TABLE 2.
Antimicrobial resistance profiles and transferability of the oxazolidinone resistance genes
| Donor | Resistance genes | Transconjuganta | Transfer rate for donorb: |
Phenicol/oxazolidinone resistance gene(s) present |
MIC (μg/ml) for: |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | optrA | poxtA | cfr | fexA | cat | CHL | FFC | LZD | TZD | |||
| L10 | aph(3′)-III, aac(6′)-aph(2″), spc, lnu(B), lsa(A), erm(A), erm(B), optrA, cat, fex(A), tet(L), tet(M), dfrG | OG1RF-L10 | 3 × 10−8 | NT | NT | + | + | + | 128 | 64 | 8 | 1.0 | ||
| L11 | aph(3′)-III, aac(6′)-aph(2″), spc, lnu(B), lsa(A), erm(A), erm(B), optrA, cat, fex(A), tet(L), tet(M), dfrG | NT | NT | NT | ||||||||||
| L12 | ant(6)-Ia, aph(3′)-III, aac(6′)-aph(2″), spc, lnu(B), lsa(A), erm(A), erm(B), optrA, cat, fex(A), tet(L), tet(M), dfrG | NT | NT | NT | ||||||||||
| L13 | ant(6)-Ia, aph(3′)-III, aac(6′)-aph(2″), spc, lnu(B), lsa(A), erm(A), erm(B), optrA, cat, fex(A), tet(L), tet(M), dfrG | OG1RF-L13 | 10−9 | NT | NT | + | + | + | 128 | 64 | 8 | 1.0 | ||
| L15 | ant(6)-Ia, aph(3′)-III, aac(6′)-aph(2″), spc, lnu(B), lsa(A), erm(A), erm(B), optrA, cat, fex(A), tet(L), tet(M), dfrG | OG1RF-L15 | 5 × 10−8 | 5.2 × 10−9 | 1.6 × 10−9 | +/+/+ | −/−/− | −/−/− | +/+/+ | 128 | 64 | 8 | 1.0 | |
| L16 | ant(6)-Ia, aph(3′)-III, aac(6′)-aph(2″), spc, lnu(B), lsa(A), erm(A), erm(B), optrA, cat, fex(A), tet(L), tet(M), dfrG | OG1RF-L16 | 1.1 × 10−8 | NT | NT | + | + | + | ≥256 | 128 | 32 | 1.0 | ||
| L18 | ant(6)-Ia, aph(3′)-III, aac(6′)-aph(2″), spc, lnu(B), lsa(A), erm(A), erm(B), optrA, cat, fex(A), tet(L), tet(M), dfrG | NT | NT | NT | ||||||||||
| L21 | ant(6)-Ia, aph(3′)-III, aac(6′)-aph(2″), aadD, spc, lnu(B), lsa(A), erm(A), erm(B), optrA, cat, fex(A), tet(L), tet(M), dfrG | NT | NT | NT | ||||||||||
| L8 | ant(6)-Ia, aph(3′)-III, aac(6′)-aph(2″), spc, lnu(C), lnu(B), lnu(G), lsa(A), erm(A), erm(B), optrA, tet(L), tet(M), dfrG | OG1RF-L8 | NT | NT | SC | + | − | − | 64 | 32 | 8 | 0.5 | ||
| L14 | str, lnu(B), lsa(A), erm(B), optrA, cat, fex(A), tet(L), tet(M) | OG1RF-L14 | 6.4 × 10−7 | 8.2 × 10−8 | 5.8 × 10−8 | +/+/+ | −/−/− | +/+/+ | +/+/+ | 128 | 64 | 8 | 0.5 | |
| L17 | str, lnu(B), lsa(A), erm(B), optrA, cat, fex(A), tet(L), tet(M) | OG1RF-L17 | 3.7 × 10−6 | 1.8 × 10−8 | 1.7 × 10−8 | +/+/+ | −/−/− | +/+/+ | +/+/+ | 128 | 64 | 8 | 0.5 | |
| L19 | str, lnu(B), lsa(A), erm(B), optrA, cat, fex(A), tet(L), tet(M) | OG1RF-L19 | 3.4 × 10−6 | 2.8 × 10−8 | 2.7 × 10−8 | +/+/+ | +/+/+ | +/+/+ | 128 | 64 | 8 | 0.5 | ||
| L9 | str, lsa(A), optrA, cfr, fex(A), tet(L), tet(M), tet(S) | OG1RF-L9 | 4 × 10−7 | NT | SC | +/+ | −/+ | +/+ | −/− | 128 | 64 | 8 | 0.5 | |
a
Transconjugants were selected on BHI medium containing (A) 25 μg/ml chloramphenicol, 25 μg/ml fusidic acid, and 25 μg/ml rifampin; (B) 20 μg/ml chloramphenicol, 25 μg/ml fusidic acid, and 25 μg/ml rifampin; or (C) 10 μg/ml chloramphenicol, 25 μg/ml fusidic acid, and 25 μg/ml rifampin. PCR detection of the optrA, poxtA, cfr, fexA, and cat genes, in addition to chloramphenicol/florfenicol/linezolid/tedizolid MIC determination, was performed to confirm the transconjugants.
b
NT, no transconjugant; SC, small colonies (not countable).