TABLE 1.
Pathotype distribution among the 256 E. coli isolates from chickens fed with antimicrobial agents in the two studies
| Study and treatment (n) | No. (%) of isolates |
||
|---|---|---|---|
| “Other” ExPEC | APEC | Commensal | |
| I | |||
| Control (20) | 3 (15.0) | 6 (3.3) | 11 (55.0) |
| Bambermycin (14) | 2 (14.3) | 3 (21.4) | 9 (64.3) |
| Penicillin (17) | 2 (11.8) | 7 (41.2) | 8 (47.0) |
| Salinomycin (21) | 4 (19.0) | 4 (19.0) | 13 (62.0) |
| Bacitracin (19) | 3 (15.8) | 1 (5.3) | 15 (78.9) |
| Salinomycin + bacitracin (18) | 1 (5.6) | 6 (3.3) | 11 (61.1) |
| Total (109) | 15 (13.8) | 27 (24.7) | 67 (61.5) |
| Pa | 0.50 | 0.17 | 0.50 |
| II | |||
| Control (29) | 0 (0.0) | 3 (10.3) | 26 (89.7) |
| Chlortetracycline (18) | 0 (0.0) | 0 (0.0) | 18 (100) |
| Virginiamycin, 11 ppm (23) | 0 (0.0) | 7 (30.4) | 16 (69.6) |
| Virginiamycin, 22 ppm (31) | 0 (0.0) | 2 (6.5) | 29 (93.5) |
| Monensin (21) | 0 (0.0) | 1 (4.8) | 20 (95.2) |
| Narasin (25) | 0 (0.0) | 4 (16.0) | 21 (84.0) |
| Total (147) | 0 (0.0) | 17 (11.6) | 130 (88.4) |
| P | NDb | 0.02* | 0.02* |
| Total (256) | 15 (5.8) | 44 (17.2) | 197 (77.0) |
a
P value obtained by Cochran-Mantel-Haenszel test. *, statistically significant difference between treatment groups (P ≤ 0.05).
b
ND, not determined (or estimated).