Urinary tract infections (UTIs) are highly prevalent in adults [1], accounting for nearly 70% of all nosocomial infections [2], [3]. Enterobacteria such as Escherichia coli (E. coli), Klebsiella spp, and Proteus spp are the primary causative agents of UTIs [4]. Extended-spectrum β-lactamase (ESBL) producers are increasingly prevalent in community and healthcare settings [5].

ESBL-producing Enterobacteria are usually resistant to penicillins, aztreonam, and first-, second-, and third-generation cephalosporins. However, these bacteria are not resistant to cephamycins and carbapenems [6]. Carbapenems are recommended as the first-line empiric therapy for UTIs [7], [8]. Narrow-spectrum antibiotics, such as first- and second-generation cephalosporins (e.g., cefazolin, cefotiam) and aminopenicillins (e.g., ampicillin, ampicillin/sulbactam), are used for definitive treatment after determining antibiotic susceptibility [9].

ESBL-producing and non-producing enterobacterial strains are resistant to aminopenicillins and first-generation cephalosporins [10], [11]. Second- and third-generation cephalosporins are effective against penicillinase-producing Enterobacteria [10], [11]. However, in 2023, Japan had a shortage of cefotiam (CTM), and the supply was not fully restored. Hence, the demand for third-generation cephalosporins, such as cefotaxime (CTX) and ceftriaxone (CTRX), for treating UTIs increased during the CTM shortage. Several water-soluble, renally excreted β-lactam antibiotics are commonly used in clinical practice. The high water solubility and urinary excretion increase the urine concentration of these antibiotics, making them suitable for treating UTIs.

The Japanese guidelines recommend using CTRX to treat UTIs [12]. However, the urinary excretion rate of CTRX (33–67%) is lower than that of other β-lactam antibiotics [13]. Moreover, CTRX treatment of complicated UTIs is associated with prolonged hospitalization, reinfections, and organ complications [14]. Despite these concerns, the efficacy of CTRX and other β-lactam antibiotics for treating UTIs is unclear.

This propensity score-matched cohort study retrospectively compared the efficacy of CTRX and other β-lactam antibiotics for treating Enterobacterales bacteremia and pyelonephritis.