Peritoneal cultures and antibiotic treatment in patients with perforated appendicitis

Objective: To question the common practice of sending material for microbiological examination during appendicectomy for perforated appendixes. Design: Uncontrolled retrospective study. Setting: Teaching hospital, Israel. Subjects: 89 patients who had their perforated appendixes removed. Interventions: Appendicectomy and antibiotic treatment. Main outcome measure: Whether a change in antibiotic regimen was required after bacteriological identification of bacteria isolated during the operation. Results: In only 43 of the cultures (48%) taken during the operation were bacteria grown, and these were mainly Escherichia call. In 65 patients (73%) there was no need to change the previously initiated antibiotic regimen, and in 23 (26%) it was changed purely on clinical grounds. In only one patient (1%) was the change the consequence of microbiological testing, as the organisms identified in 42 of the 43 cultures (98%) were sensitive to at least one of the antibiotics that had already been given. Conclusion: The practice of culturing samples taken from a ruptured appendix is redundant, because the antibiotic that has already been initiated is effective in most of the patients and the decision to modify the therapeutic regimen is, dominated by clinical considerations.