Construction and Characterization of OXA-48 Producing E. coli

Mueller-Hinton (MH) agar and broth were purchased from Thermo Fisher Scientific (East Grinstead, United Kingdom). Luria-Bertani (LB) broth, LB agar, ampicillin, amoxicillin, cefepime, CAZ, imipenem, meropenem, piperacillin, and tazobactam were obtained from Sigma-Aldrich (St. Louis, MO). Nitrocefin was purchased from Merck (Darmstadt, Germany). All strains used and constructed within this study are listed in Table 1. The characteristics of the clinical E. coli strain 50579417 harboring the OXA-48 plasmid (p50579417_3_OXA-48) have been described previously (61 (link), 62 (link)). The plasmid p50579417_3_OXA-48 was conjugated into rifampin-resistant E. coli TOP10 and subsequently isolated using a plasmid mini-purification kit (Qiagen, Germany). E. coli MG1655 (DA4201) was electroporated with p50579417_3_OXA-48 as published previously (63 (link)). Transformants positive for bla_OXA-48 were checked by PCR using REDTaq ready mix (Sigma-Aldrich, St. Louis, MO) and preOXA-48 primers (61 (link)).