Effects of Bacillus coagulans on kidney injury caused by Klebsiella pneumoniae in rabbits.

Klebsiella pneumoniae (KP) is a zoonotic conditionally pathogenic bacterium with a high prevalence of infection. It often induces purulent inflammation of the rabbit lungs, kidneys and other tissues, with high morbidity and mortality. Bacillus coagulans (BC) has the ability to regulate the balance of host intestinal flora and improve host immunity. However, the mechanism of the protective effect of BC on KP-induced kidney injury in rabbits is not clear. To explore this, we randomly divided fifty 35-day-old Eyplus rabbits into five groups: control, KP, low-dose BC (LBC), medium-dose BC (MBC) and high-dose BC (HBC). On the 1st day of the experiment, rabbits in LBC, MBC and HBC groups were fed diets containing 1 × 10⁶ CFU/g, 5 × 10⁶ CFU/g and 1 × 10⁷ CFU/g BC, respectively, and rabbits in CK and KP groups were fed basal diets. On the 8th day, each rabbit in the KP, LBC, MBC and HBC groups was infused with 4 mL of 1 × 10¹¹ CFU/mL KP bacterial solution, and the CK group was infused with the same amount of sterilised saline for a total of 7 days. Rabbit kidney tissues were collected on the 15th d. HE staining was used to observe the pathological changes of rabbit kidney tissues, oxidative stress-related indexes were detected by biochemical kits, and the content of inflammatory factors and apoptosis-related factors in kidney tissues were detected by ELISA. The results showed that KP disrupts the normal structure of the kidney, induces oxidative stress and inflammatory responses, and mediates apoptosis by regulating the levels of Bcl-2 family proteins. BC pretreatment significantly reduced kidney structural damage, oxidative stress, inflammatory response, and apoptosis in rabbits. To alleviate KP-induced kidney injury by increasing the activity of antioxidant enzymes and the content of anti-apoptotic proteins. Compared with the LBC group and the HBC group, the remission effect was more pronounced in the MBC group. Therefore, in this study, the effect of 5 × 10⁶ CFU/g BC was more significant.