Concentrations Of Metronidazole Research Articles

In vitro activity of amixicile against T. vaginalis from clinical isolates.

Trichomoniasis is a sexually transmitted infection in humans caused by the protozoan Trichomonas vaginalis, the leading causative agent of vaginitis in women and urethritis in men worldwide. Metronidazole is the standard treatment for trichomoniasis, with tinidazole as the second line. There are currently no FDA-approved non-nitroimidazole alternative treatments for resistant strains. This study compares the efficacy of a newly synthesized non-nitroimidazole oral drug, amixicile, to that of both metronidazole and the synthetic precursor of amixicile, nitazoxanide with in vitro sensitivity testing. One standard strain from ATCC and three patient-isolated strains of T. vaginalis were used to compare treatments under anaerobic conditions. The minimum inhibitory concentration for metronidazole, nitazoxanide, and amixicile were 12.5μM, 100μM, and 6.25μM, respectively. These results suggest that amixicile may be highly active against T. vaginalis and warrants further investigation as a potential alternative to metronidazole in the treatment of trichomoniasis.

Impact of Subinhibitory Concentrations of Metronidazole on Morphology, Motility, Biofilm Formation and Colonization of Clostridioides difficile.

Clostridioides difficile infection (CDI) is the primary cause of health-care-associated infectious diarrhea. Treatment requires mostly specific antibiotics such as metronidazole (MTZ), vancomycin or fidaxomicin. However, approximately 20% of treated patients experience recurrences. Treatment with MTZ is complicated by reduced susceptibility to this molecule, which could result in high failure and recurrence rates. However, the mechanism remains unclear. In this study, we investigated the impact of subinhibitory concentrations of MTZ on morphology, motility, biofilm formation, bacterial adherence to the intestinal Caco-2/TC7 differentiated monolayers, and colonization in monoxenic and conventional mouse models of two C. difficile strains (VPI 10463 and CD17-146), showing different susceptibility profiles to MTZ. Our results revealed that in addition to the inhibition of motility and the downregulation of flagellar genes for both strains, sub-inhibitory concentrations of MTZ induced various in vitro phenotypes for the strain CD17-146 exhibiting a reduced susceptibility to this antibiotic: elongated morphology, enhanced biofilm production and increased adherence to Caco-2/TC7 cells. Weak doses of MTZ induced higher level of colonization in the conventional mouse model and a trend to thicker 3-D structures entrapping bacteria in monoxenic mouse model. Thus, sub-inhibitory concentrations of MTZ can have a wide range of physiological effects on bacteria, which may contribute to their persistence after treatment.

Metronidazole and 2-Methylimidazole as Corrosion Inhibitors in Microbiologically Influenced Corrosion

Microbial corrosion behavior of mild steel was studied by exposing mild steel coupons in Barr’s medium inoculated with sulfate-reducing bacteria (Desulfovibrio desulphuricans). During the investigation, a considerable loss in weight and deterioration of microstructure of mild steel coupons surface was observed. Coupons were further exposed to culture media containing different concentrations of metronidazole (MNZ) and 2- methylimidazole (MIZ) inhibitors. The corrosion behavior of mild steel was measured by weight loss, electrochemical studies, and SEM. Polarization studies indicated the mixed-type behavior of these inhibitors. MNZ and MIZ exhibited 82.23 and 78.30 % inhibition efficiencies, respectively, as revealed by polarization measurements. The results show that the inhibition efficiencies increased with inhibitor concentration. The surface analysis was performed by scanning electron microscopy (SEM).

Metronidazole elimination from wastewater through photo-Fenton process using green-synthesized alginate-based hydrogel coated bimetallic iron‑copper nanocomposite beads as a reusable heterogeneous catalyst

The photo-Fenton process on heterogeneous nano-catalyst was applied for the metronidazole elimination from a wastewater. The iron‑copper nano-catalyst was synthesized through the green synthesis and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX). The response surface methodology (RSM) based on Box-Behnken design (BBD) was used to investigate and optimize five significant variables (including catalyst loading, initial рН, reaction time, metronidazole, and H2O2 concentration) through forty-six experiments. A quadratic model (with P-value < 0.0001 and R2 = 93.5) was properly derived. The optimum conditions were at 44.7 mg/L of catalyst, 3.5 рН, 85 min of reaction time, 10 mg/L of metronidazole and 33.17 mmol/L of H2O2. 95.0% of metronidazole was experimentally eliminated under the optimum conditions which agreed well with the model. Furthermore, it was concluded that the selected magnetic catalyst can easily be recovered by magnetic separation or passing through a suitable filter.

Impact of reaction parameters for photodegradation pharmaceuticals in wastewater over gold/titania photocatalyst synthesized by pyrolysis of NH2-MIL-125(Ti)

The efficient remediation of pharmaceuticals, including wastewater, remains a remarkably challenging issue for water regeneration. Herein, porous Au/TiO2 synthesized by pyrolysis of NH2-MIL-125(Ti) was utilized to be an efficient photocatalyst for mineralization of trimethoprim (TMP) and Metronidazole (MNZ) as the parent compound. The effects of different factors, including TMP and MNZ concentrations, light intensity, H2O2 concentration, Au/TiO2 dosage, and pH value of reaction solution on the degradation and mineralization performances during UV and visible light (VIS), were addressed. The porous Au/TiO2 photocatalyst exhibited superior photocatalytic degradation of TMP and MNZ under UV and VIS illumination. The optimum pH values were 4; the optimum dosage of Au/TiO2 was 1.5 g/L, H2O2 concentration was 9.8 mM, TMP and MNZ concentrations was 10 ppm, and their photodegradation efficiency was 100% after 30 min illumination time and mineralization efficiency 98.2% after 3 h illumination for TMP and MNZ, respectively under UV illumination, however, the photodegradation efficiency was 100% after 50 min illumination and mineralization efficiency 96.3% after 4.5 h illumination time for TMP and MNZ, respectively under VIS illumination. The real wastewater matrix with 10 mg/L of TMP and MNZ were subjected to 60 min of illumination under similar optimum conditions of synthetic solution. The results indicated that photodegradation efficiency was determined to be 100% after 70 min illumination time for removal of both TMP (k = 3.4 × 10−2 min−1) and MNZ (k = 2.87 × 10−2 min−1). This is ascribed to the incorporation of Au NPs onto TiO2, reducing the photoinduced electron-hole recombination, thus promoting the photocatalytic performance. The possible mechanism for photodegradation of antibiotics was also discussed. The demonstration of photocatalysis mechanism over Au/TiO2 photocatalyst can provide some directing in the enhancement of novel photocatalysts based on MOFs doped by noble metal.

Facile synthesis of Z-scheme ZnO-nanorod @ BiOBr-nanosheet heterojunction as efficient visible-light responsive photocatalyst: The effect of electrolyte and scavengers

A series of Z-scheme 3D ZnO@BiOBr photocatalysts were prepared by the hydrothermal method. The morphology of BiOBr facing the surface of the ZnO nanorods was controlled under regulating the proper experimental conditions. The photocatalysts were characterized by XRD, FT-IR, FE-SEM, TEM, BET-BJH, UV–vis DRS and PL analyses. The ZnO@BiOBr composites showed the highest photodegradation ability of metronidazole (MTZ), which was about 9.75 and 3.54 times higher than those of the pure ZnO and BiOBr, respectively. In addition, the Z-scheme ZnO@BiOBr photocatalysts indicated high stability after four cycles of MTZ photoreduction. The optimal values of the operating parameters were determined by the Box-Behnken design (BBD) with irradiation time = 112 min, pH = 6, initial MTZ concentration = 20 ppm, and catalyst dose 0.5 g/l. The maximum total organic carbon (TOC) degradation efficiencies in the presence of 3D ZnO@BiOBr reached 76.7% at the optimum conditions. The maximum MTZ removal efficiency was 87.72%. The photodegradation of MTZ by a binary composite followed the first-order kinetics. In addition, the effects of adding inorganic ions at different concentrations on the degradation of MTZ were investigated. Based on the trapping experiments, OH• and O2–• improved the photodegradation process.

Anti-Inflammatory and Repairing Effects of Mesoporous Silica-Loaded Metronidazole Composite Hydrogel on Human Dental Pulp Cells.

In order to test an effective biopolymer scaffold in promoting the growth of human dental pulp stem cells (HDPSCs), mesoporous silica @ hydrogel (MSN@Gel) nanocomposites are invented as a new type of biopolymer scaffold for HDPSCs proliferation in this paper. The expression levels of alkaline phosphatase (ALP), dentin matrix protein 1 (DMP1), and dentin sialophosphoprotein (DSPP) are significantly increased in the MSN@Gel group so as to better repair damaged dentin. In order to inhibit the proliferation of bacteria in the dental pulp, metronidazole (MTR) is loaded into MSN. The study found that MSN could effectively prolong the half-life of MTR by 1.75 times, and the viability of HDPSCs could be better maintained in the MSN-MTR@Gel group so as to better promote its proliferation to repair pulpitis. However, with the increase of the MTR concentration, its proliferation effect on HDPSCs decreased gradually, and the proliferation effect is the best in 10 μmol/L. Therefore, the MSN-MTR@Gel scaffold is expected to become an effective method for pulpitis therapy in the future.

Enhanced degradation of metronidazole by cobalt doped TiO2/sulfite process under visible light

The degradation of metronidazole (MNZ) by cobalt doped TiO2 activation of sulfite has been studied in this work. The Co-TiO2 was synthesized using a sol–gel method and characterized by TEM, EDS, DRS, XPS and EPR. The catalytic stability was tested by consecutive reuses. Up to 94% of MNZ was removed after 18 min reaction with Co-TiO2 and sulfite dosage being 0.1 g/L and 5 mM, respectively. The influencing parameters, such as the initial concentration of MNZ (0.03–0.2 mM), sulfite dosage (1–10 mM), catalyst dosage (0.1–0.8 g/L) and pH (2–12) were examined. The MNZ removal was pH-dependent with an optimal pH of 7.0. The presence of halides and nitrite could inhibit the process effectively. The reaction mechanisms were explored by radical quenching experiments and EPR measurements, and investigated by the XPS spectra of the catalysts before and after reactions. The formation of Co-SO3 complex and the Co2+–Co3+–Co2+ redox processes on the surface of the catalyst were crucial for sulfite activation. Compared to other Co species/persulfate processes, Co-TiO2/sulfite/LED combined the advantages of TiO2 photocatalysis and activation of sulfite with transition metal. The study suggests a novel and promising process for the treatment of antibiotics in water.

Efficacy of Ciprofloxacin, Metronidazole and Minocycline in Ordered Mesoporous Silica against Enterococcus faecalis for Dental Pulp Revascularization: An In-Vitro Study.

Pulp revascularization of teeth with necrotic pulp has become an alternative treatment in cases with immature apex. Microbial control is essential to achieve a successful outcome and continued root development. Enterococcus faecalis (E. faecalis) is the most frequently isolated bacterial species in root canals of endodontically failed teeth. Our main goal was to compare the in-vitro antimicrobial efficacy of different antibiotic formulations delivered by ordered mesoporous silica (OMS) against E. faecalis. To determine antibiotic susceptibility, we tested OMS and triple antibiotic paste (TAP; ciprofloxacin:metronidazole:minocycline) with different reagents in different concentrations, using the Kirby–Bauer disk diffusion method. OMS and metronidazole showed no antibacterial activity against E. faecalis. Mixtures of OMS and antibiotics in proportions of 2:2:14 and 4:1:7 (mg/L of ciprofloxacin:metronidazole:minocycline, respectively) showed the lowest antibacterial activity. The antibacterial activity of the combined solutions of ciprofloxacin and metronidazole was significantly higher (p < 0.005). Combinations in different concentrations of minocycline, ciprofloxacin, and metronidazole in OMS have shown activity against E. faecalis, although the combined use of ciprofloxacin and metronidazole has shown the most effective results. This study demonstrates the efficacy of intracanal antibiotic combination paste activity against E. faecalis, avoiding the use of minocycline, whose undesirable effect of teeth staining is a common problem for patients and professionals in dental clinic.

Metronidazole-resistant Clostridioides difficile: genomic and transcriptomic traits acquired under in-vitro metronidazole induction

Decreased effectiveness of metronidazole for the treatment of Clostridioides difficile infection has been documented. One reason for this is that levels of metronidazole in the colon are generally low; therefore, a modest increase in the minimum inhibitory concentration of metronidazole for C. difficile may result in an insufficient therapeutic concentration. Due to the lack of efficient genetic manipulation tools for C. difficile strains, the resistance mechanism is largely unknown. In this study, a metronidazole-resistant strain (SH182IR) was acquired by in-vitro induction with metronidazole from a clinical metronidazole-heteroresistant strain (SH182), and the genomic and transcriptional changes were investigated through whole-genome sequencing and RNA-seq. The morphology of the two strains was studied by transmission electron microscopy, and the roles of drug efflux pumps in metronidazole resistance were determined by inhibition assay. Genomic analysis showed that the ferrous iron transporter feoB3 was truncated in SH182IR, indicating that feoB3 contributed to the metronidazole resistance of C. difficile. RNA-seq analysis showed that genes involved in peptidoglycan synthesis, efflux pumps and metronidazole reductive action were expressed differentially between the two strains. Further cell imaging confirmed that cell wall thickness was significantly greater in SH182IR. The efflux pump inhibitor test showed that addition of reserpine or cyanide 3-chlorophenylhydrazone reduced metronidazole resistance in SH182IR, thus proving the role of efflux pumps in metronidazole resistance. These results found an association between genomic variation and metronidazole resistance in C. difficile, and show that metronidazole resistance in C. difficile is multi-factorial, involving metronidazole metabolism, cell wall thickness and efflux pumps. These findings will help improve knowledge and understanding of metronidazole resistance of C. difficile.

Photodegradation and mineralization of metronidazole by a novel quadripartite SnO2@TiO2/ZrTiO4/ZrO2 photocatalyst: Comprehensive photocatalyst characterization and kinetic study

A facile hydrothermal technique was used to prepare a novel quadripartite SnO2@TiO2/ZrTiO4/ZrO2 (STZZ) photocatalyst, and the photocatalytic activity of STZZ was successfully tested in the metronidazole (MNZ) photodegradation under UV irradiation in water. The effects of photocatalyst type, pH, photocatalyst dosage, MNZ initial concentration on the photodegradation of MNZ were also evaluated. The maximum degradation of MNZ was achieved with STZZ photocatalyst at pH = 6.5 with a photocatalyst dosage of 0.07 g L−1 and MNZ concentration of 20 mg L−1. The rate constants of MNZ photodegradation and mineralization processes were 0.017 min−1 (t1/2 = 40.76 min) and 0.066 min−1 (t1/2 = 10.50 min), respectively. The activation energy of the photodegradation process calculated from the Arrhenius equation was 10.6 kJ/mol. A positive ΔG value was obtained for the MNZ photodegradation by the STZZ photocatalyst that contained a positive ΔH and a negative ΔS (−0.2039 kJ/mol).

Synthesis of Fe3O4@activated carbon to treat metronidazole effluents by adsorption and heterogeneous Fenton with effluent bioassay

Metronidazole (MNZ), widely used to treat human bacterial infections, enters surface water and groundwater through sewage effluent that endangers the aqueous environment. In this study, MNZ is removed from real and synthetic wastewater through adsorption and heterogeneous Fenton processes. The Fe3O4 magnetic-activated carbon (AC) nanocomposite (Fe3O4@AC) was synthesized by coprecipitation and characterized by Fourier transform infrared spectroscopy, Field emission scanning electron microscope, Energy dispersive spectroscopy, Brunauer–Emmett–Teller, X-ray powder diffraction and Vibrating sample magnetometer analyzes. MNZ removal efficiency was studied under the influence of several parameters such as pH (3–11), Fe3O4@AC dose (0.1–1 g/L), H2O2 concentration (5–30 mmol/L), initial MNZ concentration (5–30 mg/L), contact time (5–60 min) and temperature (20–60 °C). Bioassay of treated effluents was evaluated by the germination index. Fe3O4@AC was synthesized with high magnetic strength (43.48 emu/g) and large surface area (210.95 m2/g) at nanoscale with a pseudo spherical structure. The maximum MNZ removal efficiency from real and synthetic wastewater by adsorption was 73.77% and 97.6% at pH 7, respectively; whereas, 74.75% and 98.03% at pH 5, respectively, was obtained by the heterogeneous Fenton process. MNZ adsorption is an exothermic process, it follows pseudo-second order kinetics, Langmuir and Freundlich isotherms. Whilst, MNZ oxidation follows pseudo-first order kinetics. Finally, the MNZ removal efficiency during the recovery and regeneration of Fe3O4@AC nanocomposite in the adsorption and heterogeneous Fenton processes was 86.88% and 78.34%, respectively. Bioassay results showed significant reductions in effluent toxicity after treatment with both processes. Clearly, the Fe3O4@AC nanocomposite produced a high efficiency in the treatment of wastewater containing antibiotics.

G–C3N4 induced acceleration of Fe3+/Fe2+ cycles for enhancing metronidazole degradation in Fe3+/peroxymonosulfate process under visible light

In this study, a Fe3+/g-C3N4 hybrid catalyst system was proposed to activate peroxymonosulfate (PMS) for the metronidazole (MNZ) photocatalytic degradation. The two catalysts, Fe3+ and g-C3N4, exhibited an obvious synergistic effect in the photocatalytic degradation process. When 1 mM PMS, 0.04 mM Fe3+ and 0.05 g L−1 g-C3N4 were applied, the rate constant of the Fe3+/g-C3N4/PMS/LED process at 0.07288 min−1 is around 3.6 to 6.8 times faster than that of Fe3+/PMS/LED and g-C3N4/PMS/LED processes at 0.0198 and 0.01076 min−1, respectively. Under visible light, electron transfer from photo-activated g-C3N4 to Fe3+, resulting in the continuous regeneration of Fe2+ in the system, which ensures non-stopping production of radicals for MNZ degradation. UV–visible spectra were used to confirm the regeneration of Fe2+. In addition, EPR tests were used to identify the reactive oxygen species involved in the reaction system. Typically, the effects of various operation parameters, including the catalyst dosage, PMS dosage, initial concentration of MNZ and initial pH were examined. This work provided a new idea of promoting pollutant degradation by accelerating Fe3+/Fe2+ redox through semiconductor, which could help to use the catalyst more effectively for wastewater treatment and/or chemical industries.

Elaboration of a novel nanosensor using nanoparticles of α-Fe2O3 magnetic cores for the detection of metronidazole drug. Urine human and tap water

Metronidazole (MTZ) is a widely used antibiotic to treat infections caused by anaerobic bacteria, protozoa, and bacteroids such as trichromonosis and vaginosis. In this study, we present a simple strategy for constructing an electroanalysis platform for metronidazole in real samples. We prepared a modified carbon paste with α-Fe2O3 magnetic core nanoparticles to construct an α-Fe2O3@CPE electrochemical sensor. The surface morphology and composition of the sensor were evaluated using several methods, such as X-ray diffraction and scanning electron microscope. The average size of the α-Fe2O3 magnetic core nanoparticles was around 34.30 ​nm. Cyclic voltammetry, electrochemical impedance spectroscopy and chrono-coulometry were performed for the understanding of the electron transfer behavior on the electrocatalytic surface of α-Fe2O3@CPE and the unmodified electrode CPE. The resulting sensor demonstrates a very good shift of the Metronidazole reduction peak to a more positive potential (−0.57v vs Ag/AgCl) compared to the unmodified CPE electrode (−0.71v .vs Ag/AgCl). The Metronidazole peak reduction current Ipc varies linearly with metronidazole concentration in the range of 10-4 ​M to 0.8x10-6 ​M with a limit of detection and limit of quantification of 2.852x10-7 ​M and 9.509x10-7 ​M respectively. Exceeding the detection limits of several existing analytical methods. The proposed procedure has been successfully demonstrated on pharmaceutical tablets and real tap water and urine samples.

Detection and recognition of veterinary drug residues in beef using hyperspectral discrete wavelet transform and deep learning

A fast, non-destructive recognition method for veterinary drug residues in beef was proposed to mitigate the laborious sample preparation and long detection times associated with conventional chemical detection techniques. Control beef samples free of veterinary drug residues and four groups of beef sprayed with relevant concentrations of metronidazole, ofloxacin, salbutamol, and dexamethasone under ambient conditions were analyzed by 400-1000 nm hyperspectral imaging followed by multiplicative scatter correction preprocessing. Data dimension reduction was performed using Competitive Adaptive Reweighted Sampling (CARS), Principal Component Analysis (PCA), and Discrete Wavelet Transform (DWT) based on Haar, db3, bior1.5, sym5, and rbio1.3 wavelet basis functions. Treated data were subjected to Convolutional Neural Network (CNN), Multilayer Perceptron (MLP), Random Forest (RF), and Support Vector Machine (SVM) modelling. CNN, MLP, SVM, and RF algorithms achieved overall accuracies of 91.6%, 88.6%, 87.6%, and 86.2%, respectively, when combined with DWT (wavelet basis functions and numbers of transform layers being Haar-4, db3-2, bior1.5-4, and sym5-3, respectively). The algorithm Kappa coefficients (0.89, 0.86, 0.85, and 0.83, respectively) and time consumption for prediction (140.60 ms, 57.85 ms, 70.67 ms, and 87.16 ms, respectively) were also superior to models based on CARS and PCA. DWT combined with deep learning can shorten prediction times, considerably improve the accuracy of classification and recognition, and alleviate the Hughes phenomenon, thus providing a new method for the fast, non-destructive detection and recognition of veterinary drug residues in beef. Keywords: hyperspectral, beef, veterinary drug residues, discrete wavelet transform, convolutional neural network, deep learning DOI: 10.25165/j.ijabe.20221501.6459 Citation: Jiang R C, Shen J X, Li X R, Gao R, Zhao Q H, Su Z B. Detection and recognition of veterinary drug residues in beef using hyperspectral discrete wavelet transform and deep learning. Int J Agric & Biol Eng, 2022; 15(1): 224–232.

Inflammatory modulation and outer membrane vesicles (OMV) production associated to Bacteroides fragilis response to subinhibitory concentrations of metronidazole during experimental infection

ObjectiveAn experimental infection based on a tissue cage model was reproduced to evaluate the interference subinhibitory concentration (SIC) of metronidazole in Bacteroides fragilis OMV production patterns and immunological and histological characteristics of the host facing the experimental challenge. MethodsA tissue cage model was reproduced for B. fragilis experimental challenge in three Wistar rats groups: negative control group (NC) without bacterial inoculation; positive control group (PC) infected with parental strain; and experimental group (EG) infected with the parental strain and treated with metronidazole SIC. Tissue cage sections and histological preparations were evaluated under optical and transmission electron microscope. Observations included OMV identification and count and cellular envelope evaluation. Transcriptional analyses were performed to evaluate cytokines expression levels. ResultsTotal counts of leukocytes and neutrophils were higher for EG, and slight increase in PC group. It was observed an exacerbated inflammatory infiltrate after 8 days on infection. The expression of TNF-α was increased during the experiments, along with IL-1α and IL-6. MCP-1 levels were suppressed in almost every evaluated time-point. The IL-10 was exacerbated in EG group. A massive production and release of OMV and cell wall thickening were observed especially the EG group. ConclusionsDespite literature data suggest positive association between OMV and antimicrobial stress for Gram negatives, no correlations are made for B. fragilis and drug-response during experimental model of infection. Results corroborate observations in which OMV may be involved in bacterial pathogenicity once the phenomenon was observed along histological evidence of exacerbated inflammation and cytokines modulation.

Phenotypical and Genotypical Comparison of Clostridium difficile Isolated from Clinical Samples: Homebrew DNA Fingerprinting versus Antibiotic Susceptibility Testing (AST) and Clostridial Toxin Genes.

Background Clostridium (Clostridioides) difficile is recognized as the major cause of healthcare antibiotic-associated diarrhea. We surveyed a molecular epidemiological correlation between the clinical isolates from two general hospitals in Iran through clustering toxigenic types and antibiotic susceptibility testing (AST) accuracy. Methods Study population included 460 diarrhoeic specimens from inpatients with a history of antibiotic therapy. All samples underwent enriched anaerobic culture, confirmed by detection of gluD gene with PCR. Toxin status and AST were assessed by the disk diffusion method (DDM) and minimal inhibitory concentrations (MICs) of metronidazole, vancomycin, and rifampin. C. difficile outbreak was analyzed through conventional PCR by tracing toxin genes and Homebrew pulsed-field gel electrophoresis (PFGE) for characterizing isolates within our healthcare systems. Results A total of 29 C. difficile strains were isolated by enriched anaerobic culture from the clinical samples. Among them, 22 (4.8%) toxigenic profiles yielded toxins A and B (tcdA, tcdB) and binary toxins (cdtA, cdtB). The minimum inhibitory concentration (MIC) was 18.1% and 9% for vancomycin and metronidazole, and all isolates were susceptible to rifampicin and its minimum inhibitory concentration was at <0.003 μg/mL. The most dominant toxigenic and antibiotic-resistant “pulsotype F” was detected through PFGE combined with multiple Clostridial toxigenic pattern and AST. Conclusions DNA fingerprinting studies represent a powerful tool in surveying hypervirulent C. difficile strains in clinical settings. Resistance to vancomycin and metronidazole, as first-line antibiotics, necessitate accomplishment of proper control strategies and also prescription of tigecycline as a more appropriate option.

Gut microbiota in burned patients with Clostridioides difficile infection

BackgroundThe survival rate of patients with severe burn is positively associated with increasing the incidence of the Clostridioides difficile (C. difficile) infection (CDI). The surviving rate of severe burn patients now has an improved but the incidence of Clostridioides difficile (C. difficile) infection (CDI) has been continues increasing during recent two decades.This study assessed the molecular typing and phenotypic characterization isolates of C. difficile in burn patients with diarrhea, as well as environmental and skin infections with C. difficile spores at a referral burn hospital in Isfahan, Iran. It mainly aimed to evaluate the dominant bacterial structure in the gut microbiome of burned subjects with and without CDI. MethodsIn general, 309 samples were collected from 189 burned patients with hospital-acquired diarrhea and 120 swabs were collected from the healthcare workers’ dominant hands, different sites of patients’ skin, and medical tools. In addition, C. difficile isolates were characterized considering the existence of antibiotic resistance and toxin genes. Clinical cultures with identification of organisms and antibiotic susceptibility were done. C. difficle isolates were then genotyped and compared to clinical outcomes. Finally, the clinical characteristics of the participants were gathered through their records, and the bacterial targets of the gut microbiome were detected using quantitative real-time polymerase chain reaction (PCR). ResultsBased on the findings, 51 C. difficile isolates were detected from 189 severe burn patients hospitalized in the hospital. Further, PCR amplification tcdB and tcdA showed 23 isolates (12.2%) as toxigenic. Overall, 18.3% (22/120) of skin and environment samples demonstrated a positive result for C. difficile colonization. A low concentration of metronidazole and vancomycin (MIC90, 0.5, and 1.2 mg/L) inhibited all toxigenic C. difficile strains. Moreover, these isolates represented the highest rates of resistance to moxifloxacin and clindamycin (MIC90, 0.5, and 1.6 mg/L). A significantly reduced abundance of Clostridium spp., Bacteroidetes, and Bifidobacterium and an increase in the quantity of Firmicutes was observed in the gastrointestinal microbiome of burn patients (P < 0.01). Burn patients with CDI showed a significant decrease in Faecalibacterium prausnitzii (F. prausnitzii) while higher Akkermansia muciniphila (A. muciniphila) loads in comparison with healthy controls (P < 0.001 and P < 0.05). Contrarily, burned cases displayed increased levels of opportunistic pathogenic bacteria including the members of Enterococcus spp. and Escherichia coli (P < 0.05). ConclusionsDespite appropriate infection control strategies in the burn intensive care unit, CDI remains prevalent in severe burn patients. Eventually, the overgrowth of A. muciniphila and the decreased abundance of F. prausnitzii in burn cases with CDI could be potential predictive microbiome biomarkers in burned patients.

Efficient photocatalytic degradation of metronidazole from aqueous solutions using Co/g-C3N4/Fe3O4 nanocomposite under visible light irradiation.

Herein, the efficient degradation of a highly consumed antibiotic known as metronidazole (MNZ) in aqueous solutions using Co/g-C3N4/Fe3O4 nanocomposite under visible light irradiation was accomplished. Initially, the photocatalyst (Co/g-C3N4/Fe3O4) was synthesized by a simple hydrothermal method and then characterized by several analytical techniques, namely EDS, SEM, XRD, UV-vis DRS, and FTIR. The efficiency of the synthesized photocatalyst with regard to the degradation of the studied antibiotic (MNZ) under visible light irradiation was fully evaluated. The influential operational parameters affecting the efficiency of the degradation process such as pH (2-10), nanocomposite dosage (0.2-1g/L), MNZ concentration (5-20mg/L), and irradiation time (0-80min) were optimized. The results revealed that the maximum degradation efficiency for MNZ was obtained under the following conditions: irradiation time of 60min, pH = 8, MNZ concentration of 5mg/L, and photocatalyst dosage of 0.7g/L. In addition, the degradation of MNZ followed the pseudo-first-order kinetic model. The best rate constant (k) value was determined to be 0.0102min-1 with the correlation coefficient (R2) of 0.992. According to the results of the quenching tests, it was found out that hydroxyl radicals (OH°) were the main species responsible for the MNZ degradation. Furthermore, the applied photocatalyst (Co/g-C3N4/Fe3O4) exhibited a high level of recovery and stability after five cycles of reuse. Co/g-C3N4/Fe3O4/Vis system exhibited an excellent performance in the treatment of wastewater and real water samples. Finally, it was concluded that the synthesized nanocomposite could be potentially used as a promising and suitable photocatalyst in the degradation of other antibiotics.

Gut microbiome affects the metabolism of metronidazole in mice through regulation of hepatic cytochromes P450 expression.

Microbiome is now considered as a significant metabolic organ with an immense potential to influence overall human health. A number of diseases that are associated with pharmacotherapy interventions was linked with altered gut microbiota. Moreover, it has been reported earlier that gut microbiome modulates the fate of more than 30 commonly used drugs and, vice versa, drugs have been shown to affect the composition of the gut microbiome. The molecular mechanisms of this mutual relationship, however, remain mostly elusive. Recent studies indicate an indirect effect of the gut microbiome through its metabolites on the expression of biotransformation enzymes in the liver. The aim of this study was to analyse the effect of gut microbiome on the fate of metronidazole in the mice through modulation of system of drug metabolizing enzymes, namely by alteration of the expression and activity of selected cytochromes P450 (CYPs). To assess the influence of gut microbiome, germ-free mice (GF) in comparison to control specific-pathogen-free (SPF) mice were used. First, it has been found that the absence of microbiota significantly affected plasma concentration of metronidazole, resulting in higher levels (by 30%) of the parent drug in murine plasma of GF mice. Further, the significant interaction between presence/absence of the gut microbiome and effect of metronidazole application, which together influence mRNA expression of CAR, PPARα, Cyp2b10 and Cyp2c38 was determined. Administration of metronidazole itself influenced significantly mRNA expression of Cyp1a2, Cyp2b10, Cyp2c38 and Cyp2d22. Finally, GF mice have shown lower level of enzyme activity of CYP2A and CYP3A than their SPF counterparts. The results hence have shown that, beside direct bacterial metabolism, different expression and enzyme activity of hepatic CYPs in the presence/absence of gut microbiota may be responsible for the altered metronidazole metabolism.