Assessment of intra-abdominal infections

Before starting antibiotic therapy for an intra-abdominal infection, consider noninfectious differential diagnoses. For example, ischaemic colitis usually presents as sudden-onset abdominal pain, associated with rectal bleeding and progressively worsening diarrhoea. Uncomplicated ischaemic colitis does not require antibiotic treatment unless there is a strong suspicion of perforated viscus and peritonitis (or peritoneal soiling).

Obtain samples from infected sites for culture and susceptibility testing; samples of pus are preferred to swabs. Direct aspiration of potentially infected fluid collections, or operative debridement of infected tissue are the most reliable methods of obtaining samples for culture. Samples collected from indwelling surgical drains are often contaminated; avoid using these samples for culture, as the results can be inaccurate and misleading.