Prognostic importance of gram-negative intestinal colonization preceding pancreatic infection in severe acute pancreatitis. Results of a controlled clinical trial of selective decontamination

OBJECTIVES: To establish, firstly, whether gram-negative (re)-colonization of the gut leads to an increased risk of gram-negative pancreatic infections and whether this event is time-related and, secondly, whether the difference in the quantity and quality of micro-organisms colonizing the digestive tract influences morbidity and mortality. DESIGN: Prospective analysis of the results of systematic semi-quantitative cultures of several body areas taken from patients with severe acute pancreatitis, during a controlled multicenter trial of adjuvant selective decontamination. SETTING: Surgical intensive care units of 16 hospitals. PATIENTS: A total of 2,159 semi-quantitative cultures from the oropharynx, rectum and pancreatic tissues taken from 90 patients were analyzed. Interventions: Surveillance cultures from the oropharynx and rectum were taken on admission and repeated twice weekly and from the (peri)-pancreatic devitalized tissues (i. e. necrosis) at every relaparotomy and from drainage. MEASUREMENTS AND RESULTS: All gram-negative pancreatic infections were preceded by intestinal colonization with the same micro-organisms. The risk of developing a pancreatic infection following gram-negative intestinal colonization (15/42 patients) was significantly higher as compared to patients without gram-negative colonization (0/10 patients) (p < 0.001) or to patients in whom E. coli was the only intestinal micro-organism cultured (0/30 patients) (p < 0.001). The occurrence of intestinal E. coli did not increase the risk of pancreatic infection. Gram-negative colonization of the rectum and oropharynx significantly correlated with the later development of pancreatic infection: relative risks 73.7 (p < 0.001) and 13.6 (p < 0.001), respectively. However, when both areas were evaluated simultaneously, the rectum was more significant (p < 0.001). The severity of intestinal intestinal colonization until the moment of pancreatic infection showed an increase in time in all 15 patients. In 11 of 15 patients (73%) these infections occurred within 1 week following the first isolation from the digestive tract. Gram-negative intestinal colonization was associated with a 3.7 fold increased mortality risk (p = 0.004). CONCLUSIONS: Gram-negative intestinal colonization, E. coli excepted, is an early prognostic parameter in patients in whom pancreatic infection has not yet occurred and represents a significantly increased risk of pancreatic infections and mortality.