Bacterial translocation from the gastrointestinal tract in healthy and injured rats

To study the phenomenon of asymptomatic penetration of bacteria from the gastrointestinal tract into various tissues of healthy rats and rats with skin wounds and closed fractures at different doses and with different species of bacteria.

Healthy rats and rats with full-thickness skin wounds and closed femoral fractures were given varying doses of radiolabeled bacteria (S. aureus 209P or B. subtilis 534) per os in doses of up to 1010 bacteria per 1kg of body mass. Six hours later, these animals were euthanised and, together with blood smears, tissue samples of liver, spleen, stomach, small and large intestine, lung, hypothalamus, posterior pituitary gland, epinephros and skin and muscle from the wound site were subjected to bacteriological and histological analysis.

In total, 99 rats were used for the experiments. Viable bacteria were found to systemically penetrate into the tissues of the internal organs in 45 healthy animals, 27 rats with incisions and 27 rats with fractures. In healthy animals, viable bacteria mostly accumulated in the stomach wall, the mucous membranes of the small intestine, the mesenteric lymph nodes and in the spleen and liver. Translocation was registered in uninjured animals receiving 1x106 and more bacteria per 1kg of rat's weight and in injured rats receiving 1x104 bacteria and more. Bacteria penetrated the local tissues at both wound sites (skin wounds and fracture sites).

Bacterial translocation is a protective mechanism that gives the immune system constant contact with external antigens, although it can contribute to the spreading of infection in an organism. In healthy animals, small amounts of bacteria penetrate systemically from the tract and small intestine into the tissues of the spleen and liver. During injury, translocated bacteria also appear at the focus of injury.

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