沙门菌噬菌体抗性菌的筛选鉴定及致病力研究

【目的】筛选鉴定沙门菌噬菌体侵染裂解过程中的抗性菌株,研究抗性菌株的生物学特性及致病力的差异,为解决噬菌体治疗应用中的抗性菌问题提供理论依据。【方法】本研究通过次级感染法和双层平板法筛选沙门菌噬菌体抗性菌,通过生物学特性和毒力基因检测比较宿主菌ATCC 13076及其噬菌体抗性菌株R3之间的差异,并通过小鼠攻毒实验和细胞粘附实验比较致病力强弱。【结果】噬菌体抗性菌株R3的生长速度较宿主菌略慢;生化及毒力基因检测均表明抗性菌株与宿主菌无差异;与宿主菌相比,抗性菌R3的LD50增加了74.8%(P0.05);对MODE-K细胞粘附能力稍弱,但是差异不显著。【结论】该研究表明,与噬菌体宿主菌相比,噬菌体抗性菌株的生物学特性和毒力基因并没有改变,对小鼠致病力减弱,但是对MODE-K细胞粘附能力差异不显著。

Screening, identification and pathogenicity of phage-resistant strain of Salmonella

Objective] To screen and identify resistant strains of Salmonella phage in the process of lysis, the differences of biological characteristics and the pathogenicity between resistant strains and the host strains were studied, to provide theoretical basis for solving the problem of presence of resistant bacteria in the phage therapy. Methods] Salmonella phage-resistant bacteria were screened by secondary infection method and double-layer plate method. The differences between host strain ATCC 13076 and its phage-resistant strain R3 were compared by biological characteristics and virulence genes detection. The virulence of the bacteria was compared using mice challenge test and cell adhesion test. Results] The growth curve of phage-resistant strain R3 was slightly slower than that of host strain; biochemical and virulent genetic tests showed that there was no difference between the resistant strain and host strain; compared to the host strain, the pathogenicity of the resistant strain to mice (Lethal Dose, 50%, LD₅₀) increased by 74.8% (P>0.05); and the adhesion ability to MODE-K cells were slightly weaker, but the difference was not significant. Conclusion] Compared with the host strain, the biological characteristics and virulence genes of the bacteriophage-resistant strains did not change, and the pathogenicity of the strains was weakened in mice, but the adhesion ability to MODE-K cells was not significantly different.