An experimental study of susceptibility to infection after hemorrhagic shock

Hemorrhagic shock has been associated with an increased risk of infection after injury. The immediate and long term effects of hemorrhagic shock without tissue injury on the susceptibility of an animal to infection and the efficacy of antibiotic prophylaxis to prevent infection in this setting were examined. Sprague-Dawley rats were subjected to hemorrhagic shock (LD₁₅) by bleeding to a mean arterial pressure of 45 millimeters of mercury for 45 minutes and were resuscitated with shed blood and normal saline solution. In one experiment, dorsal wounds were inoculated one hour before or after shock with either 10⁶, 10⁸, 10¹⁰ Staphylococcus aureus. In a second experiment, rats were infected at one hour, or one, three or five days after shock with 10⁶, 10⁷ or 10⁸ S. aureus. Equivalent numbers of rats received cefamandole nafate prior to bacterial challenge. Hemorrhagic shock increased the susceptibility to wound infection at all inocula. Infection increased whether rats were wounded before or after shock, and this effect was sustained for up to three days. Antibiotic prophylaxis was of limited value in reducing the incidence of wound infection after shock.