Mice Models of Experimental Sepsis

The P. aeruginosa 203-2 strain was used for the induction of experimental sepsis in animals. A single colony of pure 18–24 h culture of bacteria grown on 5% blood agar was grown overnight in LB at 37 °C. The bacteria were collected by centrifugation at 3000 rpm for 10 min, and the pellet was suspended in 0.9% NaCl. The concentration of the bacterial suspension was determined by the visual comparison of the suspension with the 0.5 MF turbidity standard. To clarify the content of viable cells in the infecting suspensions, seeding from a number of dilutions to a dense nutrient medium was carried out, followed by counting the colonies after 24 h of incubation.

To simulate the infection, 5 groups of animals (six mice each) were formed, four of which were administered different doses of P. aeruginosa 203-2 obtained by 10-fold serial dilution of the initial concentration of inoculums (5 × 10⁶, 5 × 10⁷, 5 × 10⁸, 5 × 10⁹ KFU/mice). The control group of animals was administered a sterile saline buffer. Sepsis was modeled by a single intraperitoneal injection of 0.5 mL inoculate of a strain. The duration of observation was 7 days, after which the survived animals were euthanized by the administration of diethyl ether using ether-impregnated cotton. As the evaluation of virulence, the LD₅₀ and LD₁₀₀ were determined.