Table 1.
Broth microdilution MIC testing of lincosamide antibiotics against L. monocytogenes, E. faecalis and B. subtilis strains
| Species/strain | Antibiotic MIC, mg/L | ||
|---|---|---|---|
| lincomycin | clindamycin | iboxamycin | |
| L. monocytogenes 10403S | 4–8 | 2 | 0.125–0.25 |
| L. monocytogenes EDG-e | 8 | 1–2 | 0.125–0.5 |
| L. monocytogenes EDG-e Δlmo0919 | 0.25–1 | 0.125–0.5 | 0.0625 |
| E. faecalis ΔlsaA pCIEspec | 0.125 | 0.125 | 0.0625 |
| E. faecalis ΔlsaA pCIEspec LsaA | 16–32 | 16 | 0.5 |
| B. subtilis WT 168 | 80 | 4 | 2 |
| B. subtilis ΔvmlR | 2.5 | 0.125 | 0.06 |
| B. subtilis ΔvmlR thrC::Phy-spank-vmlR (IPTG: 1 mM) | 160 | 8 | 4 |
| B. subtilis thrC::Phy-spank-cfr (IPTG: 1 mM) | >640 | 640 | 16–32 |
| B. subtilis ΔvmlR thrC::Phy-spank-cfr (IPTG: 1 mM) | >640 | 320 | 2 |
In the case of L. monocytogenes strains, MIC testing was carried out in MH-F broth and growth inhibition was scored after 48 h incubation at 37°C. E. faecalis MIC testing was carried out in BHI broth supplemented with 2 mg/mL kanamycin (to prevent lsa revertants), 0.1 mg/mL spectinomycin (to maintain the pCIEspec plasmid) and 100 ng/mL of cCF10 peptide (to induce expression of LsaA protein). B. subtilis MIC testing was carried out in either LB medium or LB supplemented with 1 mM IPTG to induce expression of either VmlR or Cfr protein, and growth inhibition was scored after 16–20 h at 37°C. The MIC experiments were performed as three (L. monocytogenes strains) or two (B. subtilis and E. faecalis strains) biological replicates.