Ertapenem versus piperacillin-tazobactam for treatment of mixed anaerobic complicated intra-abdominal, complicated skin and skin structure, and acute pelvic infections.

BACKGROUND

Anaerobes are an important component of many serious, deep tissue infections, especially complicated intra-abdominal (IAI), complicated skin and skin structure (SSSI), and acute pelvic (PI) infections. This study compares the efficacy of ertapenem, 1 g once a day, in the treatment of adults with anaerobic IAI, SSSI, and PI to piperacillin-tazobactam, 3.375 g every 6 hours.

METHODS

Three randomized, double-blind trials comparing ertapenem to piperacillin-tazobactam for treatment of IAI, SSSI, and PI were conducted. This subgroup analysis included 623 patients, whose baseline culture grew one or more anaerobic pathogens, from these three studies.

RESULTS

Anaerobes most commonly isolated were Bacteroides fragilis group (IAI) and peptostreptococci (SSSI and PI). The median duration of ertapenem and piperacillin-tazobactam therapy, respectively, in these subgroups was 6 and 7 days for IAI, 7 and 8 days for SSSI, and 4 and 5 days for PI. Cure rates for all evaluable patients with anaerobic infection were 89.3% (242/271) for ertapenem and 85.9% (220/256) for piperacillin-tazobactam (95% CI for the difference, adjusting for infection, -2.6% to 9.3%), indicating that the two treatments were equivalent. Cure rates by infection, for ertapenem and piperacillin-tazobactam, respectively, were as follows: IAI, 86.4% (133/154) and 82.4% (117/142); SSSI, 84.4% (27/32) and 82.4% (28/34); PI, 96.5% (82/85) and 93.8% (75/80). The frequency and severity of drug-related adverse experiences were comparable in both treatment groups.

CONCLUSION

In this subgroup analysis, ertapenem was as effective as piperacillin-tazobactam for treatment of adults with moderate to severe anaerobic IAI, SSSI, and PI, was generally well tolerated, and had a similar safety profile.