Antimicrobial activity of tebipenem to Escherichia coli isolates from outpatients with complicated urinary tract infections.

Extended-spectrum β-lactamases (ESBL)-producing Escherichia coli have emerged as a global concern in urinary tract infections (UTIs). This study investigated the susceptibility of clinical isolates of E. coli from complicated UTIs (cUTIs) to tebipenem pivoxil (TBPM), an oral carbapenem developed in Japan. In 2019, 229 non-ESBL-producing and 61 ESBL-producing E. coli strains were collected from five major hospitals in the Gifu Prefecture. Susceptibility was assessed following the Clinical and Laboratory Standards Institute guidelines (M07 and M100), and TBPM was compared with other commonly used antibiotics. The MIC50 and MIC90 values of TBPM for non-ESBL and ESBL-producing E. coli were ≤0.03 μg/mL, with MIC ranges of ≤0.03-0.25 μg/mL and ≤0.03-0.06 μg/mL, respectively, indicating its strong antimicrobial activity. Notably, no strains demonstrated reduced susceptibility to TBPM. These results were comparable to those of intravenous carbapenems such as imipenem and meropenem. Additionally, these findings align with the national Japanese surveillance data, suggesting that the trends observed in this study may reflect broader patterns across Japan. In the United States, an ongoing study is evaluating TBPM hydrobromide for cUTIs, highlighting its potential as an effective oral carbapenem. TBPM may be a promising treatment option for cUTIs caused by ESBL-producing E. coli, offering an alternative to intravenous therapies and potentially reducing the need for hospitalization. However, careful use of TBPM in antimicrobial stewardship programs is crucial to prevent resistance and ensure its continued efficacy in outpatient settings.