Linezolid

Auranofin, linezolid (Chem-Impex International, Wood Dale, IL), vancomycin hydrochloride (Gold Biotechnology, St. Louis, MO) metronidazole (Beantown Chemical Corporation, Hudson, NH), sodium selenite (MP Biomedicals, Santa Ana, CA), and fidaxomicin (Apexbio, Houston, TX) were procured from commercial vendors. Brain heart infusion (BHI) was purchased from Becton, Dickinson and Company (Cockeysville, MD). Phosphate buffered saline, fetal bovine serum and non-essential amino acids (NEAA) were purchased from Fisher Scientific (Waltham, MA). Yeast extract, L-cysteine, vitamin K, hemin, Dulbecco’s Modified Eagle’s medium (DMEM), and penicillin/streptomycin were obtained from Sigma-Aldrich (St. Louis, MO). C. difficile and enterococcal isolates (Table 1) were obtained from the American Type Culture Collection (ATCC) and Biodefense and Emerging Infections Research Resources Repository (BEI Resources).

Bacterial strains were obtained from various sources as listed in Table S10 and S11. Cation-adjusted Mueller Hinton broth, tryptic soy broth (TSB) and tryptic soy agar (TSA) were purchased from Fisher Scientific (Waltham, MA, USA). Linezolid (Chem-Impex International, Wood Dale, IL, USA), vancomycin hydrochloride (Gold Biotechnology, St. Louis, MO, USA), daptomycin (AK Scientific, Union City, CA, USA), ciprofloxacin (Sigma Aldrich, St. Louis, MO, USA), menaquinone-9 (Cayman Chemical, Ann Arbor, MI, USA), deferoxamine mesylate (Cayman Chemical, Ann Arbor, MI, USA), 2,3-Dihydroxybenzoic acid (Sigma Aldrich, St. Louis, MO, USA), ferrichrome (Sigma Aldrich, St. Louis, MO, USA), hemin (Sigma Aldrich, St. Louis, MO, USA), hemoglobin (Sigma Aldrich, St. Louis, MO, USA), ammonium iron(II) sulfate hexahydrate (Sigma Aldrich, St. Louis, MO, USA), and EDDHA (Arctom Chemical, Westlake Village, CA, USA) were purchased commercially. Tris-minimal succinate (TMS) was prepared as previously described.^{75 (link)} Compounds were previously synthesized in our laboratory and used as DMSO stock solutions.