TABLE 5.
Distribution of antibiotic resistance genes among 104 selected tetracycline-resistant E. coli isolatesa
| Antibacterial | Gene | No. (%) of tetracycline-resistant E. coli isolates detected relative to no. tested (n) carrying the indicated gene per treatmentb
|
||||||
|---|---|---|---|---|---|---|---|---|
| C (n = 19) | BBM (n = 14) | PEN (n = 16) | SAL (n = 20) | BAC (n = 19) | SAL + BAC (n = 16) | Total (n = 104)d | ||
| β-Lactam (amoxicillin) | 17 (89.5)c | 14 (100.0) | 16 (100.0) | 20 (100.0) | 16 (84.2) | 12 (75) | 95 (91.3) | |
| blaTEM | 8 (57.14) | 4 (25.00) | 8 (40.0) | 8 (50.0) | 6 (50.5) | 40 (42.1) | ||
| blaSHV | 1 (5.9) | 5 (35.7) | 0 (0.00) | 0 (0.0) | 0 (0.00) | 2 (16.7) | 8 (8.4) | |
| blaTEM + blaSHV | 0 (0.0) | 2 (14.3) | 0 (0.0) | 0 (0.0) | 0 (0.00) | 0 (0.0) | 2 (2.1) | |
| Aminoglycoside (streptomycin) | 13 (68.4) | 11 (78.6) | 12 (75) | 15 (75.0) | 15 (78.9) | 7 (43.7) | 73 (70.2) | |
| ant(3″)-Ia (aadA) | 8 (61.5) | 5 (45.4) | 4 (30.7) | 12 (80.0) | 10 (66.7) | 4 (57.1) | 43 (58.9)* | |
| Tetracyclinec | ||||||||
| tet(A) | 13 (68.4) | 12 (85.7) | 9 (56.2) | 17 (85.0) | 15 (78.9) | 10 (62.5) | 76 (73.1) | |
| tet(B) | 11 (57.9) | 8 (57.1) | 9 (56.2) | 12 (60.0) | 11 (57.9) | 8 (50.0) | 59 (56.7) | |
| tet(A) + tet(B) | 5 (26.3) | 6 (42.8) | 2 (12.5) | 9 (45.0) | 7 (36.8) | 2 (12.5) | 31 (29.8) | |
| tet(A) + tet(C) | 9 (5.3) | 0 (0.0) | 0 (0.0) | 2 (10.0) | 1 (5.3) | 2 (12.5) | 6 (5.8) | |
| tet(A) + tet(B) + tet(C) | 2 (10.5) | 1 (7.1) | 0 (0.0) | 3 (15.0) | 2 (10.5) | 0 (0.0) | 8 (7.7) | |
| Sulfonamide (sulfadimethoxime) | 12 (63.1) | 10 (71.4) | 10 (62.5) | 17 (85.0) | 13 (68.4) | 7 (43.7) | 69 (66.3) | |
| sulI | 7 (58.3) | 5 (50.0) | 2 (20.0) | 12 (70.6) | 10 (76.9) | 4 (57.1) | 40 (58.0)* | |
| sulII | 10 (83.3) | 9 (90.0) | 10 (100.0) | 16 (94.1) | 13 (100.0) | 5 (71.4) | 63 (91.3) | |
| sulI + sulI | 5 (41.7) | 5 (50.0) | 2 (20.0) | 10 (58.8) | 10 (76.9) | 1 (14.3) | 35 (50.7)* | |
| dhfrI + sulII | 1 (8.3) | 0 (0.0) | 1 (10.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 2 (2.9) | |
| Phenicol (chloramphenicol) | 10 (52.6) | 9 (64.3) | 9 (56.2) | 13 (65.0) | 12 (63.2) | 5 (31.2) | 58 (55.8) | |
| floR | 8 (80.0) | 9 (100.0) | 9 (100.0) | 13 (100.0) | 12 (100.0) | 5 (100.0) | 56 (96.6) | |
| Class 1 integron in the 104 tetR genes | ||||||||
| int1(1) + int1(2) + int1(3) | 7 (36.84) | 5 (35.71) | 3 (18.75) | 12 (60.00) | 10 (52.63) | 4 (25.00) | 41 (39.42)* | |
a
Table shows the distribution of antibiotic resistance genes among 104 selected tetracycline-resistant E. coli isolates from the guts of chickens fed with antibiotic growth promoters.
b
C, control; BBM, bambermycin; PEN, penicillin; SAL, salinomycin; BAC, bacitracin; SAL + BAC, salinomycin with bacitracin.
c
None of the isolates were positive to tet(C) alone or to the tet(B)-tet(C) combination.
d
*, values are statistically different (P < 0.05).