TABLE 3.

Twenty-year perspective on INH^r mutants based on survey results

Location of resistance mutation(s)	Results for survey period:
	September 2013 to December 2019 (current study)			January 2000 to August 2013 (Seifert et al.)			January 2000 to December 2019 (both studies)
	No. of INHr mutants	Total no. of INHr	%	No. of INHr mutants	Total no. of INHr	%	No. of INHr mutants	Total no. of INHr	%
katG315	4,271	5,804	73.6	5,400	8,416	64.2	9,671	14,220	68.0
inhA-15	787	5,804	13.6	1,189a	6,192	19.2	1,976a	11,996	16.5
inhA-8	106	5,804	1.8	77a	5,955	1.3e	183a	11,759	1.6
katG	4,391	5,804	75.7	4,068b	6,136f	66.3b	8,459b	11,940f	70.8b
inhA	978	5,804	16.9	926c	4,495f	20.6c	1,904c	10,299f	18.5c
oxyR′-ahpC	107	5,804	1.8	91d	1,685f	5.4d	198d	7,489f	2.6d
katG and inhA	4,894	5,804	84.3	1,271b,c	1,582f	80.3b,c	6,165b,c	7,386f	83.5b,c
katG and inhA and oxyR′-ahpC	4,967	5,804	85.6	1,328b,c,d	1,583f	83.9b,c,d	6,295b,c,d	7,387f	85.2b,c,d
Unexplained INHr	837	5,804	14.4	1,406f	8,786	16	2,243f	14,590	15.4

^aCalculated from the counts of total INH^r isolates and frequency of mutation reported by Seifert et al. (9).

^bOnly codons 309, 311, 315, and 316 were considered by Seifert et al. (9), although they report other mutations in the gene in their supplemental tables. This is thus a lower bound for the sensitivity of katG for their reported period.

^cOnly positions −15, −8, −47, and −17 were considered by Seifert et al. (9), although they report other mutations in their supplemental tables. This is thus a lower bound for sensitivity of inhA for their reported period.

^dOnly positions −10, −6, −39, −48, −15, −12, and −9 were considered by Seifert et al. (9), although they report other mutations in the region in their supplemental tables. This is thus a lower bound for the sensitivity of the oxyR′-ahpC intergenic region for their reported period.

^eThis table reflects the value as reported by Seifert et al. However, I believe that this value was incorrectly calculated, and the correct frequency should be 2.25%. Please see Discussion.

^fTotal count is calculated from mutant INH^r count and the frequency of the mutation reported by Seifert et al. (9).