Antibiotic Residues Research Articles

Effect of the residual levofloxacin on hydroponic vegetables with sewage treatment plant tailwater: Microbial community, discharge risk and control strategy

Tailwater-based hydroponic vegetable is a promising strategy for domestic wastewater recycling. However, the effect of residual antibiotics on the hydroponic vegetable system and the relation between hydroponic culture parameters and the residual water quality are still unclear. Here, the typical antibiotic Levofloxacin (LVFX) was employed, and the effect of LVFX (5 mg/L) on the residual water quality, plant growth and microbial community of water spinach hydroponic culture system were investigated under different hydraulic residence times (HRT). Obvious toxic effects on water spinach were observed, and the highest removal rate of LVFX (about 6 %) and TN (25.67±1.43 %) was observed when HRT was 7 days. Hydroponic culture increased the microbial abundance, diversity, and microbial community stability. To optimize the hydroponic culture, actual sewage plant tailwater spiked with 20 μg/L LVFX, along with three common planting substrates (sponge, ceramsite, and activated carbon) were used for the hydroponic culture of lettuce (seasonal reasons). The inhibition effect of LVFX on the removal of NO3--N and TN was observed even as the LVFX concentration decreased significantly (from 14.62 ± 0.44 μg/L to 0.65 ± 0.07 μg/L). The best growth situation of lettuce and removal rates of NH4+-N, NO3--N, TN, especially LVFX (up to 95.65 ± 0.54 %) were observed in the activated carbon treated group. The overall results indicate the negative effect of residual antibiotics on the hydroponic vegetable systems, and adding activated carbon as substrate is an effective strategy for supporting plant growth and controlling discharged risk.

Seamless carbon nitride growth on bimetallic oxide for antibiotic residue degradation

Seamless carbon nitride growth on bimetallic oxide for antibiotic residue degradation

Assessment of Veterinary Antibiotic Use and Occurrence of Veterinary Antibiotics in Livestock Manure from Farms in Rongai Sub-County, Kenya

Veterinary antibiotics are commonly used in livestock rearing to prevent diseases and stimulate growth. The release of antibiotics into the environment has become a significant environmental and public health concern. This research evaluated antibiotic use, livestock treatment, manure utilization, livestock waste treatment methods and antibiotic residues in livestock manure. Questionnaires were administered to 170 farmers rearing both cattle and poultry. Subsequently, 28 livestock manure samples from 15 cattle and 13 poultry rearing farms were collected from various farms to assess concentrations of tetracyclines (Tetracycline, Oxytetracycline) and sulfonamides (Sulfadiazine, Sulfamethoxazole) residues. Residues analysis was done using High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD). Veterinarians were the most preferred in treating both cattle and poultry in farms. Tetracyclines and sulfonamides were the most consumed class of antibiotics among both poultry and cattle rearing farmers. Compost manure and Biogas were the most preferred use of animal waste within farms. Antibiotic presence in samples was detected in 80% and 93% of cattle and poultry manure respectively. Maximum antibiotic concentrations of 16.24 and 15.18 (mg/kg) were recorded in poultry and cattle manure, respectively. There was a statistically significant difference in antibiotic concentrations in poultry and cattle manure (P<0.05). The results of this research are important in monitoring rising concerns about veterinary antibiotics on environmental and public health.

How policy advocacy promotes regulated antibiotic use: Evidence from meat duck farmers of China

Antibiotic residues resulting from the misuse of veterinary antibiotics pose a serious threat to global food safety and the ecological environment. Regulating the use of antibiotics is currently a major concern; however, existing literature on this issue remains insufficient. Therefore, to advance research in this area, this study utilizes data from 988 questionnaires collected across 9 provinces in China and employs the 3SLS systematic estimation method. It constructs an analytical framework to explore the mechanisms through which policy advocacy (PA) influences regulating antibiotics use (RAU) among meat duck farmers. Specifically, the study examines two pathways: “ PA - public opinion pressure perception (POPP) - RAU” and “ PA - moral responsibility (MR) - RAU.” Additionally, it explores the potential mechanisms through which PA impacts RAU among farmers. The results show that PA (Coef = 0.070, SE = 0.014) can promote RAU by increasing the level of POPP (Coef = 0.173, SE = 0.091). PA (Coef = 0.351, SE = 0.028) can also promote RAU by enhancing MR (Coef = 0.239, SE = 0.035). Meanwhile, this study introduces Internet use (IU) and reputational incentives (RI) as moderating variables to analyze their role in moderating the impact of PA on RAU. It was demonstrated that IU (Coef = 0.088, SE = 0.016) significantly enhances farmers' awareness of the value of RAU and amplifies the impact of PA on MR. However, IU (Coef = −0.017, SE = 0.008) was found to inhibit the effect of PA on POPP. RI fully satisfies farmers' need for “ honor “ and enhances the effectiveness of PA in promoting both POPP (Coef = 0.009, SE = 0.002) and MR (Coef = 0.058, SE = 0.004). Finally, the study proposes that the government expand PA channels, innovate methods, and combine online outreach with demonstrations to improve farmers' awareness of antibiotic use and address their reputational needs.

Enhanced adsorption and catalytic degradation of antibiotics by CoFe2O4–NH2@DJB2-900 activated peroxymonosulfate: An experimental and mechanistic investigation

In recent years, with the widespread use of antibiotics in clinical, a large number of residual antibiotics have been discharged into aquatic environments, posing a substantial threat to human well-being. In this paper, the recyclable magnetic catalyst CoFe2O4–NH2@DJB2-900 (CFN@DJB2-900) was prepared by combining biochar derived from diaphragma juglans (DJ) with magnetic material CoFe2O4–NH2 (CFN). This catalyst could not only effectively activate peroxymonosulfate (PMS) to degrade levofloxacin (LEF), but also realize rapid separation from the matrix. After four cycles, the LEF removal rate could still maintain at 83.91 %. The quenching experiments and electron paramagnetic resonance (EPR) analysis demonstrated that LEF was degraded by defluorination, depiperazinylation, demethylation and ring opening in CFN@DJB2-900/PMS system with the help of O2∙-, 1O2 and electron transfer. The LEF removal rate of 94.32 % was achieved within 10 min. Moreover, the material exhibited wide applicability, good anti-interference ability and reusability. Therefore, this study provided a simple and feasible strategy to prepare an efficient activator CFN@DJB2-900 for the degradation of levofloxacin.

Multidrug-resistant high-risk clonal Escherichia coli lineages occur along an antibiotic residue gradient in the Baltic Sea

The global spread of multidrug-resistant Escherichia coli threatens human, animal, and environmental health. Despite the recognition of water bodies as potential reservoirs, research on antimicrobial resistance (AMR) and antibiotic residues in the Baltic Sea is limited. In this study, we examined the presence of ESBL-producing E. coli in surface water in northeastern Germany. We then conducted phenotypic and genotypic analyses of the strains, which encompassed AMR and heavy metal/metalloid tolerance, biofilm formation, and detailed plasmid examination. In addition, we used solid-phase extraction with ultra-high performance liquid chromatography and mass spectrometry to quantify antibiotic residues. Our analysis identified 30 ESBL-producing E. coli isolates, some of which were associated with clinically relevant high-risk clonal lineages. We detected antibiotic residues in the environmental samples, but the antibiotic concentrations were significantly lower compared to wastewater samples. These results suggest that the Baltic Sea surface water could serve as a reservoir for ESBL-producing E. coli and clinically relevant antibiotics.

Development of purity certified reference materials to establish metrological traceability for the measurement of nitroimidazoles in agricultural products.

It is of significant importance to public health that reliable monitoring of nitroimidazoles be conducted, while certified reference materials (CRMs) are essential for accurate and reliable detection. A project has been initiated with the objective of developing nitroimidazole purity CRMs to ensure that results from nationwide monitoring laboratories for nitroimidazoles in antibiotic residues can be compared and traced. The candidates were successively characterized in terms of their structure by means of infrared (IR) spectroscopy and mass spectrometry (MS). The mass balance (MB) method and the quantitative nuclear magnetic resonance (qNMR) method were utilized to determine the purity of nitroimidazoles with remarkable accuracy. Furthermore, a methodical investigation was conducted on homogeneity, stability, and uncertainty. Six nitroimidazole purity CRMs, including tinidazole (GBW09252), secnidazole (GBW09286), ronidazole (GBW09288), metronidazole (GBW(E)090755), dimetridazole (GBW(E)090819), and ornidazole (GBW(E)090820), were finally manufactured following authorization from China's State Administration for Market Regulation (SAMR). By using these CRMs, it is possible to improve the traceability, accuracy, and comparability of nitroimidazole measurements in a range of agricultural products, protecting public health.

Regional distribution differences of antibiotics in tropical marine aquaculture area: Insights into antibiotic management and risk assessment

In recent years, global demand for marine aquaculture products has led to a significant rise in antibiotic use, particularly in tropical coastal aquaculture areas However, research on antibiotic residues in these environments remains limited, hindering a comprehensive understanding of their environmental presence and associated risks. This study investigates the regional distribution, ecological risks, and sources of 44 antibiotics in seawater across four coastal aquaculture areas in Hainan island (Wenchang, Sanya, Danzhou, and Wanning). Among the 44 antibiotics tested across 42 sampling sites, all were detected with a 100 % detection rate. Antibiotics such as Trimethoprim (TMP), Sulfanitran (APNPS), Sulfaquinoxaline (SQ), Sulfadimethoxine (SDT), Chloramphenicol (CHP), and Florfenicol (FLO) were consistently detected across all sampling sites. Total concentrations of detected antibiotics ranged from 0 to 818.79 ng.L−1, with sulfonamide antibiotics ranging from 0 to 629.49 ng.L−1, chloramphenicol antibiotics from 0 to 87.39 ng.L−1, tetracyclines from 0 to 221.39 ng.L−1, and fluoquinolones from 0 to 272.08 ng.L−1. The highest levels of antibiotic pollution were observed at the W5 sampling site in Wenchang, attributed to aquaculture wastewater discharge, while no antibiotics were found at D12 in Danzhou. In these regions, source analysis identified aquaculture and domestic sewage as the primary contributors to antibiotic pollution in these regions. Correlation analysis with environmental factors revealed significant influences of factors such as SAL, kPa, TN, SPC, and pH on sulfonamide and chloramphenicol antibiotics. Health risk assessment indicated moderate to high risks to aquatic organisms from antibiotics like NOR, CIP, ENR, OFL, TMP, and SMX in the study areas, underscoring the need for preventive measures, stricter regulation of antibiotic use, and enhanced ecological risk monitoring in aquaculture regions. This study provides critical insights into antibiotic contamination in Hainan's coastal aquaculture areas, highlighting the urgent need for further research into the occurrence and ecological impacts of these emerging pollutants in marine environments.

Fast and Simple Extraction for LCMSMS Analysis of Oxytetracycline Residue in Pork

Pork is very popular as an animal-base protein source of peoples in the Lao PDR. The pig growth promotion, treatment and prevention of diseases frequently relies on the use of antibiotics. In terms of food safety, the analysis of antibiotic residue in pork would be therefore important. Oxytetracycline (OTC) is one of antibiotics used in the pig husbandry. In this study, a fast and simple extraction and analysis method for determining OTC residue in pork was developed. Briefly, 1.0 g of homogenized pork sample in a 50mL-centrifµge tube was extracted with 10 mL of CH3OH: H2O mixture (9:1 ratio) assisted with vortex for 10 min, treated with QuEChERS salt and subjected to centrifugation at 5000 rpm. The methanolic extract (1.5 mL) was then cleaned up with 2mL-dSPE tube (containing MgSO4, PSA, and C18), filtered through syringe filter 0.45 micron and analyzed with ESI-LCMS/MS optimized and operated in MRM positive mode. Calibration was prepared with OTC standard solutions (5-100 ng/g). The analytical method was validated with triplicated recovery tests at a spiked level of 50 ng/g. The results unveiled that the method gave very good recovery of 88.7±3.24%. The limits of detection (LOD) and quantification (LOQ) were achieved with 0.36 ± 0.02 and 1.19 ±0.04 ng/g. In consequence, the developed method would be suitable for OTC determination in pork samples.

Development of improved technologies for protecting fish from infections in aquaculture

The current intensification of marine aquaculture is inevitably associated with such environmental issues as growing infections and the need to apply antibiotic and other antimicrobial preparations. This leads to antibiotic pollution in the environment. Latest technologies aimed at preventing fish infections in aquaculture are based on the vaccination of the objects under cultivation. These technologies allow the use of antibiotics to be reduced and the balance of the microbial environment in aquaculture to be restored, eventually minimizing the negative effects of antibiotic residues on the human health. In this work, we set out to study molecular mechanisms underlying the immune response of fish to viral infections. Data on the expression of some genes of the most important aquaculture objects in Russia and China in response to infection and during its progression was obtained. The research results can be used when developing vaccines against vibriosis with the purpose of minimizing the application of medical preparations, such as antibiotics. These measures are important for maintaining healthy fish habitats and, as a consequence, the human health.

Wood- and Manure-Derived Biochars Reduce Antibiotic Residues and Shift Antibiotic Resistance Genes and Microbial Communities in Manure Applied Forage–Soil Systems

The increasing use of antibiotics in livestock poses environmental risks, leading to contamination of agricultural soils and propagation of microbial antibiotic-resistant genes (ARGs). This study examined the impacts of wood- and manure-derived biochar (BC) on antibiotic residues, ARGs, and microbial communities in sandy loam and clay loam soils amended with manure in Cynodon dactylon pastures. We hypothesized that BC amendments would influence the degradation of antibiotics and the structure of microbial communities based on their physicochemical properties and soil types. Our results demonstrated that wood BC reduced the concentrations of tetracycline and sulfonamides, particularly in sandy loam soil, due to its larger surface area and hydrophobic properties. In contrast, manure BC provided additional nutrients and supported atmospheric nitrogen-fixing microbial groups, especially in clay loam soil, while exhibiting variable efficiency in reducing antibiotic residues due to its lower surface area and higher ash content. These findings underscore the differential impacts of each BC type, emphasizing the need for tailored BC applications based on soil type to effectively mitigate antibiotic contamination and promote sustainable agricultural practices. In conclusion, wood BC was more effective in enhancing soil health by reducing antibiotic residues and improving microbial diversity, particularly in sandy loam soils, while manure BC was beneficial for nutrient cycling in clay loam soils.

Food Additives Derived from Fruits and Vegetables for Sustainable Animal Production and Their Impact in Latin America: An Alternative to the Use of Antibiotics.

The production of healthy animal-derived food entails the effective control of foodborne pathogens and strategies to mitigate microbial threats during rearing. Antibiotics have been traditionally employed in animal farming to manage bacterial infections. However, the prohibition of antibiotic growth promoters in livestock farming has brought significant changes in animal production practices. Although antibiotics are now restricted to treating and preventing bacterial infections, their overuse has caused serious public health issues, including antibiotic resistance and the presence of antibiotic residues in food and wastewater. Therefore, sustainable animal production is crucial in reducing the spread of antibiotic-resistant bacteria. Annually, 40-50% of fruit and vegetable production is discarded worldwide. These discards present significant potential for extracting value-added ingredients, which can reduce costs, decrease waste, and enhance the food economy. This review highlights the negative impacts of antibiotic use in livestock farming and stresses the importance of analyzing the challenges and safety concerns of extracting value-added ingredients from fruit and vegetable co-products at an industrial scale. It also explores the current trends in reducing antibiotic use in livestock, with a focus on Latin American contexts. Finally, the suitability of using value-added ingredients derived from fruit and vegetable co-products for animal feeds is also discussed.

Selective Interaction of Chiral Carbon Dots with Nucleic Acids: A Promising Nanosensing Platform.

Carbon dots (CDs) represent an emerging class of nanomaterials that combine outstanding photoluminescent properties with low toxicity and excellent biocompatibility. These unique features have garnered significant interest for potential applications in sensing as well as nanovectors for bioactive compounds. Within this context, the possibility of synthesizing chiral carbon dots (CCDs) has paved the way for a plethora of bioapplications in their interaction with chiral biomolecules. In this study we report the synthesis and characterization of CCDs with opposite chiralities and their selective interaction with nucleic acids. A systematic study on their interaction with different oligonucleotides (ODNs) using UV-vis, photoluminescence, and circular dichroism analyses highlighted how the chiral surface of the CCDs induces distinct spectroscopic responses in CCDs-ODN conjugates. These findings establish the foundation for innovative applications of CCDs as nanosensors and nanocarriers for nucleic acids. Additionally, the antioxidant properties of CCDs were investigated, highlighting their dual potential as both sensing and preservative nanomaterials for genetic material. Our results suggest significant implications for the development of chiral-specific diagnostic tools, drug delivery systems, and therapeutic agents. Furthermore, these properties open new avenues for the use of CCDs in antibiotic residue detection, fluorescence imaging, and photodynamic therapy.

Antibiotic residues in the cirata reservoir, Indonesia and their effect on ecology and the selection for antibiotic-resistant bacteria

Antibiotic residues, their mixture toxicity, and the potential selection for antibiotic-resistant bacteria could pose a problem for water use and the ecosystem of reservoirs. This study aims to provide a comprehensive understanding of the occurrence, concentration, distribution, and ecological risks associated with various antibiotics in the Cirata reservoir, Indonesia. In our water and sediment samples, we detected 24 out of the 65 antibiotic residues analyzed, revealing a diverse range of antibiotic classes present. Notably, sulphonamides, diaminopyrimidine, and lincosamides were frequently found in the water, while the sediment predominantly contained tetracyclines and fluoroquinolones. Most antibiotic classes reached their highest concentrations in the water during the dry season. However, fluoroquinolones and tetracyclines showed their highest concentrations in the water during the wet season. Ecotoxicological risk assessments indicated that the impact of most antibiotic residues on aquatic organisms was negligible, except for fluoroquinolones. Looking at the impact on cyanobacteria, however, varying risks were indicated, ranging from medium to critical, with antibiotics like sulfamethoxazole, ciprofloxacin, norfloxacin, and lincomycin posing substantial threats. Among these, ciprofloxacin emerged as the antibiotic with the strongest risk. Furthermore, fluoroquinolones may have the potential to contribute to the selection of antibiotic-resistant bacteria. The presence of mixtures of antibiotic residues during the wet season significantly impacted species loss, with Potentially Affected Fraction of Species (msPAF) values exceeding 0.75 in almost 90% of locations. However, the impact of mixtures of antibiotic residues in sediment remained consistently low across all locations and seasons. Based on their occurrences and associated risks, 12 priority antibiotic residues were identified for monitoring in the reservoir and its tributaries. Moreover, the study suggests that river inflow serves as the most significant source of antibiotic residues in the reservoir. Further investigations into the relative share attribution of antibiotic sources in the reservoir is recommended to help identify effective interventions.

Screening of oxytetracycline-degrading strains in the intestine of the black soldier fly larvae and their degradation characteristics

The presence of excessive antibiotic residues poses a significant threat to human health and the environment. This study was designed to identify an effective oxytetracycline (OTC)-degrading strain through the screening of the intestine of black soldier fly larvae (BSFL). A strain designated “B2” was selected using a series of traditional microbial screening methods. It could be identified as Enterococcus faecalis by Gram staining and 16S rDNA sequencing, with a similarity of 99.93%. Its ability to degrade OTC was then assessed using high-performance liquid chromatography (HPLC). The degradation of the strain was characterized using a one-way test to assess the effects of the substrate concentration, inoculum amount, and initial pH on the degrading bacteria. The results indicate that strain B2 exhibited optimal OTC-degrading performance at a substrate concentration of 50 mg/L, with an inoculum amount of 6% and a pH value of 5.0. Specifically, strain B2 achieved degradation rates of 71.11%, 56.14%, and 45.03%. These findings demonstrate the effectiveness of strain B2 in degrading OTC, indicating its potential for use in environmental remediation efforts.

Challenges and effective tracking down strategies of antibiotic contamination in aquatic ecosystem.

A growing environmental concern revolves around the widespread use of medicines, particularly antibiotics, which adversely impact water quality and various life forms. The unregulated production and utilization of antibiotics not only affect non-targeted organisms but also exert significant evolutionary pressures, leading to the rapid development of antimicrobial resistance (AMR) in bacterial communities. To address this issue, global studies have been conducted to assess the prevalence and quantities of antibiotics in various environmental components including freshwater, ocean, local sewage, and fish. These studies aim to establish effective analytical methods for identifying and measuring antibiotic residues in environmental matrices that might enable authorities to establish norms for the containment and disposal of antibiotics. This article offers a comprehensive overview of methods used to extract antibiotics from environmental matrices exploring purification techniques such as liquid-liquid extraction, solid-phase extraction, green extraction techniques, and concentration methods like lyophilization and rotary evaporation. It further highlights qualitative and quantitative analysis methods, high-performance liquid chromatography, ultra-high-performance liquid chromatography, and liquid chromatography-tandem along with analytical methods such as UV-Vis and tandem mass spectrometry for detecting and measuring antibiotics. Urgency is underscored for proactive strategies to curb antibiotic contamination, safeguarding the integrity of aquatic ecosystems and public health on a global scale.

Low-cost biosecurity measures are associated with reduced detection of non-Typhoidal Salmonella in Nigerian poultry while inappropriate antibiotic use is widespread

Large-scale poultry production in low- and middle-income countries may be a source of adulterated products (e.g., Salmonella contamination, antibiotic residues) that can be disseminated over wide areas. We employed a cross-sectional survey of 199 randomly selected poultry farms in Lagos State, Nigeria, to estimate the prevalence of non-typhoidal Salmonella (NTS), and biosecurity and antibiotic use practices. Pooled fecal samples were collected from laying chickens and from poultry handlers. Selective culture, biochemical assays, and PCR (invA) were used to isolate and confirm NTS isolates. NTS was detected at 14% of farms (28/199) and from 10% of farm workers (6/60). Multivariate logistic regression analysis indicated that antiseptic foot dips reduced the odds ratio (OR) for detecting NTS in chicken feces [OR: 0.55; 95% confidence interval (CI) 0.07–0.58]. Most farms (94.5%, 188/199) used antibiotics for treatment and prophylaxis, but no farms (0/199) exercised withdrawal before sale of products. Most farms (86.4%, 172/199) reported using antibiotic cocktails that included medically important colistin, ciprofloxacin, chloramphenicol, and gentamicin. Egg production in Lagos State relies heavily on antibiotics and antibiotic residues are likely passed to consumers through poultry products, but there is evidence that low-cost biosecurity controls are effective for limiting the presence of NTS on farms.

Simultaneous detection of enrofloxacin and chloramphenicol antibiotics using surface-enhanced Raman spectroscopy combined with triangular silver nanoplates

The emergence of antibiotic residues in the environment and food requires the development of sensitive and selective detection methods for monitoring these contaminants. In fact, many different types of antibiotics will be used simultaneously to prevent diseases in livestock and aquatic animals, causing antibiotic residues in food and the environment. Rapid and accurate simultaneous analysis of multiple antibiotics at low concentrations remains a major challenge in in the field of rapid detection. This study presents a sensitive and selective method for the simultaneous detection of two widely used antibiotics, enrofloxacin and chloramphenicol, by combining surface-enhanced Raman spectroscopy (SERS) with triangular silver nanoplates. Triangular silver nanoplates (TAgNPls) in the form of colloid were simply synthesized by chemical reduction method and then used as an effective SERS substrate, enhancing the Raman signals of the target antibiotics and enabling the detection of these antibiotics at trace levels. It was found that with a SERS substrate assembled from the above TAgNPls, the antibiotics enrofloxacin and chloramphenicol could be detected with detection limits of 2.6 µg/L and 4.3 µg/L, respectively. In addition, this SERS substrate also allows simultaneous detection of the above two antibiotics in one analytical sample with concentrations as low as 10 µg/L for both substances. The proposed method holds promise for addressing concerns related to antibiotic contamination in various environments and food sources, contributing to the advancement of analytical techniques for the trace detection of pharmaceutical residues.

The effect of combinations of a glyphosate-based herbicide with various clinically used antibiotics on phenotypic traits of Gram-negative species from the ESKAPEE group

The emission of glyphosate and antibiotic residues from human activities threatens the diversity and functioning of the microbial community. This study examines the impact of a glyphosate-based herbicide (GBH) and common antibiotics on Gram-negative bacteria within the ESKAPEE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli). Ten strains, including type and multidrug-resistant strains for each species were analysed and eight antibiotics (cefotaxime, meropenem, aztreonam, ciprofloxacin, gentamicin, tigecycline, sulfamethoxazole-trimethoprim, and colistin) were combined with the GBH. While most combinations yielded additive or indifferent effects in 70 associations, antagonistic effects were observed with ciprofloxacin and gentamicin in five strains. GBH notably decreased the minimum inhibitory concentration of colistin in eight strains and displayed synergistic activity with meropenem against metallo-β-lactamase (MBL)-producing strains. Investigation into the effect of GBH properties on outer membrane permeability involved exposing strains to a combination of this GBH and vancomycin. Results indicated that GBH rendered strains sensitive to vancomycin, which is typically ineffective against Gram-negative bacteria. Furthermore, we examined the impact of GBH in combination with three carbapenem agents on 14 strains exhibiting varying carbapenem-resistance mechanisms to assess its effect on carbapenemase activity. The GBH efficiently inhibited MBL activity, demonstrating similar effects to EDTA (ethylenediaminetetraacetic acid). Chelating effect of GBH may have multifaceted impacts on bacterial cells, potentially by increasing outer membrane permeability and inactivating metalloenzyme activity.

Key role of NH4+-N in the removal of oxacillin during managed aquifer recharge: Reconsidering the recharge limitation

Frequent occurrence of trace antibiotics in reclaimed water is concerning, which inevitably causes aquifer contamination in the case of managed aquifer recharge (MAR). Global governments have formulated strict reclaimed water standards to ensure the safety of water reuse. Recent studies have found that improved antibiotics removal is intimately associated with high ammonia-oxidizing activity. However, the role of NH4+-N in the removal of residual antibiotics of reclaimed water during MAR remains unknown. NH4+-N removal and the effects of ammonia oxidation on antibiotics biodegradation in the aquifer are the most significant facts for solving the above collision. In this work, the effects of NH4+-N (0, 1 and 5 mg/L) in a model refractory antibiotic (oxacillin (OXA), 100 μg/L) attenuation were deciphered by employing three individual simulated MAR columns, which so called N0, N1 and N5. The results showed that 5 mg/L NH4+-N in influent upregulated the abundance of amo genes by 28.9 %-68.0 % in N5. And the enriched functional genes encoding key degradation enzymes enhanced the OXA removal by 18.7 % and alleviated the oxidative stress caused by antibiotics. Subsequently, antibiotic resistance genes (ARGs), mobile gene elements (MGEs) and human bacterial pathogens (HBPs) abundance were all significantly decreased. Moreover, the intimate association between ammonia-oxidizing microorganisms (AOM) and candidate OXA degraders based on microbial network analysis further supported the significance of AOM on OXA biodegradation. This study provides comprehensive evidence that appropriate amounts of NH4+-N are beneficial in antibiotics and antibiotic resistance risk reduction, providing compelling insights for refine NH4+-N recharge limitation.