Primary antimicrobial resistance rates and prevalence of Helicobacter pylori infection in the north of Spain. A 13-year retrospective study

Rapid diagnosis and precision treatment of Helicobacter pylori infection in clinical settings

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of approximately half of the worldwide population, with higher prevalence in densely populated areas like Asia, the Caribbean, Latin America, and Africa. H. pylori infections range from asymptomatic cases to potentially fatal diseases, including peptic ulcers, chronic gastritis, and stomach adenocarcinoma. The management of these conditions has become more difficult due to the rising prevalence of drug-resistant H. pylori infections, which ultimately lead to gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. In 1994, the International Agency for Research on Cancer (IARC) categorized H. pylori as a Group I carcinogen, contributing to approximately 780,000 cancer cases annually. Antibiotic resistance against drugs used to treat H. pylori infections ranges between 15% and 50% worldwide, with Asian countries having exceptionally high rates. This review systematically examines the impacts of H. pylori infection, the increasing prevalence of antibiotic resistance, and the urgent need for accurate diagnosis and precision treatment. The present status of precision treatment strategies and prospective approaches for eradicating infections caused by antibiotic-resistant H. pylori will also be evaluated.

A review for non-antibiotic treatment of Helicobacter pylori: new insight

Gastric ulcers and gastric cancer are brought on by the Helicobacter pylori bacteria, which colonizes under the stomach mucous membrane. Different medication regimens are used to remove it, but the illness returns and becomes more resistant, which lowers the treatment rates. Additionally, this bacterium now exhibits a skyrocketing level of multi-drug resistance, necessitating recurrent therapeutic treatments. The negative effects of synthetic medications in comparison to conventional therapies are another significant factor in favor of non-pharmacological therapy. The most significant side effects of popular anti-gastric ulcer medications include nausea, vomiting, and diarrhea. Stomach ulcers have previously been treated with herbal remedies and complementary treatments like probiotics. When probiotics are ingested, the host experiences several advantages that may be brought about by altering the bacterial flora in the digestive system. Additionally, stronger-acting chemical compounds and plant extracts can be employed to treat patients. In this article, we look at the substances and medications that are utilized in place of synthetic stomach ulcer-curing treatments.

A comprehensive review on pharmacological, toxicity, and pharmacokinetic properties of phillygenin: Current landscape and future perspectives

Forsythiae Fructus is a traditional Chinese medicine frequently in clinics. It is extensive in the treatment of various inflammation-related diseases and is renowned as 'the holy medicine of sores'. Phillygenin (C21H24O6, PHI) is a component of lignan that has been extracted from Forsythiae Fructus and exhibits notable biological activity. Modern pharmacological studies have confirmed that PHI demonstrates significant activities in the treatment of various diseases, including inflammatory diseases, liver diseases, cancer, bacterial infection and virus infection. Therefore, this review comprehensively summarizes the pharmacological effects of PHI up to June 2023 by searching PubMed, Web of Science, Science Direct, CNKI, and SciFinder databases. According to the data, PHI shows remarkable anti-inflammatory, antioxidant, hepatoprotective, antitumour, antibacterial, antiviral, immunoregulatory, analgesic, antihypertensive and vasodilatory activities. More importantly, NF-κB, MAPK, PI3K/AKT, P2X7R/NLRP3, Nrf2-ARE, JAK/STAT, Ca2+-calcineurin-TFEB, TGF-β/Smads, Notch1 and AMPK/ERK/NF-κB signaling pathways are considered as important molecular targets for PHI to exert these pharmacological activities. Studies of its toxicity and pharmacokinetic properties have shown that PHI has very low toxicity, incomplete absorption in vivo and low oral bioavailability. In addition, the physico-chemical properties, new formulations, derivatives and existing challenges and prospects of PHI are also reviewed and discussed in this paper, aiming to provide direction and rationale for the further development and clinical application of PHI.

Epidemiology of Helicobacter pylori Resistance to Antibiotics (A Narrative Review)

Helicobacter pylori (H. pylori) is the most common bacterial infection worldwide and one of the main etiological factors of chronic gastritis, peptic ulcer disease, and stomach neoplasms. The mass application of antibiotics without testing, especially during the last years of the pandemic of SARS-CoV-2, could lead to a dramatic increase in antibiotic resistance and reduced effectiveness of eradication regimens for H. pylori infection. The epidemiology of H. pylori resistance to antibiotics still has unclear mechanisms. Antibiotic policy should be intensified to optimize treatment, and regular monitoring of resistance of H. pylori in different geographical regions should be conducted. Individualized treatment according to susceptibility testing is strongly advisable, and the best treatment regimens should be selected. The mutations in the genes encoding the antibiotic target protein are significant risk factors for H. pylori resistance. Iatrogenic errors in diagnosis and prescribing treatment for the failure of H. pylori eradication are other important risk factors. The low level of awareness and compliance with the correct treatment influence the rate of H. pylori resistance. Epidemiological surveillance of antibiotic resistance and the adoption of new treatment strategies are needed. The discovery of an efficient vaccine against H. pylori could reduce the pressure of the world's growing antibiotic resistance.

Therapeutic effect of demethylated hydroxylated phillygenin derivative on Helicobacter pylori infection

Modifying and transforming natural antibacterial products is a novel idea for developing new efficacious compounds. Phillygenin has an inhibitory effect on H. pylori. The aim of the present study was to prepare a phillygenin derivative (PHI-Der) through demethylation and hydroxylation. The minimum inhibitory concentration of 18 strains of H. pylori from different sources was 8-32 μg/mL in vitro, and the activity increased 2-8 times than that of phillygenin. PHI-Der could significantly inhibit the colonization of H. pylori in vivo, reduce the inflammatory response, and promote the repair of inflammatory damage. Further, we used SwissTargetPrediction to predict that its main targets are ALOX5, MCL1, and SLC6A4, and find that it can inhibit bacterial biofilm formation and reduce bacterial infection of cells. It can enhance the intracellular oxidative capacity of H. pylori to inhibit H. pylori growth. Further, it could prevent the oxidation of H. pylori-infected cells and reduce the inflammatory response, which plays a role in protection. In conclusion, compared to phillygenin, PHI-Der had better antibacterial activity and was more effective in treating H. pylori infection. It has characteristics of high safety, specificity, resistance to drug resistance and better antibacterial activity than phillygenin, it's a good antioxidant for host cells.

Antimicrobial Resistance Molecular Mechanisms of Helicobacter pylori in Jordanian Children: A Cross-Sectional Observational Study

Background: H. pylori antimicrobial resistance causes increasing treatment failure rates among H. pylori gastritis in children. This study investigates the molecular mechanisms of H. pylori antimicrobial resistance among Jordanian children. Methods: Demographic, clinical, and laboratory data were recorded for children referred to Prince Hamzah Hospital. Clarithromycin, Metronidazole, and Levofloxacin susceptibility were tested via E-test. Clarithromycin-related mutations were investigated using Real-Time (RT)-PCR and Levofloxacin resistance was analyzed with DNA sequencing of the gyrA gene. Results: 116 children were recruited, including 55.2% females and 55.2% in the age range of 10.1 to 14 years. A total of 82.7% were naïve to eradication therapy. H. pylori positivity was 93.9%, 89.6%, 61.7%, and 84.3% according to Rapid Urease Test, histology, culture, and RT-PCR, respectively. Resistance rates were 25.9% for Clarithromycin, 50% for Metronidazole, and 6.9% for Levofloxacin via E-test. A2142G or A2143G or a combination of both mutations concerning Clarithromycin resistance were documented in 26.1% of samples, while mutations in gyrA gen-related to Levofloxacin resistance were reported in 5.3% of samples. Antibiotic resistance was significantly affected by abdominal pain, anemia, hematemesis, and histological findings (p < 0.05). Conclusion: H. pylori resistance was documented for Metronidazole and Clarithromycin. RT-PCR for H. pylori identification and microbial resistance determination are valuable alternatives for cultures in determining antimicrobial susceptibility.

Evolution of Helicobacter pylori Resistance to Antibiotics: A Topic of Increasing Concern

Antibiotic resistance among Helicobacter pylori strains is the major cause of eradication failure. Resistance prevalence is dynamic and can greatly vary among countries over the years. We revealed H. pylori resistance trends for five antibiotics in 14 countries through articles predominantly published in 2018-2022, since the latest data can best show the most recent trends in resistance evolution. Amoxicillin resistance generally exhibited no evolution, yet it increased in Bulgaria, Iran, China, and Vietnam. Metronidazole resistance exhibited different trends, including an increase, a decrease and no evolution in six, three, and five studies, respectively. Clarithromycin resistance increased in Australia, Belgium, Bulgaria, Italy, Iran, and Taiwan, but remained stable in France, Spain, Russia, China, Chile, and Colombia. Tetracycline resistance was low and stable except in Iran. Levofloxacin resistance increased in four European and six other countries/regions, without significant increases in France, Spain, and Chile. In Chile, triple resistance also increased. In countries such as France and Spain, resistance to most antibiotics was stabilized, while in Bulgaria, Belgium, Iran and Taiwan, resistance to three or more agents was reported. Use of non-recommended regimens, national antibiotic consumption, patient's compliance, host factors, strain virulence, migrations, and azithromycin overuse during the COVID-19 pandemic can influence resistance evolution. New drugs, eradication regimens and diagnostic methods, such as next-generation sequencing can improve H. pylori infection control.

The prevalence of clarithromycin-resistant Helicobacter pylori isolates: a systematic review and meta-analysis

Background

Knowledge of global clarithromycin (CLA)-resistant rates of Helicobacter pylori (H. pylori) is crucial for decision of the most appropriate eradication therapies with good clinical outcomes. Therefore, this review and meta-analysis aimed to evaluate the global prevalence of the CLA resistance in H. pylori to provide some guidance for selecting the first-line antibiotics.

Method

A comprehensive search was performed for relevant literature until April 2021 in PubMed, Embase, and Web of Science databases. Freeman-Tukey double arcsine transformation was performed to estimate the weighted pooled prevalence of resistance.

Results

The meta-analysis included 248 articles. The prevalence of CLA-resistant H. pylori was 27.53% (95% CI [25.41-29.69]). The heterogeneity between reports was significant (I² = 97.80%, P < 0.01). The resistance rate increased from 24.28% in 2010-2017 to 32.14% in 2018-2021 (P < 0.01). Iran, with 38 articles, has the most report. Nevertheless, Switzerland, Portugal, and Israel had the highest resistance rates (67.16%, 48.11%, and 46.12%, respectively). The heterogeneity between the continents and the antimicrobial susceptibility methods also interpreted standard guidelines and breakpoints was insignificant (P > 0.05).

Conclusion

Overall CLA resistance rate was 27.53%, worldwide. The difference in CLA resistance rate among the included studies can be due to several reasons such as differences in antibiotic prescription rates in various geographic areas, use of different breakpoints or inaccurate criteria in performed studies, and the emergence of multidrug-resistant (MDR) strains.

V Spanish Consensus Conference on Helicobacter pylori infection treatment

Helicobacter pylori infection is very common in the Spanish population and represents the main cause of chronic gastritis, peptic ulcer, and gastric cancer. The last iteration of Spanish consensus guidelines on H. pylori infection was conducted in 2016. Recent changes in therapeutic schemes along with increasing supporting evidence were key for developing the V Spanish Consensus Conference (May 2021). Fourteen experts performed a systematic review of the scientific evidence and developed a series of recommendations that were subjected to an anonymous Delphi process of iterative voting. Scientific evidence and the strength of the recommendation were classified using GRADE guidelines. An eradication therapy, when prescribed empirically, is considered acceptable when it reliably achieves, or preferably surpass, 90% cure rates. Currently, only quadruple therapies (with or without bismuth) and generally lasting 14 days, accomplish this goal in first- and second-line therapies. A non-bismuth quadruple concomitant regimen (proton pump inhibitor, clarithromycin, amoxicillin, and metronidazole) or a quadruple bismuth-based combination (proton pump inhibitor, bismuth, tetracycline, and metronidazole), are recommended as first-line regimens. Rescue therapies after eradication failure and management of H. pylori infection in peptic ulcer disease were also reviewed.

Antibiotic resistances and eradication rates in Helicobacter pylori infection

INTRODUCTION

The resistance to antibiotics of Helicobacter pylori (H. pylori) is the main factor that affects current therapeutic treatments. The main objective of this study is to describe the pattern of antibiotic resistances in children with an infection due to H. pylori.

PATIENTS AND METHODS

An observational, retrospective study was conducted from 2014 to 2019, which included patients between 5 and 17 years old, on whom a gastroscopy, with a gastric biopsy culture positive for H. pylori, and an antibiotic sensitivity study was performed. The antibiotic sensitivity studies were performed using an epsilometer (E-test). The cut-off points to define the resistances were those proposed by the European Committee on Antimicrobial Susceptibility Testing - EUCAST. The eradication study was performed using the 13C-urea breath test or the H. pylori monoclonal test in faeces 6-8 weeks after finalising the treatment.

RESULTS

The study included 80 patients (63.8% females), with a mean age of 11.9 years (SD ± 2.7 DS). Over one-third (38.8%) of the patients had received previous treatment for H. pylori. In the endoscopy, peptic ulcer lesions were observed in 10% of patients. More than two-thirds (67.5%) had resistance to at least one drug. 16.3% presented double resistance. The primary resistances were: clarithromycin, 44.9%, metronidazole 16.3%, levofloxacine 7.9%, and amoxicillin 2%. Patients that received treatment according to the new ESPGHAN 2017 guidelines had significantly higher eradication rates compared to those that received treatment according to previous guidelines (80% vs. 55.8%, P = 0.04).

CONCLUSIONS

The high rate of H. pylori resistances, and as a result, the low eradication rates, are still a very important cause for concern. The first line treatment, when this is indicated must be given following the antibiotic sensitivity studies, and in the cases where these cannot be done or are not available, at least in accordance with the regional resistance rates. The correct application of the new guidelines significantly improves the eradication rate.

Antibiotic Resistance Prevalence and Trends in Patients Infected with Helicobacter pylori in the Period 2013-2020: Results of the European Registry on H. pylori Management (Hp-EuReg)

Background: Bacterial antibiotic resistance changes over time depending on multiple factors; therefore, it is essential to monitor the susceptibility trends to reduce the resistance impact on the effectiveness of various treatments. Objective: To conduct a time-trend analysis of Helicobacter pylori resistance to antibiotics in Europe. Methods: The international prospective European Registry on Helicobacter pylori Management (Hp-EuReg) collected data on all infected adult patients diagnosed with culture and antimicrobial susceptibility testing positive results that were registered at AEG-REDCap e-CRF until December 2020. Results: Overall, 41,562 patients were included in the Hp-EuReg. Culture and antimicrobial susceptibility testing were performed on gastric biopsies of 3974 (9.5%) patients, of whom 2852 (7%) were naive cases included for analysis. The number of positive cultures decreased by 35% from the period 2013–2016 to 2017–2020. Concerning naïve patients, no antibiotic resistance was found in 48% of the cases. The most frequent resistances were reported against metronidazole (30%), clarithromycin (25%), and levofloxacin (20%), whereas resistances to tetracycline and amoxicillin were below 1%. Dual and triple resistances were found in 13% and 6% of the cases, respectively. A decrease (p < 0.001) in the metronidazole resistance rate was observed between the 2013–2016 (33%) and 2017–2020 (24%) periods. Conclusion: Culture and antimicrobial susceptibility testing for Helicobacter pylori are scarcely performed (<10%) in Europe. In naïve patients, Helicobacter pylori resistance to clarithromycin remained above 15% throughout the period 2013–2020 and resistance to levofloxacin, as well as dual or triple resistances, were high. A progressive decrease in metronidazole resistance was observed.

Antibacterial activity of Zn-loaded Cuban zeolite against Helicobacter pylori in comparison to its Na-loaded and unmodified counterparts

Helicobacter pylori can be found in the stomach of about half of the humans, and a large population can be associated with serious diseases. To survive in the stomach H. pylori increases the pH locally by producing ammonia which binds to H⁺ becoming ammonium. This work investigated the effects on the in-vitro growth of H. pylori of a natural cation-exchanger mainly composed (≈70%) of clinoptilolite and mordenite. The zeolitized material from Cuba was evaluated in its original form (M), as well as in its Na- (M-Na) and Zn-exchanged (M-Zn) counterparts. In the preliminary agar cup diffusion test, H. pylori revealed susceptibility only to M-Zn, with a direct relationship between concentration and width of inhibition halo. Further experiments evidenced that bacterium replication increases when ammonium is supplied to the growth medium and decreases when zeolites subtract NH₄⁺ via ion exchange. Due to the multi-cationic population of its zeolites M was not effective enough in removing ammonium and, in the Minimum Inhibitory Concentration (MIC) test, allowed bacterial growth even at a concentration of 50 mg/mL. Inhibition was achieved with M-Na because it contained sodium zeolites capable of maximizing NH₄⁺ subtraction, although the MIC was high (30 mg/mL). M-Zn evidenced a more effective inhibitory capacity, with a MIC of 4 mg/mL. Zinc has antimicrobial properties and H. pylori growth was affected by Zn²⁺ released from clinoptilolite and mordenite. These zeolites, being more selective towards NH₄⁺ than Zn²⁺, can also subtract ammonium to the bacterium, thus enhancing the efficacy of M-Zn.

[Antibiotic resistances and eradication rates in Helicobacter pylori infection]

INTRODUCTION

The resistance to antibiotics of Helicobacter pylori (H. pylori) is the main factor that affects current therapeutic treatments. The main objective of this study is to describe the pattern of antibiotic resistances in children with an infection due to H. pylori.

PATIENTS AND METHODS

An observational, retrospective study was conducted from 2014 to 2019, which included patients between 5 and 17 years old, on whom a gastroscopy, with a gastric biopsy culture positive for H. pylori, and an antibiotic sensitivity study was performed. The antibiotic sensitivity studies were performed using an epsilometer (E-test). The cut-off points to define the resistances were those proposed by the European Committee on Antimicrobial Susceptibility Testing - EUCAST. The eradication study was performed using the 13C-urea breath test or the H. pylori monoclonal test in faeces 6-8 weeks after finalising the treatment.

RESULTS

The study included 80 patients (63.8% females), with a mean age of 11.9 years (SD±2.7DS). Over one-third (38.8%) of the patients had received previous treatment for H. pylori. In the endoscopy, peptic ulcer lesions were observed in 10% of patients. More than two-thirds (67.5%) had resistance to at least one drug. 16.3% presented double resistance. The primary resistances were: clarithromycin, 44.9%, metronidazole 16.3%, levofloxacine 7.9%, and amoxicillin 2%. Patients that received treatment according to the new ESPGHAN 2017 guidelines had significantly higher eradication rates compared to those that received treatment according to previous guidelines (80% vs. 55.8%, P=.04).

CONCLUSIONS

The high rate of H.pylori resistances, and as a result, the low eradication rates, are still a very important cause for concern. The first line treatment, when this is indicated must be given following the antibiotic sensitivity studies, and in the cases where these cannot be done or are not available, at least in accordance with the regional resistance rates. The correct application of the new guidelines significantly improves the eradication rate.

Review - Treatment of Helicobacter pylori infection 2020

This review summarizes important studies regarding Helicobacter pylori therapy published from April 2019 to April 2020. The main themes that emerge involve studies assessing antibiotic resistance, and there is also growing momentum behind the utility of vonoprazan as an alternative to proton pump inhibitor (PPI) therapy and also bismuth-based regimens as a first-line regimen. Antibiotic resistance is rising wherever it is being assessed, and clarithromycin resistance in particular has reached a point where it may no longer be a viable therapy without previous testing in many regions of the world. The evidence for the efficacy of a bismuth-based quadruple therapy as a first-line therapy is now very clearly established, and there is substantial evidence that it is the best performing first-line therapy. The utility of vonoprazan as an alternative to PPI therapy, especially in resistant and difficult-to-treat groups, has also been considered in great detail this year, and it may offer an opportunity in the near future to reduce the problem of antibiotic resistance.

Epidemiological investigation of Helicobacter pylori infection in elderly people in Beijing

BACKGROUND

The Helicobacter pylori (H. pylori) infection rate in China is approximately 50%. H. pylori is a pathogenic factor of peptic ulcer and chronic gastritis. In addition, H. pylori infection may also be associated with a variety of cardiovascular diseases in elderly people, such as arteriosclerosis, coronary heart disease, and cerebral infarction, having deleterious effect on their health. With the aging of the population, the disease characteristics of the elderly population have been increasingly valued by the whole society. We conducted an epidemiological survey of H. pylori infection among elderly people in Beijing to provide a basis for health management of H. pylori infection.

AIM

To understand the epidemiological characteristics of H. pylori infection in elderly people in Beijing.

METHODS

A total of 1090 elderly people aged more than 60 years from different parts of Beijing (urban and rural areas) were selected using the random cluster sampling method. Structured questionnaires were completed during home visits and the ¹³C-urea breath test was conducted for H. pylori detection.

RESULTS

The prevalence of H. pylori infection was 46.5% (507/1090). The infection rate in men was 51.8%, which was significantly higher than that in women (42.5%; P < 0.05). The H. pylori infection rate in illiterate people was significantly higher than that in literate persons (53.5% vs 44.8%, P < 0.05). The total infection rate of H. pylori gradually increased with age and the difference was statistically significant (P < 0.01). The H. pylori infection rate in smokers was significantly higher than that in non-smokers and those who had quit smoking (P < 0.05).

CONCLUSION

The prevalence of H. pylori infection among elderly people is 46.5% and the infection rate gradually increases with age. Sex, education level, age, and smoking were determined to be H. pylori infection risk factors. The relationship of H. pylori infection with region, occupation, drinking, and diet structure needs to be further studied.

High Primary Antibiotic Resistance of Helicobacter pylori Strains Isolated from Pediatric and Adult Patients in Poland during 2016-2018

Monitoring the antibiotic resistance of H. pylori is an important step in the effective treatment of this bacterium, thus the aim of the present study was to assess the prevalence of antimicrobial resistance of H. pylori strains isolated from pediatric and adult patients with primary infections in 2016–2018. Antral biopsies from 334 treatment-naïve patients (126 children and 208 adults) were obtained. A total of 71 clinical H. pylori strains (22 from children and 49 from adults) were isolated and examined for amoxicillin (AMX), clarithromycin (CLR), metronidazole (MTZ), tetracycline (TET), and levofloxacin (LEV) susceptibility. The activity of the antibiotics was measured by E-tests. Strains were considered as resistant to antibiotics with minimum inhibitory concentrations (MICs) equal to ≥0.125 μg/mL (AMX), ≥0.5 μg/mL (CLR), ≥8 μg/mL (MTZ), and ≥1 μg/mL (TET and LEV). The highest prevalence of antibiotic resistance in H. pylori strains was observed for CLR and MTZ, at frequencies of 54.5% and 31.8% vs. 30.6% and 46.9% for children and adults, respectively. A much lower frequency of isolation of resistant strains was demonstrated for LEV and TET, this being 9.1% and 4.5% vs. 18.4% and 4.1% for pediatric and adult patients, respectively. The presence of AMX-resistant strains was not observed. The H. pylori strains isolated from Polish patients with primary infections showed a high level of antibiotic resistance to CLR and MTZ (>30%).

Treatment strategies and preventive methods for drug-resistant Helicobacter pylori infection

The infection and drug resistance rates of Helicobacter pylori (H. pylori) are high and must be prevented and treated by better strategies. Based on recent research advances in this field as well as the results from our team and those on traditional Chinese medicine, we review the causes of drug resistance, and prevention and treatment strategies for drug-resistant H. pylori infection, with an aim to make suggestions for the development of new drugs, such as establishment of new target identification and screening systems, modification of existing drug structures, use of new technologies, application of natural products, and using a commercial compound library. This article may provide reference for eradication of drug-resistant H. pylori.

Update on quinolone-containing rescue therapies for Helicobacter pylori infection

Third generation of quinolones, such as levofloxacin and moxifloxacin, -containing regimens are often used in second-line or rescue treatment of Helicobacter pylori infection. However, the increasing antibiotic resistance to quinolones affects the efficacies of quinolones-containing therapies in recent years. Therefore, there is a need to enhance the effectiveness of quinolones-containing therapies. Sitafloxacin, a fourth-generation quinolone, and vonoprazan, a novel potassium-competitive acid blocker, are now available as more effective treatment options. The aim of this paper is to summarize the current evidence of quinolone-containing therapies in rescue treatments, and to discuss the importance of drug sensitivity tests or analysis of gyrA mutation before treatments.

Evaluation of Antibiotic Resistance of Helicobacter pylori Strains Isolated in Bari, Southern Italy, in 2017-2018 by Phenotypic and Genotyping Methods

Objective: Helicobacter pylori antibiotic resistance is a constantly evolving process and local surveillance is warranted to guide clinicians in the choice of therapy. Materials and Methods: Antibiotic susceptibility testing was performed by E-test on 92 H. pylori strains, and resistance to clarithromycin and levofloxacin was also evaluated using a commercially available genotyping method. Results: In naïve patients the resistance to clarithromycin, levofloxacin, and metronidazole was 37.7%, 26.2%, and 16.4%, respectively, significantly lower than the percentage found in treated patients. Concomitant resistance to ≥2 antibiotics was also observed in naïve patients. The A2143G mutation of the 23S-rRNA gene was the most frequently detected, also in naïve patients. The highest minimum inhibitory concentration (MIC)₅₀ value (256 mg/L) was associated with A2142 mutations in all the patients carrying them. For levofloxacin resistance a mutation in codon 87 was detected in 63.9% and in codon 91 in 36.1% of the H. pylori strains, without significant differences in the patients groups. A mutation in codon 87 was associated with the highest MIC₅₀ value (32 mg/L). Conclusions: In our area, a high prevalence of H. pylori primary resistance was detected; these rates were higher in patients who had experienced failure of several courses of therapy. A better knowledge of the local epidemiology of resistance, and the genotypes responsible, will improve the H. pylori eradication rates.