H. pylori is an important human pathogen which plays a significant role in the pathogenesis of upper gastrointestinal tract diseases. Actual infection rates is nearly 50% of the world’s population and varies geographically, being higher in developing countries [17–18]. Unfortunately, H. pylori is a relatively difficult infection to treat. The gastric habitat offers sanctuaries beneath the mucous layer and within the lumen of gastric glands and pits that partially shelter H. pylori from the topical or luminal effects of some antibiotics. Gastric acidity inactivates many other antibiotics. Furthermore, H. pylori has shown a propensity to rapidly acquire resistance to many classes of antibiotics after exposure to those agents in the form of monotherapy. These include the fluoroquinolones, the macrolides, the nitroimidazoles. For these reasons, antibiotic resistance remains the major determinant of treatment outcomes, the success rate of eradication has been seriously limited for the progressive increase in antibiotic resistance [19]. Thus, in order to determine the status of H. pylori resistance and its patterns in patients and reliably select sensitive antibiotics for clinical use, it is necessary to perform an investigation especially in the absence of individualized H. pylori culture and antibiotic susceptibility test in Nanjing area.
Previous studies reported that the resistance rates of H. pylori strains collected by different geographic areas in China were 0.01%- 6.8% to amoxicillin, 17.6%- 37.5% to clarithromycin, 20.6%- 33.5% to levofloxacin, 0.01%- 0.1% to furazolidone, 0.01%- 5.8% to tetracycline and 60%- 70% to metronidazole [9, 15, 20–21]. Our current data showed that the overall resistance rates of amoxicillin, clarithromycin, levofloxacin, furazolidone, tetracycline, and metronidazole were 2.74%, 47.03%, 33.59%, 0.91%, 0.52% and 80.76%, respectively. Resistance to metronidazole has been observed worldwide and presently occurs quite commonly in several countries. The 80.76% resistant rate of this study from July 2017 to December 2019 is higher than that in the past. The high resistant rate was attributable to previous treatment of gynecologic infection or to the therapy of intestinal parasitic infections, which occur frequently in our country. Our data illustrated that the resistance rate of clarithromycin was 47.03%, whereas it was 29.47% in the period of May 2014 to May 2015. According to Maastricht V consensus, when the resistance rate of H. pylori to clarithromycin in a certain area exceeds 15%, the triple therapy based on PPI containing clarithromycin should not be used as an empirical eradication program of H. pylori, and clarithromycin resistance test is recommended. The resistance rate of H. pylori to levofloxacin reported in the our study was higher than the 14.74% that was reported in the period of May 2014 to May 2015. Levofloxacin was also widely used in the treatment of urogenital system and respiratory tract infection, which may be the reason for the high resistance rate. However, the prevalence of resistance to amoxicillin, furazolidone and tetracycline were low. Besides, they were all cheap. Therefore, the three antibiotics were recommended due to a lack of resistance and low cost.
We also found that the resistance rates of H. pylori (primary Vs post-treatment) to amoxicillin, clarithromycin, levofloxacin, furazolidone, tetracycline and metronidazole were 1.83% Vs 6.08%, 38.62% Vs 77.81%, 27.41% Vs 56.23%, 0.58% Vs 2.13%, 0.33% Vs 1.22%, 78.57% Vs 88.75%, respectively. Compared with the primary resistance rates, the post-treatment resistance rates to six antibiotics were higher. Among them, clarithromycin, levofloxacin and metronidazole increased significantly. So it was suggested that such drugs should be carefully selected when it was not the first time a patient has been eradicated. The post-treatment resistance rates to furazolidone and tetracycline were still relatively low. Compared with the primary resistance rate, the post-treatment resistance rate to amoxicillin was higher. For post-treatment eradication of H. pylori patients, drug sensitivity test was recommended to clarify the drug resistance of amoxicillin and guide accurate treatment.