Primary Antibiotic Resistance of Helicobacter pylori in Different Regions of China: A Systematic Review and Meta-Analysis

Aim: Understanding the prevalence of antibiotic resistance can provide reliable information for selecting treatment options. The goal of this meta-analysis was to observe the primary antibiotic resistance of Helicobacter pylori (H. pylori) in different regions and time periods of China. Method: We searched PubMed, EMBASE, Chinese Biomedical databases and the China National Knowledge Infrastructure from inception to 20 February 2022. Data on the prevalence of H. pylori primary resistance at various time points were included. A random-effect model was established to calculate the pooled antibiotic resistance. Results: In total, 2150 articles were searched, with 70 meeting the inclusion criteria. The resistance to clarithromycin, metronidazole, levofloxacin amoxicillin, tetracycline and furazolidone in 2016–2020 were 34% (95% CI: 30–39%), 78% (95% CI: 73–84%), 35% (95% CI: 30–40%), 3% (95% CI: 1–5%), 2% (95%CI: 1–4%) and 1% (95% CI: 0–4%), respectively. Clarithromycin showed regional difference, as the resistance was higher in northern (37%, 95% CI: 32–41%) and western China (35%, 95% CI: 17–54%) than that in southern (24%, 95% CI: 17–32%) and eastern China (24%, 95% CI: 20–28%). Conclusion: The resistance of H. pylori to clarithromycin and metronidazole was high and increased over time, whereas resistance to levofloxacin, amoxicillin, tetracycline and furazolidone remained stable.


Introduction
Though decreasing in developed countries, the prevalence of Helicobacter pylori (H. pylori) is still high in China, causing a major health burden due to peptic ulcer disease complications and gastric cancer [1,2]. As an infectious disease, antibiotics-based therapies play a leading role in the treatment [3,4]. However, we face the serious challenge of high antimicrobial resistance because of the previous use of these antibiotics [5]. The primary antibiotic resistance decreases the efficiency of first-line treatment. The overall effect is dependent on both the cure rate with resistant strains and the proportion with resistance, especially clarithromycin and levofloxacin-containing regimen [6,7]. Empirical anti-H. pylori therapy is commonly used in current clinical practice instead of susceptibilityguided therapy which is unavailable in most of China. Therefore, obtaining high-quality local data and the antibiotic resistance pattern is needed to get good clinical outcomes [8].
In this study, we reviewed and analyzed primary antibiotic resistance rates of H. pylori in different regions and time periods in China over two decades to provide some guidance for selecting the first-line antibiotics.
Further subgroup analysis showed there was no statistical difference of the levofloxacin resistance in northern China (p = 0.364, Figures 3 and S11) and eastern China (p = 0.052, Figures 3 and S12) during the same time periods.

Primary Resistance of H. pylori to Amoxicillin, Tetracycline and Furazolidone
The primary resistance of H. pylori to amoxicillin (3%), tetracycline (2%) and furazolidone (1%) were low (Figures S13-S15) and have remained relatively stable in the past two decades (Figure 3)

Influence of Gender on the Primary Resistance of H. pylori to Clarithromycin, Levofloxacin and Metronidazole
The level of resistance depending on the gender of patients was shown in Table S1. The results showed no difference in the resistance rates of clarithromycin (p = 0.5459), levofloxacin (p = 0.6522) or metronidazole (p = 0.2311) between male and female (Figures S16-S18).

Meta-Regression Analysis of Antibiotics Resistance of H. pylori
Meta-regression analysis including regions, time periods and method was performed ( Table 2   A positive correlation could be found between time periods and clarithromycin resistance based on multivariate analysis (p < 0.0001). Metronidazole resistance was higher in 2016-2020 (Difference: 0.22; 95% CI: 0.09, 0.35; p = 0.0009) than that before 2005.

Discussion
Supervising the prevalence of primary antibiotic resistance in a region can provide reliable information for the choice of treatment options [8].
In our study, we showed the mean overall resistance of H. pylori in China to clarithromycin, metronidazole and levofloxacin was 30.0%, 70.0% and 31.0% and increased over time, but that of amoxicillin, tetracycline and furazolidone was 3.0%, 3.0% and 1.0%, respectively, and remained low during these years.
H. pylori has similar characteristics of clarithromycin and levofloxacin resistance with a clear mechanism by some certain gene mutation (23S rRNA and gyrA, respectively), which has an all-or-none effect on the efficacy. That means that the efficacy of treatment does not improve by increasing dose and duration [80][81][82]. Our study showed that the clarithromycin resistance in China has now reached 34%, while it seemed lower in eastern (24%) and southern China (24%). The levofloxacin resistance rate is currently 31%. Lower resistance could be found in the western China. In contrast, an increasing trend could be observed in eastern China, from 25% in 2011-2015 to 37% in 2016-2020. The resistance of clarithromycin and levofloxacin are both above the threshold of empirical use of these antibiotics.
Metronidazole, a class of nitroimidazole compound, is different from clarithromycin and levofloxacin, and the mechanism of resistance is not completely clarified at present. Meanwhile, different susceptibility methods or culture methods also affected the results as our previous work demonstrated that the resistance might be overestimated by E-test when compared with agar dilution in the area with high-level metronidazole resistance [83]. Previous studies have demonstrated that the resistance can be overcome by a high dose and long duration [80,84]. Our data showed that the resistance of metronidazole was 70%, ranging from 64 to 83% in different regions. It was noticeable that the metronidazole resistance in northern China had decreased from 71% to 62% in these years.
The overall primary resistance rate of H. pylori to amoxicillin, tetracycline and furazolidone remained low, and all of them were lower than 5%, with the exception of a few studies that reported higher rates of resistance.
Other studies from Asia, Europe and Latin America have also reported primary resistance of H. pylori, which was lower than that in China, as these data showed that clarithromycin resistance ranged from 12 to 21.4%, levofloxacin resistance ranged from 15 to 18% and metronidazole resistance ranged from 38.9 to 53% with an increasing trend over time.
The increasing resistance to clarithromycin, levofloxacin and metronidazole might be contributed to by the increasing consumption of these antibiotics and cross resistance to the corresponding antibiotics. Megraud et al. reported that the community consumption of these antibiotics was associated with its corresponding H. pylori resistance in European countries [5]. Similarly, Yang et al. found that the macrolide and quinolones ranked third and fourth in consumption of antibiotics, respectively, in China during 2018-2020 [85]. There are no definitive data on imidazole consumption in China. However, since metronidazole was produced in the 1960s, it had been widely used in the treatment of anaerobic infections in China. Compared with macrolide and quinolone, imidazole has been present in the community for a longer time, which has led to a high metronidazole resistance in China.
The success rate of clarithromycin-containing triple therapy has been reported less than 80% in China [86]. The addition of bismuth to the triple therapy, which has been recommended as a first-line therapy, improves cure rates despite a high prevalence of antimicrobial resistance. The effect of bismuth is to attain an additional 30-40% in the success with resistant infections [87]. The rising resistance to clarithromycin and levofloxacin can severely reduce the efficacy of this modified quadruple therapy failing to reach a 90% success rate. For metronidazole, resistance has no clinical significance since it can be overcome after increasing the dosage and prolonging the duration [80]. At present, amoxicillin is widely used in clinical practice, as long as patients have no allergic reaction. Despite the poor accessibility in China, tetracycline combined with metronidazole is often used as a first-line therapy in areas with high clarithromycin and levofloxacin resistance [3]. Furazolidone is a special drug, which is widely used in China due to its low resistance rate. Although it may be accompanied by adverse reactions such as peripheral neuritis, the treatment success rate is high [88].
There are still limitations in our review. Firstly, since it was a single rate meta-analysis, there was obvious heterogeneity among different studies. Second, most of the enrolled studies were from northern and eastern China and data from other regions was lacking, thus causing potential publication bias.  Table S1: Characteristics of the enrolled studies on resistance rate of H. pylori to antibiotics based on Gender.
Author Contributions: H.L. conceived the study. J.C. and P.L. wrote the protocol and collected data. J.C. and Y.H. performed the systematic review. P.L., Z.D. and Y.G. did the statistical analysis. J.C. and P.L. wrote the article, which was revised by H.L. All authors have read and agreed to the published version of the manuscript.

Conflicts of Interest:
The authors declare no conflict of interest.