Antibiotic prophylaxis diminishes bacterial translocation but not mortality in experimental burn wound sepsis

Pseudomonas (PSA) burn wound sepsis results in prolonged bacterial translocation (BT) of enteric organisms such as E. coli to the mesenteric lymph nodes (MLN) and organs in rats. Intestinal decontamination with oral antibiotics may improve mortality after burn injury, perhaps due to decreased BT. To determine the effect of oral antibiotic prophylaxis effective against E. coli but not PSA on BT and subsequent mortality in a model of PSA burn wound sepsis, rats were given a 30% scald burn and wound inoculation with 108 PSA followed by randomization to either ampicillin (50 mg/kg/d) or saline gavage. Cultures of MLN, organs, blood, and cecal contents were obtained on days 1, 4, and 7 after injury, with additional animals observed for 14-day mortality. Although oral antibiotic prophylaxis resulted in increased cecal colony counts, the incidence of BT was unchanged. The number of organisms present in both the MLN and organs, however, was significantly reduced with prophylaxis, indicating cecal overgrowth by non-translocating bacteria. Reduction of the number of translocating organisms did not result in improved mean survival time after injury, suggesting that mortality from PSA burn wound sepsis occurs independently of bacterial translocation.