Doripenem

Tigecycline was obtained from Chem-Impex International (Wood Dale, IL, USA). Doripenem and ertapenem were acquired from Cayman Chemical (Ann Arbor, MI, USA) and TOKU-E (Bellingham, WA, USA), respectively. Other chemicals were purchased from Sigma-Aldrich (St. Louis, MO, USA).

Raw materials of antibiotics of doripenem, tigecycline, and tetracycline were provided by Cayman Chemical Company (Michigan, USA) and cefepime was provided by Demo S.A. Pharmaceutical (Votanikos, Greece). doripenem and cefepime were suspended in saline while tigecycline and tetracycline were suspended in distilled water. The antibiotic disks of tigecycline (15 µg), doripenem (10 µg), oxacillin (1 µg), and cefoxitin (30 µg) were provided by Oxoid (Hampshire, UK), while cefepime (30 µg) and tetracycline (30 µg) were provided by Bioanalyse (Ankara, Turkey). The antibiotic E-strips of tigecycline (0.016-256 µg/ml), tetracycline (0.016-256 µg/ml), cefepime (0.016-256 µg/ml), oxacillin (0.016-256 µg/ml), cefoxitin (0.016-256 µg/ml), and doripenem (0.002-32 µg/ml) were provided by HiMedia (Mumbai, India).

Clinical isolates (KBN12P05816. KBN12P05795, and KBN12P06081) were supplied by the Gyeongsang National University Hospital Branch of the National Culture Collection for Pathogens (GNUH-NCCP, Jinju, Korea). These strains were incubated at 37 °C in trypticase soy broth (TSB; Difco, Becton, Dickinson, and Company, Sparks, MD, USA) and sub-cultured on MacConkey agar (MAC; Difco, Becton, Dickinson and Company, Sparks, MD, USA). Doripenem was purchased from Cayman Chemical (Ann Arbor, MI, USA) and dissolved in dimethyl sulfoxide (DMSO). In all analyses, the final concentration of DMSO used as the control was less than 2%.