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Table 1 Resistance rates according to the agar dilution method (ADM) and E-test

From: E-test versus agar dilution for antibiotic susceptibility testing of Helicobacter pylori: a comparison study

Antibiotic

Clinical breakpoint (mg/L)

Resistance rate (%) n = 72

MIC50a (mg/L)

MIC90a (mg/L)

Essential agreement (%)

Kappa coefficient

95% confidence

interval

ADM

E-test

ADM

E-test

ADM

E-test

   

Amoxicillin

> 0.125

3/72 (4.2)

4/72 (5.6)

0.032

0.016

0.064

0.125

93.1

0.25

− 0.38 to 0.88

Metronidazole

> 8

30/72 (41.7)

33/72 (45.8)

8

8

64

64

84.7

0.69

0.52 to 0.85

Clarithromycin

> 0.5

3/72 (4.2)

5/72 (6.9)

0.032

0.032

0.25

0.25

94.4

0.47

− 0.29 to 0.97

Levofloxacin

> 1

18/72 (25.0)

19/71 (26.4)

0.25

0.25

8

8

93.1

0.81

0.66 to 0.97

Tetracycline

> 1

0/72 (0.0)

2/71 (2.8)

0.125

0.064

0.5

0.25

97.2

  1. aMIC50/MIC90: minimum inhibitory concentrations that inhibited 50 and 90% of the isolates. For comparability with ADM, the upper limits were set as 1 mg/L for amoxicillin, 2 mg/L for clarithromycin and tetracycline, 8 mg/L for levofloxacin, and 64 mg/L for metronidazole, and the lower limits were set as 0.016 mg/L for amoxicillin, 0.032 mg/L for clarithromycin and tetracycline, 0.125 mg/L for levofloxacin, and 1 mg/L for metronidazole