Background: The clinical outcome of patients with secondary bacterial peritonitis depends on the production of superoxides involved in bacterial killing and the endogenous level of antioxidants. The prognostic significance of their levels has not previously been investigated.
Patients and methods: Forty-five patients undergoing surgery for secondary peritonitis were prospectively evaluated. Severity of illness at admission (APACHE II score) was correlated with admission levels of superoxide radicals and antioxidants (superoxide dismutase (SOD), catalase and glutathione peroxidase). Levels were compared with general surgery controls (n = 10). Superoxide and antioxidant levels at admission (day 1) and post-operative days 3 and 5/7 were then correlated with outcome.
Results: Nine of the 45 patients died (20% mortality) and 17 patients had complications (47% morbidity). The mean APACHE II score on admission was significantly higher among non-survivors than survivors (p < 0.01). The APACHE II score on admission correlated with the level of free radicals (r = 0.477, p < 0.01), catalase (r = -0.489, p < 0.01) and SOD (r = -0.357, p < 0.05). Admission superoxide levels were higher and antioxidant levels lower in peritonitis patients than controls. Levels did not significantly change following surgical intervention and post-operative levels did not correlate with outcome.
Conclusion: The levels of superoxide and antioxidants correlate with the severity of illness on admission in patients with secondary peritonitis, but serial levels following surgical intervention do not predict outcome.