Molecular Basis of Macrolide Resistance in Campylobacter Strains Isolated from Poultry in South Korea
Table 2
Characteristics of macrolide-resistance genes in Campylobacter coli strains showing varied resistance to azithromycin and erythromycin.
Strain
Source
MIC (μg/mL)
cmeB
ermB
Mutations
Azithromycin
Erythromycin
23S rRNA
L4
L22
-EPI
+EPI
Fold
-EPI
+EPI
Fold
A16-CF-319-1
CM
4
1
4
1
0.5
2
-
-
wt
wt
wt
A16-CF-330-1
CM
4
1
4
1
0.5
2
-
-
wt
V196A
I65V, A74G
A16-CF-130-1-S1
BC
8
8
1
2
0.5
4
+
-
wt
wt
I65V, A74G
A16-CF-128-1-S1
BC
8
8
1
128
64
2
-
-
wt
V121A, V196A
I65V, A74G
CM13-HL-BS-020
CM
16
0.5
32
32
0.5
64
-
-
wt
V196A
I65V, A74G
CM13-HL-BL-031
CM
16
1
16
64
0.25
256
-
-
wt
V196A
I65V, A74G
CM13-MC-BS-006
CM
16
0.125
128
64
2
32
-
-
wt
V196A
I65V, A74G
DM13-MWC-SS-013
DM
32
2
16
4
0.125
32
-
-
wt
V196A
I65V, A74G
DM13-MP-WS-007
DM
32
0.5
64
8
0.5
16
-
-
wt
V196A
I65V, A74G
A16-CF-130-2-S1
BC
64
64
1
32
32
1
-
-
wt
V196A
I65V, A74G
A16-CF-107-2-S2
BC
64
64
1
64
32
2
-
-
A2075G
wt
I65V, A74G, S109A
A16-CF-128-1-S4
BC
128
2
64
128
4
32
-
-
wt
V196A
I65V, A74G, S109A
A16-CF-124-2-S3
BC
128
4
32
128
2
64
-
-
wt
V196A
I65V, A74G, S109A
A16-CF-107-2-S4
BC
≥512
64
8
≥512
64
8
-
-
A2075G
wt
I65V, A74G, S109A
A16-CF-124-1-S1
BC
≥512
≥512
1
≥512
64
8
-
-
A2075G
wt
I65V, A74G, S109A
A16-CF-124-1-S4
BC
≥512
≥512
1
≥512
64
8
-
-
A2075G
wt
I65V, A74G, S109A
A16-CF-126-2-S1
BC
≥512
64
8
≥512
32
16
-
-
A2075G
wt
I65V, A74G, S109A
A16-CF-124-1-S5
BC
≥512
≥512
1
≥512
64
8
-
-
A2075G
wt
I65V, A74G, S109A
A16-CF-126-2-S2
BC
≥512
≥512
1
≥512
64
8
-
-
A2075G
V196A
I65V, A74G, S109A
A16-CF-126-2-S4
BC
≥512
≥512
1
≥512
64
8
-
-
A2075G
V121A, V196A
I65V, A74G, S109A
A16-CF-118-2-S3
BC
≥512
≥512
1
≥512
64
8
+
-
A2075G
V121A, V196A
I65V, A74G, S109A
A16-CF-126-1-S3
BC
≥512
≥512
1
≥512
32
16
+
-
A2075G
V121A, V196A
I65V, A74G, S109A
A16-CF-126-2-S3
BC
≥512
≥512
1
≥512
32
16
+
-
A2075G
V121A, V196A
I65V, A74G, S109A
a. Abbreviations: CM: chicken meat; BC: breeder chicken; DM: duck meat; EPI: efflux pump inhibitor; A, Ala; G: Gly; I: Ile; S: Ser; V: Val; 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.
