Table 2.
Antibiograms of enterococci (n = 176) isolated from feedlot cattle feces from cattle fed tylosin for the FIRST-78%, LAST-75%, or continuously (CON) during the feeding period.
| Profile | Phenotypec | No. isolates (%) within treatments and daysa, b | Total | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| FIRST-78 | LAST-75 | CON | |||||||||
|
d 0 (n = 20) |
d 81 (n = 20) |
d 160 (n = 20) |
d 0 (n = 20) |
d 81 (n = 18) |
d 160 (n = 20) |
d 0 (n = 20) |
d 81 (n = 18) |
d 160 (n = 20) |
|||
| A1 | No Resistance | 6 (30.0) | 2 (10.0) | 6 (30.0) | 1 (5.6) | 5 (25.0) | 1 (5.6) | 21 | |||
| A2 | NIT | 1 (5.0) | 1 | ||||||||
| A3 | Tyl | 1 (5.0) | 1 (5.6) | 1 (5.0) | 3 | ||||||
| A4 | ery-nit | 1 (5.0) | 1 | ||||||||
| A5 | ERY-TYL | 7 (35.0) | 16 (80.0) | 4 (20.0) | 7 (35.0) | 7 (38.9) | 10 (50.0) | 7 (35.0) | 12 (66.7) | 11 (55.0) | 81 |
| A6 | nit-tyl | 1 (5.0) | 1 (5.0) | 2 | |||||||
| A7 | dox-ERY-TYL | 2 (10.0) | 3 (15.0) | 9 (45.0) | 1 (5.0) | 10 (55.6) | 5 (25.0) | 3 (15.0) | 4 (22.2) | 5 (25.0) | 42 |
| A8 | ery-lin-NIT | 1 (5.0) | 1 | ||||||||
| A9 | ERY-nit-TYL | 1 (5.0) | 1 (5.0) | 1 (5.0) | 1 (5.0) | 1 (5.0) | 5 | ||||
| A10 | ERY-q-d-TYL | 1 (5.0) | 2 (10.0) | 1 (5.0) | 4 | ||||||
| A11 | ERY-str-TYL | 1 (5.0) | 1 | ||||||||
| A12 | lin-NIT-TYL | 1 (5.0) | 1 | ||||||||
| A13 | DOX-ERY-NIT-TYL | 2 (10.0) | 1 (5.0) | 2 (10.0) | 1 (5.0) | 2 (10.0) | 2 (10.0) | 10 | |||
| A14 | ery-NIT-TIG-tyl | 1 (5.0) | 1 | ||||||||
| A15 | dox-ERY-NIT-q-d-TYL | 1 (5.0) | 1 | ||||||||
| A16 | dox-ery-lin-NIT-TIG-TYL | 1 (5.0) | 1 | ||||||||
a
Enterococci were isolated from BEA and BEAE media.
b
Tylosin inclusion at 11 ppm; FIRST-78% = tylosin in-feed from d 0 to d 125; LAST-75% = tylosin in-feed from d 41 to d 161; CON, control, continuous feeding of tylosin (d 0 to d 161). Fecal samples were collected on d 0, d 81, and d 160.
c
DOX, Doxycycline; ERY, Erythromycin; LIN, Linezolid; NIT, Nitrofurantoin; Q-D, Quinupristin-dalfopristin; STR, Streptomycin; TIG, Tigecycline; TYL, Tylosin. Upper case denotes complete resistance and lower case denotes intermediate resistance.