Inactivation Of Antibiotic Resistant Bacteria Research Articles

Removal of antibiotic resistant bacteria and plasmid-encoded antibiotic resistance genes in water by ozonation and electro-peroxone process

The electro-peroxone (EP) process is an electricity-based oxidation process enabled by electrochemically generating hydrogen peroxide (H2O2) from cathodic oxygen (O2) reduction during ozonation. In this study, the removal of antibiotic resistant bacteria (ARB) and plasmid-encoded antibiotic resistance genes (ARGs) during groundwater treatment by ozonation alone and the EP process was compared. Owing to the H2O2-promoted ozone (O3) conversion to hydroxyl radicals (•OH), higher •OH exposures, but lower O3 exposures were obtained during the EP process than ozonation alone. This opposite change of O3 and •OH exposures decreases the efficiency of ARB inactivation and ARG degradation moderately during the EP process compared with ozonation alone. These results suggest that regarding ARB inactivation and ARG degradation, the reduction of O3 exposures may not be fully counterbalanced by the rise of •OH exposures when changing ozonation to the EP process. However, due to the rise of •OH exposure, plasmid DNA was more effectively cleaved to shorter fragments during the EP process than ozonation alone, which may decrease the risks of natural transformation of ARGs. These findings highlight that the influence of the EP process on ARB and ARG inactivation needs to be considered when implementing this process in water treatment.

Inactivation of antibiotic-resistant bacteria and antibiotic-resistance genes in wastewater streams: Current challenges and future perspectives.

The discovery of antibiotics, which was once regarded as a timely medical intervention now leaves a bitter aftertaste: antimicrobial resistance (AMR), due to the unregulated use of these compounds and the poor management receiving wastewaters before discharge into pristine environments or the recycling of such treated waters. Wastewater treatment plants (WWTPs) have been regarded a central sink for the mostly unmetabolized or partially metabolised antibiotics and is also pivotal to the incidence of antibiotic resistance bacteria (ARBs) and their resistance genes (ARGs), which consistently contribute to the global disease burden and deteriorating prophylaxis. In this regard, we highlighted WWTP-antibiotics consumption-ARBs-ARGs nexus, which might be critical to understanding the epidemiology of AMR and also guide the precise prevention and remediation of such occurrences. We also discovered the unsophistication of conventional WWTPs and treatment techniques for adequate treatment of antibiotics, ARBs and ARGs, due to their lack of compliance with environmental sustainability, then ultimately assessed the prospects of cold atmospheric plasma (CAP). Herein, we observed that CAP technologies not only has the capability to disinfect wastewater polluted with copious amounts of chemicals and biologicals, but also have a potential to augment bioelectricity generation, when integrated into bio electrochemical modules, which future WWTPs should be retrofitted to accommodate. Therefore, further research should be conducted to unveil more of the unknowns, which only a snippet has been highlighted in this study.

Periodate activation by pyrite for the disinfection of antibiotic-resistant bacteria: Performance and mechanisms

The propagation of antibiotic-resistant bacteria (ARB) greatly endangers the ecological safety and human health. This study employed pyrite (FeS2, naturally abundant mineral) for periodate (PI) activation to disinfect ARB. FeS2/PI system could disinfect 1 × 107 CFU mL−1 of kanamycin-resistant E.coli below the limit of detection in 20 min. Efficient ARB inactivation performance was achieved in pH from 3 to 9, ionic strength from 0 to 300 mM, with HA (0.1–10 mg L−1) in suspension, and in real water samples including tap water, river water and sewage. FeS2/PI system could also efficiently disinfect gentamycin-resistant E.coli and Gram-positive B. subtilis. The generated reactive species including Fe(IV), ·O2– and ·OH would attack cell membrane and overwhelmed intracellular defense system. The intracellular kanamycin resistance genes in cells would be released and then degraded in FeS2/PI system. PI preferred to be adsorbed on Fe site of FeS2 (with lower adsorption energy, more occupancy of bonding state and stronger bonding strength). The subsequent transfer of electron cloud from Fe site to PI would cleave IO bond to generate reactive species. Moreover, FeS2/PI system could also combine with sand filtration system to efficiently capture and disinfect ARB. Therefore, FeS2/PI system is a promising approach to inactivate ARB in different scenarios.

Inactivation of antibiotic resistant bacteria from stormwater runoff using UVA/LED and its potential risks.

Recently, increasing attention has been paid to antibiotic resistance in stormwater runoff. However, there is no available literature about the control of antibiotic resistant bacteria (ARB) through 365 nm ultraviolet light-emitting diode (UVA/LED). In this study, batch experiments were conducted to investigate ARB inactivation kinetics, effects of light intensity and water matrix (including suspended solid (SS) concentration, initial pH and bacteria concentration), and potential transmission risks after UVA/LED irradiation. Results showed that ARB inactivation efficiencies reached 6.31 log reduction at 8 mW/cm2 (86 J/cm2) of UVA/LED for 180 min. ARB inactivation efficiencies increased with the increase of light intensity, and showed a linear relationship. ARB inactivation decreased with increasing SS levels, and the largest inactivation efficiencies was 3.56 log reduction at 50 mg/L of SS. Initial pH had slight effect on ARB inactivation through UVA/LED irradiation. A low initial bacteria concentration (105 CFU/mL) was not necessarily associated with good ARB inactivation (3.59 log reduction). After UVA/LED irradiation, ARB was hardly detected during 12 hr of dark repair, and the transfer frequency of kanamycin resistance gene was increased to 5.43 × 10-4. These suggested that the application of UVA/LED to inactivate ARB in stormwater runoff was feasible and desirable in this study.

The inactivation of antibiotic-resistant bacteria and the damage of antibiotic-resistant genes using an electrified carbon nanotube membrane-NaClO system

The inactivation of antibiotic-resistant bacteria (ARB) and damage of antibiotic resistance genes (ARGs) in aquatic environments have become major concerns worldwide in controlling the rapid spread of antibiotic resistance. In this study, an electrified carbon nanotube membrane (ECM) was combined with chlorine disinfection (denoted as ECM-NaClO system) to treat the sulphonamide resistance bacteria (HLS-6) and tetracycline resistance bacteria (TOP-10F) in water samples. The ECM-NaClO system effectively inactivated the HLS-6 and TOP-10F by damaging the cell membrane and increasing amounts of intracellular reactive oxygen species (ROS). In addition, the absolute abundances of the sulphonamide resistance gene (sul1) and tetracycline resistance gene (tetA) in the effluent decreased by 3.5 and 1.7 logs, respectively. Furthermore, the absolute abundance of mobile genetic elements (intI1) decreased by 4.1–4.7 logs. The ROS probe compound degradation and quenching experiments revealed that the •OH generated via the 2-electron oxygen reduction reaction played a dominant role in the damage of sul1 gene, while •O2– generated through the activation of NaClO was a key contributor to the damage of tetA gene. Hence, the ECM-NaClO system is a potential method to inactivate ARB and damage ARGs in water and sewage treatment plants.

Removal of antibiotic resistant bacteria, genes and inhibition of plasmid-mediated horizontal transfer by peroxymonosulfate: Efficiency and mechanisms

As the emerging contaminants, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have caught considerable research attention, horizontal gene transfer is one of the most primary contributors to antibiotic resistance dissemination. The application of the oxidant peroxymonosulfate (PMS) as a disinfection alternative has been systemically explored. Also, the effects of various process parameters on ARB inactivation and plasmid-mediated horizontal transfer inhibition, initial bacterial concentration, pH value and temperature, were systemically investigated. The changes in cell substances (cell membrane integrity and intracellular reactive oxygen species) were determined by flow cytometry. The results suggested that the inactivation efficiency of Escherichia coli DH5α (donor) and Pseudomonas sp. HLS-6 (recipient) by 0.8 mM PMS treatment reached 4.45 log and 4.15 log in 30 min, respectively. The conjugative transfer didn’t arise after treatment for only 1 min when the dosage of PMS exceeded 0.4 mM. PMS could work in a wide pH and ambient temperature range. It also showed significant removal efficiency on intracellular ARGs and extracellular ARGs. To identify the underlying mechanisms of restraining conjugative transfer, the mRNA expression of conjugative genes, oxidative stress genes, save our souls (SOS) response-related gene, cell outer membrane proteins genes and global regulatory genes were evaluated. The results demonstrated that the expressions of these genes were altered by 0.8 mM PMS treatment. PMS has the advantages of low cost, easy operation and technical applicability. This study illustrated that PMS treatment showed great potential for controlling the antibiotic resistance for wastewater treatment.

Application of Nucleotide-Based Kinetic Modeling Approaches to Predict Antibiotic Resistance Gene Degradation during UV- and Chlorine-Based Wastewater Disinfection Processes: From Bench- to Full-Scale.

This study investigated antibiotic resistance gene (ARG) degradation kinetics in wastewaters during bench- and full-scale treatment with UV light and chlorine─with the latter maintained as free available chlorine (FAC) in low-ammonia wastewater and converted into monochloramine (NH2Cl) in high-ammonia wastewater. Twenty-three 142-1509 bp segments (i.e., amplicons) of seven ARGs (blt, mecA, vanA, tet(A), ampC, blaNDM, blaKPC) and the 16S rRNA gene from antibiotic resistant bacteria (ARB) strains Bacillus subtilis, Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae were monitored as disinfection targets by qPCR. Rate constants for ARG and 16S rRNA gene amplicon degradation by UV, FAC, and NH2Cl were measured in phosphate buffer and used to expand and validate several recently developed approaches to predict DNA segment degradation rate constants based solely on their nucleotide contents, which were then applied to model ARG degradation during bench-scale treatment in buffer and wastewater matrixes. Kinetics of extracellular and intracellular ARG degradation by UV and FAC were well predicted up to ∼1-2-log10 elimination, although with decreasing accuracy at higher levels for intracellular genes, while NH2Cl yielded minimal degradation under all conditions (agreeing with predictions). ARB inactivation kinetics varied substantially across strains, with intracellular gene degradation lagging cell inactivation in each case. ARG degradation levels observed during full-scale disinfection at two wastewater treatment facilities were consistent with bench-scale measurements and predictions, where UV provided ∼1-log10 ARG degradation, and chlorination of high-ammonia wastewater (dominated by NH2Cl) yielded minimal ARG degradation.

Inactivation of vancomycin-resistant Enterococcus faecalis and degradation of intracellular vanB gene under exposure to UV and UV/H2O2

The proliferation of antibiotic resistance in water environment which may cause antibiotic therapy failure has attracted worldwide attention. However, the effects of UV-based advanced oxidation processes on inactivation of antibiotic resistant bacteria (ARB) and degradation of antibiotic resistance genes (ARGs) have not been well studied. This study aimed to comparatively investigate the removal efficacy in inactivating the vancomycin-resistant Enterococcus faecalis (VRE) and degrading its containing vanB gene under exposure to UV and UV/H2O2. The results showed that VRE was readily inactivated in both UV and UV/H2O2 processes. Although UV/H2O2 was only slightly superior to UV alone in VRE inactivation, it significantly inhibited the bacterial photoactivation and regrowth. UV/H2O2 indeed achieved synergistic degradation of intracellular vanB (0.1–0.8 log), which could be further enhanced by increasing the UV intensity, lowering pH and adding H2O2 in batches. The enhanced induction of OH resulted in the cell membrane damage, facilitating the entrance of excess OH and more efficiently oxidizing the released intracellular ARGs. Overall, the presence of humic acid inhibited the inactivation of VRE and degradation of vanB, while lower concentrations of humic acid (2.5–5 mg/L) could act as free radical initiator and slightly promoted vanB degradation in UV/H2O2 process. Our findings suggested that UV/H2O2 has more advantages on the control of ARB and intracellular ARGs compared to UV alone.

Antibiotic resistant bacteria inactivation through metal-free electrochemical disinfection with carbon catalysts and its potential risks

Recently, increasing attention has been paid to the inactivation of antibiotic resistant bacteria (ARB) during the electrochemical disinfection. However, no available information could be found on ARB inactivation in water during metal-free electrochemical disinfection. In this study, polyvinylidene fluoride (PVDF)-based carbon catalyst (PPC) was chosen as working electrode. Batch experiments were conducted to investigate key design for ARB inactivation, effects of water matrix and potential risks after the disinfection under the pre-determined conditions. The disinfection with current density at 2.25 mA/cm2 and Air/Water ratio of 10:1 was optimal with the largest ARB inactivation (5.0 log reduction for 40 min), which was in line with the profile and yield of hydrogen peroxide (H2O2) during the disinfection. Effects of water matrix analysis implied that ARB inactivation efficiencies during the disinfection in acidic solutions were better than the one in alkaline solutions, which could be due to rich CC levels on surface of PPC cathode. After the optimal disinfection, ARB counts increased slightly at the first 2 h and then tended to disappear, and there were no conjugation transfer and little transformation for target antibiotic resistance genes, indicating that potential risks could be blocked after the disinfection for 40 min. Furthermore, intermittent flow was more effective in inactivating ARB compared with continuous flow. These suggested that the application of metal-free electrochemical disinfection with PPC to inactivate ARB in water was feasible and desirable in this study.

Advanced wastewater treatment with ozonation and granular activated carbon filtration: Inactivation of antibiotic resistance targets in a long-term pilot study

The inactivation of antibiotic resistant bacteria (ARB) and genes (ARGs) in an advanced plant combining ozonation and granular activated carbon (GAC) filtration applied for effluent after conventional activated sludge treatment at a full-scale urban wastewater treatment plant was investigated for over 13 consecutive months. The nitrite compensated specific ozone dose ranged between 0.4 and 0.7 g O3/g DOC with short-time sampling campaigns (0.2–0.9 g O3/g DOC). Samples were analysed with culture-dependent methods for bacterial targets and with qPCR for genes. The log removal values were correlated with a decrease of the matrix UV absorption at 254 nm (ΔUV254) and indicated a range of ΔUV254 that corresponds to a sufficient membrane damage to affect DNA. For trimethoprim/sulfamethoxazole resistant E. coli, sul1, ermB and tetW, this phase was observed at ΔUV254 of ~30 % (~0.5 g O3/g DOC). For ampicillin resistant E. coli and blaTEM-1, it was observed around 35–40 % (~0.7 g O3/g DOC), which can be linked to mechanisms related to oxidative damages in bacteria resistant to bactericidal antibiotics. GAC treatment resulted in a further abatement for trimethoprim/sulfamethoxazole E. coli, sul1 and tetW, and in increase in absolute and relative abundance of ermB and blaTEM-1.

Electroactive Ultrafiltration Membrane for Simultaneous Removal of Antibiotic, Antibiotic Resistant Bacteria, and Antibiotic Resistance Genes from Wastewater Effluent.

To combat the spread of antibiotic resistance into the environment, we should adequately manage wastewater effluent treatment to achieve simultaneous removal of antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistance genes (ARGs). Herein, we fabricate a multifunctional electroactive poly(vinylidene fluoride) ultrafiltration membrane (C/PVDF) by phase inversion on conductive carbon cloth. The membrane possesses not only excellent retention toward ARB and ARGs but also exhibits high oxidation capacity as an electrode. Notably, sulfamethoxazole degradation involving hydroxylation and hydrolysis by the anode membrane is predominant, and the degradation efficiency is up to 81.5% at +4 V. Both electro-filtration processes exhibit significant ARB inactivation, anode filtration is superior to cathode filtration. Moreover, the degradation of intracellular ARGs (iARGs) located in the genome is more efficient than those located in the plasmid, and these degradation efficiencies at -2 V are higher than +2 V. The degradation efficiencies of extracellular ARGs (eARGs) are opposite and are lower than iARGs. Compared with regular filtration, the normalized flux of electroactive ultrafiltration membrane is improved by 18.0% at -2 V, 15.9% at +2 V, and 30.4% at +4 V during treating wastewater effluent, confirming its antifouling properties and feasibility for practical application.

The enhanced catalytic degradation of sulfamethoxazole over Fe@nitrogen-doped carbon-supported nanocomposite: Insight into the mechanism

An environmentally friendly Fe@nitrogen-doped carbon nanocomposite catalyst (Fe@N-CNs) was prepared via a facile and economical process using carboxymethyl chitosan (CMCs) hydrogel as a template to achieve Fe-anchoring and N-doping simultaneously for peroxymonosulfate (PMS) activation to efficiently degrade sulfamethoxazole (SMX). The “core–shell” structure of Fe@N-CNs displayed that Fe nanoparticles identified as Fe3C and Fe3N were encapsulated in nitrogen-doped carbon nanosheets. The formation of FexNy sites and the high content of graphitic N obtained from CMCs facilitated the catalytic reaction. With excellent catalytic activity to achieve complete degradation of SMX in less than 10 min, Fe@N-CNs/PMS system also exhibited stable catalytic degradation efficiency over a wide pH range (3.0–9.0) and under high-salinity conditions. Singlet oxygen was identified as the dominant reactive species in catalytic oxidation and played a vital role in the non-radical pathway. The potential SMX degradation pathway and mechanism in the Fe@N-CNs/PMS reaction system were proposed according to DFT calculations and product detection results. Quantitative structure–activity relationship (QSAR) prediction verified the efficient elimination of SMX degradation products toxicity. Moreover, the Fe@N-CNs/PMS system was also confirmed to be effective towards the inactivation of antibiotic-resistant bacteria (ARB) and antibiotics resistance genes (ARGs).

Photoelectrocatalytic inactivation mechanism of E. coli DH5α (TET) and synergistic degradation of corresponding antibiotics in water

The occurrence and proliferation of antibiotic-resistance genes (ARGs) / antibiotic-resistant bacteria (ARB) have been currently aggravating due to the increase of antibiotic residues in the aquatic environment. The interaction of ARB/ARGs with antibiotics inevitably occurred during water purification, yet their synergistic purification mechanism remains unclear. Herein, a systematic approach was developed to understand, in-depth, the synergistic mechanism in the coexisted E. coli DH5α (TET) inactivation and tetracycline hydrochloride (TET) degradation using photoelectrocatalysis (PEC) as a model technology. Results showed that low dosage (0 – 40 ppm) of TET exerted a negative influence on ARB inactivation with prolonged bactericidal time from 60 to 160 min. Addition of TET in environmental concentration (5 – 60 ppm) resulted in sub-lethal damage and prolonged PEC treatment time (100 – 160 min), accounting for inhibition effects on ARB inactivation. The major reactive species (RSs) involved in ARB inactivation and TET degradation were evidenced as photogenerated hole, •OH and O2•−, whereas hole and O2•− were demonstrated to be the major disinfectants for ARB/ARG inactivation. The bacterial defense system displayed increased antioxidative activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) to protect ARB cells against oxidative stress. Exposure to 60 ppm TET was a threshold where certain ARB cells were induced into viable but nonculturable bacterial cell (VBNC) state, as evidenced by plate counting and ATP activity analysis, together with the integral cell membranes observed by flow cytometry (FCM) and scanning electron microscope (SEM). These findings appeal for appropriate technical adjustments for water and wastewater treatment to ensure safety of water.

Inactivation of Antibiotic-Resistant Bacteria in Wastewater by Ozone-Based Advanced Water Treatment Processes.

The inactivating effect of ozone (O3)-based advanced oxidation processes (AOPs) (O3/H2O2, O3/UV, and O3/UV/H2O2 systems) on antimicrobial-resistant bacteria (AMRB) and antimicrobial-susceptible bacteria (AMSB) in sewage treatment plant (STP) wastewater was investigated. The AMRB were grouped into six classes: carbapenem-resistant Enterobacteriaceae (CRE), extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E), multidrug-resistant Acinetobacter (MDRA), multidrug-resistant Pseudomonas aeruginosa (MDRP), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE); these classes constituted the World Health Organization (WHO) global priority list of AMRB. The results indicate that O3-based advanced wastewater treatment inactivated all AMRB and AMSB (>99.9%) after 10 min of treatment, and significant differences (p < 0.5) were not observed in the disinfection of AMRB and AMSB by each treatment. Altered taxonomic diversity of micro-organisms based on 16S rRNA gene sequencing via O3/UV and O3/UV/H2O2 treatment showed that advanced wastewater treatments not only inactivated AMRB but also removed antimicrobial resistance genes (AMRGs) in the wastewater. Consequently, this study recommends the use of advanced wastewater treatments for treating the STP effluent, reducing environmental pollution, and alleviating the potential hazard to human health caused by AMRB, AMSB, and infectious diseases. Overall, this study provides a new method for assessing environmental risks associated with the spread of AMRB and AMSB in aquatic environments, while keeping the water environment safe and maintaining human health.

Applicability of bio-synthesized nanoparticles in fungal secondary metabolites products and plant extracts for eliminating antibiotic-resistant bacteria risks in non-clinical environments

The abundance of antibiotic-resistant bacteria in the prawn pond effluents can substantially impact the natural environment. The settlement ponds, which are the most common treatment method for farms wastewater, might effectively reduce the suspended solids and organic matter. However, the method is insufficient for bacterial inactivation. The current paper seeks to highlight the environmental issue associated with the distribution of antibiotic resistant bacteria (ARB) from prawn farm wastewater and their impact on the microbial complex community in the surface water which receiving these wastes. The inactivation of antibiotic-resistant bacteria in prawn wastewater is strongly recommended because the presence of antibiotic-resistant bacteria in the environment causes water pollution and public health issues. The nanoparticles are more efficient for bacterial inactivation. They are widely accepted due to their high chemical and mechanical stability, broad spectrum of radiation absorption, high catalytic activity, and high antimicrobial activity. Many studies have examined the use of fungi or plants extract to synthesis zinc oxide nanoparticles (ZnO NPs). It is evident from recent papers in the literature that green synthesized ZnO NPs from microbes and plant extracts are non-toxic and effective. ZnO NPs inactivate the bacterial cells as a function for releasing reactive oxygen species (ROS) and zinc ions. The inactivation of antibiotic-resistant bacteria tends to be more than 90% which exhibit strong antimicrobial behavior against bacterial species.

Roles of reactive oxygen species in antibiotic resistant bacteria inactivation and micropollutant degradation in Fenton and photo-Fenton processes

Reactive oxygen species play a critical role in degrading chemical or biological contaminants in advanced oxidation processes. However, it is still not clear whether conventional Fenton and photo-Fenton processes generate different reactive oxygen species, respectively. This study revealed the roles of reactive oxygen species (ROS) for simultaneous removal of antibiotic resistant bacteria (ARB) and recalcitrant micropollutant using three processes, i.e., conventional Fenton, photo-Fenton, and ethylenediamine-N, N′-disuccinic acid (EDDS) modified photo-Fenton. Both chemical scavengers and electron paramagnetic resonance spectroscopy confirmed the generation of various ROS and their contribution towards bacterial inactivation and micropollutant degradation. Results showed ARB and carbamazepine (CBZ) elimination efficiency in the order: EDDS modified photo-Fenton process > photo-Fenton process > Fenton process. The ARB detection limit (6-log ARB) was observed within 10 min at lower doses of 0.1 mM Fe3+, 0.2 mM EDDS, and 0.5 mM hydrogen peroxide (H2O2). With the same dose, it took longer (60 min) to remove CBZ, while 2.5 times higher H2O2 dose (1.25 mM) removed around 99% of CBZ within 10 min treatment. The present study highlighted that the hydroxyl radical (HO•) plays a dominant role, while singlet oxygen (1O2) and superoxide radical anion (O2•-) exhibit moderate effects to remove the hazards. Our findings provide mechanistic insights into the role of various reactive oxygen species on degrading micropollutants and inactivating ARB.

Influence of silver ion release on the inactivation of antibiotic resistant bacteria using light-activated silver nanoparticles.

The widespread increase in antibiotic resistance (AR), in an extensive range of microorganisms, demands the development of alternative antimicrobials with novel non-specific low-mutation bacterial targets. Silver nanoparticles (AgNPs) and photosensitizers (PSs) are promising antimicrobial agents with broad-spectrum activity and low tendency for antimicrobial resistance development. Herein, we investigated the light-mediated oxidation of AgNPs for accelerated release of Ag+ in the antibacterial synergy of PS-AgNP conjugates using protoporphyrin IX (PpIX) as a PS. Also, the influence of polyethyleneimine (PEI) coated AgNPs in promoting antibacterial activity was examined. We synthesized, characterized and tested the antimicrobial effect of three nanoparticles: AgNPs, PpIX-AgNPs, and PEI-PpIX-AgNPs against a methicillin-resistant Staphylococcus aureus strain (MRSA) and a wild-type multidrug resistant (MDR) E. coli. PpIX-AgNPs were the most effective material achieving >7 log inactivation of MRSA and MDR E. coli. The order of bacterial log inactivation was PpIX-AgNPs > PEI-PpIX-AgNPs > AgNPs. This order correlates with the trend of Ag+ concentration released by the NPs (PpIX-AgNPs > PEI-PpIX-AgNPs > AgNPs). Our study confirms a synergistic effect between PpIX and AgNPs in the inactivation of AR pathogens with about 10-fold increase in inactivation of ARB relative to AgNPs only. The concentration of Ag+ released from NPs determined the log inactivation of MRSA and MDR E. coli more than either the phototoxic effect or the electrostatic interaction promoted by surface charge of nanoparticles with bacteria cells. All NPs showed negligible cytotoxicity to mammalian cells at the bacterial inhibitory concentration after 24 h exposure. These observations confirm the crucial role of optimized Ag+ release for enhanced performance of AgNP-based antimicrobials against AR pathogens.

Inactivation of Antibiotic Resistant Bacteria and Degradation of Plasmid-Encoded Antibiotic Resistance Genes in Groundwater by Conventional Ozonation and Electro-Peroxone Process

Inactivation of Antibiotic Resistant Bacteria and Degradation of Plasmid-Encoded Antibiotic Resistance Genes in Groundwater by Conventional Ozonation and Electro-Peroxone Process

Antibiotic Resistant Bacteria Inactivation Through Electro-Fenton Disinfection with Carbon Catalysts and its Potential Risks

Antibiotic Resistant Bacteria Inactivation Through Electro-Fenton Disinfection with Carbon Catalysts and its Potential Risks

Simultaneous removal of antibiotic-resistant bacteria and its resistance genes in water by plasma oxidation: Highlights the effects of inorganic ions

Antibiotic-resistant bacteria (ARB) and their resistance genes (ARGs), which are commonly detected in waters, are emerging environmental contaminants with strong pathogenicity. Simultaneous removal of ARB and ARGs in water by mesoporous plasma was explored in this study, focusing on evaluating the impacts of common inorganic ions on ARB inactivation, antibiotic resistance reduction, and change in ARGs profiles. The antibiotic-resistant Escherichia coli (AR E. coli) was selected as the model ARB. The experimental results demonstrated that the presence of NO3−, Cu2+, and Fe2+ all promoted AR E. coli inactivation and ARGs elimination, reduced its antibiotic resistance, and also inhibited horizontal gene transfer of ARGs; whereas CO32− inhibited these processes, and SO42− did not have distinct effect. During the plasma treatment process, Fe2+ significant enhancement on OH formation via reactions with H2O, the highest performance was observed in the presence of Fe2+. The membrane structure, disruption of biological processes, dissolution of intracellular components, and DNA. These finding shed light on the potential effects of inorganic ions on ARB and ARGs elimination induced by the mesoporous plasma.