TABLE 1.

Comparison of all agar dilution and E test results for clarithromycin and metronidazole by site and method

Drug, methodb	Avg % agreement by site ± SDc								% Agreement by method
	1	2	3	4	5	6	7	8
CLA, AD	94 ± 0.9	69 ± 2.8	76 ± 1.3	100 ± 1.3	80 ± 2.5	100 ± 0.6	100 ± 0.9	100 ± 0.8	90 ± 1.4
CLA, ETd	100 ± 1.6	67 ± 2.5	65 ± 1.6	100 ± 1.0	72 ± 2.9	93 ± 1.2	85 ± 1.0	94 ± 1.7	85 ± 1.7
MET, AD	88 ± 1.5	50 ± 3.7	94 ± 1.6	88 ± 2.2	80 ± 2.4	73 ± 2.1	100 ± 0.7	94 ± 1.5	83 ± 2.0
MET, ETd	72 ± 1.8	50 ± 3.2	94 ± 2.0	53 ± 3.3	87 ± 2.1	93 ± 1.8	92 ± 2.0	56 ± 2.4	75 ± 2.1
% Agreement by sitea	89 ± 1.6	59 ± 3.0	82 ± 1.7	85 ± 1.7	80 ± 2.4	90 ± 1.5	94 ± 1.0	86 ± 1.6	83 ± 1.8

^aSites frequently underestimated MICs by E test relative to the MICs obtained by agar dilution. Site 2 had 10 errors and failed to complete 14 of 17 E tests with clarithromycin and 11 of 17 E tests with metronidazole. When the results from site 2 were excluded from the analysis, all agreements by method increased by 3 to 5% and the overall agreement by site and method increased to 87%.

^bCLA, claritnromycin; AD, agar diluation method; MET, metronidazole; ET, E test.

^cPercentage of results equal to or less than the accepted 2 log₂ dilutions different from the reference average agar dilution MIC for each H. pylori strain. SD, SDs from the MIC.

^dE test results compared with reference MICs.