Antimicrobial susceptibility of Helicobacter pylori strains isolated from children in Israel

Antibiotic Resistance and Therapeutic Efficacy of Helicobacter pylori Infection in Pediatric Patients-A Tertiary Center Experience

One of the most widespread bacterial infections worldwide, Helicobacter pylori is thought to affect almost half of the world's population. Due to rising antibiotic resistance, treatment should be tailored according to antibiotic susceptibility testing (AST). This study aims to evaluate Helicobacter pylori antibiotic resistance and its therapeutic efficacy in children. We conducted a prospective, single-center study, that evaluated 68 children referred for upper gastrointestinal endoscopy (UGE) following chronic dyspeptic syndrome. Each patient underwent multiple biopsies to perform bacterial cultures with AST and histopathological examinations for the diagnosis. Patients without antibiotic resistance or negative cultures received a 10-day sequential therapy, while the others had the antibiotic regimen tailored based on AST. Fifty-nine patients with a positive biopsy-based diagnosis (24 males) were finally included. Bacterial cultures with AST were positive for 13 patients (22.03%) and the antibiotic resistance for clarithromycin was 15.38%. Fifty-seven patients were administered sequential therapy with an eradication rate of 94.73%. Clarithromycin-resistant patients were successfully treated with 10-day triple therapy of esomeprazole, amoxicillin, and metronidazole. Although bacterial cultures had a low positivity rate, sequential therapy had a successful eradication rate. Further studies are necessary to better assess Helicobacter pylori antibiotic resistance to provide tailored treatment and identify children that need closer monitoring.

A High-Throughput Metabolic Microarray Assay Reveals Antibacterial Effects of Black and Red Raspberries and Blackberries against Helicobacter pylori Infection

Helicobacter pylori infection is commonly treated with a combination of antibiotics and proton pump inhibitors. However, since H. pylori is becoming increasingly resistant to standard antibiotic regimens, novel treatment strategies are needed. Previous studies have demonstrated that black and red berries may have antibacterial properties. Therefore, we analyzed the antibacterial effects of black and red raspberries and blackberries on H. pylori. Freeze-dried powders and organic extracts from black and red raspberries and blackberries were prepared, and high-performance liquid chromatography was used to measure the concentrations of anthocyanins, which are considered the major active ingredients. To monitor antibiotic effects of the berry preparations on H. pylori, a high-throughput metabolic growth assay based on the Biolog system was developed and validated with the antibiotic metronidazole. Biocompatibility was analyzed using human gastric organoids. All berry preparations tested had significant bactericidal effects in vitro, with MIC90 values ranging from 0.49 to 4.17%. Antimicrobial activity was higher for extracts than powders and appeared to be independent of the anthocyanin concentration. Importantly, human gastric epithelial cell viability was not negatively impacted by black raspberry extract applied at the concentration required for complete bacterial growth inhibition. Our data suggest that black and red raspberry and blackberry extracts may have potential applications in the treatment and prevention of H. pylori infection but differ widely in their MICs. Moreover, we demonstrate that the Biolog metabolic assay is suitable for high-throughput antimicrobial susceptibility screening of H. pylori.

Genomic Analysis of Antimicrobial Resistance Genotype-to-Phenotype Agreement in Helicobacter pylori

Antimicrobial resistance (AMR) in Helicobacter pylori is increasing and can result in treatment failure and inappropriate antibiotic usage. This study used whole genome sequencing (WGS) to comprehensively analyze the H. pylori resistome and phylogeny in order to characterize Israeli H. pylori. Israeli H. pylori isolates (n = 48) underwent antimicrobial susceptibility testing (AST) against five antimicrobials and WGS analysis. Literature review identified 111 mutations reported to correlate with phenotypic resistance to these antimicrobials. Analysis was conducted via our in-house bioinformatics pipeline targeting point mutations in the relevant genes (pbp1A, 23S rRNA, gyrA, rdxA, frxA, and rpoB) in order to assess genotype-to-phenotype correlation. Resistance rates of study isolates were as follows: clarithromycin 54%, metronidazole 31%, amoxicillin 10%, rifampicin 4%, and levofloxacin 2%. Genotype-to-phenotype correlation was inconsistent; for every analyzed gene at least one phenotypically susceptible isolate was found to have a mutation previously associated with resistance. This was also observed regarding mutations commonly used in commercial kits to diagnose AMR in H. pylori cases. Furthermore, 11 novel point mutations associated with a resistant phenotype were detected. Analysis of a unique set of H. pylori isolates demonstrates that inferring resistance phenotypes from WGS in H. pylori remains challenging and should be optimized further.

Phenotypic and Genotypic Analysis of Resistant Helicobacter pylori Strains Isolated from Children with Gastrointestinal Diseases

Antibiotic resistance of Helicobacter pylori is currently a global issue. The aim of this study was to analyze actual antibiotic resistance rates of H. pylori strains isolated from children with primary infections and to compare the incidence of mutations that determine resistance to clarithromycin (CH) and metronidazole (MET) in children with different clinical diagnoses. A total of 91 H. pylori strains were isolated from 108 children with primary infections. Drug susceptibility testing of the strains was performed using E-test method. Classical sequencing of DNA fragments was used to detect point mutations for CH and MET resistance. Resistance to CH was detected in 31% of isolated strains (28/91), while resistance to MET and CH was detected in 35% (32/91) of strains. A2143G was the most frequently detected mutation and was dominant among strains isolated from children with peptic ulcer disease (80%). Mutations in the rdxA gene were found significantly more frequently among MET-resistant strains than MET-sensitive strains (p = 0.03, Chi2 = 4.3909). In children, a higher frequency of H. pylori multiresistant strains was observed compared with the previous study in the same area. Differences were found in the occurrence of point mutations among H. pylori strains resistant to CH isolated from children with different clinical diagnoses.

Novel high resolution melt curve assay for the analysis of predominance of Helicobacter pylori clarithromycin resistance

Clarithromycin resistance is the most common cause of Helicobacter pylori treatment failure and it is attributed to three point mutations, A2142G, A2142C and A2143G, within the 23S rRNA gene. We aimed to determine the prevalence of H. pylori clarithromycin resistance using a novel high resolution melt assay. A total of 151 stool samples were collected from treatment-naïve patients with general gastric discomfort who also performed 13CO2 breath tests. Stool antigen tests were also performed on 126 of the 151 stool samples collected. Bacterial DNA was extracted from the stool and analyzed by comparing it with four reference plasmids incorporating the three mutations and the wild type (WT) sequences. The melt assay detected 106 H. pylori positive samples, of which 54 had a WT sequence, and 52 had a point mutation associated with clarithromycin resistance, including A2142G in 10, A2142C in 13, A2143G in 18 and heterozygosity (multiple peaks) in 11. Compared with the gold standards (13CO2 breath and stool antigen tests), the melt assay had a sensitivity of 100% and 99% and a specificity of 82% and 78%, respectively. Therefore, our stool-based molecular assay is able to identify H. pylori infection and clarithromycin resistance. It could be used for screening prior to administration of clarithromycin eradication therapy.

Impact of Previous Exposure to Macrolide Antibiotics on Helicobacter pylori Infection Treatment Outcomes

OBJECTIVES

Helicobacter pylori (H. pylori) guidelines, including the recent ACG clinical guideline, recommend avoiding clarithromycin-based triple therapy (TT-C) among patients with past macrolide exposure. Data to support this recommendation are scarce, and the impact of macrolide exposure on quadruple therapies is unclear. We aimed to determine the impact of macrolide exposure on the efficacy of H. pylori treatment in our region.

METHODS

We searched the Clalit Health Services database to identify subjects aged 25-60 years who underwent the first-ever C-urea breath test between 2010 and 2015. Patients who underwent a previous H. pylori stool antigen test or gastroscopy were excluded. Pharmacy dispensation data were retrieved.

RESULTS

We identified 7,842 subjects (36.1% male individuals, age: 40.3 ± 10.5 years), including 3,062 (39.0%) with previous macrolide exposure. The efficacy of TT-C was 74.3% and 82.4% among subjects with and without macrolide exposure, respectively (odds ratio (OR), 0.62; 95% confidence interval (CI), 0.55-0.70; P < 0.0001). TT success was adversely affected by exposure to clarithromycin (55.5%; OR, 0.31; 95% CI, 0.24-0.39; P < 0.0001), roxythromycin (74.4%; OR, 0.65; 95% CI, 0.58-0.74; P < 0.0001), and erythromycin (73.9%; OR, 0.72; 95% CI, 0.57-0.89; P < 0.01) but not by exposure to azithromycin. A greater time elapsed because exposure to clarithromycin and roxythromycin was associated with higher eradication (OR, 1.007; 95% CI, 1.002-1.012; P < 0.01 and OR, 1.004; 95% CI, 1.002-1.006; P < 0.0001). A higher dose of clarithromycin and roxythromycin was associated with a lower likelihood of successful eradication (OR, 0.99988; 95% CI, 0.99982-0.99996; P < 0.01 and OR, 0.99981; 95% CI, 0.99971-0.99992; P < 0.001). The efficacies of sequential and concomitant therapies were 82.7% and 81.3%, respectively, and were not significantly affected by macrolide exposure.

CONCLUSIONS

TT-C is adversely affected by previous exposure to macrolide antibiotics. Sequential, concomitant, and bismuth-based treatment may be preferred in this setting.

Helicobacter pylori resistance to clarithromycin and fluoroquinolones in a pediatric population in Turkey: A cross-sectional study

BACKGROUND

Helicobacter pylori antimicrobial resistance is gradually increasing around the world. However, there are a limited number of studies reporting on this issue in the pediatric population. In this study, we aimed to determine H pylori resistance to clarithromycin and fluoroquinolones in the pediatric patients living in Kırıkkale province that were detected with H pylori in gastric biopsies. Moreover, we also aimed to investigate the concordance between the histopathologic and molecular methods used in the diagnosis of H pylori infection.

MATERIALS AND METHODS

Patients aged 2-18 years who had a history of epigastric pain and/or nausea persisting for longer than 1 month underwent upper gastrointestinal endoscopy. Biopsies were taken from the gastric antral mucosa. In the samples detected with H pylori in the histopathologic examination, the presence of H pylori and H pylori resistance to clarithromycin and fluoroquinolones was investigated using the GenoType HelicoDR test which allows the detection of wild-type and mutant genes. The strains detected with more than one mutant gene are defined as hetero-resistant strains.

RESULTS

The 93 patients that underwent DNA extraction and amplification included 68 (73.1%) girls and 25 (26.9%) boys with a median age of 15 ± 2.62 (range 6-17) years. The overall concordance for the diagnosis of H pylori infection between histopathology and PCR was 94%, and H pylori resistance to clarithromycin and fluoroquinolones was 27% and 15%, respectively.

CONCLUSIONS

The high H pylori resistance to clarithromycin and fluoroquinolones among the pediatric patients in our region implicates that the antibiotic sensitivity of strains should be studied prior to administration in accordance with the recommendations provided in the guidelines. Moreover, the presence of hetero-resistant strains in our patients may be a reason for treatment failure.

Temporal Trends in Helicobacter pylori Eradication Success in a Test-and-Treat Population

BACKGROUND/AIMS

Although the efficacy of first-line treatment for Helicobacter pylori infection should aim to be > 90%, it is unclear whether this target has been achieved in Israel. We aimed to determine the success rate of treatment for H. pylori and to describe temporal changes in our region. Methods: Adult patients who underwent a first-time -C13-urea breath test (C13-UBT) at Clalit Health Services between January 1, 2010 and December 31, 2015 were included. In order to isolate a naïve "test-and-treat" population who were unlikely to have undergone an initial endoscopy-based H. pylori test, we excluded patients ≥45 years and those with any previous C13-UBT.

RESULTS

A total of 94,590 subjects (36.1% male, age 28.5 ± 6.0) who underwent at least one C13-UBT during the study period were included. C13-UBT was positive in 48,509 (51.3%) subjects. A confirmatory post-treatment C13-UBT was performed in 37.8, 44.1, 46.6, and 45.9% following 1st, 2nd, 3rd, and 4th-line treatment respectively. Eradication was successful in 65.4% following first-line treatment, and eradication success improved during the study period (59.2, 63.3, 65.7, 66.0, 69.0, and 73.1% in 2010, 2011, 2012, 2013, 2014, and 2015 respectively; OR 1.11; 95% CI 1.09-1.13; p < 0.0001). Eradication was successful in 44.7% following second-line treatment, although eradication success did not significantly improve during the study period (OR 1.05; 95% CI 0.99-1.10; p = 0.09).

CONCLUSIONS

Despite the increasing success of first-line treatment for H. pylori infection over the study period, eradication rates remain suboptimal. Initiatives to implement the Toronto and Maastricht Consensus Reports should be advanced.

Helicobacter pylori drug resistance: therapy changes and challenges

Helicobacter pylori is a Gram-negative bacterium that causes chronic gastritis, dyspepsia, peptic ulcers, and gastric cancer. Over half the world's population is infected with H. pylori, with higher prevalence in developing countries. Areas covered: In this review, current guidelines on H. pylori therapy, such as the Toronto consensus statement, the Maastricht V/Florence consensus report, and the American College of Gastroenterology guidelines, are compared. Also, we analyzed reports of antimicrobial resistance of H. pylori published in PubMed in the last years to determine current antimicrobial resistance worldwide. Expert commentary: Although H. pylori antimicrobial resistance varies by geographic area, its prevalence has been increasing over time, causing therapy failures and low eradication rates. To best optimize the management of H. pylori infection, H. pylori therapy should be based on patterns of local and individual antimicrobial resistance, if possible.