Fluoroquinolone Resistance among Clonal Complex 1 Group B Streptococcus Strains

Table 2

Characteristics of mutations observed in GyrA, GyrB, ParC, and ParE among ST459 and ST1 group B Streptococcus isolates used in this study.

ST	Number of isolates	⁢Predicted amino acid substitution				Antibiotic			MIC (mg/L)			Year	Reference
		GyrB	GyrA	ParC	ParE	LVX	NOR	CIP	LVX	NOR	CIP
1	3		E85K	S79F		R	R	R	>32	>32	>32	2010, 2012	[7, 10]
1	1		S81L	S79F		R	R	R	>32	>32	>32	2011	[7, 9]
1	1	V79I				S	R	NS	1.5	8	1	2010	This study
1	1	E224G				S	R	NS	1.5	16	1	2010	This study
1	1	E566D				S	R	NS	1	4	1	2012	This study
1	1		G717S			S	R	NS	1.5	4	1	2010	This study
1	1			S79F		I	R	R	4	>32	4	2010	[7, 10, 11]
1	1			D83G, D806G		I	R	R	4	16	2	2011	[7, 10]
1	1				R449S	S	R	NS	2	16	1	2010	This study
1	1				Q444K	S	R	R	1.5	8	8	2011	This study
1	1				A218T	S	R	NS	1.5	4	1	2012	This study
459	1	S412L				S	R	NS	1	8	1	2012	This study
459	2		R474H			S	R	NS	1	4	1	2010, 2012	This study
459	1			D83V		I	R	R	4	32	4	2012	This study
459	1			D83Y		I	R	R	4	>32	4	2012	[10]
459	2			S79F		I	R	R	4	>32	4	2011	[7]
459	1				V627I	S	R	R	1.5	8	2	2010	This study
459	1				V206I	S	R	NS	1	4	1	2012	This study

R: resistant, S: susceptible, I: intermediate resistance, and NS: increased MIC. For levofloxacin (LVX), MIC of ≥8 mg/L: resistant, 4 mg/L: intermediate resistant, and ≤2 mg/L: susceptible. For norfloxacin (NOR), MIC of ≥4 mg/L: resistant; ≤1 mg/L: susceptible. For ciprofloxacin (CIP), MIC of >2 mg/L: resistant; ≤0.125: susceptible. Values which were in the range of 0.125 to 2 were considered as having reduced susceptibility (NS).