Comparative Pulmonary Effects of Intraperitoneal Inoculation of Live v Dead Escherichia coli

• We studied the effect of 2.5 ×10⁹ live Escherichia coli per kilogram v 2.7 × 10⁹ dead E coli per kilogram injected into the peritoneal cavity of sheep with chronic pulmonary lymph fistulas. The effects of dead E coli were compared with those of live E coli, with respect to (1) pulmonary hypertension, (2) hemodynamic failure, (3) damage to the pulmonary microvasculature, (4) systemic arterial hypoxemia, (5) neutropenia and lymphopenia, (6) thrombocytopenia and platelet aggregation, (7) plasma fibrinogen concentration, and (8) classic- and alternative-pathway hemolytic complement. The time after injection of the bacteria was divided into an early period (zero to two hours) and a late period (two to seven hours). We made two conclusions: (1) The early period effects, with the exception of the absolute neutrophil count and Pao₂, were independent of bacterial viability, whereas the late period effects were strongly dependent on bacterial viability. (2) The early notable difference between the live v dead groups, with respect to the absolute neutrophil count and Pao₂, could not be explained on the basis of an increase in bacterial numbers alone.