TABLE 2.

Summary of 10 amino acid mutations in the first 900 amino acid residues^a of the rpoB gene products of 26 (14 MDR, 7 XDR, and 5 fully susceptible) M. tuberculosis isolates from South Africa deduced by Ion Torrent sequencing, Hain LPA genotyping, and culture

No. of isolates	Amino acid substitution(s)b yielded by the rpoB gene (3,619 bp)	Rifampin result by:
		Ion Torrentc	Hain LPA	Bactec MGIT 960
9	S531L	Resistant	Resistant	Resistant
1	S531L, V194I	Resistant	Resistant	Resistant
1	S531L, Y645H	Resistant	Resistant	Resistant
1	H526D	Resistant	Resistant	Resistant
1	H526Y, S509R	Resistant	Resistant	Resistant
1	H526R	Resistant	Resistantd	Resistant
5	Wild typeb	Sensitive	Sensitive	Sensitive
6	D516G, L533P	Resistant	Resistantd	Resistant
1	D516V	Resistant	Resistant	Resistant

^aThere were 5 rpoB mutations yielding amino acid substitutions (R908C, Q1042H, P1043A, I1187T, and V1249F) noted in at least 1 strain at the 3′ end (residues 900 to 1253).

^bCompared to the H37Rv reference strain.

^cRifampin resistance is known to occur in rpoB at positions corresponding to amino acids 531(S→T), 526 (H→Y/D), and 516 (D→V).

^dUsing Hain LPA, strains with an uncommon glycine substitution at position 516 and an arginine at position 526 were indirectly determined as resistant by absence of a wild-type band.