Outcome of intra-abdominal infection in pigs depends more on host responses than on microbiology.

ABSTRACT

OBJECTIVE: To assess the effects of mortality of the presence and proliferation of bacteria, and the host's response to infection, in pigs with peritonitis. DESIGN: Laboratory study. SETTING: University hospital. MATERIAL: 71 Swedish Landrace pigs, 63 with peritonitis and 8 without (controls). INTERVENTIONS: Induction of peritonitis by intraperitoneal infusion of equal amounts of Escherichia coli and Bacteroides fragilis (10(9) to 10(11) bacteria/animal); sterile faeces were added in half the experiments. MAIN OUTCOME MEASURES: Microbiological events were quantified as the area under the bacterial concentration curve from 0-6 hours. Host responses were quantified with a score of 8 physiological variables measured between 4-6 hours after the induction of peritonitis. RESULTS: Of the 63 infected animals, 37 (59%) died within 6-24 hours and both the physiological response and the bacterial load were significantly higher in those that died. Logistic regression analysis with death as the dependent variable showed that the physiology score carried more predictive information than the quantification of bacterial load. CONCLUSION: The quantification of local events within the abdomen is of only limited predictive value compared with the extent of the physiological alterations.