Arginine reduces bacterial invasion in rats with head injury

OBJECTIVES: The benefit of arginine in intensive care unit patients with severe sepsis is still controversial. An excessive supply of arginine could lead to an overproduction of nitric oxide and could be responsible for septic shock and multiorgan failure. However, this claim is not supported by any experimental or clinical data. We set out to determine whether an enteral supply of arginine would modulate bacterial invasion in rats with head injury. METHODS: Male Sprague-Dawley rats with head injury were randomized into two groups. Group 1 included rats with head injury fed a standard enteral nutrition (Sondalis HP, n = 10) and group 2 included rats with head injury fed the standard enteral nutrition plus arginine (4 g/kg/d, n = 11). Two days after head injury, the rats received a single enteral bolus of luminescent Escherichia coli Xen 14. Bacterial proliferation was evaluated in vivo at time + 2 hrs and time + 6 hrs after E. coli challenge. Four days after head injury, blood was sampled for arginine and fibrinogen assay. Muscles, intestine, spleen, and thymus were removed and weighed. RESULTS: There was no mortality in either group. The luminescence signal was similar in the two groups at time +2 hrs (group 1: 414 [5-823] vs. group 2: 496 [0.1-993] (median value[min-max]; not significant) and was significantly lower at time +6 hrs in group 2 (group 1: 71 [0-142] vs. group 2: 8.5 [0-17]; p = .026). Arginine treatment did not improve any nutritional parameters. CONCLUSIONS: Arginine was not responsible for mortality in rats with head injury with infectious complications and reduced the intensity of bacterial invasion.