Acute serogroup A streptococcal shock: A porcine model

To elucidate the pathophysiology of acute shock caused by serogroup A strep tococci (GAS), GAS were given intravenously to 25 pigs, Short-time infusion s of GAS (n = 11) caused variable and unpredictable responses. A continuous infusion of 5 x 10(8) cfu/kg/h (n = 8) caused pulmonary hypertension, arte rial hypotension, and reduced cardiac output and liver perfusion, progressi ng to circulatory shock within 2-4 h. Halving the infusion rate (n = 6) ind uced a more gradual development of shock and doubled the mean survival time from 2.1 to 4.0 h. Mean tumor necrosis factor-alpha levels (+/-SE) increas ed from 25 +/- 1 to 40 +/- 3 pg/mL. Only slight signs of organ dysfunction were observed, which indicates that this is primarily a model of acute sept ic shock, Light microscopy revealed moderate inflammatory reactions in lung , liver, and gut biopsy samples, although high numbers of viable, M-typeabl e GAS were recovered from tissues. The present model may be useful to study mechanisms involved in acute septic shock as well as therapeutic intervent ions.