Helicobacter pylori acquisition of metronidazole resistance by natural transformation in vitro

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Prevalence of primary Helicobacter pylori resistance to metronidazole and clarithromycin in Singapore

INTRODUCTIONEradication of Helicobacter pylori,a bacteriumresiding in stomach and causing peptic ulcer disease,can be achieved by using combination therapiesconsisting of one or two antibiotics with a protonpump inhibitor (PPI).The major antibiotics widelyused in the regimens to eradicate H.pylori aremetronidazole and clarithromycin.However,resistance to these antibiotics by H.pylori

Simultaneous determination of metronidazole and tinidazole in plasma by using HPLC-DAD coupled with second-order calibration

A method using HPLC-DAD coupled with second-order calibration was developed to simultaneously determine metronidazole and tinidazole in plasma samples in this paper. The second-order calibration method based on APTLD （alternating penalty trilinear decomposition） algorithm was proposed to analyze the three-way HPLC-DAD data from both standard and prediction samples, which makes it possible that calibration can be performed even in the presence of unknown interferences with a simple and green chromatographic condition and short analysis time. The results showed that good recoveries were obtained although the chromatographic and spectral profiles of the analytes of interest as well as background were partially overlapped with each other in plasma samples.

Ultrasensitive electrochemical determination of metronidazole based on polydopamine/carboxylic multi-walled carbon nanotubes nanocomposites modified GCE

An ultrasensitive electrochemical sensor based on polydopamine/carboxylic multi-walled carbon nanotubes(MWCNTs à COOH) nanocomposites modified glassy carbon electrode(GCE) was presented in this work, which has been developed for highly selective and highly sensitive determination of an antimicrobial drug, metronidazole. The preparation of polydopamine/MWCNTs–COOH nanocomposites/GCE sensor is simple and possesses high reproducible, where polydopamine can be coated on the surface of MWCNTs–COOH via a simple electropolymerization process. Under optimized conditions, the proposed sensor showed ultrasensitive determination for metronidazole with a wide linear detection range from5 to 5000 mmol/dm^3 and a low detection limit of 0.25 mmol/dm^3(S/N=3). Moreover, the proposed sensor has been successfully applied for the quantitative determination of metronidazole in real drug samples. This work may provide a novel and effective analytical platform for determination of metronidazole in application of real pharmaceutical and biological samples analysis.

Ethnicity association of Helicobacter pylori virulence genotype and metronidazole susceptibility

AIM:To characterise the cag pathogenicity island in Helicobacter pylori(H.pylori) isolates by analysing the strains' vacA alleles and metronidazole susceptibilities in light of patient ethnicity and clinical outcome.METHODS:Ninety-five H.pylori clinical isolates obtained from patients with dyspepsia living in Malaysia were analysed in this study.Six genes in the cagPAI region(cagE,cagM,cagT,cag13,cag10 and cag67) andvacA alleles of theH.pylori isolates were identified by polymerase chain reaction.The isolates' metronidazole susceptibility was also determined using the E-test method,and the resistant gene was characterised by sequencing.RESULTS:More than 90% of the tested isolates had at least one gene in the cagPAI region,and cag67 was predominantly detected in the strains isolated from the Chinese patients,compared with the Malay and Indian patients(P < 0.0001).The majority of the isolates(88%) exhibited partial deletion(rearrangement) in the cagPAI region,with nineteen different patterns observed.Strains with intact or deleted cagPAI regions were detected in 3.2% and 8.4% of isolates,respectively.The prevalence of vacA s1m1 was significantly higher in the Malay and Indian isolates,whereas the isolates from the Chinese patients were predominantly genotyped as vacA s1m2(P = 0.018).Additionally,the isolates from the Chinese patients were more sensitive to metronidazole than the isolates from the Malay and Indian patients(P = 0.047).Although we attempted to relate the cagPAI genotypes,vacA alleles and metronidazole susceptibilities to disease outcome,no association was observed.The vacA alleles were distributed evenly among the strains with intact,partially deleted or deleted cagPAI regions.Interestingly,the strains exhibiting an intact cagPAI region were sensitive to metronidazole,whereas the strains with a deleted cagPAI were more resistant.CONCLUSION:Successful colonisation by different H.pylori genotypes is dependent on the host's genetic makeup and may play an important role in the clinical outcome.

A sensitive electrochemical detection of metronidazole in synthetic serum and urine samples using low-cost screen-printed electrodes modified with reduced graphene oxide and C60

Monitoring the concentration of antibiotics in body fluids is essential to optimizing the therapy and minimizing the risk of bacteria resistance,which can be made with electrochemical sensors tailored with appropriate materials.In this paper,we report on sensors made with screen-printed electrodes(SPE)coated with fullerene(C60),reduced graphene oxide(rGO)and Nafion(NF)(C60-rGO-NF/SPE)to determine the antibiotic metronidazole(MTZ).Under optimized conditions,the C60-rGO-NF/SPE sensor exhibited a linear response in square wave voltammetry for MTZ concentrations from 2.5×10^(-7) to 34×10^(-6) mol/L,with a detection limit of 2.1×10^(-7) mol/L.This sensor was also capable of detecting MTZ in serum and urine,with recovery between 94%and 100%,which are similar to those of the standard chromatographic method(HPLC-UV).Because the C60-rGO-NF/SPE sensor is amenable to mass production and allows for MTZ determination with simple principles of detection,it fulfills the requirements of therapeutic drug monitoring programs.

Determination of metronidazole in a rat stomach by HPLC for obtaining basic data of the eradication therapy of Helicobacter pylori

In the eradication therapy of Helicobacter pylori changes of antibiotics as these concentrations or amount in the stomach after oral administration were not clear. A simple and accurate method for determining the concentration of metronidazole （MTZ） in homogenate of rat stomach was developed in order to obtain basic data to design a pharmaceutical preparation having targeting ability to the surface of gastric-mucosa. This method included a deproteinization process by methanol, separation with reversed-phase high-performance liquid chromatography, and detection with an ultraviolet wavelength of 370 nm. Regression analysis showed that the method was linear over a standard curve nmge from 5 ug/mL to 2000 g/mL. The inter-day precision and accuracy values between thc ranges were 5.0% or better and -7.5 to 5.2%, respectively. The newly developed method was applied to an analysis of gastric samples after oral administration of MTZ at a dose of 5 mg/kg. It was found that the residual MTZ in the stomach was determined within 5 h after dosing. This method is useful for monitoring MTZ in stomach after its oral administration to rats.

An early report: a modified porphyrin-linked metronidazole targeting intracellular Porphyromonas gingivalis in cultured oral epithelial cells

Porphyromonas gingivalis （P. gingivalis） has a strong association with the pathogenesis of periodontal disease. Recurrence of periodontal disease following therapy is attributed to numerous factors, and of growing interest is the potential problem of intracellular bacteria that are able to persist and multiply within the host cell, thereby facilitating relapse of infection. The effect of antibiotic therapy in controlling P. gingivalis is questionable. Accordingly, while metronidazole is very effective against anaerobic extracellular P. gingivalis by disrupting the DNA of anaerobic microbial cells, this antibiotic does not effectively penetrate into mammalian cells to inhibit intracellular bacteria. Therefore in the present study, a modified porphyrin-linked metronidazole adducts, developed in our laboratory, was used to kill intracellular P. gingivalis. A series of experiments were performed, including cytotoxicity assays and cellular uptake of adducts by flow cytometry coupled with live cell imaging analysis, P. gingivalis invasion and elimination assays, and the analysis of colocalization of P. gingivalis and porphyrin-linked metronidazole by confocal laser scanning microscopy. Findings indicated that P. gingivalis and porphyrin-linked metronidazole were colocalized in the cytoplasm, and this compound was able to kill P. gingivalis intracellular with a sufficient culture time. This is a novel antimicrobial approach in the elimination of P. gingivalis from the oral cavity.

An Evaluation of Metronidazole Degradation in a Plasma-Assisted Rotating Disk Reactor Coupled with TiO2 in Aqueous Solution

Pollution involving pharmaceutical components in bodies of water is an increasingly serious environmental issue.Plasma discharge for the degradation of antibiotics is an emerging technology that may be relevant toward addressing this issue.In this work,a plasma-assisted rotating disk reactor(plasma-RDR)and a photocatalyst—namely,titanium dioxide(TiO_(2))—were coupled for the treatment of metronidazole(MNZ).Discharge uniformity was improved by the use of a rotating electrode in the plasma-RDR,which contributed to the utilization of ultraviolet(UV)light radiation in the presence of TiO_(2).The experimental results showed that the degradation efficiency of MNZ and the concentration of generated hydroxyl radicals respectively increased by 41%and 2.954 mg∙L^(-1) as the rotational speed increased from 0 to 500 r∙min^(-1).The synergistic effect of plasma-RDR plus TiO_(2) on the generation of hydroxyl radicals was evaluated.Major intermediate products were identified using three-dimensional(3D)excitation emission fluorescence matrices(EEFMs)and liquid chromatography-mass spectrometry(LC-MS),and a possible degradation pathway is proposed herein.This plasma-catalytic process has bright prospects in the field of antibiotics degradation.

Introducing nitazoxanide as a promising alternative treatment for symptomatic to metronidazole-resistant giardiasis in clinical isolates

Objective:To identify the frequencies(F) of ferredoxin and nitroreductase mutations were identified on Iranian clinical isolates of Giardia lamblia in order to predict whether the nitazoxanide can be prescribed as suitable drug for symptomatic to metronidazoleresistant giardiasis.Methods:Forty Giardia lamblia isolates as of 38 symptomatic and two metronidazole-resistant patients were collected from Iran.DNAs were extracted and amplified by targeting ferredoxin and Gl NR genes.The amplicons were directly sequenced to determine gene mutations.Results:The various amino acid substitutions(F:20%,Haplotype diversity:0.891,Tajima's D:-0.44013) were identified by analyzing ferredoxin gene in four symptomatic and two resistant isolates.Only,two haplotypes(F:5%,HD:0.345; Tajima's D:0.77815) characterized in metronidazole-resistant isolates of Gl NR,however,no point mutations was found in symptomatic isolates.Conclusions:Non-synonymous mutations of ferredoxin oxidoreductase gene reduce translational regulatory protein's binding affinity which concludes reduction of ferredoxin expression and its activity.This leads to decrease in metronidazole drug delivery into the cells.Mutations in these isolates may lead to their resistance to metronidazole.No to low synonymous mutations of Gl NR demonstrates that nitazoxanide can be prescribed as promising alternative treatment for symptomatic to metronidazole-resistant giardiasis in Iranian clinical isolates.

Effect of Hypericum perforatum L. compared with metronidazole in bacterial vaginosis:a double-blind randomized trial

Objective:To compare effect of Hypericum perforatum(H.perforatum) vaginal gel with metronidazole on bacterial vaginosis(BV) in terms of initial response to treatment and preventing recurrence(primary outcomes) and also patient complaints(secondary outcomes).Methods:In this double-blind,double dummy trial,married women aged 18-49 with BV were randomized into two groups and administered 5 g of 3%H.perforatum and placebo of metronidazole(n=82),or 5 g of 0.75%metronidazole and placebo of H.peiforatum(n=80)vaginally for 5 d.Amsel criteria were used for diagnosis and assessing cure and recurrence of BV.The comparisons was done using Chi-square,Fisher's exact and logistic regression.Results:At 10-12 d.cure rate was 82%in the H.perforatum and 85%in metronidazole group(risk ratio 0.9.95%confidence interval 0.6 to 1.3).Among the cured women,recurrence rate was 9%in the H.perforatum and 13%in the metronidazole group at the 30-35 d visit(risk ratio 0.8,95%confidence interval 0.4 to 1.3),There was no statistically significant difference between the groups regarding any patient complaints,except itching which was less in H.perforatum group(5%vs.16%,P=0.018 at the first and 13%vs.43%,P<0.001 at the second follow-up).No significant adverse event was reported at any groups.Conclusions:H.peiforatum could be a good option for treatment of BV.However,further studies arc needed for its public use.

Synthesis and Crystal Structure of Metronidazole-derived Compound

A MET-OH derivative, MET-OTs 1, was designed, prepared and structurally characterized by single-crystal X-ray diffraction. X-ray structure analysis reveals that 1 crystallizes in the monoelinic system, space group P21/c, with a = 16.1178（14）, b = 7.5473（6）, c = 13.4161（11）A, V= 1520.3（2）A3,β=111.3210（10）°, Z= 4, Dc =1.421 g/cm^3 and F（000） = 680.

Efficacy and Tolerability of Second-Line Metronidazole Triple Therapy Using Vonoprazan for Helicobacter pylori Eradication in Japan—Comparative Study: Vonoprazan vs. Proton Pump Inhibitors

Aim: To investigate the efficacy and tolerability of second-line metronidazole triple therapy with vonoprazan (VPZ) for Helicobacter pylori (H. pylori). Methods: We retrospectively reviewed medical records of patients who experienced clarithromycin triple therapy failure and were treated with second-line (20 mg VPZ (n = 274)/30 mg lansoprazole (n = 323) or 10 mg rabeprazole (n = 141) twice daily, 750 mg amoxicillin twice daily, 250 mg metronidazole twice daily for 7 days) eradication therapies. Successful eradication rates were compared between two groups: those receiving VPZ and those receiving a proton pump inhibitor (PPI). Adverse events were also investigated. Results: Successful second-line eradication rates according to ITT analysis and PP analysis, respectively, were 79.9% and 92.4% for VPZ therapy and 83.6% and 93.3% for PPI therapy. There were no significant differences between treatment groups. The eradication rates in those who had received first-line VPZ therapy previously according to ITT and PP analysis were 75.2% and 88.1%, respectively;in contrast, values were 82.5% and 95.4%, respectively, for those who had received first-line PPI therapy previously. In second-line therapy, the overall adverse event rate for VPZ therapy was the same as for PPI therapy. Conclusions: The efficacy and tolerability of metronidazole-containing second-line triple therapy with VPZ or a PPI were equivalent.

Influence of Some Physicochemical Exposure Factors on the Metronidazole Content of a Pharmaceutical Product: Flagyl®250 mg Tablet

The present work aims to study the influence of some physicochemical parameters (light, temperature, ethanol, bile salts, potassium hydroxide, hydrogen peroxide) on the content of Metronidazole (MTZ) contained in the reference substance (SR) and in a pharmaceutical specialty Flagyl® 250 mg tablet (FLG). The method developed was linear and accurate in accordance with USP 38 and the MTZ contents were obtained by UV-visible spectrophotometry at 278 nm. These contents ranged from 225 mg to 275 mg and were thus consistent with the concentration present in the proprietary medicines (250 mg). The study of the influence of physicochemical parameters on the MTZ content in SR and FLG showed that MTZ contents are unstable in the presence of Ethanol at 96˚, KOH at 0.1N and bile salts but also when the temperature is higher than 25˚C. However, they remain stable in the presence of light and H2O2 and undergo degradation in an acidic environment.

STUDY ON THE DETERMINATION OF METRONIDAZOLE IN HUMAN SERUM BY ADSORPTIVE STRIPPING VOLTAMMETRY

In Britton-Robinson buffer,metronidazole is preconcentreted on HHDE at 0.0 V(Vs.Ag- AgCI),An adsorptive stripping peak is observed at-0.62 V.Tho response is linear from 1x10^(-8)to 1×10^(-6)mol/L with 1.5 min accumulation.The method has been successfully applied to the deternation of metronidazole in human serum and formulations.

Amebic liver abscess: An update

Amebic liver abscess(ALA)is still a common problem in the tropical world,where it affects over three-quarters of patients with liver abscess.It is caused by an anaerobic protozoan Entamoeba hystolytica,which primarily colonises the cecum.It is a non-suppurative infection of the liver consisting primarily of dead hepatocytes and cellular debris.People of the male gender,during their reproductive years,are most prone to ALA,and this appears to be due to a poorly mounted immune response linked to serum testosterone levels.ALA is more common in the right lobe of the liver,is strongly associated with alcohol consumption,and can heal without the need for drainage.While majority of ALA patients have an uncomplicated course,a number of complications have been described,including rupture into abdomino-thoracic structures,biliary fistula,vascular thrombosis,bilio-vascular compression,and secondary bacterial infection.Based on clinico-radiological findings,a classification system for ALA has emerged recently,which can assist clinicians in making treatment decisions.Recent research has revealed the role of venous thrombosis-related ischemia in the severity of ALA.Recent years have seen the development and refinement of newer molecular diagnostic techniques that can greatly aid in overcoming the diagnostic challenge in endemic area where serology-based tests have limited accuracy.Metronidazole has been the drug of choice for ALA patients for many years.However,concerns over the resistance and adverse effects necessitate the creation of new,safe,and potent antiamebic medications.Although the indication of the drainage of uncomplicated ALA has become more clear,high-quality randomised trials are still necessary for robust conclusions.Percutaneous drainage appears to be a viable option for patients with ruptured ALA and diffuse peritonitis,for whom surgery represents a significant risk of mortality.With regard to all of the aforementioned issues,this article intends to present an updated review of ALA.

Clinical efficacy and safety of moxifloxacin versus levofloxacin plus metronidazole for community-acquired pneumonia with aspiration factors

Background Community-acquired pneumonia （CAP） is a common infectious disease throughout the world and the incidence continues to grow as the population ages.Aspiration is an important pathogenic mechanism for pneumonia in the elderly and the management of patients with community-acquired pneumonia with aspiration factors is a major medical problem.Our study aimed to assess whether moxifloxacin in comparison to levofloxacin plus metronidazole are effective and safe in the treatment of community-acquired pneumonia with aspiration factors.Methods In this prospective,multicenter,open-label,randomized controlled trial,77 patients with mild-to-moderate community-acquired pneumonia with aspiration factors were enrolled and randomly assigned to receive moxifloxacin or levofloxacin plus metronidazole.The primary efficacy variables were clinical outcomes in evaluable patients at a follow-up visit 7 to 14 days after the end of therapy.Results Seven days after the end of therapy a clinical cure was achieved for 76.7％ （23 of 37） of efficacy-evaluable patients in the moxifloxacin group and 51.7％ （15 of 40） of patients in the levofloxacin plus metronidazole group.There was a significant difference between the two groups （x2=4.002,P ＜0.05）.Bacteriological success rates were similar in the moxifloxacin group （93.3％） and levofloxacin plus metronidazole group （96.4％）,there was no significant difference between the two groups （P ＞0.05）.The overall adverse event rate was 10.8％ （4/37） in the moxifloxacin group versus 17.5％ （7/40） in the levofloxacin plus metronidazole group,there was no significant difference between the two groups （P＞0.05）.No serious adverse events were observed.Conclusions Moxifloxacin is effective and safe for treatment of community-acquired pneumonia with aspiration factors.And the regimen of moxifloxacin monotherapy is more convenient compared with levofloxacin plus metronidazole.

Photocatalytic Degradation of Metronidazole in Aqueous Solution by Niobate K_6Nb_(10.8)O_(30)

The photocatalytic degradation of antibiotic metroni-dazole in aqueous solution by niobate K6Nb10.8O30 photocatalyst that was prepared using a soft-chemical method was studied by Fourier transform infrared spectroscopy and UV-Vis absorption spectrum. Metronidazole is very stable and is difficult to degrade under UV irradiation. K6Nb10.8O30 photocatalyst cannot degrade metronidazole without UV irradiation and shows very high photo-catalytic activity for the degradation of metronidazole under UV irradiation. The photocatalytic degradation rate of metronidazole increased with increasing the dosage of K6Nb10.8O30 photocatalyst. The photocatalytic degradation reaction of metronidazole by nio-bate K6Nb10.8O30 follows the first-order kinetic equation.

Degradation of metronidazole by dielectric barrier discharge in an aqueous solution

Degradation of metronidazole (MNZ) which is a representative and stable antibiotic by dielectric barrier discharge (DBD) in an aqueous solution has been studied. Effects of initial MNZ concentration, solution pH and coexisting organics on the degradation were investigated. The results illustrated that increasing the input power and the discharge frequency can improve the removal of MNZ. At low initial concentration, the removal of MNZ can reach up to 99.1%. Acidic and neutral conditions are more favorable for MNZ removal than alkaline condition in the early stage of degradation. However, the difference in MNZ removal between those in acidic or neutral media and that in alkaline one could be neglected with prolonging of the treatment time. Therefore, this method can be applied to MNZ degradation with a wide pH range. Coexisting organic matter in water can attenuate the removal to some extent. This study could provide valuable references for the degradation of nitroimidazole antibiotics by DBD.

Supramolecular Assemblies of Three New Metronidazole Derivatives Constructed with Various Dihydroxy-benzoic Acids via Hydrogen Bonds

Metronidazole(MTZ)is an important antibiotic,which has been widely applied to cure protozoal and bacterial diseases for human beings or animals.Herein,three novel drug supramolecular crystals constructed by MTZ with 2.5-dihydroxy-benzoic acid(2.5-DHBA)(1),2.6-dihydroxy-benzoic acid(2.6-DHBA)(2)and 3,5-dihydroxy-benzoic acid(3.5-DHBA)(3),respectively,have been discovered.The hydrogen bonds of N-H…O(O-H…N).C-H…O and O-H…O play important roles in the 3D supramolecular framework formation for crystals 1-3.Interestingly.due to the vary locations of the substituent groups,the two-dimensional layers in crystals 1 or 2 are constructed via intermolecular hydrogen bonds between MTZ and 2,5-DHBA or 2.6-DHBA,while in crystal 3 water molecules play a significant role except the intermolecular hydrogen bonds between MTZ and 3,5-DHBA.In addition,five synthons of I R^22(8),ⅡR3(9)in crystal 1,ⅢR1(4),ⅣR2(8)in crystal 2 andⅤR2(7)in crystal 3 formed through various hydrogen bonds are founded in this work.Systematic studies of syntheses,crystal structures and thermal analysis are reported.