Small molecule MarR modulators potentiate metronidazole antibiotic activity in aerobic E. coli by inducing activation by the nitroreductase NfsA.

Antibiotic-resistant Enterobacterales pose a major threat to healthcare systems worldwide, necessitating the development of novel strategies to fight such hard-to-kill bacteria. One potential approach is to develop molecules that force bacteria to hyper-activate prodrug antibiotics, thus rendering them more effective. In the present work, we aimed to obtain proof-of-concept data to support that small molecules targeting transcriptional regulators can potentiate the antibiotic activity of the prodrug metronidazole (MTZ) against Escherichia coli under aerobic conditions. By screening a chemical library of small molecules, a series of structurally related molecules were identified that had little inherent antibiotic activity but showed substantial activity in combination with ineffective concentrations of MTZ. Transcriptome analyses, functional genetics, thermal shift assays, and electrophoretic mobility shift assays were then used to demonstrate that these MTZ boosters target the transcriptional repressor MarR, resulting in the upregulation of the marRAB operon and its downstream MarA regulon. The associated upregulation of the flavin-containing nitroreductase, NfsA, was then shown to be critical for the booster-mediated potentiation of MTZ antibiotic activity. Transcriptomic studies, biochemical assays, and electron paramagnetic resonance measurements were then used to show that under aerobic conditions, NfsA catalyzed 1-electron reduction of MTZ to the MTZ radical anion which in turn induced lethal DNA damage in E. coli. This work reports the first example of prodrug boosting in Enterobacterales by transcriptional modulators and highlights that MTZ antibiotic activity can be chemically induced under anaerobic growth conditions.

NTR 2.0: a rationally engineered prodrug-converting enzyme with substantially enhanced efficacy for targeted cell ablation.

Transgenic expression of bacterial nitroreductase (NTR) enzymes sensitizes eukaryotic cells to prodrugs such as metronidazole (MTZ), enabling selective cell-ablation paradigms that have expanded studies of cell function and regeneration in vertebrates. However, first-generation NTRs required confoundingly toxic prodrug treatments to achieve effective cell ablation, and some cell types have proven resistant. Here we used rational engineering and cross-species screening to develop an NTR variant, NTR 2.0, which exhibits ~100-fold improvement in MTZ-mediated cell-specific ablation efficacy, eliminating the need for near-toxic prodrug treatment regimens. NTR 2.0 therefore enables sustained cell-loss paradigms and ablation of previously resistant cell types. These properties permit enhanced interrogations of cell function, extended challenges to the regenerative capacities of discrete stem cell niches, and novel modeling of chronic degenerative diseases. Accordingly, we have created a series of bipartite transgenic reporter/effector resources to facilitate dissemination of NTR 2.0 to the research community.

IgA coating of vaginal bacteria is reduced in the setting of bacterial vaginosis (BV) and preferentially targets BV-associated species.

Immunoglobulin (Ig) bacterial coating has been described in the gastrointestinal tract and linked to inflammatory bowel disease; however, little is known about Ig coating of vaginal bacteria and whether it plays a role in vaginal health including bacterial vaginosis (BV). We examined Ig coating in 18 women with symptomatic BV followed longitudinally before, 1 week, and 1 month after oral metronidazole treatment. Immunoglobulin A (IgA) and/or immunoglobulin G (IgG) coating of vaginal bacteria was assessed by flow cytometry, and Ig coated and uncoated bacteria were sorted and characterized using 16S rRNA sequencing. Despite higher levels of IgG compared to IgA in cervicovaginal fluid, the predominant Ig coating the bacteria was IgA. The majority of bacteria were uncoated at all visits, but IgA coating significantly increased after treatment for BV. Despite similar amounts of uncoated and IgA coated majority taxa ( >1% total) across all visits, there was preferential IgA coating of minority taxa (0.2%-1% total) associated with BV including Sneathia, several Prevotella species, and others. At the time of BV, we identified a principal component (PC) driven by proinflammatory mediators that correlated positively with an uncoated BV-associated bacterial community and negatively with an IgA coated protective Lactobacillus bacterial community. The preferential coating of BV-associated species, increase in coating following metronidazole treatment, and positive correlation between uncoated BV-associated species and inflammation suggest that coating may represent a host mechanism designed to limit bacterial diversity and reduce inflammatory responses. Elucidating the role of Ig coating in vaginal mucosal immunity may promote new strategies to prevent recurrent BV.

Apoptosis-inducing factor-like protein-mediated stress and metronidazole-responsive programmed cell death pathway in Entamoeba histolytica.

Apoptosis-inducing factor (AIF) is the major component of the caspase-independent cell death pathway that is considered to be evolutionarily ancient. Apoptosis is generally evolved with multicellularity as a prerequisite for the elimination of aged, stressed, or infected cells promoting the survival of the organism. Our study reports the presence of a putative AIF-like protein in Entamoeba histolytica, a caspase-deficient primitive protozoan, strengthening the concept of occurrence of apoptosis in unicellular organisms as well. The putative cytoplasmic EhAIF migrates to the nucleus on receiving stresses that precede its binding with DNA, following chromatin degradation and chromatin condensation as evident from both in vitro and in vivo experiments. Down-regulating the EhAIF expression attenuates the apoptotic features of insulted cells and increases the survival potency in terms of cell viability and vitality of the trophozoites, whereas over-expression of the EhAIF effectively enhances the phenomena. Interestingly, metronidazole, the most widely used drug for amoebiasis treatment, is also potent to elicit similar AIF-mediated cell death responses like other stresses indicating the AIF-mediated cell death could be the probable mechanism of trophozoite-death by metronidazole treatment. The occurrence of apoptosis in a unicellular organism is an interesting phenomenon that might signify the altruistic death that overall improves the population health.

Antigiardial and antiamebic activities of fexinidazole and its metabolites: new drug leads for giardiasis and amebiasis.

The intestinal parasites Giardia lamblia and Entamoeba histolytica are major causes of morbidity and mortality associated with diarrheal diseases. Metronidazole is the most common drug used to treat giardiasis and amebiasis. Despite its efficacy, treatment failures in giardiasis occur in up to 5%-40% of cases. Potential resistance of E. histolytica to metronidazole is an increasing concern. Therefore, it is critical to search for more effective drugs to treat giardiasis and amebiasis. We identified antigiardial and antiamebic activities of the rediscovered nitroimidazole compound, fexinidazole, and its sulfone and sulfoxide metabolites. Fexinidazole is equally active against E. histolytica and G. lamblia trophozoites, and both metabolites were 3- to 18-fold more active than the parent drug. Fexinidazole and its metabolites were also active against a metronidazole-resistant strain of G. lamblia. G. lamblia and E. histolytica cell extracts exhibited decreased residual nitroreductase activity when metabolites were used as substrates, indicating nitroreductase may be central to the mechanism of action of fexinidazole. In a cell invasion model, fexinidazole and its metabolites significantly reduced the invasiveness of E. histolytica trophozoites through basement membrane matrix. A q.d. oral dose of fexinidazole and its metabolites at 10 mg/kg for 3 days reduced G. lamblia infection significantly in mice compared to control. The newly discovered antigiardial and antiamebic activities of fexinidazole, combined with its FDA-approval and inclusion in the WHO Model List of Essential Medicines for the treatment of human African trypanosomiasis, offer decreased risk and a shortened development timeline toward clinical use of fexinidazole for treatment of giardiasis or amebiasis.

Antibacterial activity of ibezapolstat against antimicrobial-resistant clinical strains of Clostridioides difficile.

Antimicrobial resistance is emerging in clinical strains of Clostridioides difficile. Ibezapolstat (IBZ) is a DNA polymerase IIIC inhibitor that has completed phase II clinical trials. IBZ has potent in vitro activity against wild-type, susceptible strains but its effect on C. difficile strains with reduced susceptibility to metronidazole (MTZ), vancomycin (VAN), or fidaxomicin (FDX) has not been tested. The primary objective of this study was to test the antibacterial properties of IBZ against multidrug-resistant C. difficile strains. The in vitro activity, bactericidal, and time-kill activity of IBZ versus comparators were evaluated against 100 clinical strains of which 59 had reduced susceptibility to other C. difficile antibiotics. Morphologic changes against a multidrug resistance strain were visualized by light and scanning electron microscopy. The overall IBZ MIC50/90 values (µg/mL) for evaluated C. difficile strains were 4/8, compared with 2/4 for VAN, 0.5/1 for FDX, and 0.25/4 for MTZ. IBZ MIC50/90 values did not differ based on non-susceptibility to antibiotic class or number of classes to which strains were non-susceptible. IBZ bactericidal activity was similar to the minimum inhibitory concentration (MIC) and maintained in wild-type and non-susceptible strains. Time-kill assays against two laboratory wild-type and two clinical non-susceptible strains demonstrated sustained IBZ activity despite reduced killing by comparator antibiotics for IBZ and VAN non-susceptible strains. Microscopy visualized increased cell lengthening and cellular damage in multidrug-resistant strains exposed to IBZ sub-MIC concentrations. This study demonstrated the potent antibacterial activity of IBZ against a large collection of C. difficile strains including multidrug-resistant strains. This study highlights the therapeutic potential of IBZ against multidrug-resistant strains of C. difficile.

Genetic determinants of resistance to antimicrobial therapeutics are rare in publicly available Clostridioides difficile genome sequences.

OBJECTIVES: To determine the frequencies and clonal distributions of putative genetic determinants of resistance to antimicrobials applied for treatment of Clostridioides difficile infection (CDI), as documented in the genomic record. METHODS: We scanned 26 557 C. difficile genome sequences publicly available from the EnteroBase platform for plasmids, point mutations and gene truncations previously reported to reduce susceptibility to vancomycin, fidaxomicin or metronidazole, respectively. We measured the antimicrobial susceptibility of 143 selected C. difficile isolates. RESULTS: The frequency of mutations causing reduced susceptibility to vancomycin and metronidazole, respectively, increased strongly after 2000, peaking at up to 52% of all sequenced C. difficile genomes. However, both mutations declined sharply more recently, reflecting major changes in CDI epidemiology. We detected mutations associated with fidaxomicin resistance in several major genotypes, but found no evidence of international spread of resistant clones. The pCD-METRO plasmid, conferring metronidazole resistance, was detected in a single previously unreported C. difficile isolate, recovered from a hospital patient in Germany in 2008. The pX18-498 plasmid, putatively associated with decreased vancomycin susceptibility, was confined to related, recent isolates from the USA. Phenotype measurements confirmed that most of those genetic features were useful predictors of antibiotic susceptibility, even though ranges of MICs typically overlapped among isolates with and without specific mutations. CONCLUSIONS: Genomic data suggested that resistance to therapeutic antimicrobial drugs is rare in C. difficile. Public antimicrobial resistance marker databases were not equipped to detect most of the genetic determinants relevant to antibiotic therapy of CDI.

Giardia duodenalis: Flavohemoglobin is involved in drug biotransformation and resistance to albendazole.

Giardia duodenalis causes giardiasis, a major diarrheal disease in humans worldwide whose treatment relies mainly on metronidazole (MTZ) and albendazole (ABZ). The emergence of ABZ resistance in this parasite has prompted studies to elucidate the molecular mechanisms underlying this phenomenon. G. duodenalis trophozoites convert ABZ into its sulfoxide (ABZSO) and sulfone (ABZSOO) forms, despite lacking canonical enzymes involved in these processes, such as cytochrome P450s (CYP450s) and flavin-containing monooxygenases (FMOs). This study aims to identify the enzyme responsible for ABZ metabolism and its role in ABZ resistance in G. duodenalis. We first determined that the iron-containing cofactor heme induces higher mRNA expression levels of flavohemoglobin (gFlHb) in Giardia trophozoites. Molecular docking analyses predict favorable interactions of gFlHb with ABZ, ABZSO and ABZSOO. Spectral analyses of recombinant gFlHb in the presence of ABZ, ABZSO and ABZSOO showed high affinities for each of these compounds with Kd values of 22.7, 19.1 and 23.8 nM respectively. ABZ and ABZSO enhanced gFlHb NADH oxidase activity (turnover number 14.5 min-1), whereas LC-MS/MS analyses of the reaction products showed that gFlHb slowly oxygenates ABZ into ABZSO at a much lower rate (turnover number 0.01 min-1). Further spectroscopic analyses showed that ABZ is indirectly oxidized to ABZSO by superoxide generated from the NADH oxidase activity of gFlHb. In a similar manner, the superoxide-generating enzyme xanthine oxidase was able to produce ABZSO in the presence of xanthine and ABZ. Interestingly, we find that gFlHb mRNA expression is lower in albendazole-resistant clones compared to those that are sensitive to this drug. Furthermore, all albendazole-resistant clones transfected to overexpress gFlHb displayed higher susceptibility to the drug than the parent clones. Collectively these findings indicate a role for gFlHb in ABZ conversion to its sulfoxide and that gFlHb down-regulation acts as a passive pharmacokinetic mechanism of resistance in this parasite.

Antibiotic resistance and virulence genes in Helicobacter pylori strains isolated from children in Shanghai, China (2019-2022).

BACKGROUND: The increasing prevalence of antibiotic-resistant Helicobacter pylori strains poses a significant threat to children's health. This study investigated antibiotic resistance rates in Helicobacter pylori strains isolated from children in Shanghai and analyzed the presence of virulence genes in these strains. METHODS: We obtained 201 Helicobacter pylori strains from pediatric patients with upper gastrointestinal symptoms who underwent gastrointestinal endoscopy between 2019 and 2022. Subsequently, we performed antibiotic susceptibility tests and virulence gene PCR assays on these strains. RESULTS: Helicobacter pylori resistance rates of 45.8%, 15.4%, 1.0%, and 2.5% were detected for metronidazole, clarithromycin, amoxicillin, and levofloxacin, respectively. Among all isolates, 64.7% exhibited resistance to at least one antibiotic. Resistance to metronidazole and clarithromycin increased from 2019 to 2022. The predominant vacA gene subtype was vacA s1a/m2. The prevalence of vacA m2 and dupA exhibited an upward trend, while oipA presented a decreasing trend from 2019 to 2022. The prevalence of dupA was significantly higher in gastritis than peptic ulcer disease, and in non-treatment compared to treatment groups. CONCLUSIONS: Helicobacter pylori antibiotic resistance remains high in children and has risen in recent years. Therefore, the increasing use of metronidazole and clarithromycin requires increased monitoring in children. No association was observed between antibiotic resistance and virulence gene phenotypes.

Toxin genotypes, antibiotic resistance and their correlations in Clostridioides difficile isolated from hospitals in Xi'an, China.

BACKGROUND: Clostridioides difficile is the main pathogen of antimicrobial-associated diarrhoea and health care facility-associated infectious diarrhoea. This study aimed to investigate the prevalence, toxin genotypes, and antibiotic resistance of C. difficile among hospitalized patients in Xi'an, China. RESULTS: We isolated and cultured 156 strains of C. difficile, representing 12.67% of the 1231 inpatient stool samples collected. Among the isolates, tcdA + B + strains were predominant, accounting for 78.2% (122/156), followed by 27 tcdA-B + strains (27/156, 17.3%) and 6 binary toxin gene-positive strains. The positive rates of three regulatory genes, tcdC, tcdR, and tcdE, were 89.1% (139/156), 96.8% (151/156), and 100%, respectively. All isolates were sensitive to metronidazole, and the resistance rates to clindamycin and cephalosporins were also high. Six strains were found to be resistant to vancomycin. CONCLUSION: Currently, the prevalence rate of C. difficile infection (CDI) in Xi'an is 12.67% (156/1231), with the major toxin genotype of the isolates being tcdA + tcdB + cdtA-/B-. Metronidazole and vancomycin were still effective drugs for the treatment of CDI, but we should pay attention to antibiotic management and epidemiological surveillance of CDI.

Design and evaluation of antibacterials crosslinked chitosan nanoparticle as a novel carrier for the delivery of metronidazole to treat bacterial vaginosis.

Bacterial vaginosis (BV) is a recurring, chronic infection that is difficult to treat due to the limited bioavailability of antimicrobials within vaginal epithelial cells. Vaginal administration, because of lower dosing and systemic exposure offers a viable option for treating vaginal infections. In this study, Metronidazole-loaded chitosan nanoparticles were synthesised employing borax (BX) or tannic acid (TA) as an antimicrobial crosslinking agent for treating BV. The prepared NPs were characterized for various physical, physicochemical, pharmaceutical, thermal and antibacterial properties. Morphological investigation revealed that nanoparticles prepared from 0.5 % w/v chitosan, 1.2 % w/v BX, and 0.4 % w/v metronidazole (MTZ) were non-spherical, with particle sizes of 377.4 ± 37.3 nm and a zeta potential of 34 ± 2.1 mV. The optimised formulation has MIC values of 24 ± 0.5 and 59 ± 0.5 µg/mL, against Escherichia coli (E.coli) and Candida albicans (C.albicans) respectively. The results of DSC and XRD demonstrated no change in the physical state of the drug in the finished formulation. Under simulated vaginal fluid, the optimised formulation demonstrates a cumulative drug release of about 90 % within 6h. The prepared borax crosslinked NPs exhibit anti-fungal activities by inhibiting ergosterol synthesis. The in-vivo antibacterial data indicated a comparable reduction in bacterial count compared to the marketed formulation in female Swiss albino mice treated with optimised nanoparticles. According to histopathological findings, the prepared nanoparticle was safe for vaginal use. Based on the experimental findings, it was concluded that MBCSNPs, due to their good physiochemical and antimicrobial properties, could serve as a potential topical alternative for treating BV and reducing fungal infection.

Blastocystis species growth inhibition in vitro by plant extracts.

BACKGROUND: The protist Blastocystis species (sp.) inhabits the gastrointestinal tracts of humans and animals. In recent decades, alternative natural products derived from plants have demonstrated potential as effective treatments for Blastocystis infection. The anti-Blastocystis activity of three herbal ethanolic extracts- Odontites linkii subsp. cyprius, Ptilostemon chamaepeuce subsp. cyprius and Quercus alnifolia-were investigated in this study. METHODS: Three distinct isolates of Blastocystis sp. maintained in vitro were molecularly subtyped. Cytotoxicity analysis was performed on individual Blastocystis sp. isolates using 250, 500, 1000, and 2000 µg/mL herbal ethanolic extracts for 24 and 48 hours. Quantitative, morphological, and size alterations of Blastocystis cells assessed the cytotoxicity of herbal anti-Blastocystis effect. RESULTS: Following subtyping analysis, one strain of Blastocystis had ST3 and ST1 mixed subtypes, and two strains had ST1 subtypes. Starting after 24 h of incubation, P. cham. subsp. cyprius (1000 µg/mL) exhibited the most pronounced and consistent anti-Blastocystis cytotoxicity against all three strains, comparable to metronidazole. The Ptilostemon chamaepeuce subsp. cyprius anti-Blastocystis cytotoxicity was evident in parasite quantitative distress, morphological alterations, and significant reductions in cell size. Odontites linkii subsp. cyprius cytotoxicity varied among the three Blastocystis strains. The three Blastocystis strains were resistant to Quercus alnifolia. CONCLUSION: P. cham. subsp. cyprius was a potent and promising new herbal extract against Blastocystis sp. in vitro assays.

Anti-quorum sensing activity of α-amidoamides against Agrobacterium tumefaciensNT1: Insights from molecular docking and dynamic investigations to synergistic approach of metronidazole release from gel formulations.

A unique approach is imperative for the development of drugs aimed at inhibiting various stages of infection, rather than solely focusing on bacterial viability. Among the array of unconventional targets explored for formulating novel antimicrobial medications, blocking the quorum-sensing (QS) system emerges as a highly effective and promising strategy against a variety of pathogenic microbes. In this investigation, we have successfully assessed nine α-aminoamides for their anti-QS activity using Agrobacterium tumefaciensNT1 as a biosensor strain. Among these compounds, three (2, 3and, 4) have been identified as potential anti-QS candidates. Molecular docking studies have further reinforced these findings, indicating that these compounds exhibit favorable pharmacokinetic profiles. Additionally, we have assessed the ligand's stability within the protein's binding pocket using molecular dynamics (MD) simulations and MMGBSA analysis. Further, combination of antiquorum sensing properties with antibiotics viaself-assembly represents a promising approach to enhance antibacterial efficacy, overcome resistance, and mitigate the virulence of bacterial pathogens. The release study also reflects a slow and gradual release of the metronidazole at both pH 6.5 and pH 7.4, avoiding the peaks and troughs associated with more immediate release formulations.

Associations between biofilm formation and virulence factors among clinical Helicobacter pylori isolates.

INTRODUCTION: Helicobacter pylori (H. pylori) causes several gastrointestinal diseases. Its virulence factors contributing to disease development include biofilm formation, cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) proteins that induce host tissue damage. In addition, urease activity enables H. pylori growth in the gastric acidic environment. This work aimed to characterize bacterial factors associated with biofilm production among 89 clinical H. pylori isolates, collected from patient gastric biopsies. METHODS: Biofilm production was detected using the crystal violet method. PCR was performed to determine vacA genotype (s1m1, s1m2, s2m1 and s2m2) and cagA gene presence. Urease activity was measured via the phenol red method. Susceptibility to six antibiotics was assessed by the Etest method. RESULTS: Most H. pylori isolates produced biofilm. No association was found between biofilm-formation capacity and cagA presence or vacA genotype. Urease activity levels varied across isolates; no association was found between biofilm-formation and urease activity. Clarithromycin resistance was measured in 49 % of the isolates. Isolates susceptible to tetracycline were more commonly strong biofilm producers. In contrast, a significantly higher rate of strong biofilm producers was observed among resistant isolates to amoxicillin, levofloxacin and rifampicin, compared to susceptible isolates. Non-biofilm producers were more common among isolates sensitive to rifampicin and metronidazole, compared to resistant isolates. CONCLUSIONS: Further studies are needed to understand the factors that regulate biofilm production in order to search for treatments for H. pylori biofilm destruction.

An organometallic hybrid antibiotic of metronidazole with a Gold(I) N-Heterocyclic Carbene overcomes metronidazole resistance in Clostridioides difficile.

Antimicrobial resistance (AMR) has been emerging as a major global health threat and calls for the development of novel drug candidates. Metal complexes have been demonstrating high efficiency as antibacterial agents that differ substantially from the established types of antibiotics in their chemical structures and their mechanism of action. One strategy to exploit this potential is the design of metal-based hybrid organometallics that consist of an established antibiotic and a metal-based warhead that contributes an additional mechanism of action different from that of the parent antibiotic. In this communication, we describe the organometallic hybrid antibiotic 2c, in which the drug metronidazole is connected to a gold(I) N-heterocyclic carbene warhead that inhibits bacterial thioredoxin reductase (TrxR). Metronidazole can be used for the treatment with the obligatory anaerobic pathogen Clostridioides difficile (C. difficile), however, resistance to the drug hampers its clinical success. The gold organometallic conjugate 2c was an efficient inhibitor of TrxR and it was inactive or showed only minor effects against eucaryotic cells and bacteria grown under aerobic conditions. In contrast, a strong antibacterial effect was observed against both metronidazole-sensitive and -resistant strains of C. difficile. This report presents a proof-of-concept that the design of metal-based hybrid antibiotics can be a viable approach to efficiently tackle AMR.

Exposure of Tritrichomonas foetus to sublethal doses of metronidazole induces a specific proinflammatory response in murine macrophages.

Tritrichomonas foetus is a flagellated parasite that primarily infects the reproductive tissues of livestock, causing bovine trichomoniasis. The cytoplasmic membrane of T. foetus contains various compounds that contribute to adherence, colonization, and pathogenicity. Metronidazole (MTZ) is the main treatment for trichomoniasis, but the emergence of drug-resistant strains is a concern due to improper use and dosing. T. foetus infection induces inflammation, and macrophages are key players in the immune response. However, our understanding of the host's immune response to T. foetus is limited, and the specific mechanisms underlying these responses are not well understood. This study aimed to investigate the impact of T. foetus surface proteins from trophozoites cultured under different sublethal MTZ conditions (MTZ-treated T. foetus MPs) on macrophage activation. By analyzing cytokine levels and gene expression in murine macrophages, we demonstrated that MTZ-treated T. foetus MPs induce a specific proinflammatory response. MTZ-treated T. foetus MPs-exposed macrophages exhibited a higher NO and H2 O2 production and overexpression of iNOS and NOX-2 genes in comparison to untreated T. foetus. Additionally, MTZ-treated T. foetus MPs triggered a significant induction of the proinflammatory cytokines IL-1ß, IL-6, TNF-α, and IFN-γ, as well as the overexpression of the TLR4, MyD88, and NF-κB genes on murine macrophages. The study aimed to unravel the immunological response and potential proinflammatory pathways involved in T. foetus infection and MTZ stress. Understanding the immune responses and mechanisms through which T. foetus surface proteins activate macrophages can contribute to the development of new therapeutic strategies for controlling bovine trichomoniasis.

Antibiotic resistance of Helicobacter pylori in Chinese children: A multicenter study from 2016 to 2023.

BACKGROUND: To investigate the antibiotic resistance of Helicobacter pylori (H. pylori) strains to clarithromycin, metronidazole, amoxicillin, levofloxacin, furazolidone, and tetracycline in Chinese children. MATERIALS AND METHODS: This multicenter, retrospective study was conducted from January 2016 through May 2023. Gastric mucosa biopsies were obtained from pediatric participants who underwent upper gastrointestinal endoscopy at 96 hospitals in northern, southwestern, and southeastern China. The susceptibility of H. pylori to six commonly used antibiotics was determined by agar dilution method. RESULTS: Among the 3074 H. pylori isolates, 36.7% were resistant to clarithromycin, 77.3% to metronidazole, 16.6% to levofloxacin, and 0.3% to amoxicillin. No strains were detected to be resistant to furazolidone or tetracycline. During the 8-year study period, resistance to clarithromycin and metronidazole showed a significant upward trend, while the resistance pattern of the other antibiotics demonstrated a slight but nonsignificant fluctuation. Significant regional differences were found in the distribution of clarithromycin resistance among the northern (66.0%), southwestern (48.2%), and southeastern (34.6%) regions. The metronidazole resistance rate was significantly lower in the southeastern coastal region (76.3%) than in the other two regions (88.2% in the north and 87.7% in the southwest). Multi-drug resistance for two or more antibiotics was detected in 36.3% of the H. pylori strains, and the predominant multi-resistance pattern was the dual resistance to clarithromycin and metronidazole. CONCLUSIONS: The prevalence of H. pylori resistance to clarithromycin and metronidazole is rather high in Chinese children and has been increasing over time. A relatively high resistance rate to levofloxacin was also noticed in children, while almost all strains were susceptible to amoxicillin, furazolidone, and tetracycline. It will be of great clinical significance to continuously monitor the antibiotic-resistance patterns of H. pylori in the pediatric population.

Refractoriness to anti-Helicobacter pylori treatment attributed to phenotypic resistance patterns in patients with gastroduodenopathy in Guayaquil-Ecuador.

BACKGROUND: Treatment of Helicobacter pylori gastric infection is complex and associated with increased rates of therapeutic failure. This research aimed to characterize the H. pylori infection status, strain resistance to antimicrobial agents, and the predominant lesion pattern in the gastroduodenal mucosa of patients with clinical suspicion of refractoriness to first- and second-line treatment who were diagnosed and treated in a health center in Guayaquil, Ecuador. METHODS: A total of 374 patients with upper gastrointestinal symptoms and H. pylori infection were preselected and prescribed one of three triple therapy regimens for primary infection, as judged by the treating physician. Subsequently, 121 patients who returned to the follow-up visit with persistent symptoms after treatment were studied. RESULTS: All patients had H. pylori infection. Histopathological examination diagnosed chronic active gastritis in 91.7% of cases; premalignant lesions were observed in 15.8%. The three triple therapy schemes applied showed suboptimal efficacy (between 47.6% and 77.2%), with the best performance corresponding to the scheme consisting of a proton pump inhibitor + amoxicillin + levofloxacin. Bacterial strains showed very high phenotypic resistance to all five antimicrobials tested: clarithromycin, 82.9%; metronidazole, 69.7%; amoxicillin and levofloxacin, almost 50%; tetracycline, 38.2%. Concurrent resistance to clarithromycin-amoxicillin was 43.4%, to tetracycline-metronidazole 30.3%, to amoxicillin-levofloxacin 27.6%, and to clarithromycin-metronidazole 59.2%. CONCLUSIONS: In vitro testing revealed resistance to all five antibiotics, indicating that H. pylori exhibited resistance phenotypes to these antibiotics. Consequently, the effectiveness of triple treatments may be compromised, and further studies are needed to assess refractoriness in quadruple and concomitant therapies.

Primary antibiotic resistance of Helicobacter pylori in India over the past two decades: A systematic review.

BACKGROUND: Helicobacter pylori antibiotic resistance has undergone vast changes in the last two decades. No systematic review has been done on the prevalence of antibiotic resistant H. pylori in India in the last two decades. We evaluated the pattern of resistance rates across various regions of India. MATERIALS AND METHODS: A systematic review of the geographical variations in antibiotic resistance pattern of H. pylori was conducted using PubMed, Google Scholar, Web of Science, Science Direct, etc. for articles published between January 1, 2000 and May 30, 2023. Random effects-model-based Cochran's Q test, I2 statistics, and chi-squared tests were used to measure heterogeneity. RESULTS: The overall resistance was highest against metronidazole (77.65%) followed by amoxicillin (37.78%), levofloxacin (32.8%), clarithromycin (35.64%), furazolidone (12.03%), and tetracycline (11.63%). 14.7% of the H. pylori isolates were multi-drug resistant. Under meta-analysis of each antibiotic, high heterogeneity levels were observed having I2 ranges from 86.53% to 97.70% at p < 0.0001. In sub-group analysis, Metronidazole has a stable rate of resistance as compared to other antibiotics. Other antibiotics have had a downtrend in the last 5 years except for levofloxacin, which has had an uptrend in the resistance rate for the past 5 years. Hence, one should avoid using metronidazole for any kind of first-line treatment. CONCLUSIONS: Metronidazole resistance is high in most regions of India except Assam and Mumbai while clarithromycin is found to be ineffective in South India, Gujarat, and Kashmir. As compared to other antibiotics, resistance to amoxicillin is generally low except in certain regions (Hyderabad, Chennai, and the Gangetic belt of North India). Tetracycline and Furazolidone have the least resistance rates and should be part of anti- H. pylori regimens. The resurgence of high single and multidrug resistance to the commonly used drugs suggests the need for newer antibiotics and regular resistance surveillance studies.

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

BACKGROUND: 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. METHOD: 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). RESULTS: 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). CONCLUSIONS: 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.