Clarithromycin (CLA)、amoxicillin (AMO)、metronidazole (MET)、levofloxacin (LEV) and tetracycline (TET) are commonly used antibiotics for Helicobacter pylori (Hp) therapy. However, the efficacy of treatment for Helicobacter pylori infection has decreased due to increasing resistance to CLA, MET and LEV. Studies had reported that beside antibiotics resistance, other factors such as age, sex, underlying disease, etc. may also affect the treatment efficacy. In some cases, when the MIC values were beyond the breakpoint, H. pylori strains with lower MIC value had better eradication than the ones with higher MIC value. However, few study investigated the relationship between MIC values and treatment outcome.

The investigators aimed to analyze the impact of influencing factors, especially minimal inhibitory concentration (MIC) value, on the efficacy of different treatment regimens.

Inclusion Criteria:

• patients (aged ≥ 20 years old) with H. pylori infection between Jan. 1994 to Mar. 2018

Exclusion Criteria:

• without antibiotics susceptible test result, without treatment outcome, history of any gastrointestinal surgery, serious concomitant (renal failure, liver cirrhosis, heart failure and disease need immunosuppressant for therapy.

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