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Antibiotic prophylaxis diminishes bacterial translocation but not mortality in experimental burn wound sepsis
W G Jones1, A E Barber, J P Minei
1Department of Surgery, Cornell University Medical College, New York, New York 10021.
Insights
Oral antibiotics reduced bacterial translocation to organs in a rat model of Pseudomonas (PSA) burn wound sepsis. However, this did not improve survival, suggesting mortality is independent of bacterial translocation.
Area of Science:
- Infectious Diseases
- Sepsis Research
- Surgical Infections
Background:
- Pseudomonas (PSA) burn wound sepsis can lead to bacterial translocation (BT) of enteric organisms.
- Oral antibiotic intestinal decontamination may reduce mortality after burn injury by decreasing BT.
Purpose of the Study:
- To investigate the effect of oral antibiotic prophylaxis on bacterial translocation and mortality in a rat model of PSA burn wound sepsis.
- To determine if reducing E. coli translocation impacts survival rates.
Main Methods:
- Rats with a 30% scald burn and PSA wound inoculation were treated with ampicillin or saline.
- Cultures of mesenteric lymph nodes, organs, blood, and cecal contents were analyzed.
- Mortality was observed for 14 days post-injury.
Main Results:
- Oral ampicillin prophylaxis increased cecal bacterial counts but did not alter the incidence of bacterial translocation.
- A significant reduction in translocating organisms in mesenteric lymph nodes and organs was observed.
- No improvement in mean survival time was noted despite reduced translocation.
Conclusions:
- Oral antibiotic prophylaxis effectively reduced bacterial translocation to organs in PSA burn wound sepsis.
- Mortality in this model appears to be independent of bacterial translocation.
- Further research is needed to understand the mechanisms driving mortality in severe burn sepsis.
Abstract:
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 10(8) 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.