TABLE 3.

Pairwise amino acid and nucleotide sequence analysis of RdxA proteins from 11 pairs of metronidazole-sensitive and -resistant H. pylori isolates

H. pylori strain	MIC (μg/ml)	Genetic alterationsa in:
		Amino acid sequenceb	Nucleotide sequencec
5413	8	No specific change	No specific changed
6102	8	No specific change	No specific change
1838	32	W at position 209 to stop codon	Nonsense mutation (G to A at position 626)
6413	32	W at position 209 to stop codon	Nonsense mutation (G to A at position 627)
1950	64	D at position 157 to N	Missense mutation (G to A at position 467)e
2312	64	G at position 189 to C; A at position 206 to T	Missense mutations (G to T at position 565; G to A at position 616)e
2228	128	Generated a stop codon at position 15	Frameshift due to one nucleotide (T) addition at position 17
1740	128	Q at position 50 to stop codon	Nonsense mutation (C to T at position 148)
1857	128	E at position 35 to stop codon	Nonsense mutation (G to T at position 103)
5078	128	Generated a stop codon at position 98	Frameshift due to one nucleotide (A) addition at position 228
8076	128	Q at position 50 to stop codon	Nonsense mutation (C to T at position 148)

^aPairwise amino acid and nucleotide sequence alignment was performed against the metronidazole-sensitive partner strain from the same patient who failed anti-H. pylori therapy containing metronidazole. If the RdxA proteins from metronidazole-resistant strains were not truncated, the amino acid sequences were aligned not only with the partner metronidazole-sensitive strain but also with all other metronidazole-sensitive RdxA amino acid sequences, including H. pylori ATCC 700392 (26) and H. pylori J99 (1). 

^bThe initiation amino acid (methionine) was counted as +1. 

^cNucleotide A from the first codon (ATG) for RdxA was counted as +1. 

^dNo specific change, no nucleotide substitution for the specific amino acid change. 

^eThe shown missense mutations were not found at the indicated positions in RdxA proteins from the 11 paired pretreatment metronidazole-sensitive H. pylori strains, H. pylori ATCC 700392 (26), or J99 (1).