Group B streptococcal (GBSS) newborn septic shock model: the role of prostaglandins

Group B beta hemolytic streptococcal sepsis has many of the characteristics of gram negative sepsis (Hellerqvist, et al., 1981). This is further shown in the model developed for this study. The newborn piglet septic model developed for this study appears to be an adequate model for group B, beta-streptococcal sepsis characterized by the development of significant hypotension by six hours. As with human sepsis, this model develops hypoglycemia, hemoconcentration as noted by the increased hematocrit, thrombocytopenia and a significant drop in WBC with an increase in immature forms (Wilson, 1986). The only finding not correlated to the septic newborn is the development of DIC as characterized by an increased PT/PTT and increased FSP. As with other animal models for both gram positive and negative sepsis, the cyclooxygenase inhibitor, indomethacin significantly increased survival out to 72 hours. Previous studies with thromboxane synthetase inhibitors have not shown increased survival, but shunting into the prostacyclin pathway has occurred and the effect of this on survival could not be ruled out (Short, et al., 1983). The use of a thromboxane receptor site antagonist should not cause this shunt, and thus may help to evaluate the effect of thromboxane blockade. In this model no effect of the receptor site antagonist was noted, but due to the short half-life of this compound, a different dosing schedule may be needed before its efficacy can be determined. In summary, the cyclooxygenase inhibitors do appear to have a protective effect in gram positive sepsis, but the mechanisms of action are still to be determined.