TABLE 4.

Frequency of mutations in rifampin-resistant isolates reported by four groups^a

Mutation position	Frequency of codon substitution (no. [%] of isolates)a
	Telenti et al. (n = 66)	Williams et al. (n = 110)	Suzuki et al. (n = 46)	This study (n = 90)
Leu-511	2 (3.0)			1 (1.1)
Gln-513	2 (3.0)	1 (0.9)		5 (5.6)
514-Phe ins.b		1 (0.9)		2 (2.2)
Met-515			1 (2.1)
Asp-516	6 (9.1)	8 (7.3)	4 (8.5)	13 (14.4)
Asn-518 del.c	1 (1.5)	1 (0.9)
Leu-521		1 (0.9)
Ser-522	1 (1.5)	2 (1.9)	1 (2.1)	1 (1.1)
His-526	18 (27.3)	37 (33.6)	13 (27.6)	15 (16.7)
Ser-531	33 (50.0)	46 (41.7)	23 (48.9)	48 (53.3)
Leu-533	1 (1.5)	3 (2.7)
Ser-509, His-526d		1 (0.9)
His-526, Lys-527d		1 (0.9)	1 (2.1)
None	2 (3.0)	8 (7.3)	3 (6.4)	5 (5.6)

^aRefer to the reports by Telenti et al. (31), Williams et al. (33), and Suzuki et al. (28). 

^bPhe ins., Phe insertion. 

^cAsn del., Asn deletion. 

^dDouble mutation.