Concentrations Of Metronidazole Research Articles

2555. Metronidazole Dosing in Patients with and without Obesity Undergoing Colorectal Surgery: Should body size or composition be a factor?

Abstract Background Metronidazole (MET) is administered on a fixed-dose basis irrespective of body size in adults but studies suggest that dose adjustment may be needed (PMID: 33969405). This study evaluated plasma and fat tissue pharmacokinetics (PK) of MET in patients undergoing elective colorectal surgery.Table 1.Patient demographics, body size, morphomic and pharmacokinetic values by obese group. Data reported as median (5th, 95th percentile) valuesFigure 1.Visual predictive check illustrating observed and model predicted metronidazole concentrations in plasma and fat tissue samples stratified by patients with and with out obesity Methods Adult patients (age ≥ 18 years) undergoing elective colorectal procedures with a preoperative CT scan available were prospectively enrolled. MET was administered as standard of care (500 mg) intravenously 15-60 prior to incision with blood sampling performed at the end of infusion, before incision, and at surgical closure. Fat tissue samples were collected at incision and closure. Samples were assayed by an LC-MS/MS method. Population PK analyses were performed by co-modeling plasma and fat MET concentrations and comparing weight, body surface area (BSA), morphomics, and conventional patient demographics as covariates. Morphomics are body dimensions and composition (e.g. muscle and fat areas) parameters generated using CT scan data. Results Data were acquired from 67 patients (n=36 male) with comparisons between groups reported in Table 1. A 1-compartment model adequately characterized plasma MET profiles with a mean (CV) volume of distribution (V) and clearance (CL) of 24.4 (62.5%) L and 4.04 (34.2%) L/h. A two-compartment structure with transfer rate constants, with vertebral height (compared to weight or BSA) as a covariate of V and age as a covariate of CL provided the best co-model fit for plasma and fat tissue (Figure 1). The median [5th, 95th percentile] sampling period was 3.3 [1.6, 6.4] hours with an AUCτ of 44.0 [22.0, 83.4] h*mg/L and 6.79 [3.11, 13.6] h*mg/L in plasma and fat tissue. No significant difference was observed in plasma or fat exposures or their ratio as a surrogate for tissue penetration between obese and non-obese patients. Simulations suggest a lower probability (≤62.6%) of achieving an AUC∞/MIC of 70 in adults under the age of 50 years. Conclusion Plasma and fat tissue exposures of MET are similar in obese and non-obese patients undergoing elective colorectal surgeries. Age may be a more relevant factor than body size or composition for metronidazole dose adjustment. Disclosures Stewart Wang, MD, PhD, Applied Morphomics, Inc.: patent for analytic morphomics|Applied Morphomics, Inc.: Ownership Interest|mBioHealth: Ownership Interest|Surgical Risk Management: Ownership Interest

The Effect of Subinhibitory Concentration of Metronidazole on the Growth and Biofilm Formation on Toxigenic Clostridioides difficile Strains Belonging to Different Ribotypes.

Clostridioides difficile is a predominant nosocomial pathogen within the healthcare setting able to produce biofilms. Sub-minimum inhibitory concentrations (sub-MICs) of antibiotics trigger mechanisms affecting bacterial virulence, including increased adhesion and biofilm formation. The aim of this study was to investigate how sub-MICs of metronidazole affect the biofilm formation of C. difficile strains. We tested 14 reference and clinical C. difficile strains, including hypervirulent strains of RT027. The MICs of metronidazole for the tested strains were determined using the broth microdilution method. Biofilm formation was evaluated using confocal laser scanning microscopy. The C. difficile strains belonging to RT027 produced the highest amounts of biofilm. The results of confocal laser scanning microscopy showed that all the tested C. difficile strains developed larger biofilms with diversified architectures upon exposure to sub-MICs of metronidazole. In our study, we reveal that sub-MIC concentrations of metronidazole affect the biofilm formation of clinical and reference strains of C. difficile. Importantly, metronidazole induces biofilm formation via hypervirulent RT027 strains.

Pleural penetration of amoxicillin and metronidazole during pleural infection: An ambispective cohort study

The pharmacokinetics of antibiotics in pleural fluid during pleural infections has been poorly described. This study aimed to explore amoxicillin and metronidazole diffusion into the pleural space. This was an ambispective, single-centre study that included patients with complicated parapneumonic effusion or pleural empyema managed with repeated therapeutic thoracentesis as first-line treatment between 2014 and 2022. Pleural steady-state or trough concentrations of amoxicillin and metronidazole were measured, with a lower limit of quantification of 5 mg/L. Seventy paired blood and pleural samples were analysed from 40 patients. The median (interquartile range) patient age was 55 years (45-67 years) and 88% were male. The median patient weight was 65.8 kg (57.3-82 kg) and median plasma albumin concentration was 29.7 g/L (23.7-33.9 g/L). Median creatinine clearance was 106 mL/min (95-117 mL/min). Median amoxicillin pleural concentrations in patients treated with oral, bolus and continuous intravenous administrations (6 g/day) were, respectively, 5.2 (<5-6.4), 9.4 (8-13.1) and 10.8 (7.1-13.1) mg/L. Pleural concentrations were <5 mg/L in 5/11 samples (45%) with oral treatment and 6/59 (10%) with intravenous treatment. Median metronidazole pleural concentrations were 18.4 (15.7-22.8) mg/L, with all patients being treated orally (1.5 g/day). Oral metronidazole (1.5 g/day) and intravenous amoxicillin (6 g/day) achieved therapeutic targets in pleural fluid in most cases, but oral amoxicillin did not.

Antimicrobial-resistant Helicobacter pylori in Japan: Report of nationwide surveillance for 2018-2020.

Antimicrobial therapy is necessary to eradicate Helicobacter pylori infection. The emergence of antimicrobial-resistant bacteria poses a threat to continued treatment with antimicrobial agents. For those who prescribe antimicrobial therapy, it is necessary to constantly monitor the emergence of antimicrobial-resistant bacteria. H. pylori clinical isolates were collected in Japan from August 2018 to December 2020 for antimicrobial susceptibility testing. The agar dilution method was used for the determination of the minimum inhibitory concentration (MIC) of clarithromycin (CLR), amoxicillin (AMX), metronidazole (MNZ), and sitafloxacin (STX). MICs for 938 H. pylori isolates were examined. The primary resistance rates of H. pylori clinical isolates for CLR, AMX, MNZ, and STX in Japan were 35.5%, 2.7%, 4.2%, and 27.6%, respectively. The primary resistance rates for CLR, AMX, and MNZ were significantly higher than those of the 2002-2005 isolates. The resistance rate for CLR was significantly higher in females (males: 30.7%, females: 41.5%, p < 0.001) and higher in the ≤29 years age group (54.8%) than in the other age groups, although there were no significant differences (p = 0.104). The MNZ resistance rate was significantly higher in the ≤29 years age group than in the other age groups (p = 0.004). The resistance rate for STX increased with age, but a significant difference was only seen between the 30-49 years age group and the ≥70 years age group (p < 0.001), and the resistance rate was significantly higher in strains isolated in the Kyushu region than in the other regions (p < 0.001). The primary resistance rates for CLR, AMX, and MNZ of H. pylori clinical isolates in Japan were higher than those of the 2002-2005 isolates. Continuous surveillance is needed to monitor the trends in antimicrobial-resistant H. pylori.

A fluorescence-based assay for Trichomonas vaginalis drug screening

BackgroundThe emergence and spread of drug resistance in Trichomonas vaginalis parasites has become an important concern in trichomoniasis treatment. Fast and reliable growth assessment is critical for validating in vitro drug susceptibility and high-throughput screening of newly developed drugs.MethodsModified media without yeast extract were evaluated for their ability to support the growth of T. vaginalis parasites. The potential of the nucleic acid-binding dye SYBR Green I for detecting T. vaginalis drug resistance was characterized, and seeding parasite concentration and incubation time were optimized. The fluorescence assay based on SYBR Green I was further validated in four T. vaginalis isolates with different susceptibilities to the antibiotics metronidazole, tinidazole, ornidazole and secnidazole, and compared with the traditional method that detects minimum lethal concentrations (MLCs).ResultsA modified medium consisting of RPMI 1640 and Tryptone Plus as replacements for yeast extract and tryptone, respectively, in traditional trypticase-yeast extract-maltose (TYM) medium exhibited similar performance as TYM medium in maintaining T. vaginalis growth, while it showed much lower background fluorescent signals. The T. vaginalis SYBR Green I-based fluorescence (TSF) drug assay was found to have to satisfy one of two conditions to demonstrate the 50% inhibitory concentration of metronidazole for the sensitive isolate TV-334: (i) a seeding density of 3 × 104 parasites/ml and an incubation time of 48 h; or (ii) a seeding density of 1 × 104 parasites/ml and an incubation time of 72 h. Subsequent validation experiments revealed that the 48-h incubation/3 × 104 parasites/ml seeding density condition had a greater sensitivity to detect drug resistance than the 72-h condition. The TSF assay also exhibited high efficiency in identifying parasite drug resistance, as evidenced by its strong correlation with the standard MLC assay results (P = 0.003).ConclusionsThis study presents a robust TSF assay that has the potential to facilitate high-throughput, automated in vitro anti-trichomoniasis susceptibility testing for drug resistance monitoring and drug development. In comparison to the standard MLC method, this assay offers the advantages of reduced labor and elimination of subjective examination.Graphical

Catalytic wet peroxide oxidation of metronidazole over Fe and Mn supported UiO-66 catalysts: Kinetic study

The metronidazole (MNZ) antibiotic is widely used to treat infections caused by anaerobic bacteria and it is difficult to biodegrade in the pharmaceutical wastewaters. In this study, Fe-UiO-66, Mn-UiO-66 and Fe/Mn-UiO-66 catalysts were prepared for the kinetic study of catalytic wet peroxide oxidation (CWPO) degradation of metronidazole in pharmaceutical wastewater. The catalysts were characterized by XRD, FT-IR, N2 adsorption-desorption, SEM, and TGA. The effects of Fe and Mn loading rate, catalyst dosage, MNZ concentrations, calcined temperature of Mn-UiO-66 and Fe/Mn ratio on the CWPO of metronidazole wastewater were systematically studied. Fe-UiO-66 catalysts exhibited better catalytic activity for the CWPO degradation of metronidazole wastewater (XMNZ = 93 %, XH2O2 = 78 %) compared to Mn-UiO-66 catalysts (XMNZ = 20 %, XH2O2 = 30 %). The kinetics study indicates that the CWPO process is fitted for the pseudo-first-order reaction with activation energy of 89.37 kJ/mol and 95.08 kJ/mol obtained on the Fe-UiO-66 and 2Fe/Mn-UiO-66 catalysts, respectively. The supported Fe and Mn UiO-66 catalysts showed good catalytic activity for CWPO of metronidazole which exhibited potential application in the wastewater treatment process.

Preparation of a composite sensor based on a fluorescent and magnetic molecular imprint polymer for metronidazole extraction–detection

We developed a metronidazole (MNZ)-selective sensor, combining magnetic and fluorescent molecularly imprinted polymers (MFMIP) with a non-imprinted reference composite (MFNIP). Using isothermal titration calorimetry (ITC), we optimized the MNZ-to-APTES ratio during polymerization, obtaining a specific MNZ-APTES bonded complex (Kb= 2.575 × 103 L/mol, ΔH° = −1.079 kJ mol−1, TΔS° = 18.389 kJ mol−1, and ΔG° = −19.468 kJ mol−1). The MFMIP composite, incorporating Fe3O4@TEOS magnetite nanoparticles and CdTe@TGA quantum dots, exhibited cavity-specific interactions with MNZ, as confirmed by surface plasmon resonance (SPR) studies. Compared to MFNIP, the MFMIP sensor demonstrated superior selectivity in water samples (5–60 μM, with LOD and LOQ values of 1.28 and 5.00 μM), and even in the presence of interferents. In addition, the use of CdTe quantum dots enabled real-time analysis via Stern–Volmer quenching mechanisms without complex sample preparation. In conclusion, our MFMIP sensor offers sensitive and selective MNZ detection. It presents practical advantages, including real-time analysis and ease of handling, making it a promising extraction–determination system for trace concentrations of MNZ.

Selective Cell Ablation Using an Improved Prodrug-Converting Nitroreductase.

Selective cell ablation is an invaluable tool to investigate the function of cell types, the regeneration of cells, and the modeling of diseases associated with cell loss. The nitroreductase (NTR)-mediated cell ablation system is a simple method enabling the elimination of targeted cells through the expression of a nitroreductase enzyme and the application of a prodrug (such as metronidazole). The prodrug is reduced to a cytotoxic product by nitroreductase, thereby leading to DNA damage-induced cell death. In species with elevated regenerative capacity such as zebrafish, removing the prodrug allows endogenous tissue to replace the lost cells. Herein, we describe a method for the use of a markedly improved nitroreductase enzyme for spatially and temporally controlled targeted cell ablation in the zebrafish. Recently, we identified an NTR variant (NTR 2.0) that achieves effective targeted cell ablation at concentrations of metronidazole well below those causing toxic side effects. NTR 2.0 thereby enables the ablation of "resistant" cell types and novel cell ablation paradigms. These advances simplify investigations of cell function, enable interrogations of the effects of chronic inflammation on regenerative processes and facilitate modeling of degenerative diseases associated with chronic cell loss. Techniques for transgenic nitroreductase expression and prodrug application are discussed.

Synthesis of Fluorescent Carbon Quantum Dots based on Boletus speciosus and Analysis of Metronidazole

Background: Metronidazole is widely used due to its clinical excellence in treating systemic or local infections caused by anaerobic bacteria. However, it is easily soluble in water, not easy to biodegrade and adsorb and stays for a long time in environments, causing great harm to human health and food safety. Therefore, it is important to choose highly selective and sensitive methods for metronidazole content determination in environments. In this paper, the edible fungus Boletus speciosus was used as the carbon precursor to successfully prepare carbon dots by one-step hydrothermal method, and were used to analyze metronidazole. Methods: Characterization of the prepared carbon dots from B. speciosus (Bs-CDs) were studied by Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-Ray Diffraction. Results: The linear equation was y=0.06231+0.01099x (R2=0.9970) with a metronidazole concentration of 2.5~50 μM, and the detection limit was 71 nM. The fluorescence quenching mechanism of Bs-CDs detecting metronidazole belonged to the internal filtration effect. Bs-CDs were applied to detect metronidazole in actual water samples, presenting good sensitivity and a high recovery rate (97.0~106.0%). Conclusion: This method provides a new idea for the application of carbon dots in metronidazole content detection.

The Comparative Survey on the Cytotoxic Effects of Amphipathic Peptide mCM11 (Modified CM11) and Metronidazole on ST1 and ST3 of Blastocystis sp.

Background: Blastocystis sp. is an opportunistic worldwide protozoan that is life-threatening in immunocompromised individuals; several efforts were performed against Blastocystis sp. in in vivo and in vitro conditions to find an alternative for metronidazole (MTZ). Objectives: The aim of the present study was to survey the cytotoxic effects of peptide mCM11 (modified CM11) and MTZ on ST1 and ST3 of Blastocystis sp. in vitro. Materials and Methods: In the present study, after the culture of the parasite (in Dulbecco’s modified Eagle medium [DMEM] and Caco-2 cell lines), the anti-parasitic effect of different concentrations of either MTZ (1.25-80 μg/mL) or mCM11 (1-128 μg/mL) for 24, 48, and 72 hours was evaluated via a 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay and flow cytometry. Results: A dose-time-dependent decrease in cell viability was detected after cell line and parasite exposure. The cytotoxic effect of the peptide on cell lines increased during 24, 48, and 72 hours, and the greatest anti-parasitic effect was observed at the highest concentration (128) after 72 hours. In addition, the ST3 showed more sensitivity to the mCM11. Conclusion: The findings of the current research about the mCM11 peptide were promising compared to MTZ, and by further optimizing the peptide, better effects can be imagined for it, so that it can be a potential alternative to MTZ. However, more studies with a case-control design seem to be necessary in in vivo conditions.

Investigation of the adsorption and degradation of metronidazole residues in agricultural wastewater by nanocomposite based on nZVI on MXene

Metronidazole is a widely used antibiotic with powerful antimicrobial properties, but its presence in water can be detrimental to aquatic life and human health. To address this issue, we developed a novel composite material, zero-valent iron nanoparticles on alkalized Ti3C2Tx nanoflakes (NZVI/Ti3C2Tx), using an in-situ growth technique, aiming to efficiently adsorb and degrade metronidazole from aqueous solutions. The incorporation of Ti3C2Tx in NZVI/Ti3C2Tx resulted in enhanced dispersion, stability, and reactivity of NZVI. Our study demonstrated that NZVI/Ti3C2Tx exhibited the highest metronidazole removal efficiency (95.80%) within just 10 min of reaction time, outperforming NZVI and Ti3C2Tx alone. To optimize the removal process, we investigated the influence of various parameters on the degradation of metronidazole by NZVI/Ti3C2Tx, including the NZVI/Ti3C2Tx ratio, initial metronidazole concentration, pH, and reaction temperature. The highest removal rate was achieved with an NZVI/Ti3C2Tx ratio of 2:1 after 90 min of reaction time. As the initial concentration and pH of metronidazole increased, the removal efficiency decreased, while higher reaction temperatures improved the removal efficiency. Kinetic studies revealed that the degradation of metronidazole by NZVI/Ti3C2Tx followed a modified second-order parameter pseudo-first-order kinetic model, highlighting the effective reduction reaction. The unique properties of MXene nanosheets and NZVI synergistically contributed to the enhanced removal performance, with NZVI/Ti3C2Tx acting as an efficient adsorbent and reducing agent. Uur findings demonstrate the potential of the NZVI/Ti3C2Tx nanocomposite as an efficient and eco-friendly approach for the removal of metronidazole from agricultural wastewater. The combination of NZVI and Ti3C2Tx offers enhanced removal efficiency and stability, making it a promising material for water purification and environmental applications.

The influence of exposure to various concentrations of five antimicrobial agents on intracellular cytotoxin B production in &lt;i&gt;Clostridioides difficile&lt;/i&gt;

Background: Clostridioides difficile is an important cause of healthcare-associated diarrhea. Several anti- microbial agents are known to promote C. difficile infection (CDI). The impact of various concentrations of ampicillin (AMP), cefotaxime (CTX), clindamycin (CC), metronidazole (MTZ) and vancomycin (VAN) on intra-cellular cytotoxin B production was investigated in this study.&#x0D; Methodology: Six clinical strains of C. difficile were grown at minimum inhibitory concentration (MIC) and sub-MIC concentrations of these antibiotics. Inoculum standardization was performed by Miles and Misra method. Intracellular toxin B production was detected using Vero cell cytotoxicity assay in sonicated cultures on days 1, 2, 3, 4, 5 and 7 days of incubation.&#x0D; Results: There was a heterogeneous relationship between antibiotic exposure and the intra-cellular toxin production by the toxigenic strains. Clinical strains of C. difficile when exposed to MIC and sub-inhibitory concentrations of certain antibiotics produced high cytotoxin levels. All toxigenic isolates produced increased levels of cell-bound cytotoxin after exposure to antibiotics but there was no consistent pattern and the response to different doses varied considerably. Metronidazole was the most potent inducer of cell-bound cytotoxin followed by cefotaxime and clindamycin. Vancomycin induced the least amount of cytotoxin activity.&#x0D; Conclusion: The effects of sub-inhibitory concentration of antibiotic that predispose to C. difficile infection may partially suppress the normal gut flora, allowing colonization and growth of C. difficile, and may affect the level of toxin produced.

Model-informed precision dosing of antimicrobial drugs in pediatrics: experiences from a pilot scale program.

Antibiotics are among the most utilized drugs in pediatrics. Nonetheless, there is a lack in pharmacokinetics information for this population, and dosing criteria may vary between healthcare centers. Physiological variability associated with maturation in pediatrics makes it challenging to reach a consensus on adequate dosing, which is further accentuated in more vulnerable groups, such as critically ill or oncology patients. Model-informed precision dosing is a useful practice that allows dose optimization and attainment of antibiotic-specific pharmacokinetic/pharmacodynamic targets. The aim of this study was to evaluate the needs of model-informed precision dosing of antibiotics in a pediatrics unit, at a pilot scale. Pediatric patients under antibiotic treatment were monitored with either a pharmacokinetic/pharmacodynamic optimized sampling scheme or through opportunistic sampling. Clindamycin, fluconazole, linezolid, meropenem, metronidazole, piperacillin, and vancomycin plasma concentrations were quantified through a liquid chromatography coupled to mass spectrometry method. Pharmacokinetic parameters were estimated using a Bayesian approach to verify pharmacokinetic/pharmacodynamic target attainment. A total of 23 pediatric patients aged 2 to 16years were included, and 43 dosing regimens were evaluated; 27 (63%) of them required adjustments as follows: 14 patients were underdosed, 4 were overdosed, and 9 patients needed infusion rate adjustments. Infusion rate adjustments were mostly recommended for piperacillin and meropenem; daily doses were augmented for vancomycin and metronidazole, meanwhile linezolid was adjusted for under- and overdosing. Clindamycin and fluconazole regimens were not adjusted at all. Conclusion: Results showcase a lack of antibiotic pharmacokinetic/pharmacodynamic target attainment (particularly for linezolid, vancomycin, meropenem, and piperacillin), and the need for model-informed precision dosing in pediatrics. This study provides pharmacokinetic evidence which can further improve antibiotic dosing practices. What is Known: • Model-informed precision dosing is performed in pediatrics to optimize the treatment of antimicrobial drugs such as vancomycin and aminoglycosides, while its usefulness is debated for other groups (beta-lactams, macrolides, etc.). What is New: • Vulnerable pediatric subpopulations, such as critically ill or oncology patients, can benefit the most from model-informed precision dosing of antibiotics. • Model-informed precision dosing of linezolid, meropenem, piperacillin, and vancomycin is particularly useful in pediatrics, and further research mayimprove dosing practices altogether.

Antimicrobial Effects of Sophora flavescens Alkaloids on Metronidazole-Resistant Gardnerella vaginalis in Planktonic and Biofilm Conditions

Bacterial vaginosis (BV) is a common infectious disease of the lower female reproductive tract, which is characterized by the augmentation of anaerobic bacteria. Gardnerella (G.) vaginalis plays a predominant role in BV recurrence relating to its higher virulence potential and biofilm formation ability. With the increased proportion of metronidazole-resistant G. vaginalis, controlling resistance to metronidazole and finding more effective drugs became a major concern. In this study, 30 clinical strains were cultured from the vaginal secretions of BV patients, followed by PCR and 16S rDNA sequencing identification. According to the CLSI guidelines for anaerobic drug sensitivity testing, 19 strains were identified as metronidazole-resistant (minimum inhibitory concentration, MIC ≥ 32 μg/mL), of which 4 clinical strains were observed to be strong biofilm producer and the final minimum biofilm inhibitory concentration (MBIC) of metronidazole was increased to 512 μg/mL. Sophora flavescens Alkaloids (SFAs), a traditional chinese medicine, could not only inhibit the growth of metronidazole-resistant G. vaginalis in planktonic (MIC: 0.3125–1.25 mg/mL), but also eliminate the biofilm formation (MBIC: 0.625–1.25 mg/mL). In the high-magnification scanning electron, it was observed that the morphology of biofilm changed from a thick to flaky shape and was nearly depleted. These results indicate that SFAs could not only inhibit the growth of metronidazole-resistant G. vaginalisin planktonic and biofilm levels, but also destroyed the biofilm morphology and microstructure, which may contribute to the prevention of BV recurrence.

Photocatalytic degradation of metronidazole and oxytetracycline by novel l-Arginine (C, N codoped)-TiO2/g-C3N4: RSM optimization, photodegradation mechanism, biodegradability evaluation

Removal of Metronidazole (MNZ) and Oxytetracycline (OTC) from wastewater by the prepared (C, N codoped)-TiO2/g-C3N4 (Graphitic carbon nitride) was examined. l-Arginine (C, N codoped)-TiO2 and l-Arginine (C, N codoped)-TiO2/g-C3N4 photocatalysts were successfully synthesized through the sol-gel method, and optimal ratio of l-arginine:TiO2, as well as l-arginine/TiO2:g-C3N4, was determined by a kinetic study of photodegradation process. The maximum photocatalytic removal rate (0.062 min−1 for MNZ removal) was observed using 1% l-Arginine-TiO2/g-C3N4 (1:1) under visible light illumination, 2.2 and 12.4 times greater than those of 1% l-Arginine-TiO2 and pure TiO2, respectively. l-Arginine (1%)-TiO2/g-C3N4 (1:1) (co-doped-TCN) was investigated using X-ray diffraction analysis (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX), Photo-luminescence (PL), and Differential Reflectance Spectroscopy (DRS) as the best-performing photocatalyst. Response surface methodology (RSM) was used to study the effect of co-doped-TCN dosage (0.5–1.0 g/L), pH of simulated wastewater (4–10), initial concentration of MNZ and OTC (50–100 mg/L), and irradiation time (30–90 min for MNZ and 20–40 min for OTC) on removal efficiency of the antibiotics. Also, their optimum values were determined by RSM. The treated pharmaceutical wastewater showed high biodegradability features with 5-day biological oxygen demand/chemical oxygen demand (BOD5/COD) of 0.51 and 0.46 after 40 and 100 min reaction for OTC and MNZ, respectively. The order of reactive species responsible for the photodegradation of pollutants was •O2─> •OH > h+>1O2. The effect of inorganic anions showed that all anions decreased the removal efficiency of both antibiotics in order of NO3─> Cl─ >SO42─>HPO42─ >HCO3─ for MNZ and NO3─> SO42─ > Cl─ >HPO42─ >HCO3─ for OTC. Also, introducing different oxidants improved the photocatalytic removal efficiency with the order of H2O2>K2S2O8> KBrO3.

Application of Ti-based mixed metal oxide electrodes towards electrochemical mineralization of Metronidazole: Evaluation of influencing factors and removal by-products

BackgroundThe treatment of Metronidazole (MTZ) as a persistent pharmaceutical waste in the water is a significant challenge. To reduce the adverse effect of MTZ in water, we tested a novel SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode via the electrochemical oxidation (EO) method. MethodsThe electrode was characterized by scanning electron microscopy, energy dispersive spectrum, atomic force microscopy, and cyclic voltammetry analyses. Structural characterization results were represented high resistance, compact surface, and better electrocatalytic properties for Ti/IrO2-Ta2O5-SiO2 electrode. The influence of critical operational parameters, including applied current density, initial pH, initial concentration of MTZ, and electrolysis time, was detected on electrocatalytic removal efficiency. Significant findingsIt was recognized that the high electrocatalytic power of SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode gives a high amount of •OH during the removal process. At optimum conditions (pH = 7, J = 200 mA/cm2, [MTZ]0 = 40 mg/L, t = 80 min), 98.76% MTZ removal efficiency was achieved. Besides, comparison analysis was performed with SiO2-incorporated MMO-Ti/IrO2-Ta2O5 electrode and Ti/IrO2-Ta2O5, so results point out the higher total organic carbon removal of about 78.90% and 54.30% with SiO2-incorporated MMO-Ti/IrO2-Ta2O5 than Ti/IrO2-Ta2O5, respectively. Furthermore, MTZ removal intermediates formed during the electrocatalytic oxidation process were identified by the gas chromatography–mass spectrometry technique.

Heterogeneous Sono-Fenton like catalytic degradation of metronidazole by Fe3O4@HZSM-5 magnetite nanocomposite

In this research, Fe3O4@HZSM-5 magnetic nanocomposite was synthesized via a coprecipitation method for metronidazole (MNZ) degradation from aqueous solutions under ultrasonic irradiation which showed superb sonocatalytic activity. The synthesized magnetite nanocomposite was characterized by using field-emission scanning electron microscope-energy dispersive X-ray Spectroscopy, (FESEM-EDS), Line Scan, Dot Mapping, X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Brunauer-Emmett-Teller (BET). To investigate the sonocatalytic activity of the Fe3O4@HZSM-5 magnetite nanocomposite, the sonocatalytic removal conditions were optimized by evaluating the influences of operating parameters like the dosage of catalyst, reaction time, pH, the concentration of H2O2, MNZ concentration, and pH on the MNZ removal. The MNZ maximum removal efficiency and TOC at reaction time 40 min, catalyst dose 0.4 g/L, H2O2 concentration 1 mM, MNZ initial concentration 25 mg/L, and pH 7 were achieved at 98% and 81%, respectively. Additionally, the MNZ removal efficiency in the real wastewater sample under optimal conditions was obtained at 83%. The achieved results showed that using Langmuir-Hinshelwood kinetic model KL-H = 0.40 L mg−1, KC = 1.38 mg/L min) can describe the kinetic removal of the process. The radical scavenger tests indicated that the major reactive oxygen species were formed by hydroxyl radicals in the Sono-Fenton-like process. Evaluation of the nanocomposite reusability showed an 85% reduction in the MNZ removal efficiency after seven cycles. Based on the results, it can be concluded that Fe3O4@HZSM-5 were synthesized as magnetic heterogeneous nano-catalysts to effectively degrade MNZ, and the observed stability and recyclability demonstrated that Fe3O4@HZSM-5 was promising for the treatment of wastewater contaminated with antibiotics.

B–Sn/TiO2 nanoparticles for photodegradation of metronidazole antibiotics under different lights

A novel B and Sn co-doped TiO2 (B–Sn/TiO2) nanoparticle photocatalyst with different compositions was synthesized using the sol-gel method. The weight ratios of B and Sn in TiO2 were 1:9, 6:6, and 2:3, respectively. The resultant nanoparticles have completed a detailed characterization examination using XRD, FTIR, FESEM-EDS, TEM, UV–vis DRS, PL, BET, Zeta potential, and XPS. The photocatalytic activity of B–Sn/TiO2 nanoparticles was investigated for the degradation of aqueous metronidazole (MNZ) solution with UV-C and natural sunlight irradiation. Among the different compositions of the nanoparticles, B–Sn/TiO2 (1:9) exhibited better photocatalytic activity because of its high charge separation ability, confirmed by significant PL quenching. Under ideal conditions (MNZ concentration of 10 mg/L, pH 9, catalyst dosage of 20 mg), a maximum MNZ removal efficiency of ∼96% was obtained in UV-C irradiation within 120 min. However, under the same experimental conditions in natural sunlight, the removal efficiency of MNZ was ∼94% in just 60 min. The mineralization of MNZ up to ∼53% in 3 h under sunlight was studied from the decrease in TOC values. The scavenger test was used to estimate a plausible photocatalytic degradation mechanism of MNZ, and it was observed that the •O2− radical was potentially active in the degradation of MNZ. Cyclic experiments showed that B–Sn/TiO2 (1:9) was reusable for up to four cycles, confirming that it can be used as a cost-effective and environmentally friendly photocatalyst.

Gut microbiota interspecies interactions shape the response of Clostridioides difficile to clinically relevant antibiotics.

In the human gut, the growth of the pathogen Clostridioides difficile is impacted by a complex web of interspecies interactions with members of human gut microbiota. We investigate the contribution of interspecies interactions on the antibiotic response of C. difficile to clinically relevant antibiotics using bottom-up assembly of human gut communities. We identify 2 classes of microbial interactions that alter C. difficile's antibiotic susceptibility: interactions resulting in increased ability of C. difficile to grow at high antibiotic concentrations (rare) and interactions resulting in C. difficile growth enhancement at low antibiotic concentrations (common). Based on genome-wide transcriptional profiling data, we demonstrate that metal sequestration due to hydrogen sulfide production by the prevalent gut species Desulfovibrio piger increases the minimum inhibitory concentration (MIC) of metronidazole for C. difficile. Competition with species that display higher sensitivity to the antibiotic than C. difficile leads to enhanced growth of C. difficile at low antibiotic concentrations due to competitive release. A dynamic computational model identifies the ecological principles driving this effect. Our results provide a deeper understanding of ecological and molecular principles shaping C. difficile's response to antibiotics, which could inform therapeutic interventions.

Enhanced activation performance of peroxymonosulfate by NiCo2O4/SnO2 composite for metronidazole degradation under visible light

In this study, a NiCo2O4/SnO2 complex was successfully synthesized by a convenient hydrothermal method and used for the catalytic degradation of metronidazole (MNZ) by activating peroxymonosulfate (PMS). The physicochemical properties of NiCo2O4/SnO2 were identified by a series of characterization methods. The remarkable PMS activation performance of NiCo2O4/SnO2 originated from the formation of a heterojunction between NiCo2O4 and SnO2, which led to the improvement of the light response ability and the electron conduction efficiency of the composite. The composite catalyst displayed almost 100 % MNZ degradation efficiency within 30 min under visible light. The degradation efficiency of MNZ can be maintained in a wide pH range (3−11). Furthermore, the effect of catalyst dosage, PMS concentration and MNZ concentration on the catalytic process were investigated by changing the experimental parameters. The various anions and different water substrates had only a minor influence on the degradation process of MNZ. In addition, quenching experiments and electron paramagnetic resonance techniques were employed to detect active groups in the reaction process. The results showed that superoxide radicals (O2•-), hydroxyl radicals (OH•), singlet oxygen (1O2), and sulfate radicals (SO4•-) were the main causes of MNZ degradation. Meanwhile, the liquid phase mass spectrometry (LCMS) and Toxicity Estimation Software Tool (T.E.S.T) were utilized to identify the intermediate products and their biological toxicity in the degradation process, and demonstrating a significant decline of biotoxicity compared with MNZ. Generally, this work will provide a new feasible scheme for the effective treatment of organic contaminants in water.