Clinical outcomes of flomoxef versus cefmetazole in hospitalized patients with urinary tract infections: combined retrospective analyses of two real-world databases and in vitro data

Background: Flomoxef and cefmetazole have been reported to be effective against broad-spectrum β-lactamase-producing bacteria and have gained attention as a potential alternative to carbapenems. This study aimed to compare the efficacy of these two drugs in treating urinary tract infection (UTI) by integrating in vitro data and two real-world databases. Methods: The susceptibility rates of third-generation cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae to flomoxef and cefmetazole were compared using comprehensive national antimicrobial resistance surveillance data. Combined antimicrobial activities against an extended-spectrum beta-lactamase (ESBL)-producing multidrug-resistant bacterial strain were tested by diagonal measurement of n-way drug interactions. The effectiveness of the two drugs in treating UTIs was compared using hospital stay duration data obtained from the Japan Medical Data Center (JMDC) Claims Database. Results: Third-generation cephalosporin-resistant E. coli and K. pneumoniae, including ESBL-producing strains, were similarly susceptible to flomoxef and cefmetazole. In vitro assessment against an ESBL-producing multidrug-resistant strain revealed similar antimicrobial interaction patterns. JMDC Claims data analysis showed that the median hospital stay was 11 (95% confidence interval [CI]: 11–11) and 4 (95% CI: 3–5) days in the cefmetazole and flomoxef groups, respectively (log-rank test, P < 0.001). Moreover, the flomoxef group demonstrated a significantly lower frequency of adverse events such as C. difficile infection and renal failure. Conclusions: The effectiveness of flomoxef is comparable to that of cefmetazole in treating UTIs without major complications. Thus, flomoxef is a viable treatment option for UTIs in locales with a high prevalence of ESBL-producing strains.