic resistance genes in Chishui River, a tributary of the Yangtze River, China: Occurrence, seasonal variation and its relationships with antibiotics, heavy metals and microbial communities

The large-scale use and release of antibiotics may create selective pressure on antibiotic resistance genes (ARGs), causing potential harm to human health. River ecosystems have long been considered repositories of antibiotics and ARGs. Therefore, the distribution characteristics and seasonal variation in antibiotics and ARGs in the surface water of the main stream and tributaries of the Chishui River were studied. The concentrations of antibiotics in the dry season and rainy season were 54.18-425.74 ng/L and 66.57-256.40 ng/L, respectively, gradually decreasing along the river direction. The results of antibiotics in the dry season and rainy season showed that livestock and poultry breeding were the main sources in the surface water of the Chishui River basin. Risk assessments indicated high risk levels of OFL in both seasons. In addition, analysis of ARGs and microbial community diversity showed that sul1 and sul3 were the main ARGs in the two seasons. The highest abundance of ARGs was 7.70 × 10⁷ copies/L, and intl1 was significantly positively correlated with all resistance genes (p< 0.01), indicating that it can significantly promote the transmission of ARGs. Proteobacteria were the dominant microorganisms in surface water, with a higher average abundance in the dry season (60.64 %) than in the rainy season (39.53 %). Finally, correlation analyses were performed between ARGs and antibiotics, microbial communities and heavy metals. The results showed that there was a significant positive correlation between ARGs and most microorganisms and heavy metals (p< 0.01), indicating that occurrence and transmission in the environment are influenced by various environmental factors and cross-selection. In conclusion, the persistent residue and transmission of ARGs and their transfer to pathogens are a great threat to human health and deserve further study and attention.

Presence of bromide and iodide promotes the horizontal transfer of antibiotic resistance genes during chlorination: A preliminary study

Chlorination was reported to have a great potential to increase horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs), which poses a great threat to global human health. Bromide (Br^-) and iodide (I^-) ions are widely spread ions in water and wastewater. In chlorination, Br^- and I^- can be oxidized to active bromine and iodine species. The influence of the co-existing different halogen oxidants (chlorine + bromine or iodine species) on HGT of ARGs were rarely investigated. In this study, the conjugative transfer of ARGs between a donor strain E. coli K12 and a recipient strain E. coli HB101 was investigated in chlorination without/with the presence of Br^- or I^-. Immediately after the addition of sodium hypochlorite, 53-88 % of the dosed chlorine was rapidly consumed, 10 %-42 % fast transformed into organic combined chloramines, and only low levels of free chlorine (0.02-0.8 mg/L as Cl₂) left in the diluted cultural medium. Conjugative transfer mediated by the RP4 plasmid was not significantly enhanced in chlorination without the presence of Br^- or I^-. With the presence of Br^- (0.5-5.0 mg/L) or I^- (0.05-0.5 mg/L) in chlorination, the co-existing free halogen oxidants and their organic combined ones up-regulated the mRNA expression of the oxidative stress-regulatory gene (rpoS), outer membrane protein gene (ompC), and conjugation-relevant genes (trbBp and trfAp), and caused more damage to cell entirety. As a result, the co-existing reactive halogen oxidants enhanced the HGT of ARGs probably via conjugative transfer and transformation. This study showed that the presence of Br^- and I^- of common levels in aquatic environment promoted HGT of ARGs in chlorination, thus accelerating the transmission and prevalence of ARGs.

Analysis of Antimicrobial Resistance and Genetic Correlations of Escherichia Coli in Dairy Cow Mastitis

Introduction

Escherichia coli is a widespread environmental pathogen frequently causing dairy cow mastitis. This bacterium is particularly capable of acquiring antimicrobial resistance, which can have severe impacts on animal food safety and human health. The objective of the study was to investigate antimicrobial resistance and genetic correlations of E. coli from dairy cow mastitis cases in northern China.

Material and Methods

Forty strains of E. coli from 196 mastitis milk samples were collected, susceptibility to 13 common antibiotics and the prevalence of resistance genes were tested in these strains, and the genetic characteristics were identified by multilocus sequence typing.

Results

The results showed that most isolates were multidrug resistant (MDR) (75%), and the resistance rates to cefazolin, trimethoprim-sulfamethoxazole and ampicillin were 77.5%, 55.0%, and 52.5%, respectively. The representative genes of the isolates were aadA (62.5%) and tet(B) (60.0%). Multilocus sequence typing showed 19 different sequence types (STs) and 5 clonal complexes (CCs) in the 40 isolates, mainly represented by ST10 and CC10. The strains of the same ST or CC showed a high level of genetic relatedness, but the characteristics of their antimicrobial resistance were markedly different.

Conclusion

Most E. coli isolates in the study were MDR strains. Some strains of the same ST or CC showed diverse resistance characteristics to common antimicrobials. Therefore, E. coli from dairy cow mastitis in northern China should be investigated to elucidate its antimicrobial resistance and genotypes.

Competitive adsorption and desorption of tetracycline and sulfadiazine in crop soils

In view of the environmental issues caused by antibiotics, this research studies competitive adsorption/desorption for tetracycline (TC) and sulfadiazine (SDZ) in agricultural soils. Competitive adsorption was studied in binary systems (adding equal concentrations of both antibiotics). In addition, it was compared with results from simple systems. In all cases, batch-type adsorption/desorption experiments were carried out. In the binary systems, for the highest antibiotic concentration added, adsorption percentages were always higher for TC (close to 100%) than for SDZ (10-90%). In these systems, TC desorption was lower than 5% for all soils, and generally <10% for SDZ. Comparing TC and SDZ adsorption for the different systems, SDZ was clearly affected by the presence of TC, with SDZ adsorption percentages being was much higher (with differences generally above 65%) in the binary than in the simple systems. On the contrary, comparing the results of TC adsorption in simple and binary systems, TC was not affected by the presence of SDZ, obtaining similar adsorption percentages in both systems. K_d and K_F values (in the Linear and Freundlich models), were higher in the simple systems in the case of TC, which could be due to competition with SDZ, while for SDZ K_d and K_F were higher in the binary systems, with a synergistic effect of TC favoring SDZ adsorption. Regarding desorption, it reached 100% for SDZ in some soils in simple systems, dropping to 10% in the presence of TC. TC desorption was <4%, not affected by SDZ. The results indicate that environmental risks would be higher for SDZ, showing differences when both antibiotics are present. This can be considered relevant as regards public health and environmental preservation, in view of direct toxicities and the promotion of resistance to antibiotics associated with the presence of these contaminants in the environment.