Table 2.
Characteristics of the 8 plasmid-mediated quinolone resistance-positive E. coli isolates from commercial layer.
| Isolate | Farm | PMQR genesa | β-lactamase genes | Antimicrobial resistance patternb | MICs (µg/mL)c | QRDR mutationsd | |||
|---|---|---|---|---|---|---|---|---|---|
|
|
|
||||||||
| NA | ENR | CIP | gyrA | parC | |||||
| Donor | |||||||||
| Gi-CC-4 | Farm 3 | qnrS1 | CTX-M-15 | AM, CZ, CF, CXM, CTX, CAZ, TE, SXT, G, C | ≥512 | 64 | 16 | S83L, D87N | S80I |
| Gi-CC-5 | Farm 3 | qnrS1 | CTX-M-15 | AM, AMC, CZ, CF, CXM, CTX, CAZ, TE, SXT, G, C | ≥512 | 128 | 32 | S83L, D87N | S80I |
| Gi-CC-7 | Farm 3 | qnrS1 | - | AM, TE, G | ≥512 | 8 | 4 | WT | S80I |
| Gi-CC-27 | Farm 4 | aac(6’)-Ib-cr | TEM-1 | AM, CTX, TE, SXT, G | ≥512 | 32 | 16 | S83L, D87N | S80I |
| Gi-CC-28 | Farm 4 | aac(6’)-Ib-cr | TEM-1 | AM, CZ, CF, TE, SXT, G | ≥512 | 64 | 16 | S83L, D87N | S80I |
| Gi-CC-35 | Farm 5 | qnrB4 | - | AM, TE, SXT, G, C | ≥512 | 32 | 32 | S83L, D87N | S80I |
| Gi-CC-36 | Farm 5 | qnrS1 | - | AM, CZ, CF, TE, SXT, G | ≥512 | 16 | 16 | D87N | S80I |
| Gi-CC-37 | Farm 5 | qnrS1 | TEM-1 | AM, CZ, FOX, TE, G | ≥512 | 32 | 32 | S83L, D87N | S80I |
| Recipient | |||||||||
| E. coli J53 | NT | NT | NT | 4 | 0.06 | 0.06 | NT | NT | |
| Transconjugants | |||||||||
| Gi-CC-4-T | qnrS1 | CTX-M-15 | AM, CZ, CXM, CTX, CAZ, TE, SXT, G, C | 4 | 0.125 | 0.25 | NT | NT | |
| Gi-CC-5-T | qnrS1 | CTX-M-15 | AMC, CZ, CF, CTX, CAZ, TE, SXT, G, C | 8 | 0.25 | 0.125 | NT | NT | |
| Gi-CC-28-T | aac(6’)-Ib-cr | - | AM, CZ, CF, TE, SXT | 16 | 0.06 | 0.25 | NT | NT | |
| Gi-CC-35-T | qnrB4 | - | AM, TE, C | 8 | 0.125 | 0.06 | NT | NT | |
| Gi-CC-37-T | qnrS1 | TEM-1 | AM, CZ, FOX, G | 4 | 0.125 | 0.25 | NT | NT | |
a
PMQR, plasmid-mediated quinolone resistance; NT, not tested
b
AM, ampicillin; AMC, amoxicillin-clavulanic acid; CZ, cefazolin; CF, cephalothin; FOX, cefoxitin; CXM, cefuroxime; CAZ, ceftazidime; CTX, cefotaxime; C, chloramphenicol; G, gentamicin; SXT, sulfamethoxazole/trimethoprim; TE, tetracycline
c
MICs, minimum inhibitory concentrations; NA, nalidixic acid; ENR, enrofloxacin; CIP, ciprofloxacin
d
QRDR, quinolone-resistance determining region; WT, wild type