Whole genome analysis of linezolid resistance in Streptococcus pneumoniae reveals resistance and compensatory mutations

Table 1 Chronological appearance of mutations in S. pneumoniae R6 and 1974 transformants at different levels of linezolid resistance^a.

S. pneumoniae strains/transformants^b,c	LNZ MIC (μg/ml)	No. of colonies tested	spr_ rrnaD^d	spr_ rrnaC^d	spr_ rrnaB^d	spr_ rrnaA^d	spr0188^e	spr0196^f	spr1021^g
R6	0.5	4	W	W	W	W	W	W	W
R6T1	8	4	M	W	W	M	W	W	W
R6T2	16	4	M	M	M	M	M	M	W
1974	1	4	W	W	W	W	W	W	W
1974T1	8	4	M	M	M	W	W	W	W
1974T2	16	4	M	M	M	W	W	W	W
1974T3	32	4	M	M	M	M	M	M	M

^a W (wild-type version); M (1974M1 version).
^b R6T1 and R6T2 are first and second level transformants, respectively, of S. pneumoniae R6 transformed with genomic DNA extracted from 1974M1.
^c1974T1, 1974T2 and 1974T3 are first, second and third level transformants, respectively, of S. pneumoniae 1974 transformed with genomic DNA extracted from 1974M1.
^d Mutant 1974M1 had a G2576T mutation in the four copies of spr_rrna23S.
^e Mutant 1974M1 had a T409C mutation in spr0188.
^f Mutant 1974M1 had a A235G mutation in spr0196.
^g Mutant 1974M1 had a G-29T mutation in spr1021 (the number preceded by '-' indicates the position upstream of the ATG).

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