Frequency and molecular characteristics of ciprofloxacin- and rifampicin-resistant Helicobacter pylori from gastric infections in the UK

High incidence of antibiotic resistance amongst isolates of Helicobacter pylori collected in Nottingham, UK, between 2001 and 2018

Introduction. Helicobacter pylori is the leading cause of peptic ulcers and gastric cancer. The most common treatment regimens use combinations of two or three antibiotics and a proton pump inhibitor (PPI) to suppress stomach acid. The World Health Organization designated clarithromycin-resistant H. pylori as a high priority pathogen for drug development, due to increasing antibiotic resistance globally.Hypothesis/Gap Statement. There is no routine surveillance of H. pylori primary antimicrobial sensitivities in the UK, and published data are lacking.Aim. This study aimed to characterize antimicrobial sensitivities of isolates collected in Nottingham, UK, between 2001 and 2018.Methodology. Gastric biopsy samples were collected, with informed written consent and ethics approval, from 162 patients attending the Queen's Medical Centre in Nottingham for an upper GI tract endoscopy. Antibiotic sensitivity was assessed using E-Tests and a more cost-effective disc diffusion test.Results. The clarithromycin, amoxicillin and levofloxacin disc diffusion tests provided identical results to E-Tests on a subset of 30 isolates. Disparities were observed in the metronidazole test results, however. In total, 241 isolates from 162 patients were tested using at least one method. Of all isolates, 28 % were resistant to clarithromycin, 62 % to metronidazole and 3 % to amoxicillin, which are used in first-line therapies. For those antibiotics used in second- and third-line therapies, 4 % were resistant to levofloxacin and none of the isolates were resistant to tetracycline. Resistance to more than one antibiotic was found in 27 % of isolates. The frequency of patients with a clarithromycin-resistant strain increased dramatically over time: from 16 % between 2001 and 2005 to 40 % between 2011 and 2018 (P=0.011). For the same time periods, there was also an increase in those with a metronidazole-resistant strain (from 58 to 78 %; P=0.05). The frequencies of clarithromycin and metronidazole resistance were higher in isolates from patients who had previously received eradication therapy, compared to those who had not (40 % versus 77 %, and 80 % versus 92 %, respectively). Of 79 pairs of isolates from the antrum and corpus regions of the same patient's stomach, only six had differences in their antimicrobial susceptibility profiles.Conclusion. Although there was high and increasing resistance to clarithromycin and metronidazole, there was no resistance to tetracycline and the frequencies of amoxicillin and levofloxacin resistance were very low.

Antibiotic resistance patterns of Helicobacter pylori strains isolated from the Tibet Autonomous Region, China

BACKGROUND

The prevalence of Helicobacter pylori antibiotic susceptibility in the Tibet Autonomous Region, China is not determined. This study aimed to evaluate the antibiotic resistance patterns of H. pylori isolates there.

RESULTS

A total of 153 (38.5%) H. pylori strains were successfully isolated from 397 patients in People's Hospital of Tibet Autonomous Region, China. The overall resistance rates were as follows: clarithromycin (27.4%), levofloxacin (31.3%), metronidazole (86.2%), amoxicillin (15.6%), tetracycline (0%), furazolidone (0.6%), and rifampicin (73.2%). Only 2.0% of H. pylori isolates were susceptible to all tested antimicrobials, with mono resistance, dual resistance, triple resistance, quadruple resistance, and quintuple resistance being 18.3%, 44.4%, 18.3%, 12.4%, and 4.6%, respectively. The resistance rates to levofloxacin (40.5%) and amoxicillin (21.5%) in strains isolated from female patients were significantly higher than those from male patients (21.6% and 9.5%, respectively).

CONCLUSIONS

This study demonstrates high H. pylori resistance rates to clarithromycin, levofloxacin, metronidazole, and rifampicin, whereas moderate resistance to amoxicillin, and negligible resistant to tetracycline, and furazolidone in Tibet Autonomous Region, China. The high resistance to rifampicin warns further investigation of its derivative, rifabutin.

Are molecular methods helpful for the diagnosis of Helicobacter pylori infection and for the prediction of its antimicrobial resistance?

Infections produced by Helicobacter pylori (H. pylori), a spiral Gram-negative bacterium, can cause chronic gastritis, peptic ulcer, and gastric cancer. Antibiotic therapy is the most effective treatment for H. pylori infection at present. However, owing to the increasing antibiotic resistance of H. pylori strains, it has become a serious threat to human health. Therefore, the accurate diagnosis of H. pylori infections and its antibiotic resistance markers is of great significance. Conventional microbiological diagnosis of H. pylori is based on culture; however, successful isolation of H. pylori from gastric biopsy specimens is a challenging task affected by several factors and has limitations in terms of the time of response. To improve conventional methods, some molecular techniques, such as PCR, have been recently used in both invasive and non-invasive H. pylori diagnosis, enabling simultaneous detection of H. pylori and point mutations responsible for frequent antibiotic resistance. The advantages and disadvantages of molecular methods, mainly PCR, versus conventional culture for the H. pylori identification and the detection of antibiotic resistance are discussed. As expected, the combination of both diagnostic methods will lead to the most efficient identification of the H. pylori strains and the resistance patterns.

Development and Validation of Multiplex Quantitative PCR Assay for Detection of Helicobacter pylori and Mutations Conferring Resistance to Clarithromycin and Levofloxacin in Gastric Biopsy

Aims and Objectives

More than half of the world's population is infected with Helicobacter pylori, which can cause chronic gastritis. WHO has regarded clarithromycin-resistant H. pylori as a high priority pathogen. Hence, accurate diagnosis and detection of clarithromycin- and levofloxacin-resistant H. pylori strains is essential for proper management of infection. The objective of this study was to develop and optimize multiplex quantitative PCR assay for detection of mutations associated with clarithromycin and levofloxacin resistance in H. pylori directly from the gastric biopsies.

Materials and Methods

Specific primers and probes were designed to amplify ureA and mutations in 23S rRNA and gyrA genes. Singleplex and triplex qPCR assays were optimized and the assay's sensitivities and specificities were determined. The optimized multiplex qPCR assay was performed on 571 gastric biopsies.

Results

In this study, 14.7% (84/571) of the gastric biopsies were positive for H. pylori by conventional methods and 23.8% (136/571) were positive by the ureA-qPCR with 96.4% sensitivity and 88.5% specificity, while the +LR and -LR were 8.72 and 0.04, respectively. The ureA-positive samples (n=136) were subjected to multiplex qPCR which detected A2142G and A2143G mutations in the 23S rRNA gene (20.6%, 28/136) conferring clarithromycin resistance and gyrA mutations N87K, N87I, D91N, and D91Y (11.8%, 16/136) leading to levofloxacin resistance. The sensitivity and specificity of qPCR of 23S rRNA gene were 100% and 98.7%, respectively, while 100% and 99.8% for qPCR of gyrA, respectively.

Conclusion

The effectiveness of this qPCR is that it is sensitive in detecting low bacterial load and will help in timely detection of clarithromycin- and levofloxacin-resistant strains, especially in case of mixed infections. Since it is culture independent, it can inform clinicians about antibiotics to be included in the first-line therapy, thereby improving the management of H. pylori infection at a much greater pace.

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.

Procyanidin-Rich Extract from Grape Seeds as a Putative Tool against Helicobacter pylori

Strains of Helicobacter pylori (H. pylori) resistant to various antibiotics have increased in recent years. In this context, the search for new therapeutic approaches is crucial. The aim of the present study was to demonstrate the antibacterial activity of a procyanidin-rich extract obtained from food-grade winery grape seeds against 14 H. pylori strains and elucidate its phenolic composition. Ten strains (71.4%) showed resistance to at least some of the tested antibiotics, while four isolates (28.6%) were susceptible to all antibiotics. Resistance to more than one class of antibiotics was observed in six strains (42.9%). The extract was able to inhibit the growth of all H. pylori strains in a range of a minimum inhibitory concentration (MIC) from 0.015 mg/mL to 0.125 mg/mL, confirming also the existence of a strain-dependent effect. The phenolic composition determined by reverse phase high pressure liquid chromatography, photodiode array, and mass spectrometry detection (RP-HPLC-PAD-MS) analysis revealed the presence of 43 individual compounds and allowed the quantification of 41 of them, including seven procyanidin tetramers, seven procyanidin pentamers, and six galloylated procyanidin dimers, trimers, and tetramers. The extract was composed mainly by catechin and procyanidin oligomers with a total amount of 5801 mg/100 g, which represent 92% of the total individual phenolic content. Among them, the most abundant were catechins (2047 mg/100 g), followed by procyanidin dimers (1550 mg/100 g), trimers (1176 mg/100 g), tetramers (436 mg/100 g), and pentamers (296 mg/100 g) that represent 35, 27, 20, 8, and 5%, respectively of the total flavanol constituents. The composition profile information may help to improve the production process of useful antibacterial extracts against H. pylori.

Mutations in the Antibiotic Target Genes Related to Clarithromycin, Metronidazole and Levofloxacin Resistance in Helicobacter pylori Strains from Children in China

Purpose

This study aimed to characterize common mutations of antibiotic-resistant gene of clarithromycin, metronidazole and levofloxacin in Helicobacter pylori (H. pylori) and determine their association with antibiotic resistance of H. pylori for providing a strategy for eradication therapy of H. pylori infection in children.

Patients and Methods

The antibiotic resistance to clarithromycin, metronidazole and levofloxacin for H. pylori strains isolated from children was determined by E-test. The mutation of domain V of 23S rRNA, rdxA and frxA genes, gyrA and gyrB genes was performed by PCR-based sequencing of DNA fragments.

Results

Out of the 79 H. pylori strains examined, 66 (83.5%) were resistant to at least one of the tested antibiotics and 13 (16.5%) were fully sensitive. A total of 29 (36.7%) strains were resistant to clarithromycin. Analysis of the 23S rRNA gene showed that most mutations occurred at the A2143G and T2182C sites, showing a frequency of 82.8% (24/29) and 89.7% (26/29) respectively. In the 11 sensitive strains to clarithromycin, the frequency of A2143G mutation was only 45.5%, which was significantly lower than that in resistant strains (P<0.05). There were 54 strains (68.4%) resistant to metronidazole, with most mutations occurring at G47A and T184G in the rdxA gene. T184G mutation was recognized in metronidazole-sensitive strains, but no G47A mutation was identified. Twelve strains (15.2%) were resistant to levofloxacin. Position 91 mutation of the gyrA gene occurred only in resistant strains, whereas position 87 mutations were detected in both sensitive and resistant strains to levofloxacin.

Conclusion

In H. pylori resistant strains isolated from children in China, most mutations occurred at A2143G of the 23S rRNA gene for clarithromycin; G47A mutation of rdxA gene for metronidazole; and at 91 mutation of gyrA gene for levofloxacin. It is suggested that susceptibility testing together with screening the mutation of antimicrobial-resistant gene prior to treatment is important for the eradication of H. pylori in children.

Molecular characterization and prevalence of antibiotic resistance in Helicobacter pylori isolates in Kuala Lumpur, Malaysia

Aims and objectives

Helicobacter pylori has been classified as high priority pathogen by the WHO in 2017. The emergence of antibiotic-resistant strains is one of the main causes of treatment failure in H. pylori infection. This study determined and characterized primary and secondary resistances in H. pylori in Malaysia.

Materials and methods

Gastric biopsies from antrum (n=288) and corpus (n=283) were obtained from 288 patients who underwent endoscopy at Universiti Kebangsaan Malaysia Medical Center (UKMMC), Kuala Lumpur, Malaysia. Antibiotic susceptibility to six classes of antibiotics was determined by the E-test. Mutations conferring in resistance in functional genes were identified by PCR and sequencing.

Results

Overall resistance rates to metronidazole, clarithromycin and levofloxacin were 59.3% (35/59), 35.6% (21/59) and 25.4% (15/59), respectively. Secondary isolates showed significantly higher resistance rates to clarithromycin compared to the primary isolates. Mixed infection with susceptible and resistant isolates was observed in 16.2% (6/37) of cases, of which 83.3% (n=5) had infection with the same strain. 41% (18/44) of isolates were resistant to more than one class of antibiotics of which 50% (9/18) were multidrug-resistant, two being primary and seven being secondary isolates. Mutations in rdxA, 23S rRNA and gyrA genes were associated with resistance to metronidazole, clarithromycin and levofloxacin, respectively.

Conclusion

The high level of resistance to metronidazole, clarithromycin and levofloxacin seen in H. pylori isolates in our setting warrants the need for continuous surveillance and highlights caution in use of antibiotics generally used as first-line therapy in H. pylori eradication regimen.

In Vitro Activity of 3-Bromopyruvate, an Anticancer Compound, Against Antibiotic-Susceptible and Antibiotic-Resistant Helicobacter pylori Strains

Helicobacter pylori (H. pylori) is a bacterium capable of inducing chronic active gastritis, which in some people, develops into gastric cancers. One of the substances that may be useful in the eradication of this microorganism is 3-Bromopyruvate (3-BP), an anticancer compound with antimicrobial properties. The aim of this article was to determine the activity of 3-BP against antibiotic-susceptible and antibiotic-resistant H. pylori strains. The antimicrobial activity was determined using a disk-diffusion method, broth microdilution method, time-killing assay, and checkerboard assay. The research was extended by observations using light, fluorescence, and scanning electron microscopy. The growth inhibition zones produced by 2 mg/disk with 3-BP counted for 16–32.5 mm. The minimal inhibitory concentrations (MICs) ranged from 32 to 128 μg/mL, while the minimal bactericidal concentrations (MBCs) for all tested strains had values of 128 μg/mL. The time-killing assay demonstrated the concentration-dependent and time-dependent bactericidal activity of 3-BP. The decrease in culturability below the detection threshold (<100 CFU/mL) was demonstrated after 6 h, 4 h, and 2 h of incubation for MIC, 2× MIC, and 4× MIC, respectively. Bacteria treated with 3-BP had a several times reduced mean green/red fluorescence ratio compared to the control samples, suggesting bactericidal activity, which was independent from an induction of coccoid forms. The checkerboard assay showed the existence of a synergistic/additive interaction of 3-BP with amoxicillin, tetracycline, and clarithromycin. Based on the presented results, it is suggested that 3-BP may be an interesting anti-H. pylori compound.

Molecular and Proteomic Analysis of Levofloxacin and Metronidazole Resistant Helicobacter pylori

Antibiotic resistance in bacteria incurs fitness cost, but compensatory mechanisms may ameliorate the cost and sustain the resistance even under antibiotics-free conditions. The aim of this study was to determine compensatory mechanisms of antibiotic resistance in H. pylori. Five strains of levofloxacin-sensitive H. pylori were induced in vitro to develop resistance. In addition, four pairs of metronidazole-sensitive and -resistant H. pylori strains were isolated from patients carrying dual H. pylori populations that consist of both sensitive and resistant phenotypes. Growth rate, virulence and biofilm-forming ability of the sensitive and resistant strains were compared to determine effects of compensatory response. Proteome profiles of paired sensitive and resistant strains were analyzed by liquid chromatography/mass spectrophotometry (LC/MS). Although there were no significant differences in growth rate between sensitive and resistant pairs, bacterial virulence (in terms of abilities to induce apoptosis and form biofilm) differs from pair to pair. These findings demonstrate the complex and strain-specific phenotypic changes in compensation for antibiotics resistance. Compensation for in vitro induced levofloxacin resistance involving mutations of gyrA and gyrB was functionally random. Furthermore, higher protein translation and non-functional protein degradation capabilities in naturally-occuring dual population metronidazole sensitive-resistant strains may be a possible alternative mechanism underlying resistance to metronidazole without mutations in rdxA and frxA. This may explain the lack of mutations in target genes in ~10% of metronidazole resistant strains.

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.

Susceptibility of Helicobacter pylori to Levofloxacin and Rifampicin in Israel

The aim of this study was to assess the resistance level of Helicobacter pylori to levofloxacin and rifampicin from samples collected from pediatric and adult Israeli patients from 2012 to 2013. A total of 117 isolate samples of H. pylori were collected between 2012 and 2013. Isolates were cultured from stomach antrum biopsies and identified by the microbiology laboratory. Isolates were considered susceptible to levofloxacin and rifampicin by an Etest. Out of 117 isolates, 105 were found susceptible and 12 resistant to levofloxacin. For rifampicin, 104 isolates were susceptible and 13 were resistant. Study results estimate an alarming resistance rate, which reiterates the need for prudent use of alternative antibiotics to prevent further spread of resistant strains. Therefore, we suggest subjecting cultures from biopsy samples to susceptibility testing for the purpose of identification of strains resistant to levofloxacin and rifampicin among other antibiotic agents. This will allow for successful monitoring of microbial resistance and will assure prudent use of antimicrobial modalities.

Resistotype of Helicobacter pylori isolates: the impact on eradication outcome

Antibiotic resistance is increasing worldwide, and it has been regarded as the main factor reducing the efficacy of Helicobacter pylori therapy. The aim of this study was to determine the phenotype and genotype of antibiotic-resistant strains of H. pylori in the Malaysian population and to evaluate the impact of antibiotic resistance to eradication outcome. One hundred and sixty-one H. pylori isolates were analysed in this study. Metronidazole, clarithromycin, fluoroquinolone, amoxicillin and tetracycline susceptibilities were determined by Etest. PCR followed by DNA sequencing was carried out to determine mutations. The medical records of the patients infected with resistant strains were reviewed to determine the eradication outcome. Metronidazole resistance was encountered in 36.6 % of H. pylori isolates, whereas clarithromycin and fluoroquinolone resistance was observed in 1.2  and 1.9 % of isolates, respectively. All strains tested were susceptible to amoxicillin and tetracycline. Frameshift and nonsense mutations in rdxA and frxA genes resulting in stop codons contributed to metronidazole resistance, which leads to reduced eradication efficacy. A2142G and A2143G mutations of 23S rRNA were identified as causing failure of the eradication therapy. Mutation at either codon 87 or 91 of the gyrA gene was identified in fluoroquinolone-resistant strains. However, the effect of resistance could not be assessed. This study showed that frameshift and nonsense mutations in rdxA or frxA genes and point mutations in the 23S rRNA affected the efficacy of H. pylori eradication therapy.

The efficacy of moxifloxacin-based triple therapy in treatment of Helicobacter pylori infection: a systematic review and meta-analysis of randomized clinical trials

Recent evidence shows that moxifloxacin could exert an antimicrobial effect against Helicobacter pylori in both in vitro and in vivo models. To systematically evaluate whether moxifloxacin-containing triple therapy could improve eradication rates and reduce side effects in first-line or second-line anti-H. pylori treatment, eligible articles were identified by searches of electronic databases. We included all randomized trials comparing moxifloxacin-based triple therapy with standard triple or quadruple therapy during H. pylori eradication treatment. Statistical analysis was performed with Review Manager 5.0.10. Subanalysis/sensitivity analysis was also performed. We identified seven randomized trials (n=1263). Pooled H. pylori eradication rates were 79.03% (95%CI: 75.73-82.07) and 68.33% (95%CI: 64.44-72.04) for patients with moxifloxacin-based triple therapy or with standard triple or quadruple therapy, respectively (intention-to-treat analysis). The odds ratio (OR) was 1.82 (95%CI: 1.17-2.81), the occurrence of total side effects was 15.23% (95%CI: 12.58-18.20) and 27.17% (95%CI: 23.64-30.92) for groups with or without moxifloxacin, and the summary OR was 0.45 (95%CI: 0.26-0.77). In subgroup analyses, we noted that the second-line eradication rate in the moxifloxacin group was significantly higher than that in the quadruple therapy group (73.33 vs 60.17%, OR: 1.78, 95%CI: 1.16-2.73, P<0.001). However, there was no difference in first-line eradication treatment. Findings from this meta-analysis suggest that moxifloxacin-based triple therapy is more effective and better tolerated than standard triple or quadruple therapy. Therefore, a moxifloxacin-based triple regimen should be used in the second-line treatment of H. pylori infection.

Helicobacter pylori resistance rates for levofloxacin, tetracycline and rifabutin among Irish isolates at a reference centre

INTRODUCTION

Helicobacter pylori eradication rates using conventional triple therapies are falling, making viable second-line and rescue regimens necessary. Levofloxacin, tetracycline and rifabutin are three efficacious antibiotics for rescue therapy.

AIM

We aimed to assess the resistance rates for H. pylori against these antibiotics in an Irish cohort.

METHODS

Gastric biopsies were collected from 85 patients infected with H. pylori (mean age 46 years) in the Adelaide and Meath Hospital, Dublin in 2008 and 2009. Susceptibility to antibiotics was tested using the Etest. Clinical information was obtained from endoscopy reports and chart review.

RESULTS

50.6 % of patients were females. Mean age was 47 years. Ten had prior attempts at eradication therapy with amoxicillin-clarithromycin-PPI, two had levofloxacin-based second-line therapy. 11.7 % [95 % CI (6.5-20.3 %)] (N = 10) had strains resistant to levofloxacin. There were no strains resistant to rifabutin or tetracycline. Levofloxacin resistance in the under 45 age group was 2.6 % (1/38) compared to 19.1 % (9/47) of above 45 age group (p = 0.02).

DISCUSSION

The levofloxacin rates illustrated in this study are relatively low by European standards and in line with other studies from the United Kingdom and Germany, with younger patients having very low levels of resistance. Levofloxacin, tetracycline and rifabutin are all valid options for H. pylori eradication in Irish patients but the importance of compliance cannot be underestimated.

Helicobacter pylori eradication in Western Australia using novel quadruple therapy combinations

BACKGROUND

Helicobacter pylori eradication rates with standard triple therapy are declining worldwide. The optimal management of H. pylori is evolving and new treatment combinations for antibiotic resistant H. pylori strains are required, especially for patients with penicillin allergy.

AIM

To review the effectiveness of alternative antibiotic combinations and necessity of pre-antibiotic sensitivity testing.

METHODS

A total of 310 consecutive patients who had failed at least one course of standard 7-day triple therapy initially prescribed by their physicians were included in this study between year 2007 and 2011. Antibiotics were prescribed based on pre-antibiotic sensitivity tests and, if any, patient's allergy to penicillin.

RESULTS

In 98.7% of the patients' samples, H. pylori was successfully cultured. The proportion resistant to clarithromycin and metronidazole was 94.1% and 67.6% respectively, with 65% resistant to both. For the in-house primary quadruple therapy, with Proton pump inhibitor, Amoxicillin, Rifabutin and Ciprofloxacin (PARC), H. pylori was successfully eradicated in 95.2% of patients. For patients allergic to amoxicillin, an alternative quadruple therapy using Proton pump inhibitor, Bismuth subcitrate, Rifabutin and Ciprofloxacin (PBRC) gave an eradication rate of 94.2%. Patients needing alternative salvage therapy were given novel personalised combinations consisting of bismuth, rifabutin, tetracycline or furazolidone; the eradication rate was 73.8%.

CONCLUSIONS

Patients who present with antibiotic resistant H. pylori can be confidently treated with PARC, PBRC or other personalised salvage therapies. These regimens can be used when treatment options are limited by penicillin allergy. Pre-treatment H. pylori antibiotic sensitivity tests contributed to the high eradication rate in this study.

Gemifloxacin can partially overcome quinolone resistance of H. pylori with gyrA mutation in Taiwan

BACKGROUNDS

The levofloxacin resistance caused by gyrA gene mutation is rising rapidly to limit wide application for Helicobacter pylori eradication. We investigated whether gemifloxacin has a superior antimicrobial activity to levofloxacin against H. pylori.

MATERIALS AND METHODS

 Forty-four consecutive clinical H. pylori isolates with levofloxacin resistance and 80 randomly selected levofloxacin-sensitive controls were tested for gemifloxacin sensitivity by E-test. The resistance to levofloxacin or gemifloxacin was defined as minimal inhibitory concentration (MIC) > 1 mg/L. The clinical features and GyrA mutation patterns checked by direct sequencing were also analyzed to assess its association with the H. pylori gemifloxacin resistance.

RESULTS

 All levofloxacin-sensitive H. pylori isolates were sensitive to gemifloxacin. Eight strains (18.2%) resistant to levofloxacin could be still sensitive to gemifloxacin. Gemifloxacin achieved a 5-time lower in MIC levels against levofloxacin-resistant isolates. Nearly all levofloxacin-resistant isolates (97.7%, 43/44) had GyrA mutation at amino acid position 87 or 91. Double mutation sites may play dual roles in quinolone resistance, as N87K plus H57Y or D91N plus V77A mutations showed high-level resistance to both quinolones; whereas D91Y plus A97V or D91N plus A97V mutations showed low level levofloxacin resistance to become sensitive to gemifloxacin. In H. pylori isolates with single N87K, D91Y or D91N mutation, near 20% was gemifloxacin-sensitive and levofloxacin-resistant. The gemifloxacin-resistant rate of H. pylori was higher in patients with gastric ulcer than in those without (p <.05).

CONCLUSION

 Gemifloxacin is superior to levofloxacin in antimicrobial activity against clinical H. pylori isolates, and even overcome some levofloxacin resistance.

Rescue Therapy for Helicobacter pylori Infection 2012

Helicobacter pylori infection is the main cause of gastritis, gastroduodenal ulcer disease, and gastric cancer. After 30 years of experience in H. pylori treatment, however, the ideal regimen to treat this infection has still to be found. Nowadays, apart from having to know well first-line eradication regimens, we must also be prepared to face treatment failures. In designing a treatment strategy, we should not only focus on the results of primary therapy alone but also on the final-overall-eradication rate. The choice of a "rescue" treatment depends on which treatment is used initially. If a first-line clarithromycin-based regimen was used, a second-line metronidazole-based treatment (quadruple therapy) may be used afterwards, and then a levofloxacin-based combination would be a third-line "rescue" option. Alternatively, it has recently been suggested that levofloxacin-based "rescue" therapy constitutes an encouraging 2nd-line strategy, representing an alternative to quadruple therapy in patients with previous PPI-clarithromycin-amoxicillin failure, with the advantage of efficacy, simplicity and safety. In this case, quadruple regimen may be reserved as a 3rd-line "rescue" option. Even after two consecutive failures, several studies have demonstrated that H. pylori eradication can finally be achieved in almost all patients if several "rescue" therapies are consecutively given.

Fluoroquinolone resistance in Helicobacter pylori: role of mutations at position 87 and 91 of GyrA on the level of resistance and identification of a resistance conferring mutation in GyrB

BACKGROUND AND AIMS

Fluoroquinolone-containing regimens have been suggested as an alternate to standard triple therapy for the treatment of Helicobacter pylori infections. To determine the relationship between fluoroquinolone resistance and mutations of GyrA and GyrB in H. pylori, we exchanged the mutations at positions 87 and 91 of GyrA among fluoroquinolone-resistant clinical isolates. GyrB of a strain with no mutations in GyrA was also analyzed to identify mechanisms of resistance to norfloxacin.

MATERIALS & METHODS

Natural transformation was performed using the amplified fragment of the gyrA and gyrB gene as donor DNA. The amino acid sequences of GyrA and GyrB were determined by DNA sequencing of the gyrA and gyrB genes.

RESULTS

Norfloxacin-resistant strains which had mutations at position 87 and 91 became susceptible when the mutations were converted to the wild type. When the mutation from Asp to Asn at position 91 was exchanged to the mutation from Asn to Lys at position 87, the MIC to levofloxacin, gatifloxacin, and sitafloxacin increased. Norfloxacin-resistant strain TS132 with no mutations in GyrA but had a mutation at position 463 in GyrB. Transformants obtained by natural transformation using gyrB DNA of TS132 had a mutation at position 463 of GyrB and revealed resistant to norfloxacin and levofloxacin.

CONCLUSION

Mutation from Asn to Lys at position 87 of GyrA confers higher resistance to levofloxacin and gatifloxacin than does mutation from Asp to Asn at position 91. We propose that mutation at position 463 in GyrB as a novel mechanism of fluoroquinolone resistance in H. pylori.

Review article: rifabutin in the treatment of refractory Helicobacter pylori infection

BACKGROUND

Even with the current most effective treatment regimens, a relevant proportion of patients will fail to eradicate Helicobacter pylori infection.

AIM

To evaluate the role of rifabutin in the treatment of H. pylori infection.

METHODS

Bibliographical searches were performed in MEDLINE. Data on the efficacy of rifabutin-containing regimens on H. pylori eradication were combined and meta-analysed using the generic inverse variance method.

RESULTS

Rifabutin shows good in vitro activity against H. pylori. Mean H. pylori rifabutin resistance rate (calculated from 11 studies including 2982 patients) was 1.3% (95% confidence interval = 0.9-1.7%). When only studies including patients naïve to H. pylori eradication treatment were considered, this figure was even lower (0.6%). On the other hand, higher values of rifabutin resistance were calculated (1.59%) when only post-treatment patients were considered. Overall, mean H. pylori eradication rate (intention-to-treat analysis) with rifabutin-containing regimens (1008 patients) was 73% (67-79%). Respective cure rates for second-line (223 patients), third-line (342 patients) and fourth/fifth-line (95 patients) rifabutin therapies were 79% (67-92%), 66% (55-77%) and 70% (60-79%) respectively. For treating H. pylori infection, almost all studies have administered rifabutin 300 mg/day; this dose seems to be more effective than 150 mg/day. The ideal length of treatment remains unclear, but 10- to 12-day regimens are generally recommended. The mean rate of adverse effects was 22% (19-25%). Myelotoxicity is the most significant, although this complication was rare. Until now, all patients have recovered of leucopenia uneventfully in a few days, and there have been no reports of infection or other adverse outcomes related to it.

CONCLUSION

Rifabutin-containing rescue therapy constitutes an encouraging strategy after multiple (usually three) previous eradication failures with key antibiotics such as amoxicillin, clarithromycin, metronidazole, tetracycline and levofloxacin.

Randomized trial on 14 versus 7 days of esomeprazole, moxifloxacin, and amoxicillin for second-line or rescue treatment of Helicobacter pylori infection

BACKGROUND

Triple therapy with a proton pump inhibitor, moxifloxacin, and amoxicillin has been proven effective in first-line treatment of Helicobacter pylori infection.

AIM

To explore 1, the value of triple therapy with esomeprazole, moxifloxacin, and amoxicillin in second-line or rescue treatment of Caucasian patients and 2, the impact of treatment duration on eradication success.

METHODS

H. pylori-infected patients with at least one previous treatment failure were randomized to oral esomeprazole 20 mg b.i.d., moxifloxacin 400 mg o.d., and amoxicillin 1000 mg b.i.d. for either 7 (EMA-7) or 14 days (EMA-14). Eradication was confirmed by 13C urea breath test. Antimicrobial susceptibility testing was performed in all patients at baseline and in patients who failed treatment.

RESULTS

Eighty patients were randomized, and 60% had ≥ 2 previous treatment failures. Pretreatment resistance against clarithromycin and metronidazole was found in 70.5 and 61.5% of cases, respectively. The intention-to-treat eradication rate was significantly higher after EMA-14 compared with EMA-7 (95.0 vs 78.9%, p = .036). No independent risk factor for treatment failure could be identified. There were no serious adverse events. Five of the EMA-14 patients (12.5%) compared with none of the EMA-7 patients discontinued prematurely because of adverse events (p = .031). Post-treatment resistance against moxifloxacin was found in one of seven patients with isolated organisms (14.3%).

CONCLUSION

Second-line/rescue H. pylori eradication therapy with esomeprazole, moxifloxacin, and amoxicillin is very effective and well tolerated. Fourteen days of treatment significantly increase the eradication rate but also the rate of adverse events.

Should quinolones come first in Helicobacter pylori therapy?

New generations of fluoroquinolones, like levofloxacin and moxifloxacin, exhibit a broad-spectrum activity against Gram-positive and Gram-negative bacteria, and have been successfully introduced into the treatment of Helicobacter pylori infection. Based on a large body of evidence, current guidelines recommend the use of levofloxacin- or moxifloxacin-containing proton-pump inhibitor (PPI) triple therapies in second-line or rescue treatment of H. pylori infection. The efficacy of standard PPI triple therapies has substantially declined during the last decade, mainly due to increasing resistance against the key antibiotics clarithromycin and metronidazole. Therefore, alternative strategies for first-line therapy of H. pylori infection have been evaluated in a considerable number of clinical trials including sequential regimens, nonbismuth quadruple regimens, and quinolone-containing PPI triple therapy regimens. The aim of this paper is to summarize the current body of evidence of levofloxacin- and moxifloxacin-containing regimens in first-line treatment of H. pylori infection, and to discuss the risks and benefits of these strategies in the light of increasing resistance of H. pylori to quinolones.

Genotypic resistance in Helicobacter pylori strains correlates with susceptibility test and treatment outcomes after levofloxacin- and clarithromycin-based therapies

The accuracy of genotypic resistance to levofloxacin (gyrA mutations) and its agreement with treatment outcomes after levofloxacin-based therapy have not been reported. We aimed to assess the correlation. Helicobacter pylori strains isolated from patients who received levofloxacin-based and clarithromycin-based triple therapies in a previous randomized trial were analyzed for point mutations in gyrA and 23S rRNA. PCR followed by direct sequencing was used to assess the gyrA and 23S rRNA mutations. An agar dilution test was used to determine the MICs of clarithromycin and levofloxacin. We found that the agreement between genotypic and phenotypic resistance to levofloxacin was best when the MIC breakpoint was >1 μg/ml (kappa coefficient, 0.754). The eradication rates in patients with and without gyrA mutations were 41.7% and 82.7%, respectively (P = 0.003). The agreement between genotypic and phenotypic resistance to clarithromycin was best when the MIC breakpoint was >2 μg/ml (kappa, 0.694). The eradication rates in patients with and without 23S rRNA mutations were 7.7% and 93.5%, respectively (P < 0.001). The agreements (kappa coefficient) between therapeutic outcomes after clarithromycin-based triple therapy and genotypic and phenotypic resistance were 0.671 and 0.356, respectively. The agreements (kappa coefficient) between therapeutic outcomes after levofloxacin-based triple therapy and genotypic and phenotypic resistance were 0.244 and 0.190, respectively. In conclusion, gyrA and 23S rRNA mutations in H. pylori strains appeared to be better markers than phenotypic resistance in the prediction of treatment outcomes. The optimal breakpoints for levofloxacin and clarithromycin resistance appeared to be >1 μg/ml and >2 μg/ml, respectively.

Second-line rescue therapy of helicobacter pylori infection

Helicobacter pylori infection is the main known cause of gastritis, gastroduodenal ulcer disease and gastric cancer. After more than 20 years of experience in H. pylori treatment, however, the ideal regimen to treat this infection has still to be found. Nowadays, apart from having to know well first-line eradication regimens, we must also be prepared to face treatment failures. Therefore, in designing a treatment strategy we should not focus on the results of primary therapy alone, but also on the final (overall) eradication rate. The choice of a 'rescue' treatment depends on which treatment is used initially. If a first-line clarithromycin-based regimen was used, a second-line metronidazole-based treatment (quadruple therapy) may be used afterwards, and then a levofloxacin-based combination would be a third-line 'rescue' option. Alternatively, it has recently been suggested that levofloxacin-based 'rescue' therapy constitutes an encouraging second-line strategy, representing an alternative to quadruple therapy in patients with previous PPI-clarithromycin-amoxicillin failure, with the advantage of efficacy, simplicity and safety. In this case, quadruple regimen may be reserved as a third-line 'rescue' option. Finally, rifabutin-based 'rescue' therapy constitutes an encouraging empirical fourth-line strategy after multiple previous eradication failures with key antibiotics such as amoxicillin, clarithromycin, metronidazole, tetracycline, and levofloxacin. Even after two consecutive failures, several studies have demonstrated that H. pylori eradication can finally be achieved in almost all patients if several 'rescue' therapies are consecutively given. Therefore, the attitude in H. pylori eradication therapy failure, even after two or more unsuccessful attempts, should be to fight and not to surrender.