TABLE 3.

Relationship between QRDR mutations detected by MCA and MICs of FQs for 72 S. pneumoniae strains

FQ and QRDR mutation	No. of isolates with MICa
	S	I	R
CIP
None	47	0	0
Single parC or gyrA mutation	0	3	6
parC and gyrA mutations	0	0	16
LVX
None	47	0	0
Single parC or gyrA mutation	3	0	6
parC and gyrA mutations	0	0	16
GAT
None	47	0	0
Single parC or gyrA mutation	4	4	1
parC and gyrA mutations	0	0	16
MXF
None	47	0	0
Single parC or gyrA mutation	9	0	0
parC and gyrA mutations	1	8	7

^aAbbreviations: S, susceptible; I, intermediate; and R, resistant. The CLSI MIC breakpoints were used for LVX (susceptible, ≤2 μg/ml; intermediate, 4 μg/ml; and resistant, ≥8 μg/ml), GAT (susceptible, ≤1 μg/ml; intermediate, 2 μg/ml; and resistant, ≥4 μg/ml), and MXF (susceptible, ≤1 μg/ml; intermediate, 2 μg/ml; and resistant, ≥4 μg/ml). The breakpoint standard for CIP was obtained from the interpretive guidelines supplied by the Japanese Society of Chemotherapy (susceptible, ≤1 μg/ml; intermediate, 2 μg/ml; and resistant, ≥4 μg/ml).