Bacteroides spp., which are residents of healthy intestinal microbiota, are frequently detected in anaerobic infections [1]. Disruption of the mucosal surface by inflammation, trauma, or surgery and the spread of Bacteroides spp. to the bloodstream or surrounding tissues results in clinically significant infection. Therefore, when appropriate antimicrobial therapy is not performed, the mortality associated with infections caused by Bacteroides spp. can reach 50 % [2].

Bacteroides spp. are inherently resistant to penicillin due to the production of beta-lactamase. In contrast, carbapenems and metronidazole (MNZ) have high susceptibility rates [3]. However, Bacteroides spp. acquire resistance to carbapenems and MNZ through various complex mechanisms [4]. Consequently, options for the antibiotic treatment of infections caused by Bacteroides spp. are likely to be limited [5]. Therefore, validating the efficacy of carbapenems and MNZ as current treatment options for infections caused by Bacteroides spp. is necessary.

To date, several randomized clinical trials (RCTs) and meta-analyses have compared the efficacy of carbapenem regimens and combined therapy with MNZ in infections caused by anaerobic bacteria [6,7]. Although some studies included patients infected with Bacteroides spp., none of them discussed whether carbapenems or combined therapy with MNZ showed greater efficacy because of the small sample size. Therefore, the choice of appropriate antibiotics for infections caused by Bacteroides spp. remains unclear from the perspective of antimicrobial resistance.

The present meta-analysis aimed to validate clinical efficacy between carbapenems and combined therapy with MNZ in patients infected with Bacteroides spp.