Cefalonium

The antibiotic sensitivity of L. reuteri PSC102 was determined against 14 antibiotics, including cephalexin, colistin sulfate, enrofloxacin, cefalonium, amoxicillin trihydrate, penicillin G procaine, norfloxacin, spectinomycin, tylosin base, cefuroxime sodium, florfenicol, penicillin G benzathine, gentamicin sulfate, and streptomycin sulfate (Sigma-Aldrich, St. Louis, MO, USA), as previously described [26 (link)]. Briefly, 100 µL of cultured L. reuteri PSC102 was mixed with 100 µL of diluted antibiotic solution in a 96-well plate. After finally adjusting the concentration to 10⁶ CFU/mL, the bacteria were incubated for 24 h at 37 °C. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by measuring the OD value at 600 nm using Gen5 microplate reader version 3.08 (BioTek, Winooski, VT, USA) and by streaking on Mueller–Hinton agar plate, respectively.

Penicillin G (PNG), ampicillin (AMP), amoxicillin (AMX), azlocillin (AZL), oxacillin (OXA), piperacillin (PIPC), cefalothin (KF), cefazolin (CFZ), ceftiofur (CFT), cefepime (CFP), and cefixime (CFM) were purchased from the National Institutes for Food and Drug Control (Beijing, China). Cloxacillin (CLX), dicloxacillin (DCX), cefoperazone (CPZ) and cefotaxime (CTX) were purchased from Dr. Ehrenstorfer (Augsburg, Germany). Cefalonium (CFN), CTRX, cefapirin (CFAP), horseradish peroxidase (HRP), poly (ethylene glycol) (PEG) 1500, hypoxanthine aminopterin thymidine (HAT), incomplete Freund’s adjuvant (IFA), and complete Freund’s adjuvant (CFA) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Fetal calf serum and Dulbecco’s Modified Eagle’s Medium (DMEM) were obtained from Gibco BRL (Carlsbad, CA, USA). The 3,3′,5,5′–tetramethylbenzidine (TMB) and goat anti-mouse IgG were acquired from Jackson ImmunoResearch (West Grove, PA, USA). The HRP conjugation labeling kit was from Abcam (Toronto, Canada). Reagent grade solvents and salts were supplied by Beijing Chemical Reagent Co. (Beijing, China). The buffer solutions are listed in the Supplementary Materials.

Hamamelitannin (HAM), vancomycin (VAN), cefoxitin (CFX), cefazolin (CZ), cefalonium (CL), cephalexin (CFL), linezolid (LNZ) and fusidic acid (FA) were purchased from Sigma Aldrich (Bornem, Belgium). Tobramycin (TOB) and daptomycin (DAP) were purchased from TCI (Tokyo, Japan). HAM was stored in DMSO at −20 °C. All antibiotics were dissolved in ultrapure water (with the exception of CZ, CL and CFL, which were dissolved in phosphate buffer). HAM was used at 250 μM concentrations unless otherwise mentioned.