Role of MIC levels and 23S rRNA mutation sites to clarithromycin in 14-day clarithromycin bismuth quadruple therapy for Helicobacter pylori eradication: A prospective trial in Beijing

Abstract

Background: Rising clarithromycin resistance undermines Helicobacter pylori (H. pylori) treatment efficacy. We aimed to determine clarithromycin's minimum inhibitory concentration (MIC) levels and identify specific mutation sites in the 23S ribosomal subunit (23S rRNA) that predict treatment outcomes in a 14-day regimen of clarithromycin bismuth quadruple therapy (amoxicillin 1g, clarithromycin 500 mg, rabeprazole 10 mg, and colloidal bismuth pectin 200 mg).

Materials and methods: We included adult H. pylori patients who hadn't previously undergone clarithromycin-based treatment, either as initial or rescue therapy. Exclusions were made for penicillin allergy, recent use of related medications, severe illnesses, or inability to cooperate. Patients underwent a 14-day clarithromycin bismuth quadruple therapy. Gastric mucosa specimens were obtained during endoscopy before eradication. MIC against amoxicillin and clarithromycin was determined using the E-test method. The receiver operating characteristic (ROC) curve helped to find the optimal clarithromycin resistance MIC breakpoint. Genetic sequences of H. pylori 23S rRNA were identified through Sanger Sequencing. (ChiCTR2200061476).

Results: Out of 196 patients recruited, 92 met the inclusion criteria for the per-protocol (PP) population. The overall intention-to-treat (ITT) eradication rate was 80.00 % (84/105), while the modified intention-to-treat (MITT) and PP eradication rates were 90.32 % (84/93) and 91.30 % (84/92) respectively. No amoxicillin resistance was observed, but clarithromycin resistance rates were 36.19 % (38/105), 35.48 % (33/93), and 34.78 % (33/92) in the ITT, MITT, and PP populations respectively. Compared with the traditional clarithromycin resistance breakpoint of 0.25 μg/mL, a MIC threshold of 12 μg/mL predicted better eradication. Among 173 mutations on 152 sites in the 23S rRNA gene, only the 2143A > G mutation could predict eradication outcomes (p < 0.000).

Conclusions: Interpretation of elevated MIC values is crucial in susceptibility testing, rather than a binary "susceptible" or "resistant" classification. The 2143A > G mutation has limited specificity in predicting eradication outcomes, necessitating further investigation into additional mutation sites associated with clarithromycin resistance.

Keywords: 23S rRNA mutation sites; Antibiotic resistance; Clarithromycin; Helicobacter pylori; Minimum inhibitory concentration (MIC); Receiver operating characteristic (ROC).

Fig. 1

Flow chart of the patient recruitment process.

Fig. 2

The MIC distribution of amoxicillin and clarithromycin. (A) Frequency distribution of Amoxicillin MIC in different eradication outcome groups. (B) MIC distribution peaks of Amoxicillin in eradication success and failure groups. (C)Distribution of Clarithromycin MICs for 92 H. pylori strains. (D)Frequency distribution of Clarithromycin MIC in different eradication outcome groups. (E) MIC distribution peaks of Clarithromycin in eradication success and failure groups. (F) Correlation between the frequency proportion of different Clarithromycin MICs distribution in eradication success and failure groups.

Fig. 3

The ROC curve of clarithromycin resistance MIC breakpoint in the PP population.

Fig. 4

The lollipop plot of 23S rRNA mutation sites in the PP population.

Fig. 5

Frequency and MIC distribution of selected five sites in eradication success and failure groups.