新疆阿克苏地区一株羊源沙门菌及其小菌落变异株的生物学特性

Biological characteristics of a sheep-derived strain of Salmonella and its small colony variant in Aksu, Xinjiang of China

摘要:

【背景】小菌落变异株(small colony variant, SCV)是一种具有独特的表型及致病特征且生长缓慢的细菌亚群，而国内鲜有关于食源性沙门菌SCV的研究报道。【目的】为食源性沙门菌的防治及动物性食品安全提供实验数据。【方法】使用氨基糖苷类抗生素对羊源胆汁中分离的沙门菌进行实验室诱导得到SCV，然后分别对野生株和诱导株的菌落形态、生长、生化特性、营养缺陷型检测、运动性、耐药性检测及耐药基因、毒力基因、生物被膜形成能力进行比较和分析。【结果】经卡那霉素诱导获得一株血红素依赖型沙门菌SCV，与野生株相比，诱导株生长缓慢，低于野生株84%，不利用柠檬酸盐，溶血能力增强40%，对磺胺类和氨基糖苷类药物的耐受性增强，生物被膜形成能力减弱45%，运动能力减弱78%。【结论】沙门菌SCV的生长和生理生化特性与野生株相比有显著差异，使得沙门菌SCV的分离鉴定尤为困难；并且SCV的致病性与耐药性等方面的变化可能给沙门菌病的防治带来更大挑战，其机制还有待深入研究。

关键词:沙门菌;小菌落变异株;耐药性;生物膜形成能力;生物学特性

Abstract:

[Background] The small colony variants (SCVs) of bacteria are subpopulations with small colonies, slow growth, and atypical phenotypic characteristics, leading to recurrent infection. Little is known about the food-borne SCVs of Salmonella in China. [Objective] To provide experimental data for the prevention and control of food-borne Salmonella and the guarantee of animal food safety. [Methods] The SCV was induced by the addition of aminoglycoside antibiotics in the medium of a Salmonella strain isolated from sheep bile. The colony morphology, growth, biochemical characteristics, auxotrophy, antibiotic resistance, resistance genes, virulence genes, and biofilm formation ability of the wild type and SCV were determined and compared. [Results] A heme-dependent Salmonella SCV was obtained after induction with kanamycin. Compared with the wild type, the SCV showed a growth rate decrease of 84%, the inability of using citrate, a hemolysis ability increase of 40%, increased tolerance to sulfonamides and aminoglycosides, a biofilm formation reduction of 45%, and a motility decrease of 78%. [Conclusion] The biological characteristics of the Salmonella SCV were significantly different from those of the wild type, which made it difficult to identify the SCVs of Salmonella. The changes of the pathogenicity and drug resistance of SCVs may pose great challenges to the prevention and control of salmonellosis, and the mechanism remains to be studied.

Key words:Salmonella;small colony variants;drug resistance;biofilm formation ability;biological characteristics