Secondary Peritonitis

Causative agents for small bowel, colon: anaerobes (esp B. fragilis), Enterobacteriaceae (esp E. coli, K. pneumoniae, Enterobacter spp, Proteus spp)

Infections are usually polymicrobial.

Pathogens causing tertiary peritonitis are variable and are often resistant to or not covered by the initial antimicrobial regimen; thus, a change in antimicrobials is advised.