Table 6.
Characteristics of Enterococcus spp. isolates1 and prevalence of antimicrobial resistance genes2 of pigs fed diets with two Cu and Zn sources (SF and HCl) at two Cu levels (15 and 160 mg/kg)
| AMR genes3 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Cu and Zn source | Cu level, mg/kg | Enterococcus spp. isolated, n | E. faecalis, n | E. faecium, n | Enterococcus spp., n | Mean MIC Cu, mM | tcrB, n | ermB, n | tetM, n | vanA, vanB, vanC1, and vanC2, n |
| SF | 15 | 11 | 8 | 1 | 2 | 5.41 | 0 | 0 | 0 | 0 |
| 160 | 11 | 6 | 0 | 5 | 6.68 | 0 | 0 | 1 (2.5) | 0 | |
| HCl | 15 | 8 | 6 | 0 | 2 | 7.85 | 0 | 1 (2.5) | 1 (2.5) | 0 |
| 160 | 10 | 7 | 0 | 3 | 7.05 | 0 | 2 (5) | 0 | 0 |
1Data are means of 12 replicate pens for the two-way interaction, whereas for the main effects of source and level are means of 24 replicate pens (one pig per replicate pen was sampled).
2Antimicrobial resistance genes for: Cu (tcrB), erythromycin (ermB), tetracycline (tetM), and vancomycin (vanA, vanB, vanC1, and vanC2).
3Values in parenthesis show the prevalence percentage expressed for the total Enterococcus spp. isolates.