Background and aims As with other infectious diseases, Helicobacter pylori eradication regimens should be guided by susceptibility testing to achieve excellent success rate, especially in the era of high antibiotic resistance. However, susceptibility testing for H. pylori is rarely performed, which can be partly ascribed to the current lack of standardization of testing methods and the lack of unified consensus on the antibiotic resistance breakpoints. The aim of this review was to call for an international consensus on standardization and harmonization of H. pylori susceptibility testing. Methods We summarize and compare the advantages and disadvantages of four different phenotypic antimicrobial susceptibility testing (AST) methods (agar dilution, E‐test, disk diffusion, and broth microdilution) and the molecular susceptibility testing method for H. pylori. Results The standard phenotypic testing methods and the molecular testing methods have their own advantages and disadvantages. Compared to the standard phenotypic methods, the molecular testing method does not require successful H. pylori culture, and therefore, is much more rapid and convenient for clinical use. However, the currently available molecular testing method is only suitable for detecting clarithromycin and quinolone susceptibility profiles in H. pylori. Although the standard AST is time‐consuming, it is currently the only way to test the susceptibility of H. pylori to all the commonly used antibiotics. Conclusion To make H. pylori susceptibility testing become a clinical routine, an international consensus on standardization and harmonization of H. pylori AST is needed. Future efforts are needed for optimizing broth culture of H. pylori, and developing commercial AST plates for achieving high throughput and automated susceptibility testing for H. pylori.

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.

Background The aim of this study was to evaluate the rifamycin cross-resistance in Helicobacter pylori, and whether the use of rifampicin E-test strips to screen H. pylori rifabutin resistance is appropriate. Methods A total of 89 H. pylori isolates were included. Rifampicin minimum inhibitory concentrations (MICs) were obtained by E-test, while the MICs for rifapentine, rifaximin, and rifabutin were determined by agar dilution method. The rifamycin resistance rates based on different breakpoints were compared. Isolates with high-level rifampicin resistance were subjected to whole-genome sequencing. Results A wide distribution of MICs (mostly in the range 0.125–8 mg/L) was observed for rifampicin, rifapentine, and rifaximin. Using MIC >1, ≥ 4, and > 4 mg/L as the breakpoints, resistance rates to rifampicin/rifapentine/rifaximin were 60.4%/48.3%/38.2%, 28.1%/25.8%/23.6%, and 15.7%/16.9%/7.9%, respectively. However, the rifabutin MICs of all the tested H. pylori isolates were extremely low (≤0.016 mg/L). Applying MIC ≥ 0.125 mg/L as the breakpoint, rifabutin resistance was nil. No mutation was found in the rpoB gene sequences of the 2 isolates with high-level rifampicin resistance. Conclusions There is a lack of cross-resistance between rifabutin and other rifamycins in H. pylori. The use of rifampicin E-test to predict H. pylori rifabutin resistance is inappropriate.

Background Helicobacter pylori infection is an infectious disease and thus the eradication treatment should be guided by susceptibility testing. This study aimed to assess the applicability of broth microdilution as a routine susceptibility testing method for H. pylori. Methods Susceptibility profiles of clarithromycin (CLR) and levofloxacin (LEV) resistance in 76 clinical H. pylori isolates were simultaneously assessed using agar dilution and broth microdilution methods. The correlation between the minimum inhibitory concentrations (MICs) obtained by the 2 methods was assessed by means of linear regression analysis. Results The correlation between the MICs determined by broth microdilution method and agar dilution method was good for both CLR (r = 0.966) and LEV (r = 0.959). The susceptibility agreement between the 2 methods was 100% for CLR and 96.1% for LEV. Using the broth microdilution method, the false resistance was found in 3.9% (3 of 76) strains for LEV susceptibility testing. No false susceptibility was found for either CLR or LEV, and no false resistance was found for susceptibility testing of CLR. Conclusions The broth microdilution method is suitable for routine susceptibility testing of clinical H. pylori isolates.

Background Helicobacter pylori eradication regimens should be guided by antimicrobial susceptibility testing. The objective of this study was to evaluate the molecular-based Mosprie assay for detecting H. pylori resistance to clarithromycin and levofloxacin using gastric biopsies. Methods A total of 185 culture-positive frozen gastric biopsies were included for Mosprie assay and also for 23S rRNA and gyrA gene sequencing. The susceptibility results by the Mosprie assay were compared with the E-test results retrospectively retrieved. The discordant results were analyzed by sequencing of the 23S rRNA and gyrA genes. Results Susceptibility concordance between the Mosprie assay and E-test for clarithromycin and levofloxacin was 97.30% (180/185) and 88.11% (163/185), respectively. The full agreement between clarithromycin genotypes by Mosprie assay and the 23S rRNA sequencing results was observed in the 5 samples with discordant Mosprie assay and E-test results. However, for levofloxacin, of the 16 discordant samples with resistant phenotype but a susceptible genotype by Mosprie assay, 6 were found to have levofloxacin resistance-related gyrA gene mutations. Conclusions The rapid and reliable Mosprie assay can be recommended for H. pylori susceptibility testing of clarithromycin and levofloxacin on gastric biopsies. Future technical improvements are needed in detecting levofloxacin resistance-associated gene mutations.

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