Replication of a model of chronic pulmonary infection of Pseudomonas aeruginosa in rat / 解放军医学杂志

ABSTRACT

Objective To establish a rat model of chronic pulmonary infection by inoculating Pseudomonas aeruginosa to Sprague-Dawley (SD) rats, and to evaluate the animal model with bacteriological and pathological stndies. Methods 240 healthy, clean SD rats were randomly divided into 2 groups the infected group and the control group. Pseudomonas aeruginosa were embedded in minute seaweed alginate beads using an ejection set with an acuminate hole. Then the beads were inoculated into the rats′ lung through tracheal intubation. The bacteria number in the lung and pathological scores were determined 3, 7, 14 and 35 days after inoculation. The control group was treated with the same method using the sterile normal saline instead of the bacteria suspension. Results Bacteriological values no bacterium was detected in the control group. Pseudomonas aeruginosa was detected from the rats of infected group in which the bacterial number was up over 105cfu/g at 3 and 7 days after infection, and up over 103cfu/g at 14 and 35 days after infection. Pathological changes at 3 and 7 days after infection, lung edema, consolidation and hemorrhage could be seen in rat lungs of the infected group. Under the optical microscope, alginate-Pseudomonas aeruginosa caused a pronounced inflammatory reaction with polymorphonuclear cells surrounding beads, and microcolonies formed at the periphery of beads were also seen. Atelectasis and fibrosis and granalation were the major pathological changes at 14 and 35 days after infection. While in the control group, there were little changes after the inoculation except mild congestion and inflammatory reaction in the lungs 3 days after inoculation. Conclusion The rat model of chronic pulmonary infection can be reproduced by inoculating Pseudomonas aeruginosa embedded in minute seaweed alginate beads.