Efficacy evaluation of phage EP01 on SD rat endometritis induced by Escherichia coli GXEC-K5.

Bacterial endometritis often causes significant economic losses in animal husbandry. Moreover, the problem of antibiotic resistance arising from traditional antibiotic treatments is becoming increasingly severe, making it urgent to develop new therapeutic agents that can reduce or replace antibiotics. In this study, Escherichia coli strain GXEC-K5 was isolated from sows with endometritis. The strain GXEC-K5 was identified using methods such as Gram staining, antimicrobial susceptibility testing, detection of virulence and drug resistance genes, and whole-genome sequencing. Additionally, an SD rat model of endometritis was successfully established. The experimental results showed that the use of the antibiotic enrofloxacin (ENR), phage (Phage EP01), and the combination of antibiotic and phage (ENR + EP01) all had certain therapeutic effects on metritis, among which the ENR + EP01 group showed the most significant therapeutic effect. This is specifically manifested by a decrease in the uterine index and bacterial load in uterine secretions, along with down-regulated mRNA levels of pro-inflammatory factors (IL-1β, IL-2, TNF-α and IFN-γ) and improvements in histopathological conditions. In addition, it alleviates endometritis by regulating the homeostasis of the flora, which is achieved by increasing the abundance of Delftia and Lactobacillus and decreasing the abundance of Faecalibaculum. In conclusion, this study provides a potential new strategy for the treatment of endometritis in the future and offers a new approach to addressing the issue of bacterial resistance encountered in the treatment of endometritis.