Exploration of animal model of sepsis caused by lung bacterial infection / 中国医师杂志

ABSTRACT

Objective:Animal models of sepsis are mainly established by cecal ligation and puncture which causes mixed bacterial infections in the abdominal cavity. However in internal clinic, sepsis is more common to be caused by respiratory bacterial infections. Therefore, it is necessary to establish animal models of sepsis caused by lung Infection.Methods:According to the concentration of Staphylococcus aureus (S. aureus) suspension and Pseudomonas aeruginosa (P. aeruginosa) suspension, Sprague Dawley (SD) rats were equally divided into 10 groups, including S-Cont group, S-0.75 group, S-1.5 group, S-3 group, S-6 group and P-Cont group, P-1 group, P-2 group, P-4 group, P-8 group. Rats in the control group were treated with normal saline nasal drip. Rats in each experimental group were infected by nasal dripping bacterial suspension with 0.75×10 8 CFU/ml, 1.5×10 8 CFU/ml, 3×10 8 CFU/ml, 6×10 8 CFU/ml of S. aureus suspension or 1×10 8 CFU/ml, 2×10 8 CFU/ml, 4×10 8 CFU/ml, 8×10 8CFU/ml P. aeruginosa suspension. Our study detected the body temperature (T), blood pressure (BP), heart rate (HR) of rats in each group before and after infection, as well as blood lactic acid (Lac) and procalcitonin (PCT) level after infection. The lung infections of rats in each group were observed by hematoxylin-eosin (HE) staining. Results:The blood pressure(BP) of S-1.5 group, S-3 group, S-6 group and P-8 group was lower than before infection (all P<0.05). The Lac and PCT of each S. aureus experimental group were higher than that of the S-Cont group (all P<0.01); and they showed an increasing trend with the increase of the bacterial suspension concentration ( P<0.05), except for the S-3 and S-6 group ( P>0.05). The Lac and PCT of each P. aeruginosa experimental group were higher than that of the P-Cont group (all P<0.01); and they showed an increasing trend with the increase of the bacterial suspension concentration (all P<0.05), except for the Lac in the P-4 group and P-8 group ( P>0.05). HE staining showed that different degrees of inflammatory infiltration can be seen in the lungs of the experimental rats in each group. Conclusions:Infection of rats by nasal dripping with 3×10 8 CFU/ml of S. aureus suspension or 4×10 8 CFU/ml of P. aeruginosa suspension could establish relatively stable rat sepsis model induced by lung bacterial infection, of which the former could also establish a relatively stable septic shock model.