High secondary resistance to quinolones in German Helicobacter pylori clinical isolates

Antimicrobial resistance of Helicobacter pylori in an eastern German region

BACKGROUND

Antimicrobial therapy is recommended to eradicate Helicobacter (H.) pylori in infected individuals. As first-line treatments are empiric, knowledge of antimicrobial resistance is key to successful eradication.

AIMS

We investigated primary resistance in an eastern German region to derive recommendations for eradication treatment.

METHODS

We used molecular genetic methods to examine Helicobacter rapid urease test (RUT) positive gastric specimens of 533 patients from Berlin and the federal state of Brandenburg with allegedly no prior eradication treatment. Tissue samples were removed from RUT and screened by real-time PCR for mutations conferring resistance to clarithromycin. In addition, 182 samples out of 533 were tested for resistance to levofloxacin and tetracycline.

RESULTS

Primary resistances were 10.9% (58 out of 533) to clarithromycin; 13.7% (25/182) to levofloxacin; and 2.2% to tetracycline (4/182). Combined resistance to clarithromycin/levofloxacin was low (2.2%, 4/182). Female sex was significantly associated with clarithromycin resistance.

CONCLUSION

Clarithromycin may be a suitable first-line antibiotic for about 90% of outpatients. A simple molecular test may help physicians avoid prescription of an ineffective first-line regimen.

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%).

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.

Characteristics of Helicobacter pylori antibiotic resistance: data from four different populations

Aims

To describe the characteristics of Helicobacter pylori (H. pylori) antibiotic resistance in clinical isolates from four populations.

Methods

In total, 1463 H. pylori strains were examined for antibiotic resistance. Among these strains, 804 were isolated from treatment-naïve adults, 133 from previously treated adults, 100 from treatment-naïve children and 426 from a population who participated in a health survey (age ≥ 40 years). The minimum inhibitory concentration was determined by the E-test method.

Results

In the treatment-naïve adult group, the resistance rates for metronidazole, clarithromycin, levofloxacin, amoxicillin, rifampicin and tetracycline were 78.4, 19.0, 23.3, 1.2, 1.7 and 2.3%, respectively. Compared with this group, the previously treated adult group had significantly higher resistance rates for metronidazole (99.2%), clarithromycin (58.3%) and levofloxacin (52.3%). In addition, the treatment-naïve children had a lower metronidazole resistance rate (46.0%) than the treatment-naïve adults. The resistance rate for clarithromycin was low in treatment-naïve patients with ages ranging from 10 to 24 years. For the strains isolated from the general population group, the resistance rates for metronidazole, clarithromycin, levofloxacin, amoxicillin, rifampicin and tetracycline were 78.6, 10.1, 25.1, 0.5, 2.1 and 0.9%, respectively. Compared with the treatment-naïve adult group, the general population group showed significant differences in clarithromycin resistance.

Conclusion

The resistance rates for metronidazole, clarithromycin and levofloxacin were high, especially in previously treated adults. Compared to those in treatment-naïve younger patients, the resistance rates for clarithromycin were significantly lower in treatment-naïve patients with ages ranging from 10 to 24 years and in the general population.

Histological changes in refractory Helicobacter pylori infection and its relationship with increased levels of resistance to antibiotics and therapeutic regimens: one-year follow-up

Eradication failure of Helicobacter pylori infection could play a causal role in progression of gastric disorders. In this study, infection with H. pylori was followed in gastric biopsies of symptomatic adult patients at two phases during 1-year period. Analyses were done to show association of therapeutic regimens with the refractory infection, changes in sequence types (STs) and minimum inhibitory concentration (MIC) values, and progression of histopathological changes. Infection with H. pylori was confirmed in 32.3% (57/170) of the patients. Persistent infection with H. pylori was confirmed in 14 out of the 25 patients (56%) who participated at the second phase of the study. A difference between primary and secondary resistance rates to clarithromycin (49% vs 64.3%), metronidazole (76.36% vs 100%), and ciprofloxacin (45% vs 57.1%) was detected. Although the re-emerged strains in patients with refractory infection did not show alteration in STs, their MIC₅₀ values showed twofold increases for clarithromycin and ciprofloxacin. While ciprofloxacin containing regimens were more successful, failure of metronidazole containing regimens was detected in 77% of the patients. Consequently, inappropriate medication has an impact on refractory H. pylori infection, which could cause to a rise in resistance levels to antibiotics and progression of pathological disorders.

Antimicrobial resistance of Helicobacter pylori in Germany, 2015 to 2018

OBJECTIVES

National and international guidelines recommend empiric first-line treatments of individuals infected with Helicobacter pylori without prior antimicrobial susceptibility testing. For this reason, knowledge of primary resistance to first-line antibiotics such as clarithromycin is essential. We assessed the primary resistance of H. pylori in Germany to key antibiotics by molecular genetic methods and evaluated risk factors for the development of resistance.

METHODS

Gastric tissue samples of 1851 yet treatment-naïve H. pylori-positive patients were examined with real-time PCR or PCR and Sanger sequencing for mutations conferring resistance to clarithromycin, levofloxacin and tetracycline. Clinical and epidemiological data were documented and univariable and multivariable logistic regression analyses were conducted.

RESULTS

Overall primary resistances were 11.3% (210/1851) to clarithromycin, and 13.4% (201/1497) to levofloxacin; resistance to tetracycline (2.5%, 38/1497) was as low as combined resistance to clarithromycin/levofloxacin (2.6%, 39/1497). Female sex and prior antimicrobial therapies owing to unrelated bacterial infections were risk factors for clarithromycin resistance (adjusted OR (aOR) 2.3, 95% CI 1.6-3.4; and 2.6, 95% CI 1.5-4.5, respectively); older age was associated with levofloxacin resistance (aOR for those ≥65 years compared with those 18-35 years: 6.6, 95% CI 3.1-14.2).

CONCLUSIONS

Clarithromycin might still be recommended in first-line eradication therapies in yet untreated patients, but as nearly every tenth patient may carry clarithromycin-resistant H. pylori it may be advisable to rule out resistance ahead of treatment by carrying out susceptibility testing or prescribing an alternative therapy.

CD177 Expression and Inflammation Grade in Helicobacter pylori-Infected Wild-Type and CD177-/- C57BL/6 Mice

This study was undertaken to further investigate the CD177 expression in Helicobacter pylori- (Hp-) infected wild-type and CD177^-/- C57BL/6 mice, which may be helpful to elucidate the relationship between CD177 and Hp-related gastritis. 20 WT mice were randomly assigned into the Hpss1 WT group (n = 10) and Hp49503 WT group (n = 10); 20 KO mice were randomly assigned into the Hpss1 KO group (n = 10) and Hp49503 KO group (n = 10). The remaining mice served as controls. Mice in the HpSS1 groups and Hp49503 groups were independently infected with corresponding strains. Results showed that the Hp colonization score was related to the grade of mucosal inflammation (P < 0.05). The inflammation grade was comparable between the HpSS1 group and Hp49503 group as well as between the WT group and KO group. In addition, the Hp colonization score was related to the CD177 expression score (P < 0.05). The CD177 expression in the Hp colonization group was higher than that in the non-Hp colonization group (P < 0.05). CD177 expression was positively related to the inflammation grade (P < 0.01). In conclusion, CD177 expression was similar between HP49503- and HPss1-infected WT C57BL/6 mice, and CD177 expression was undetectable in CD177^-/- mice. CD177 expression in the gastric mucosa increases with the elevation of inflammation grade. In Hp-infected mice, the inflammation grade had no relationship with the type of Hp strain and the CD177 expression, but the mucosal inflammation score in Hp-infected mice was higher than that in non-Hp infected mice.

Prevalence of Antibiotic Resistance in Helicobacter pylori: A Systematic Review and Meta-analysis in World Health Organization Regions

BACKGROUND & AIMS

In 2017, the World Health Organization (WHO) designated clarithromycin-resistant Helicobacter pylori a high priority for antibiotic research and development. However, there are no clear data on the global distribution of resistance or its clinical effects. We performed a systematic review and meta-analysis to assess the distribution of H pylori resistance to commonly used antibiotics and to measure the association between antibiotic resistance and treatment failure.

METHODS

We searched publication databases for studies that assessed rates of H pylori resistance to clarithromycin, metronidazole, levofloxacin, amoxicillin, or tetracycline. Pooled estimates of primary and secondary resistance and 95% confidence intervals (CIs) were grouped by WHO region. The association between antibiotic resistance and treatment failure was measured by extracting data on treatment efficacy in patients with resistant and susceptible isolates and pooling odds ratios with 95% CIs.

RESULTS

We identified 178 studies, comprising 66,142 isolates from 65 countries. Primary and secondary resistance rates to clarithromycin, metronidazole, and levofloxacin were ≥15% in all WHO regions, except primary clarithromycin resistance in the Americas (10%; 95% CI, 4%-16%) and South-East Asia region (10%; 95% CI, 5%-16%) and primary levofloxacin resistance in the European region (11%; 95% CI, 9%-13%). There was considerable heterogeneity (I2 > 75%) among all analyses-this might have resulted from the grouping of resistance rates by country. Increasing antibiotic resistance was observed in most WHO regions. Resistance to clarithromycin was significantly associated with failure of clarithromycin-containing regimens (odds ratio, 6.97; 95% CI, 5.23-9.28; P < .001).

CONCLUSIONS

Resistance of H pylori to antibiotics has reached alarming levels worldwide, which has a great effect on efficacy of treatment. Local surveillance networks are required to select appropriate eradication regimens for each region.

Retrospective study on outcome of salvage Helicobacter pylori eradication therapies based on molecular genetic susceptibility testing

BACKGROUND

Antimicrobial susceptibility of Helicobacter (H.) pylori is usually determined by phenotypic methods. When H. pylori cannot be grown owing to contaminations or delay in transport of gastric tissue samples to the microbiological laboratory, molecular genetic testing is a reasonable alternative. The aim of this retrospective study was to assess the outcome of salvage eradication treatments based on molecular genetic susceptibility testing.

METHODS

Data on 144 H. pylori PCR-positive gastric tissue samples of patients primarily with prior unsuccessful eradication treatments were retrospectively analyzed. Eradication treatments were recommended based on genotypic clarithromycin and/or levofloxacin susceptibility as tested by real-time PCR or reverse hybridization. Treatment success was assessed by attending physicians using urea breath test; stool-antigen ELISA; and microbiology/histopathology.

RESULTS

Overall success rate of molecular genetic testing-guided salvage treatments was low (68%); none of the regimens chosen was significantly better than another. Multivariable logistic regression analysis did not reveal any factors that may predict treatment failure.

CONCLUSIONS

Eradication success was poor despite susceptibility testing. Gastroenterologists are advised to prescribe recommended salvage treatments, considering recommended dosages and prolonged treatment duration.

Current Status of the Third-Line Helicobacter pylori Eradication

Antibiotic resistance is growing worldwide, and patients who have failed consecutive 1st- and 2nd-line H. pylori eradication regimens are increasing. Therefore, the role of the bacterial culture with antibiotic susceptibility testing and molecular susceptibility testing is important for avoiding the use of ineffective antibiotics. However, antibiotic susceptibility testing-guided treatment does not necessarily guarantee successful eradication, and there have been mixed results for the effectiveness of a 3rd-line rescue therapy. Therefore, providing patients with pretreatment medication instructions and education is important. It is also crucial to determine the reason of the eradication failure, including host-related factors (poor compliance to eradication regimen, smoking, and cytochrome P450 2C19 genetic polymorphism) or treatment-related factors (inadequate dosage or duration of therapy and gastric acidity), as such factors can be modified for a tailored therapy. Although the indications for H. pylori eradication have widened, patients at a high risk of gastric cancer can gain definitive benefits with a 3rd-line or even 4th-line therapy.

Twelve-day quintuple regime containing four antibiotics as a rescue therapy for Helicobacter pylori eradication in the central region of Portugal

BACKGROUND

Helicobacter pylori eradication rates with standard triple therapy in many countries are clinically unacceptable. Fluoroquinolone resistance is increasing and jeopardizing second-line regimens. There is a growing need for an effective strategy in patients who failed previous therapies.

METHODS

This is a single-center, non-randomized clinical study conducted in the central region of Portugal. Sixty-four patients were included with a positive 13C-urea breath test (UBT) or histology for H. pylori, and at least one failed eradication attempt. The patient cohort included 71.7% of females with a median of age of 52 (range 23-87). They were treated with a twelve-day regimen consisting of a proton-pump inhibitor (PPI) bid, amoxicillin at 1,000 mg 12/12 h and levofloxacin at 500 mg bid during the first seven days, followed by PPI bid, clarithromycin at 500 mg 12/12h and either tinidazole or metronidazole at 500 mg bid/tid for five days. Eradication was assessed by UBT. The local Ethics Committee approved this study.

RESULTS

Eradication therapy was prescribed due to dyspepsia (66.7%), peptic ulcer (10%) and thrombocytopenia (8.3%). The median number of failed therapies was one (range 1-4). The eradication rate was 64.6% according to an intention-to-treat analysis (95% CI: 53-77%), and 70% by the per-protocol analysis (95% CI: 58-82%). Age, smoking, indication for eradication, previous therapies and the use of a second-generation or full-dose PPI did not affect success rates.

CONCLUSIONS

Even though treatment with four antibiotics was used, this "reinforced" therapy achieved suboptimal results. This fact highlights the lack of effective H. pylori antimicrobials and suggests that second-line treatment in our region should be prescribed according to susceptibility testing.

Prospective multicentre clinical study on inter- and intrapatient genetic variability for antimicrobial resistance of Helicobacter pylori

OBJECTIVES

We report on a large prospective, multicentre clinical investigation on inter- and intrapatient genetic variability for antimicrobial resistance of Helicobacter pylori.

METHODS

Therapy-naive patients (n = 2004) who had undergone routine diagnostic gastroscopy were prospectively included from all geographic regions of Austria. Gastric biopsy samples were collected separately from antrum and corpus. Samples were analysed by histopathology and real-time PCR for genotypic resistance to clarithromycin and quinolones. Clinical and demographic information was analysed in relation to resistance patterns.

RESULTS

H. pylori infection was detected in 514 (26%) of 2004 patients by histopathology and confirmed in 465 (90%) of 514 patients by real-time PCR. PCR results were discordant for antrum and corpus in 27 (5%) of 514 patients, indicating inhomogeneous infections. Clarithromycin resistance rates were 17% (77/448) and 19% (84/455), and quinolone resistance rates were 12% (37/310) and 10% (32/334) in antrum and corpus samples, respectively. Combination of test results per patient yielded resistance rates of 21% (98/465) and 13% (50/383) for clarithromycin and quinolones, respectively. Overall, infection with both sensitive and resistant H. pylori was detected in 65 (14%) of 465 patients.

CONCLUSIONS

Anatomically inhomogeneous infection with different, multiple H. pylori strains is common. Prospective clinical study design, collection of samples from multiple sites and microbiologic methods that allow the detection of coinfections are mandatory for collection of reliable data on antimicrobial resistance patterns in representative patient populations. (ClinicalTrials.gov identifier: NCT02925091).

Helicobacter pylori strains from a Nigerian cohort show divergent antibiotic resistance rates and a uniform pathogenicity profile

Antibiotic resistance in Helicobacter pylori is a factor preventing its successful eradication. Particularly in developing countries, resistance against commonly used antibiotics is widespread. Here, we present an epidemiological study from Nigeria with 111 isolates. We analyzed the associated disease outcome, and performed a detailed characterization of these isolated strains with respect to their antibiotic susceptibility and their virulence characteristics. Furthermore, statistical analysis was performed on microbiological data as well as patient information and the results of the gastroenterological examination. We found that the variability concerning the production of virulence factors between strains was minimal, with 96.4% of isolates being CagA-positive and 92.8% producing detectable VacA levels. In addition, high frequency of bacterial resistance was observed for metronidazole (99.1%), followed by amoxicillin (33.3%), clarithromycin (14.4%) and tetracycline (4.5%). In conclusion, this study indicated that the infection rate of H. pylori infection within the cohort in the present study was surprisingly low (36.6%). Furthermore, an average gastric pathology was observed by histological grading and bacterial isolates showed a uniform pathogenicity profile while indicating divergent antibiotic resistance rates.

Importance of antimicrobial susceptibility testing for the management of eradication in Helicobacter pylori infection

The management of Helicobacter pylori (H. pylori) infection treatment differs from the common treatment protocol for other infectious diseases. Because culture- or molecular-guided approaches face several practical issues, such as the invasive procedures required to obtain gastric biopsy specimens and the lack of availability of routine laboratory testing in some places, H. pylori treatment includes the administration of two or three empirically selected antibiotics combined with a proton pump inhibitor rather than evidence-based eradication treatment. The efficacy of empirical therapy is decreasing, mostly due to increasing multiple resistance. Multiresistance to levofloxacin, clarithromycin, and metronidazole, which are commonly used in empirical treatments, appears to have increased in many countries. Mutations play a primary role in the antimicrobial resistance of H. pylori, but many different mechanisms can be involved in the development of antibiotic resistance. Determining and understanding these possible mechanisms might allow the development of new methods for the detection of H. pylori and the determination of antimicrobial resistance. A treatment based on the detection of antimicrobial resistance is usually more effective than empirical treatment. Nevertheless, such an approach before treatment is still not recommended in the Maastricht guidelines due to the difficulty associated with the routine application of available culture- or molecular-based susceptibility tests, which are usually administered in cases of treatment failure. The management of first and rescue treatments requires further research due to the steadily increase in antimicrobial resistance.

Management of Helicobacter pylori infection-the Maastricht V/Florence Consensus Report

Important progress has been made in the management of Helicobacter pylori infection and in this fifth edition of the Maastricht Consensus Report, key aspects related to the clinical role of H. pylori were re-evaluated in 2015. In the Maastricht V/Florence Consensus Conference, 43 experts from 24 countries examined new data related to H. pylori in five subdivided workshops: (1) Indications/Associations, (2) Diagnosis, (3) Treatment, (4) Prevention/Public Health, (5) H. pylori and the Gastric Microbiota. The results of the individual workshops were presented to a final consensus voting that included all participants. Recommendations are provided on the basis of the best available evidence and relevance to the management of H. pylori infection in the various clinical scenarios.

Rescue therapy with bismuth-containing quadruple therapy in patients infected with metronidazole-resistant Helicobacter pylori strains

BACKGROUND

The emergence of H. pylori strains that are resistant to clarithromycin, metronidazole and fluoroquinolone requires the evaluation of new and effective salvage therapies.

AIMS

To test the efficacy of a new formulation of a bismuth-containing quadruple therapy as a rescue therapy in patients who were infected with a H. pylori strain resistant to metronidazole, clarithromycin and fluoroquinolone or who failed multiple lines of treatment using these three antibiotics.

METHODS

A total of 103 patients with confirmed H. pylori infection with a resistance profile described above were treated with Pylera(®) (3-in-1 capsules containing bismuth subcitrate potassium 140mg, metronidazole 125mg and tetracycline 125mg) 3 capsules four times a day plus omeprazole 20mg two times a day for 10 days in a named patient program. Eradication was confirmed using a urea breath test at least 28 days after the end of treatment. Efficacy and safety were studied.

RESULTS

A total of 103 patients were prospectively included from June 2010 to October 2011. The eradication rate for the intent-to-treat analysis was 83% (CI95%[75-89%]); an 87% eradication rate (CI95%[80-94%]) was found for the per-protocol analysis and 81% (CI95%[80-82%]) for the intent-to-treat analysis in patients with proven resistance to metronidazole. Nine patients discontinued treatment, all due to adverse events. Two serious adverse events (AEs) were reported (memory disorders of unknown significance). Fifty-six (54%) patients reported at least one AE.

CONCLUSION

This bismuth-containing quadruple therapy achieved a remarkable eradication rate as a salvage therapy in patients infected with metronidazole-resistant H. pylori strain, despite the frequent occurrence of mild-to-moderate adverse events.

Systematic review with meta-analysis: the efficacy of levofloxacin triple therapy as the first- or second-line treatments of Helicobacter pylori infection

BACKGROUND

Levofloxacin triple therapy has been used for the first-line and second-line treatment of Helicobacter pylori infection for more than 10 years.

AIMS

To systematically review the efficacy of levofloxacin triple therapy in the first- and second-line treatment, and to assess the time trend and factors that might affect its efficacy.

METHODS

Prospective trials reporting the efficacy of levofloxacin triple therapy in either the first-line or second-line treatment of H. pylori infection in adults were searched from the PubMed and Cochrane database from January 2000 to September 2015. Meta-analysis was performed to calculate the cumulative eradication rate and the efficacies in subgroups.

RESULTS

Of the 322 articles identified, a total of 4574 patients from 41 trials, including 16 trials in the first-line treatment and 25 trials in the second-line treatment were eligible for analysis. The cumulative eradication rate was 77.3% (95% confidence intervals, CI: 74.7-79.6) and was 80.7% (95% CI 77.1-83.7) in the first-line treatment and 74.5% (95% CI: 70.9-77.8) in the second-line treatment. The efficacies of levofloxacin triple therapy before 2008, between 2009 and 2011, and after 2012 were 77.4%, 79.6% and 74.8% respectively. The eradication rate was higher when levofloxacin was given once daily (80.6%, 95% CI: 77.1-83.7) than twice daily (73.6%, 95% CI: 69.7-77.2). The efficacy was significantly higher in levofloxacin-susceptible strains than resistant strains (81.1% vs. 36.3%, risk ratio 2.18, 95% CI: 1.6-3, P < 0.001).

CONCLUSION

The efficacy of levofloxacin triple therapy has been lower than 80% in many countries and it is not recommended when the levofloxacin resistance is higher than 5-10%.

Prevalence of Primary Antimicrobial Resistance of H. pylori in Turkey: A Systematic Review

BACKGROUND

The prevalence of clarithromycin resistance has increased to the 20% or more in different regions of the world. Clarithromycin resistance is known to be responsible for most of the treatment failures in Helicobacter pylori (H. pylori) infection. The aim of this systematic review was to summarize the prevalence of primary antibiotic resistance (amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline) of H. pylori strains in different geographical regions of Turkey.

MATERIAL AND METHODS

An Internet search was performed using PubMed and the ULAKBIM Turkish Medical Database. The terms "primary antibiotic resistance (separately; amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline) of H. pylori" with and without "Turkey" or "different geographical regions of Turkey" were searched among articles published in both English and Turkish language within the time span from 1999 to 2015. Data analysis was performed using MedCalc 12.7.0. Each article was weighted according to the number of isolated H. pylori strains. Pooled proportion analysis was performed.

RESULTS

Twenty-one Turkish studies including 1059 H. pylori strains were included in this review. The overall primary antibiotic resistance rates of H. pylori strains isolated in Turkey were as follows: amoxicillin 3 (0.971%), clarithromycin 425 (24.864%), metronidazole 75 (33.747%), tetracycline 2 (3.511%), and levofloxacin 31 (23.769%).

CONCLUSIONS

Primary antibiotic resistance against H. pylori in Turkey shows differences between geographical regions and population densities. There is an increase in primary resistance rates to clarithromycin and metronidazole in different years. The data are not sufficient for tetracycline, amoxicillin, and levofloxacin. High clarithromycin resistance rates were mostly detected in overpopulated cities like Ankara (north), Izmir (west), Istanbul (west), and Bursa (west).

Antimicrobial resistance of Helicobacter pylori strains to five antibiotics, including levofloxacin, in Northwestern Turkey

INTRODUCTION

Antibiotic resistance is the main factor that affects the efficacy of current therapeutic regimens against Helicobacter pylori. This study aimed to determine the rates of resistance to efficacy clarithromycin, amoxicillin, tetracycline, levofloxacin and metronidazole among H. pylori strains isolated from Turkish patients with dyspepsia.

METHODS

H. pylori was cultured from corpus and antrum biopsies that were collected from patients with dyspeptic symptoms, and the antimicrobial susceptibility of H. pylori was determined using the E-test (clarithromycin, amoxicillin, tetracycline, metronidazole and levofloxacin) according to the EUCAST breakpoints. Point mutations in the 23S rRNA gene of clarithromycin-resistant strains were investigated using real-time PCR.

RESULTS

A total of 98 H. pylori strains were isolated, all of which were susceptible to amoxicillin and tetracycline. Of these strains, 36.7% (36/98) were resistant to clarithromycin, 35.5% (34/98) were resistant to metronidazole, and 29.5% (29/98) were resistant to levofloxacin. Multiple resistance was detected in 19.3% of the isolates. The A2143G and A2144G point mutations in the 23S rRNA-encoding gene were found in all 36 (100%) of the clarithromycin-resistant strains. Additionally, the levofloxacin MIC values increased to 32 mg/L in our H. pylori strains. Finally, among the clarithromycin-resistant strains, 27.2% were resistant to levofloxacin, and 45.4% were resistant to metronidazole.

CONCLUSIONS

We conclude that treatment failure after clarithromycin- or levofloxacin-based triple therapy is not surprising and that metronidazole is not a reliable agent for the eradication of H. pylori infection in Turkey.

Quinolone-based first, second and third-line therapies for Helicobacter pylori

Helicobacter pylori (H. pylori) is a very common bacterium that infects about 50% of the world population in urban areas and over 90% of people living in rural and developing countries. Fluoroquinolones, a class of antimicrobials, have been extensively used in eradication regimens for H. pylori. Levofloxacin is the most commonly used, and in second-line regimens, is one of the most effective options. However, an increasing resistance rate of H. pylori to fluoroquinolones is being observed, that will likely affect their effectiveness in the near future. Other novel fluoroquinolone molecules, such as moxifloxacin, sitafloxacin, gatifloxacin and gemifloxacin, have been proposed and showed encouraging results in vitro, although data on their clinical use are still limited. Further studies in large sample trials are needed to confirm their safety and efficacy profile in clinical practice.

Antibiotic treatment for Helicobacter pylori: Is the end coming?

Infection with the Gram-negative pathogen Helicobacter pylori (H. pylori) has been associated with gastro-duodenal disease and the importance of H. pylori eradication is underscored by its designation as a group I carcinogen. The standard triple therapy consists of a proton pump inhibitor, amoxicillin and clarithromycin, although many other regimens are used, including quadruple, sequential and concomitant therapy regimens supplemented with metronidazole, clarithromycin and levofloxacin. Despite these efforts, current therapeutic regimens lack efficacy in eradication due to antibiotic resistance, drug compliance and antibiotic degradation by the acidic stomach environment. Antibiotic resistance to clarithromycin and metronidazole is particularly problematic and several approaches have been proposed to overcome this issue, such as complementary probiotic therapy with Lactobacillus. Other studies have identified novel molecules with an anti-H. pylori effect, as well as tailored therapy and nanotechnology as viable alternative eradication strategies. This review discusses current antibiotic therapy for H. pylori infections, limitations of this type of therapy and predicts the availability of newly developed therapies for H. pylori eradication.

Prevalence of antibiotic resistance in Helicobacter pylori: A recent literature review

AIM: To review previous studies (the last 6 years) about the Helicobacter pylori (H. pylori) antibiotic resistance in order to evaluate the trend in antibiotic resistance.

METHODS: In this study, the PubMed, MEDLINE, Science Direct, Google Scholar and Scielo manuscripts were reviewed from 2009 to 2014.

RESULTS: On the whole rates of H. pylori antibiotic resistance were 47.22% (30.5%-75.02%) for metronidazole, 19.74% (5.46%-30.8%) for clarithromycin, 18.94% (14.19%-25.28%) for levofloxacin, and 14.67% (2%-40.87%) for amoxicillin, 11.70% (0%-50%) for tetracycline, 11.5% (0%-23%) for furazolidon and 6.75% (1%-12.45%) for rifabutin. The frequency of tetracycline, metronidazole and amoxicillin resistance was higher in Africa, while clarithromycin and levofloxacin resistance was higher in North America and Asian, respectively.

CONCLUSION: The most sensitive drug is rifabutin and the lowest sensitive drug is metronidazole in the world. The worldwide H. pylori antibiotic resistance to clarithromycin and levofloxacin has increased during the last 6 years. The present systematic review show alarming results and a novel plan is needed for eradication therapy of H. pylori infections.

Outcome of second- and third-line Helicobacter pylori eradication therapies based on antimicrobial susceptibility testing

OBJECTIVES

The objective of this study was to assess the outcome of antimicrobial susceptibility-guided therapies in Helicobacter pylori-infected individuals who had undergone unsuccessful prior eradication treatments.

METHODS

From October 2004 to December 2013, 481 H. pylori-positive patients with prior unsuccessful eradication treatments were administered susceptibility-guided salvage eradication treatments. Six months on, treatment outcome was assessed by urea breath test, stool antigen ELISA, Helicobacter urease test or microbiology and/or histopathology.

RESULTS

Resistance to metronidazole and clarithromycin was high in patients with prior unsuccessful eradication treatments and was dependent on the number of treatment failures. Susceptibility-guided salvage eradication treatments achieved eradication rates of nearly 70% in these patients. No particular regimen was significantly better than another.

CONCLUSIONS

Antimicrobial susceptibility testing prevents prescription of inefficient antimicrobials and enables individualized and promising salvage treatments in patients with prior unsuccessful eradication treatments.

The Primary Resistance of Helicobacter pylori in Taiwan after the National Policy to Restrict Antibiotic Consumption and Its Relation to Virulence Factors-A Nationwide Study

Objective

The Taiwan Government issued a policy to restrict antimicrobial usage since 2001. We aimed to assess the changes in the antibiotic consumption and the primary resistance of H. pylori after this policy and the impact of virulence factors on resistance.

Methods

The defined daily dose (DDD) of antibiotics was analyzed using the Taiwan National Health Insurance (NHI) research database. H. pylori strains isolated from treatment naïve (N=1395) and failure from prior eradication therapies (N=360) from 9 hospitals between 2000 and 2012 were used for analysis. The minimum inhibitory concentration was determined by agar dilution test. Genotyping for CagA and VacA was determined by PCR method.

Results

The DDD per 1000 persons per day of macrolides reduced from 1.12 in 1997 to 0.19 in 2008, whereas that of fluoroquinolones increased from 0.12 in 1997 to 0.35 in 2008. The primary resistance of amoxicillin, clarithromycin, metronidazole, and tetracycline remained as low as 2.2%, 7.9%, 23.7%, and 1.9% respectively. However, the primary levofloxacin resistance rose from 4.9% in 2000–2007 to 8.3% in 2008–2010 and 13.4% in 2011–2012 (p=0.001). The primary resistance of metronidazole was higher in females than males (33.1% vs. 18.8%, p<0.001), which was probably attributed to the higher consumption of nitroimidazole. Neither CagA nor VacA was associated with antibiotic resistance.

Conclusions

The low primary clarithromycin and metronidazole resistance of H. pylori in Taiwan might be attributed to the reduced consumption of macrolides and nitroimidazole after the national policy to restrict antimicrobial usage. Yet, further strategies are needed to restrict the consumption of fluoroquinolones in the face of rising levofloxacin resistance.

High rate of levofloxacin resistance in a background of clarithromycin- and metronidazole-resistant Helicobacter pylori in Vietnam

Antimicrobial resistance in Helicobacter pylori has increased worldwide and has become a major cause of treatment failure in many countries, including Vietnam. It is advisable to perform an antibiogram to provide optimal regimens for H. pylori eradication. This study evaluated the rate of antibiotic resistance to the four commonly used antibiotics against H. pylori at a tertiary care hospital in Central Vietnam and analysed point mutations in genes related to clarithromycin (CLA) and levofloxacin (LFX) resistance. A total of 92 H. pylori strains from gastric biopsy specimens were tested; 42.4% were resistant to CLA (primary, 34.2%; secondary, 73.7%), 41.3% to LFX (primary, 35.6%; secondary, 63.2%), 76.1% to metronidazole (MTZ) and 1.1% to amoxicillin. Multidrug resistance was observed in 56.5% (primary, 50.7%; secondary, 78.9%) of isolates (P<0.05). The rate of resistance to LFX was significantly higher in females than males (P<0.05). Most of the CLA- and LFX-resistant strains harboured resistance-associated mutations, with common positions at A2143G and T2182C in the 23S rRNA gene and at Asn-87 or Asp-91 in GyrA. Minimum inhibitory concentrations (MICs) increased in strains carrying quadruple mutations in their 23S rRNA gene and in strains with Asn-87 GyrA mutation (P<0.05). One high-level LFX-resistant strain (MIC=32mg/L) had new mutations with a combination of N87A, A88N and V65I. High resistance rates to CLA, MTZ and LFX discourage standard and LFX-based triple therapies as first-line treatment in Vietnam.

Helicobacter pylori

PURPOSE OF REVIEW

This review focuses on new treatment options for eradicating Helicobacter pylori that have emerged as a result of decreased efficacy of standard triple therapy due to increasing antibiotic resistance. We also report on new data regarding primary and secondary gastric cancer prevention strategies and the potential role of H. pylori as a risk factor for extragastric malignancies.

RECENT FINDINGS

Treatment options have shifted from triple to various quadruple modifications. The length of therapy duration has, in general, been extended from 7 to 10 and 14 days. Nonbismuth-based quadruple therapies prescribed as sequential, concomitant, and hybrid have shown superiority as compared to standard triple therapy in the eradication of clarithromycin-resistant H. pylori. Bismuth-based quadruple therapy appears almost totally independent of antibiotic resistance and maintains high eradication rates. Levofloxacin is an adequate substitute for clarithromycin and is recommended in second-line regimens. However, it should be used prudently as H. pylori has developed resistance to levofloxacin in many regions of the world. Strategies for primary gastric cancer prevention by H. pylori eradication are effective, whereas H. pylori eradication for secondary gastric cancer prevention is uncertain. Very recent data implicate H. pylori as a risk factor for extragastric malignancies.

SUMMARY

H. pylori therapy should be tailored according to local antibiotic resistance patterns. In many regions of the world, H. pylori is becoming increasingly resistant to clarithromycin, metronidazole, and levofloxacin. Gastric cancer prevention by H. pylori eradication is most effective, if implemented early in the course of infection. New data are provided which indicate H. pylori as risk factor for extragastric malignancies.

Antimicrobial activities of four antibiotics against clinical isolates of Helicobacter pylori

AIM: To analyze the antimicrobial activities of four antibiotics against the clinical isolates of Helicobacter pylori (H. pylori) to provide a reference for reasonably choosing antibiotics to eradicate H. pylori.

METHODS: The sensitivity of 65 clinical isolates of H. pylori to clarithromycin, amoxicillin, levofloxacin and furazolidone was analyzed using Kirby-Bauer disk diffusion test. Characteristics of drug sensitivity were analyzed.

RESULTS: The average diameters of inhibition zones for clarithromycin, amoxicillin, levofloxacin and furazolidone against clinical isolates of H. pylori were 17.246 mm ± 1.263 mm, 16.492 mm ± 1.263 mm, 14.246 mm ± 1.26 mm, 16.661 mm ± 1.263 mm, respectively, and the corresponding effective rates were 73.8%, 78.5%, 75.4% and 80%, respectively. There were no significant differences in the average diameters of inhibition zones or the effective rates among the four antibiotics (P > 0.05). There were no relationships between antimicrobial activities of antibiotics against clinical isolates of H. pylori and ¹⁴C urea breath test, sex or disease category (P > 0.05).

CONCLUSION: Clarithromycin, amoxicillin, levofloxacin and furazolidone exhibit comparable antimicrobial effects against clinical isolates of H. pylori.

Treatment of Helicobacter pylori infection 2014

This review summarizes important studies regarding H.pylori therapy published from April 2013 to April 2014. The main themes that emerge are assessing the efficacy of standard triple therapy, as well as exploring new first-line treatments, predominantly optimized triple therapies and non-bismuth quadruple schemes. Regarding newer non-bismuth quadruple regimens, the compliance and tolerance seem to be similar for sequential and concomitant regimens. Notably, no study yet has demonstrated a clear statistical superiority for either, and a systematic review and meta-analysis may be warranted. Other studies examined the role of levofloxacin and bismuth based therapies in H. pylori eradication. The efficacy of bismuth as a second-line after sequential therapy was particularly noteworthy. Levofloxacin-based therapies also appear to be useful and versatile as part of different antibiotic combinations and in first-, second-, and third-line therapies. The emerging problem of quinolone resistance remains a worry. Individualized therapy, based on factors such as antimicrobial information, resistance data, and CYP2C19 metabolism, may well be the most notable future trend to emerge this year.

Quinolone-containing therapies in the eradication of Helicobacter pylori

Fluoroquinolones, especially levofloxacin, are used in the eradication of Helicobacter pylori worldwide. Many consensus guidelines recommend that the second-line rescue therapy for H. pylori eradication consists of a proton pump inhibitor, a quinolone, and amoxicillin as an option. Unfortunately, quinolone is well associated with a risk of developing bacterial resistance. In this paper, we review quinolone-containing H. pylori eradication regimens and the challenges that influence the efficacy of eradication. It is generally suggested that the use of levofloxacin should be confined to “rescue” therapy only, in order to avoid a further rapid increase in the resistance of H. pylori to quinolone. The impact of quinolone-containing H. pylori eradication regimens on public health issues such as tuberculosis treatment must always be taken into account. Exposure to quinolone is relevant to delays in diagnosing tuberculosis and the development of drug resistance. Extending the duration of treatment to 14 days improves eradication rates by >90%. Tailored therapy to detect fluoroquinolone-resistant strains can be done by culture-based and molecular methods to provide better eradication rates. Molecular methods are achieved by using a real-time polymerase chain reaction to detect the presence of a gyrA mutation, which is predictive of treatment failure with quinolones-containing triple therapy.

Prospective multicentre study on antimicrobial resistance of Helicobacter pylori in Germany

OBJECTIVES

Antimicrobial resistance of Helicobacter pylori endangers the successful eradication of the bacteria. The aim of this prospective surveillance study (ResiNet) is to continuously keep antimicrobial resistance of H. pylori in Germany under surveillance and to identify risk factors for its development.

METHODS

From July 2001 until December 2012, we tested the antimicrobial susceptibility of H. pylori strains isolated from 1651 prospectively enrolled patients. We analysed clinical and epidemiological data and identified risk factors for the development of resistance.

RESULTS

Average primary resistances were 29.4% for metronidazole, 6.7% for clarithromycin and 3.1% for both antimicrobials. Prior unsuccessful eradication treatments, female sex and country or continent of origin were identified as independent risk factors for development of resistance.

CONCLUSIONS

H. pylori-positive patients without prior eradication therapy can be treated empirically; antimicrobial susceptibility testing is recommended in previously unsuccessfully treated patients and in patients who have received antimicrobial chemotherapies due to unrelated bacterial infections.

How antibiotic resistances could change Helicobacter pylori treatment: A matter of geography?

Therapeutic management of Helicobacter pylori (H. pylori) remains an unsolved issue. Indeed, no therapeutic regimen is able to cure the infection in all treated patients, and in many the infection persists despite the administration of several consecutive standard therapies. Although antibiotic resistance reports describe alarming results, the outcome of therapeutic regimens does not seem to parallel this scenario in most cases, since a successful performance is often reached in more than 80% of cases. However, the phenomenon of increasing antibiotic resistance is being closely studied, and the results show controversial aspects even in the same geographic area. For the continents of Europe, America, Asia, Africa, and Oceania, minimal and maximal values of resistance to the main antibiotics (clarithromycin, amoxicillin, metronidazole, and levofloxacin) feature wide ranges in different countries. The real enigma is therefore linked to the several different therapeutic regimens, which show results that often do not parallel the in vitro findings even in the same areas. A first aspect to be emphasized is that some regimens are limited by their use in very small geographic districts. Moreover, not all therapeutic trials have considered bacterial and host factors affecting the therapeutic outcome. The additional use of probiotics may help to reduce adverse events, but their therapeutic impact is doubtful. In conclusion, the “ideal therapy”, paradoxically, appears to be a “utopia”, despite the unprecedented volume of studies in the field and the real breakthrough in medical practice made by the discovery and treatment of H. pylori. The ample discrepancies observed in the different areas do not encourage the development of therapeutic guidelines that could be valid worldwide. On these bases, one of the main challenges for the future might be identifying a successful solution to overcome antibiotic resistances. In this context, geography must be considered a relevant matter.

Helicobacter pylori infection: selected aspects in clinical management

PURPOSE OF REVIEW

This review focuses on new aspects of recently published guidelines for the management of Helicobacter pylori infection as well as progress in diagnostic tests and treatment regimens. We also discuss new strategies for gastric cancer prevention.

RECENT FINDINGS

The general recommendation to treat H. pylori infection whenever diagnosed still faces resistance for reasons that are pertinent to the diversity of related clinical outcomes and to the complexity of eradication regimens. Thus, new updated guidelines for the management of H. pylori infection have been released in several continents. Progress has been made in molecular diagnostic tests for the detection of antibiotic resistance and serological tests for the detection of advanced gastric atrophic changes. Effective quadruple therapies in various combinations of 'traditional drugs' have been introduced with sequential or concomitant order of administration. Moreover, traditional drugs in a new galenic formulation have been introduced to overcome increasing H. pylori antibiotic resistance. Effective strategies for gastric cancer prevention have been adopted in some countries with high gastric cancer incidence, and have successfully contributed to lower the gastric cancer incidence. A screen-and-treat strategy for individuals at increased risk for gastric cancer needs to be further explored also in areas with low/moderate incidence of gastric cancer.

SUMMARY

New guidelines share many universal similarities across countries but respect and emphasize specific needs and requirements in individual communities. Various combinations of traditional drugs have been successfully introduced to overcome the increasing H. pylori antibiotic resistance. Gastric cancer prevention by a screen and treat strategy showed promising results.