Study on preventive effect of essential oils of oregano and cinnamon in mice infected with Citrobacter freundii

HUANG Yi-qin; MA Ming-xiang; XING Shuai; TAN Yu-xiao; ZHANG Xiao-xiao; QIAN Ya-jing; SI Hong-bin

doi:10.13557/j.cnki.issn1002-2813.2023.22.012

Abstract：The study was to investigate the pathogenicity of Citrobacter freundii in mice and the preventive effect of oregano and cinnamon essential oils on the resistance of mice to Citrobacter freundii infection.For pathogenicity test,30 mice were randomly divided into five groups.The mice in the control group were intraperitoneally injected with 0.2 mL normal saline.Mice in 1/2 times dose group,1 times dose group,2 times dose group and 4 times dose group were intraperitoneally injected with 2.5×109,5.0×109,1.0×1010,2.0×1010 CFU/mL of Citrobacter freundii bacterial solution(100 μL/g body weight).In the prevention test,mice were randomly divided into the control group,the model group,the oregano essential oils group,the cinnamon essential oils group and the combination essential oils group(oregano and cinnamon essential oil combination),mice were injected intraperitoneally with Citrobacter freundii after 7 d of oral administration of essential oils,and the bacterial load,the levels of jejunal inflammatory cytokines and the pathological changes in the jejunum were observed.The results showed that mice infected with Citrobacter freundii showed clinical signs such as eye congestion and then convulsions and died.Essential oils prophylaxis improved the survival rate of mice,reduced the levels of organ carriage and inflammatory cytokines,and increased the number of intestinal villi and thickened the intestinal wall.The experiment indicates that Citrobacter freundii is highly pathogenic to mice.Essential oils prophylaxis can strengthen the intestinal barrier of mice,prevent the colonization of the liver and spleen of mice infected by Citrobacter freundii,reduce the levels of pro-inflammatory cytokines in the jejunum of mice,and thus improve the survival rate of mice.