Comparative activity of ertapenem and piperacillin–tazobactam in a murine systemic infection model with Bacteroides fragilis and Escherichia coli

It is now well-recognized that most intra-abdominal infections involve multiple types of bacteria. The most frequently encountered organisms in intra-abdominal infections are Escherichia coli and Bacteroides fragilis. These two micro-organisms are indigenous components of faecal microbiota, but can cause intra-abdominal abscess following surgery (Goldstein & Snydman, 2004). Therefore, an effective antimicrobial agent for the treatment of intra-abdominal infections requires a broad spectrum of activity against both aerobic and anaerobic bacteria.