Table 1.

Distribution of different fluoroquinolone MICs in staphylococcus strains and QDRD amino acid substitutions responsible for elevated fluoroquinolone MICs^a

Organism and isolate no.	MIC (mg/liter)								Amino acid substitution(s)
	OZN		MXF		LVX		CIP
	−R	+R	−R	+R	−R	+R	−R	+R	GyrA	ParC
MSSA-QS
361	0.008	0.002	0.25	0.25	2	2	0.25	0.25	Ser84Leu	NM
172	0.008	0.002	0.25	0.06	0.25	0.25	0.25	0.25	Ser84Leu	NM
89.01	0.008	0.002	0.06	0.06	0.5	0.5	2	2	NM	Ser87Leu
MSSA-QR
330	0.12	0.002	8	8	16	16	64	64	Ser84Leu	NM
144	0.12	0.12	4	4	32	32	16	16	Ser84Leu	NM
440	0.12	0.12	32	32	64	64	64	64	Ser84Leu	NM
847	0.5	0.5	8	4	32	32	128	128	Ser84Leu	NM
176	0.5	0.5	16	2	64	64	256	256	Ser84Leu/Ser85Pro	NM
51	2	2	64	32	64	64	256	128	Ser84Leu/Ser85Pro	Ser80Tyr/Glu84Gly
MRSA-QR
108	0.06	0.002	2	2	16	16	16	16	Ser84Leu	NM
50	0.06	0.002	32	32	128	64	16	16	Ser84Leu	NM
908	0.12	0.12	4	4	16	16	64	64	Ser84Leu	NM
823	0.12	0.12	32	32	64	64	256	256	Ser84Leu	NM
126	2	2	32	32	512	256	256	256	Ser84Leu/Glu88Lys	Ser80Phe/Glu84Val
MSSE-QR
67	0.5	0.5	32	16	32	32	16	16	Ser84Phe	Ser80Phe
58	1	1	32	16	64	64	64	64	Ser84Phe	Ser80Phe
30	1	1	32	16	64	64	64	64	Ser84Tyr/Glu88Lys	Ser80Phe/Asp84Tyr
56	2	2	64	32	512	512	128	128	Ser84Phe/Glu88Lys	Ser80Phe
MRSE-QS
FG015	0.004	0.002	0.12	0.06	0.25	0.12	0.25	0.25	NM	NM
7602	0.03	0.008	0.06	0.06	0.5	0.25	1	0.5	NM	NM
12	0.06	0.06	0.5	0.12	0.5	0.5	1	0.5	NM	NM
69.02	0.03	0.015	1	1	2	2	2	2	Ser84Phe	NM
MRSE-QR
FG012	0.12	0.12	2	2	32	32	128	128	Ser84Phe	Ser80Phe
FG014	1	0.5	16	16	128	128	64	64	Ser84Tyr/Glu88Gly	Ser80Phe/Asp84Tyr
FG013	2	1	32	32	512	512	128	128	Ser84Tyr/Glu88Lys	Ser80Phe/Asp84Tyr
FG011	2	2	32	32	256	128	32	4	Ser84Tyr/Glu88Lys	Ser80Phe/Asp84Tyr
31	2	2	64	16	128	128	64	32	Ser84Tyr/Glu88Lys	Ser80Phe/Asp84Tyr

^aR, reserpine; QS, quinolone susceptible; QR, quinolone resistant; NM, no mutations in the gyrA and parC genes.