Comparative effectiveness of cefmetazole versus carbapenems and piperacillin/tazobactam as initial therapy for...

Carbapenems and piperacillin/tazobactam (PIPC/TAZ) are commonly used as the initial therapy to treat extended-spectrum β-lactamase (ESBL)-producing Enterobacterales in acute cholangitis. However, the overuse of these antibiotics contributes to the spread of antimicrobial resistance. Cefmetazole (CMZ) is stable to hydrolysis by ESBLs, so it may be an alternative to carbapenems and PIPC/TAZ. However, the effectiveness of CMZ compared with that of carbapenems and PIPC/TAZ as the initial therapy for acute cholangitis is unknown.

We conducted a retrospective cohort study at a university hospital between April 1, 2014, and December 31, 2022. Patients with bacteremic acute cholangitis who received CMZ, carbapenems, or PIPC/TAZ as the initial therapy were included. The patients were divided into a CMZ group and a carbapenems or PIPC/TAZ (CP) group to compare patient outcomes.

A total of 99 patients (54 in the CMZ group and 45 in the CP group) were analyzed. The baseline characteristics of the patients were similar and 30-day mortality did not differ between groups (4% vs. 7%, P = 0.66). However, the CMZ group had a shorter length of stay (LOS) (8 days vs. 15 days, P < 0.001) and lower mean antibiotic cost (98.92 USD vs. 269.49 USD, P < 0.001) than the CP group.

In bacteremic acute cholangitis, initial therapy with CMZ may contribute to a shorter LOS and lower antibiotic costs than treatment with carbapenems and PIPC/TAZ, without worsening patient outcomes.