Development and characterization of a novel model of invasive pneumococcal pneumonia in invasively ventilated PIGS

Methods Eight female Large White-Landrace pigs (33.9 ± 2.1 Kg) were anesthetized, tracheally intubated and connected to a mechanical ventilator. Ultrasound-guided arterial cannulation was performed, and a Swan-Ganz catheter was inserted into the jugular vein for hemodynamic monitoring. Following surgical preparation, and 4 hours thereafter, 15 mL of 10 cfu/mL of S. pneumonia serotype 19A, resistant to erythromycin, penicillin and tetracyclins, was instilled into each pulmonary lobe using a bronchoscope. Throughout the study, quantitative cultures of broncho-alveolar lavage (BAL) and blood cultures were performed. Every 24 hours, gas exchanges, pulmonary mechanics, hemodynamics and laboratory parameters were assessed. Fluids and vasoactive drugs were administered to sustain hemodynamic stability. Doxycyclin and aztreonam were administered to avert colonization by endogenous pathogens. The animals were euthanized 72 hours after bacterial inoculation and pulmonary lobes were sampled for quantitative microbiology studies. Pneumonia was confirmed if pulmonary tissue S. pneumoniae culture was ≥ 3 log CFU/gram tissue. Additionally, in 6 animals lung histology was evaluated.