BioMed Research International

Research Article

Molecular Basis of Macrolide Resistance in Campylobacter Strains Isolated from Poultry in South Korea

Table 1

Characteristics of macrolide resistance genes in Campylobacter jejuni strains showing varied resistance to azithromycin and .


Strain	Source	MIC (μg/mL)								Mutations			L22 insertions
		Azithromycin			Erythromycin					23S rRNA	L4	L22
		-EPI	+EPI		-EPI	+EPI				23S rRNA	L4	L22

33560	ATCC	0.25	0.06	4	1	0.25	4	nt	nt	wt	wt	wt	wt
A16-CF-329-3	CM	4	0.5	8	0.5	0.5	1	+	-	wt	V196A	A103V, S109A	wt
CM13-HL-010-1	CM	4	0.125	32	8	0.25	32	+	-	wt	V80I, V196A	A103V, S109A, V137A	wt
CM13-HL-012-1	CM	4	0.5	8	8	0.125	64	+	-	wt	V80I, V196A	A103V, S109A, V137A	wt
CM13-MWC-BS-004	CM	8	0.125	64	0.5	0.025	20	+	-	wt	V196A	A103V, S109A, V137A	wt
A16-CF-127-1-S1	BC	8	0.25	32	1	0.25	4	+	-	wt	wt	wt	wt
A16-CF-318-3	CM	8	0.25	32	1	0.015	67	+	-	wt	V121A, T177S, M192I, V196A	V137S	114VAKKAP115
DM13-MP-WS-002	DM	8	0.5	16	64	0.25	256	+	-	wt	V196A	A103V, S109A, V137A	wt
CM13-OP-004-1	CM	8	0.25	32	64	0.5	128	+	-	wt	wt	wt	wt
A16-CF-129-1-S1	CM	8	0.125	64	128	0.5	256	+	-	wt	wt	wt	wt
CM13-HL-BS-021	CM	16	1	16	32	2	16	+	-	wt	V196A	wt	wt
DM13-JDW-WL-007	DM	16	0.25	64	64	0.5	128	-	-	wt	V196A	V137A	114VAKKAP115
DM13-JDW-WL-009	DM	16	16	1	64	64	1	+	-	wt	V121A, T177S, M192I, V196A	S109A, V137A	114VAKKAP115
CM13-MWC-WL-008	CM	16	1	16	64	1	64	+	-	wt	V196A	A103V, S109A, V137A	wt
CM13-DW-BL-005	CM	16	1	16	64	1	64	+	-	wt	V196A	I65V, A103V, S109A, V137A	wt
DM13-JW-SS-017	DM	32	0.5	64	64	0.5	128	+	-	wt	V121A, V196A	I65V, A103V, S109A, V137A	wt

a. Abbreviations: ATCC, American Type Culture Collection; CM, chicken meat; BC, breeder chicken; DM, duck meat; EPI: efflux pump inhibitor; nt: not test; A: Ala; I: Ile; K: Lys; M: Met; P: Pro; S: Ser; V: Val; T: Thr; wt: wild type.
b. Fold values were calculated as MIC without EPI/MIC with EPI.
c. +/-, indicates whether or not the target genes were detected.
The MIC breakpoints for azithromycin: susceptible, ≤ 2 μg/mL; intermediate, 4 μg/mL; and resistant, ≥ 8 μg/mL; for erythromycin: susceptible, ≤ 8 μg/mL; intermediate, 16 μg/mL; and resistant, ≥ 32 μg/mL.