Rifabutin and Furazolidone Could Be the Candidates of the Rescue Regimen for Antibiotic-Resistant H. pylori in Korea

Antibiotic susceptibility pattern of Helicobacter pylori against eight antibiotics: A study from North India

BACKGROUND

The purpose of this analysis is to evaluate the antimicrobial susceptibility of eight drugs effective against Helicobacter pylori (H. pylori) strains and the genetic diversity of H. pylori virulence genes to foresee clinical outcomes in North India.

MATERIALS AND METHODS

Fifty-eight H. pylori strains isolated from patients suffering from various gastrointestinal (GI) diseases were included in the study. MICs of various antibiotics were determined by the agar dilution method. The chi-squared test and Fisher exact test were used to determine the p-value, which was considered significant at p-value ≤ 0.05. RStudio 4.0 was used to for the data visualization.

RESULTS

The prevalence of drug resistance was found to be: cefixime (CFM) (41.3%), furazolidone (FZD) (34.4%), amoxicillin (AMX) (20.7%), levofloxacin (LVFX) (70.7%), metronidazole (MTZ) (39.6%), tetracycline (TET) (20.7%), clarithromycin (CLA) (17.2%), and rifabutin (RIF) (17.2%). Out of 58 H. pylori strains, 3 were pan susceptible. There were H. pylori strains with single-drug resistance (21.8%, 12/55), dual resistance (30.9%, 17/55), triple resistance (20%, 11/55), and multidrug resistance (27.3%, 15/55). The resistance rate in MTZ, CLA and RIF were found to be significantly higher in females as compared to males (p = 0.005, p = 0.002, and p = 0.02), respectively. The resistance to TET exhibited significantly higher levels in gastritis compared to GERD, DU, and other disease groups (p = 0.04) respectively.

CONCLUSION

TET, AMX, CLA, and RIF were found to be more effective antibiotics against H. pylori infections, whereas more studies are required to provide evidence on increasing resistance rate of LVFX.

Antibiotic Resistance of Helicobacter pylori: Mechanisms and Clinical Implications

Helicobacter pylori is a pathogenic bacterium associated with various gastrointestinal diseases, including chronic gastritis, peptic ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. The increasing rates of H. pylori antibiotic resistance and the emergence of multidrug-resistant strains pose significant challenges to its treatment. This comprehensive review explores the mechanisms underlying the resistance of H. pylori to commonly used antibiotics and the clinical implications of antibiotic resistance. Additionally, potential strategies for overcoming antibiotic resistance are discussed. These approaches aim to improve the treatment outcomes of H. pylori infections while minimizing the development of antibiotic resistance. The continuous evolution of treatment perspectives and ongoing research in this field are crucial for effectively combating this challenging infection.

Effectiveness of Rifabutin-Based Regimens in Treating Helicobacter pylori Infections

Helicobacter pylori has been reported as a health problem worldwide, affecting a sizable portion of people. Peptic ulcers, gastric cancer, and various extra gastric conditions are associated with this bacterium. The rampant overprescribing of antibiotics has led to the emergence of H. pylori strains resistant to multiple antibiotics, causing a decline in the effectiveness of current treatments. Recently, there has been growing interest in researching alternative treatment options for H. pylori infections that do not respond to initial therapy. Rifabutin, a rifamycin derivative initially designed for tuberculosis treatment and preventing Mycobacterium avium complex infection, has gained attention as a potential rescue medication. It has shown efficacy against H. pylori and the potential to eradicate the bacterium when combined with other antibiotics. This systematic review article focuses on using rifabutin-based regimens as a treatment option after initial treatments have failed. The authors screened literature published in the last five years, between 2017 and 2022, across various search engines and closely examined relevant studies following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The search covered a variety of electronic databases and focused on H. pylori gastritis, rifabutin-based treatment plans, and in vivo investigations in healthy individuals. The comprehensive review provides convincing evidence that rifabutin-based regimens are effective rescue treatments for H. pylori infections. Multiple studies in various areas consistently demonstrated high eradication rates, ranging from 70% to 90%, when rifabutin-containing regimens were used. The analysis found that only a tiny percentage of H. pylori strains (1%) were resistant to rifabutin therapy, further supporting the viability of Rifabutin as an alternative when other antibiotics failed to eradicate H. pylori. The cost of Rifabutin is a significant factor that may limit its accessibility, particularly in resource-constrained settings where H. pylori infection is common. Moreover, the potential side effects of Rifabutin, such as hematological problems, rashes, and digestive issues, need to be considered. However, these side effects are typically manageable and can be reduced by combining Rifabutin with other antibiotics. In conclusion, this systematic review provides evidence supporting the effectiveness of regimens derived from Rifabutin in eliminating H. pylori infections after initial therapy failure. Due to the observation that Rifabutin effectively eradicates resistant H. pylori infections, it can be considered a suitable choice for rescue therapy. Rifabutin-containing regimens should be reserved as fourth- or later-line therapy options, considering economic factors, the risk of microbial resistance, potential side effects, and the availability of alternative medications. Future research should focus on optimizing rifabutin-based regimens and investigating combination therapies that have better H. pylori eradication rates while also addressing the problem of resistant strains.

The Inappropriateness of Using Rifampicin E-Test to Predict Rifabutin Resistance in Helicobacter pylori

BACKGROUND

The aim of this study was to evaluate the rifamycin cross-resistance in Helicobacter pylori, and whether the use of rifampicin E-test strips to screen H. pylori rifabutin resistance is appropriate.

METHODS

A total of 89 H. pylori isolates were included. Rifampicin minimum inhibitory concentrations (MICs) were obtained by E-test, while the MICs for rifapentine, rifaximin, and rifabutin were determined by agar dilution method. The rifamycin resistance rates based on different breakpoints were compared. Isolates with high-level rifampicin resistance were subjected to whole-genome sequencing.

RESULTS

A wide distribution of MICs (mostly in the range 0.125-8 mg/L) was observed for rifampicin, rifapentine, and rifaximin. Using MIC >1, ≥ 4, and > 4 mg/L as the breakpoints, resistance rates to rifampicin/rifapentine/rifaximin were 60.4%/48.3%/38.2%, 28.1%/25.8%/23.6%, and 15.7%/16.9%/7.9%, respectively. However, the rifabutin MICs of all the tested H. pylori isolates were extremely low (≤0.016 mg/L). Applying MIC ≥ 0.125 mg/L as the breakpoint, rifabutin resistance was nil. No mutation was found in the rpoB gene sequences of the 2 isolates with high-level rifampicin resistance.

CONCLUSIONS

There is a lack of cross-resistance between rifabutin and other rifamycins in H. pylori. The use of rifampicin E-test to predict H. pylori rifabutin resistance is inappropriate.

Synergistic activity and molecular modelling of fosfomycin combinations with some antibiotics against multidrug resistant Helicobacter pylori

Antibiotic resistance represents the main challenge of Helicobacter pylori infection worldwide. This study investigates the potential bactericidal effects of fosfomycin combinations with clarithromycin, metronidazole, ciprofloxacin, amoxicillin, rifampicin, and doxycycline against thirty-six H. pylori strains using the checkerboard and time-kill assay methods. The results showed that ≥ 50% of the strains were resistant to the six antibiotics. Remarkably, only six strains exerted resistance to these antibiotics, with the minimum inhibitory concentrations (MICs) ranges of (3.2–12.8 mg/l), (32–256 mg/l), (3.2–51.2 mg/l), (3.2–25.6 mg/l), (1.6–3.2 mg/l), and (25.6 > 51.2 mg/l), respectively. The seven antibiotics were evaluated through in silico studies for their permeability and ability to bind UDP-N-acetylglucosamine1-carboxyvinyltransferase (MurA) of H. pylori. The results indicated that fosfomycin exhibited the highest predicted membrane permeability (membrane ∆G insert = − 37.54 kcal/mol) and binding affinity (docking score = − 5.310 kcal/mol) for H. pylori MurA, compared to other tested antibiotics. The combinations of fosfomycin with these antibiotics exerted synergistic interactions (Fractional inhibitory concentration, FIC index < 1) against the six strains. Importantly, the combinations of fosfomycin with clarithromycin, doxycycline and rifampicin achieved bactericidal effects (reduction ≥ 3.0 Log₁₀ cfu/ml) against the most resistant H. pylori strain. Notably, these effects increased with presence of metronidazole, which enhanced the activity of the fosfomycin combination with amoxicillin from a weak inhibition to bactericidal effect. This study provides evidence that the combination of fosfomycin with either clarithromycin, amoxicillin, doxycycline, or rifampicin (especially with the presence of metronidazole) could be a promising option for treating MDR H. pylori infection.

Therapeutic Potential of Sitafloxacin as a New Drug Candidate for Helicobacter Eradication in Korea: An In Vitro Culture-Based Study

Background: Increased prevalence of antibiotic resistance to Helicobacter pylori (H. pylori) infection worldwide has driven the search for a new therapeutic candidate. Recently, sitafloxacin, a novel 4-quinolone agent, has emerged as a new therapeutic option for H. pylori eradication, in Japan. However, data on its efficacy for H. pylori eradication in Korea are limited. Therefore, we aimed to investigate the therapeutic potential of sitafloxacin as a first-line treatment for patients with Helicobacter infection through gastric tissue culture-based studies. Materials and Methods: We prospectively enrolled treatment-naïve patients with H. pylori infection who visited the Gil Medical Center between March 2015 and March 2018. After obtaining written informed consent from patients, a total of 121 H. pylori strains were collected. We tested the susceptibility of these strains to sitafloxacin, and other antibiotics for Helicobacter eradication, including clarithromycin (CLR), metronidazole (MTZ), amoxicillin (AMX), tetracycline (TET), levofloxacin (LEV), and ciprofloxacin (CIP) using the agar dilution technique. The minimum inhibitory concentration (MIC) of these antibiotics against H. pylori strains were determined. Results: None of the H. pylori strains obtained were resistant to sitafloxacin (MIC > 1, n = 0), while other conventional eradication drugs including CLR, MTZ, AMX, and TET showed 24.8% (n = 30), 30.6% (n = 37), 5.0% (n = 6), and 0.8% (n = 1) resistance, respectively. Compared to the resistance rates of other quinolones (LEV [36.4%, n = 44] and CIP [37.2%, n = 45]), sitafloxacin showed the best antibiotic performance against Helicobacter strains (0%, n = 0). Furthermore, sitafloxacin also inhibited the growth of 14 H. pylori strains (12.4%), which were resistant to both of clarithromycin, and metronidazole, and 27 strains (22.3%) with multidrug resistance. Conclusions: Sitafloxacin might be a new promising candidate for Helicobacter eradication where antibiotic resistance for Helicobacter is an emerging medical burden, such as in Korea.

In vitro synergy of 5-nitrofurans, vancomycin and sodium deoxycholate against Gram-negative pathogens

Introduction

There is an urgent need for effective therapies against bacterial infections, especially those caused by antibiotic-resistant Gram-negative pathogens.

Hypothesis

Synergistic combinations of existing antimicrobials show promise due to their enhanced efficacies and reduced dosages which can mitigate adverse effects, and therefore can be used as potential antibacterial therapy.

Aim

In this study, we sought to characterize the in vitro interaction of 5-nitrofurans, vancomycin and sodium deoxycholate (NVD) against pathogenic bacteria.

Methodology

The synergy of the NVD combination was investigated in terms of growth inhibition and bacterial killing using checkerboard and time-kill assays, respectively.

Results

Using a three-dimensional checkerboard assay, we showed that 5-nitrofurans, sodium deoxycholate and vancomycin interact synergistically in the growth inhibition of 15 out of 20 Gram-negative strains tested, including clinically significant pathogens such as carbapenemase-producing Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii, and interact indifferently against the Gram-positive strains tested. The time-kill assay further confirmed that the triple combination was bactericidal in a synergistic manner.

Conclusion

This study demonstrates the synergistic effect of 5-nitrofurans, sodium deoxycholate and vancomycin against Gram-negative pathogens and highlights the potential of the combination as a treatment for Gram-negative and Gram-positive infections.

Rifabutin for the Treatment of Helicobacter Pylori Infection: A Review

Nowadays, apart from having to know first-line Helicobacter pylori eradication regimens well, we must also be prepared to face treatment failures. The aim of this review is to summarize the role of rifabutin in the management of H. pylori infection. Bibliographical searches were performed in PubMed. Data on resistance and efficacy of rifabutin-containing regimens on H. pylori eradication were meta-analyzed. Mean H. pylori rifabutin resistance rate (39 studies, including 9721 patients) was 0.13%; when studies only including patients naïve to H. pylori eradication treatment were considered, this figure was even lower (0.07%). Mean H. pylori eradication rate (by intention-to-treat) with rifabutin-containing regimens (3052 patients) was 73%. Respective cure rates for second-, third-, fourth- and fifth-line therapies, were 79%, 69%, 69% and 72%. Most studies administered rifabutin 300 mg/day, which seemed to be more effective than 150 mg/day. The ideal length of treatment remains unclear, but 10–12-day regimens are generally recommended. Adverse events to rifabutin treatment in H. pylori studies were relatively infrequent (15%), and severe adverse events were exceptional (myelotoxicity was the most significant, although always reversible). In summary, rifabutin-containing therapy represents an encouraging strategy generally restricted, at present, to patients where previous (usually multiple) eradication regimens have failed.

Secondary Antibiotic Resistance, Correlation between Genotypic and Phenotypic Methods and Treatment in Helicobacter pylori Infected Patients: A Retrospective Study

The aim of this study was to evaluate the secondary resistance in Helicobacter pylori (Hp) infected patients who had failed a first-line therapy, and to compare the genotypic tests performed directly on gastric samples with phenotypic tests performed on culture media. The eradication rate of patients treated with bismuth quadruple therapy (BQT) is also evaluated. A total of 80 positive specimens were retrospectively examined. Antibiotic susceptibility testing of Hp strains was performed by E-test, whereas a molecular commercially available method was used for detecting the mutations involved in clarithromycin and levofloxacin resistance. High resistance levels to metronidazole and clarithromycin (61.6% and 35%, respectively) and worrying resistance levels to levofloxacin (15%) were found phenotypically. Multiple resistance to two or three antibiotics was observed as well. The polymorphism A2143G on clarithromycin 23S rRNA gene was found in 34/80 (42.5%) isolates including 10 mixed infections (29%), whereas 28/80 (35%) strains were resistant phenotypically. Levofloxacin resistance corresponded to 30% by PCR and 15% by E-test (statistically significant, p < 0.05). The knowledge of clarithromycin and levofloxacin resistance is crucial to establish an appropriate therapy in different geographical areas. The genetic methods were superior to phenotypic techniques in the absence of live bacteria or for identifying mixed infections that may lead to a resistance underestimation. The BQT eradication rate was effective (90%).

Rifamycin use for treatment of Helicobacter pylori infection: a review of recent data

Helicobacter pylori eradication has become increasingly challenging. We focused on recent data about rifamycin resistance and rifamycin-containing regimens. Rifampin (rifampicin) resistance rates were <1-18.8% (often ≤7%), while those to rifabutin were 0-<4%. To detect rifabutin resistance by rifampin, 4 mg/l breakpoint was suggested. Eradication success by rifaximin-based regimens was disappointing (<62%), while that of rifabutin-containing regimens was 54.5->96%, reaching >81% in four studies. Some newer rifamycin analogs like TNP-2092 need further investigation. Briefly, although rifabutin-based regimens carry a risk of adverse effects or increasing mycobacterial resistance, they may be a rational choice for some multidrug-resistant H. pylori strains and as a third-line eradication therapy. Bismuth addition to rifabutin-based therapy and combined rifabutin-containing capsules (Talicia) are promising treatment options.

Two-week bismuth-containing quadruple therapy and concomitant therapy are effective first-line treatments for Helicobacter pylori eradication: A prospective open-label randomized trial

BACKGROUND

Increasing levels of antibiotic resistance have reduced the Helicobacter pylori (H. pylori) eradication rates afforded by the standard triple therapy. Thus, 2-wk first-line four-drug regimens must be considered.

AIM

To analyze the eradication rates of modified bismuth-containing quadruple therapy (mBCQT) and concomitant therapy (CT), the associated adverse events, and compliance.

METHODS

Patients infected with H. pylori were prospectively randomized to receive mBCQT or CT for 2 wk. mBCQT featured a proton pump inhibitor (PPI), bismuth, metronidazole, and tetracycline, taken twice daily. CT included a PPI, clarithromycin, metronidazole, and amoxicillin, taken twice daily. The ¹³C-urea breath test was performed no earlier than 4 wk after therapy concluded to confirm eradication. If either the histological or rapid urease test was positive, H. pylori infection was diagnosed.

RESULTS

The demographic characteristics of 68 patients who received mBCQT and 68 who received CT did not differ significantly. On intention-to-treat analysis, the eradication rate was 88.2% (60/68) in the mBCQT group and 79.4% (54/68) in the CT group (P = 0.162). By per-protocol analysis, the respective eradication rates were 98.4% (60/61) and 93.1% (54/58) (P = 0.199). More CT than mBCQT patients experienced adverse events [33.8% (23/68) mBCQT vs 51.5% (35/58) CT patients, respectively, P = 0.037]. All patients showed good compliance [85.3% (58/68) mBCQT vs 82.4% (56/68) CT patients, P = 0.641].

CONCLUSION

The H. pylori eradication rates of the 2-wk mBCQT and CT regimens are high. Most patients show good compliance, and more CT than mBCQT patients experience adverse events.