Prevalence of clarithromycin resistance in Helicobacter pylori in Santiago, Chile, estimated by real-time PCR directly from gastric mucosa

Antibiotic Resistance Rates for Helicobacter pylori in Rural Arizona: A Molecular-Based Study

Helicobacter pylori (H. pylori) is a common bacterial infection linked to gastric malignancies. While H. pylori infection and gastric cancer rates are decreasing, antibiotic resistance varies greatly by community. Little is known about resistance rates among rural Indigenous populations in the United States. From 2018 to 2021, 396 endoscopy patients were recruited from a Northern Arizona clinic, where community H. pylori prevalence is near 60%. Gastric biopsy samples positive for H. pylori (n = 67) were sequenced for clarithromycin- and metronidazole-associated mutations, 23S ribosomal RNA (23S), and oxygen-insensitive NADPH nitroreductase (rdxA) regions. Medical record data were extracted for endoscopic findings and prior H. pylori history. Data analysis was restricted to individuals with no history of H. pylori infection. Of 49 individuals, representing 64 samples which amplified in the 23S region, a clarithromycin-associated mutation was present in 38.8%, with T2182C being the most common mutation at 90%. While the prevalence of metronidazole-resistance-associated mutations was higher at 93.9%, the mutations were more variable, with D95N being the most common followed by L62V. No statistically significant sex differences were observed for either antibiotic. Given the risk of treatment failure with antibiotic resistance, there is a need to consider resistance profile during treatment selection. The resistance rates in this population of American Indian patients undergoing endoscopy are similar to other high-risk populations. This is concerning given the high H. pylori prevalence and low rates of resistance testing in clinical settings. The mutations reported are associated with antibiotic resistance, but clinical resistance must be confirmed.

Mutations associated with Helicobacter pylori antimicrobial resistance in the Ecuadorian population

AIMS

We described the presence of Helicobacter pylori (HP) and estimated the prevalence of primary and secondary resistance using molecular detection in gastric biopsies of Ecuadorian patients.

METHODS AND RESULTS

66.7% (238/357) of the patients demonstrated the presence of HP using CerTest qPCR. Of these, 69.79% (104/149) were without previous HP eradication treatment and 64.42% (134/208) with prior HP eradication treatment. The mutation-associated resistance rate for clarithromycin was 33.64% (primary resistance) and 32.82% (secondary resistance), whereas that in levofloxacin the primary and secondary resistance was 37.38% and 42%, respectively. For tetracycline and rifabutin, primary and secondary resistance was 0%. Primary and secondary resistance for metronidazole and amoxicillin could not be evaluated by genotypic methods (PCR and sequencing).

CONCLUSIONS

The analysis of mutations in gyrA, 23S rRNA and 16S rRNA is useful to detect bacterial resistance as a guide for eradication therapy following failure of the first-line regimen.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study carried out in an Ecuadorian population indicates that the resistance of HP to first-line antibiotics is high, which may contribute to the high rates of treatment failure, and other treatment alternatives should be considered.

Efficacy of immunohistochemical staining in detecting <em>Helicobacter pylori</em> in Saudi patients with minimal and atypical infection

Gastric Helicobacter pylori infection is diagnosed based on histopathological evaluation of gastric mucosal biopsies, urease test, urea breath test, H. pylori culturing, or direct detection using polymerase chain reaction (PCR). This study aimed to evaluate the efficacy of immunohistochemical (IHC) staining in detecting H. pylori in gastric biopsies from patients with chronic gastritis and minimal or atypical infection. Gastric biopsies from 50 patients with chronic gastritis were subjected to routine haematoxylin and eosin (H-E), modified Giemsa, and IHC staining. The results of staining were compared with those of quantitative real-time PCR (qRT-PCR). The qRT-PCR analysis identified 32 (64%) H. pylori-positive cases, whereas IHC, H-E, and modified Giemsa staining identified 29 (58%), 27 (54%), and 21 (42%) positive cases. The sensitivity of IHC staining (87.50%) was higher than that of H-E (59.38%) and modified Giemsa (43.75%) staining. The specificity of H-E, modified Giemsa, and IHC staining was 55.56%, 61.11%, and 94.44%, respectively. IHC staining exhibited the highest diagnostic accuracy (90%), followed by H-E (58%) and modified Giemsa (50%) staining. Active gastritis, intestinal metaplasia, and lymphoid follicles were detected in 32 (64%), 4 (8%), and 22 (44%) cases, respectively, and all of these cases were H. pylori positive. In contrast to routine H-E and modified Giemsa staining, IHC allows for the accurate H. pylori detection in cases with minimal or atypical infection. Moreover, IHC can be an alternative diagnostic method to qRT-PCR for detection of H. pylori in such cases.

Mutations of Helicobacter pylori RdxA are mainly related to the phylogenetic origin of the strain and not to metronidazole resistance

OBJECTIVES

Drug resistance of Helicobacter pylori is a major clinical problem worldwide. The objective of the present study was to investigate the prevalence of antibiotic-resistant H. pylori in the city of Shenzhen in China, as well as to identify the genetic mutations specifically associated with drug resistance rather than unrelated phylogenetic signals.

METHODS

Antibiotic susceptibility testing was performed on 238 clinical strains successfully isolated from H. pylori-positive dyspeptic patients who underwent gastroscopy at the Department of Gastroenterology in Shenzhen People's Second Hospital. Following WGS of all strains using Illumina technology, mutation and phylogenetic analyses were performed.

RESULTS

The resistance rates were 84.9%, 35.3%, 25.2% and 2.1% for metronidazole, clarithromycin, ciprofloxacin and rifampicin, respectively. An A2143G conversion in the 23S rRNA gene was the primary mutation observed in clarithromycin-resistant strains, whilst N87K/I and D91G/N/Y in GyrA were detected in ciprofloxacin-resistant strains. In RdxA, our results demonstrated that only R16H/C and M21A are significant contributors to metronidazole resistance; there were 15 other sites, but these are phylogenetically related and thus unrelated to metronidazole resistance.

CONCLUSIONS

There is a high prevalence of metronidazole, clarithromycin and ciprofloxacin resistance and a low prevalence of rifampicin resistance in H. pylori from Shenzhen, China. Omission of phylogenetically related sites will help to improve identification of sites genuinely related to antibiotic resistance in H. pylori and, we believe, other species.

Phenotypic and Genotypic Antibiotic Resistance Patterns in Helicobacter pylori Strains From Ethnically Diverse Population in México

Helicobacter pylori strains carry a range of mutations in genes that confer antimicrobial resistance and restrict the available options to treat the infection. Latin America is a region that conserve a large number of indigenous communities relatively isolated that practice a traditional medicine without consumption of drugs. We hypothesized that rates of antibiotic resistance are lower in these communities. Recent progress in whole-genome sequencing has allowed the study of drug susceptibility by searching for the known mutations associated with antibiotic resistance. The aim of this work was to study trends of antibiotic resistance over a 20-year period in Mexican H. pylori strains and to compare susceptibility between strains from Mexican mestizos and from indigenous population; we also aimed to learn the prevalence of mutational patterns in genes gyrA, gyrB, rdxA, frxA, rpsU, omp11, dppA, and 23S rRNA and its association with phenotypic tests. Resistance to clarithromycin, metronidazole, amoxicillin and levofloxacin was determined in167 H. pylori isolates by E-test, and the occurrence of mutational patterns in specific genes was determined by whole genome sequencing (WGS). The trend of resistance over 20 years in mestizo isolates showed significant resistant increase for clarithromycin and levofloxacin to frequencies that banned its clinical use. Resistance in H. pylori isolates of native communities was lower for all antibiotics tested. Phenotypic resistance showed good to moderate correlation with genotypic tests. Genetic methods for characterizing antibiotic resistance require further validation in each population.

ANTIBIOTIC RESISTANCE SURVEILLANCE OF HELICOBACTER PYLORI AT THE BIOBÍO REGION (CHILE) IN A DECADE

BACKGROUND

Helicobacter pylori infection in Chile remains as a public and private health-care system's challenge, with a prevalence of the infection over 70%. Nowadays, antibiotic treatment of the infection is mandatory to prevent the arising of severe associated diseases but failures in the eradication therapy mainly due to clarithromycin resistance has been observed worldwide and first line eradication therapy seems to be not effective anymore in several geographical areas. Thus, health-care systems are committed to maintain an epidemiological surveillance upon the evolution of the antibiotic resistance of this priority 2 pathogen.

OBJECTIVE

This work reports a 10 years surveillance of the primary antibiotic resistance of H. pylori clinical isolates at the Biobío region-Chile, and the evolution of resistance toward amoxicillin, clarithromycin, levofloxacin, metronidazole, and tetracycline among the species.

METHODS

H. pylori strains were investigated during the periods 2005-2007 (1435 patients analysed) and 2015-2017 (220 patients analysed) by inoculating a saline homogenate biopsy onto the surface of Columbia agar (Oxoid, Basingstoke, UK) - supplemented with 7% horse red blood cells plus DENT inhibitor (Oxoid, Basingstoke, UK) - following by incubation at 37ºC under 10% CO2 atmosphere for five days. Antibiotic resistance pattern of the isolates was assessed using the disk diffusion test in Müeller-Hinton agar supplemented with 7% horse red blood cells followed by incubation for further three days under 10% CO2 atmosphere. Statistical analysis was done using the SPSS v22 software and P values <0.05 were considered statistically significant.

RESULTS

A total of 41% of 1435 patients were detected to be infected with H. pylori by bacteriological culture in 2005-2007 period, meanwhile 32.7% from 220 patients were also infected in 2015-2017 period. The clinical isolates of H. pylori are mostly susceptible to amoxicillin and tetracycline (both over 98% of strains), but less susceptible to levofloxacin in both periods analysed (over 79% of the strains). On the other hand, metronidazole continuous showing the highest score of resistant isolates (over 40% of resistant strains), although an 18% fewer resistant strains were observed in 2015-2017 period. Clarithromycin, the key antibiotic in eradication therapies, has an increased frequency of resistant strain isolated in the decade (22.5% in 2005-2007 and 29.2% in 2015-2017). Multidrug resistant strains (two, three and four antibiotics) were also detected in both periods with the highest scores for simultaneous resistance to clarithromycin-metronidazole (18%) and clarithromycin-metronidazole-levofloxacin (12.5%) resistant strains. According to gender, the isolates resistant to amoxicillin, clarithromycin and metronidazole were more frequent in female, with a specific increment in amoxicillin and clarithromycin resistance.

CONCLUSION

The frequency of clarithromycin resistance (29.2%) detected in 2015-2017 suggests that conventional triple therapy is no longer effective in this region.

Eradication Treatment of Helicobacter pylori Infection Based on Molecular Pathologic Antibiotic Resistance

Background

Unfortunately, the eradication rate of Helicobacter pylori (H. pylori) treatment is markedly decreasing in recent years and the major reason is antibiotic resistance. Our study was designed to determine the effect and safety of H. pylori eradication treatment based on the molecular pathologic antibiotic resistance.

Methods

261 patients were analyzed retrospectively, including 111 patients who were treated for the first time (one group as First-treated) and 150 patients who failed at least once in bismuth quadruple therapy (another group as Re-treatment). Antibiotic resistance was examined by Real-time PCR detection and conventional PCR and sequencing method. The eradication rate (ER) was compared per intention to treat (ITT) and per protocol (PP) between the two groups.

Results

The resistance rates to amoxicillin, clarithromycin, fluoroquinolone and tetracycline were 5.5%, 42.1%, 41.7% and 12.9% in the 111 first-treated patients, and 11.7%, 79.7%, 70.7% and 30.0% in the 150 re-treatment patients. The ERs in the ITT and PP analyses were 92.79% (95% CI, 87.98–97.60%, n=111) and 98.10% (95% CI, 95.48–100%, n=105), respectively, in the first-treated patients and 90.67% (95% CI, 86.01–95.32%, n=150) and 95.10% (95% CI, 91.57–98.64%, n=143), respectively, in the re-treatment patients. No significant differences were shown in the ERs between two group patients, and no serious adverse events were found.

Conclusion

H. pylori eradication treatment based on molecular pathologic antibiotic resistance showed good effect and safety in both first and re-treated patients.

High prevalence of clarithromycin resistance and effect on Helicobacter pylori eradication in a population from Santiago, Chile: cohort study and meta-analysis

Helicobacter pylori (H. pylori) eradication using standard triple therapy (STT) with proton pump inhibitors (PPI), amoxicillin and clarithromycin (CLA) has been the standard in Latin America. However, CLA resistance is a rising problem affecting eradication rates. Genetic polymorphisms of CYP2C19, a PPI metabolizer may also affect eradication. The primary aims of this study were to evaluate the effect of clarithromycin resistance on H. pylori eradication in a population from Santiago, and to establish the pooled clarithromycin resistance in Santiago, Chile. Symptomatic adult patients attending a tertiary hospital in Santiago were recruited for this study. CLA resistance and the polymorphisms of CYP2C19 were determined on DNA extracted from gastric biopsies, using PCR. The STT was indicated for 14 days and eradication was determined by a urea breath test 4–6 weeks after therapy. A meta-analysis of CLA resistance studies among adult residents in Santiago was performed. Seventy-three out of 121 consecutive patients had positive rapid urease test (RUT) and received STT. Sixty-nine patients (95%) completed the study. The H. pylori eradication rate was 63% and the prevalence of CLA resistance was 26%. According to the CYP2C19 polymorphisms, 79.5% of the RUT-positive patients were extensive metabolizers. Multivariable analyses showed that only CLA resistance was significantly and inversely associated with failure of eradication (OR: 0.13; 95% confidence interval [95% CI], 0.04–0.49). A meta-analysis of two previous studies and our sample set (combined n = 194) yielded to a pooled prevalence of CLA resistance of 31.3% (95% CI 23.9–38.7). Our study shows that CLA resistance is associated with failure of H. pylori eradication. Given the high pooled prevalence of CLA resistance, consideration of CLA free therapies in Santiago is warranted. We could recommend bismuth quadruple therapy or high-dose dual therapy, according to bismuth availability. Further studies need to evaluate the best therapy.

Review: Treatment of Helicobacter pylori Infection 2019

This review summarizes important studies regarding Helicobacter pylori therapy published from May 2018 to May 2019. The main themes that emerge involve studies assessing the efficacy of bismuth-based regimens. While in recent years the efficacy of bismuth-based quadruple therapy as a second-line therapy has been clearly established, there is now substantial evidence that it is the best performing first-line therapy. Antibiotic resistance was again intensely studied this year, and a clear and dramatic increase in resistance is noted for clarithromycin and levofloxacin; most notably, it may not be possible to support these therapies in most regions of the world much longer without testing. The utility of vonoprazan as an alternative to proton-pump inhibitor therapy, especially in resistant and difficult to treat groups, has also been considered in greater detail this year, as well as means of supporting and enhancing adherence to therapy. Several studies showed that the diversity of gut microbiota was significantly altered shortly after H pylori eradication. However, the diversity was restored to pre-treatment state after 2 months in patients treated with triple therapy. More studies are warranted to assess the long-term changes of gut microbiota after H pylori eradication.