Representative electrophoresis patterns of allele-specific PCR products. PCR products were amplified with mixed primers for determination of A2146G and A2147G mutations in 23S rRNA of H. pylori. PCR products of 320 bp are commonly observed for the H. pylori 23S rRNA gene. PCR products of 238 or 240 bp indicate the presence of a point mutation in the 23S rRNA gene. PCR products were obtained from ATCC26695 (lane 1), J99 (lane 2), and five representative CLR-resistant strains (lanes 3–7; S1, S13, S17, S26, and 174). The 100 bp marker ladder is indicated by M.