Treatment of secondary peritonitis: is a less expensive broad-spectrum antibiotic as effective as a carbapenem?

Background: In this retrospective study, the possibility of using amoxicillin/clavulanate for empirical therapy of secondary peritonitis as an alternative to imipenem was explored.

Methods: All secondary peritonitis cases at our institution between 1998 and 2000 were included. Susceptibility to imipenem and amoxicillin/clavulanate of microorganisms isolated in peritoneal fluid and success rates were compared. Therapeutic failure was defined as death, necessity of repeated surgical intervention, or clinical deterioration with persistent positive cultures.

Results: Seventy-six cases of secondary peritonitis with 156 microorganisms were found. One hundred and forty-nine (98%) were susceptible to imipenem versus 124 (82%) to amoxicillin/clavulanate (p = 0.0001). Thirteen therapeutic failures occurred in 52 patients treated with amoxicillin/clavulanate (25%) versus 3 out of 8 (38%) with imipenem (p = 0.43). The proportion of organisms resistant to amoxicillin/clavulanate in therapeutic failures was greater in nosocomial versus community-acquired secondary peritonitis (p = 0.041).

Conclusion: Despite its better in vitro bacteriological activity, clinical efficacy of imipenem was identical to amoxicillin/clavulanate. The use of amoxicillin/clavulanate instead of imipenem would save 889 Euro per case.