Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China.
FEMS Microbiol Lett. 2022 Oct 17;369(1). doi: 10.1093/femsle/fnac092.
Salmonella is one of the most important foodborne and zoonotic pathogens, and monophasic S. Typhimurium is ranked among the top-five Salmonella serovars causing animal and human infections worldwide. Resistance to the third- and higher-generation cephalosporins in Salmonella has attracted great attention. Bacteria are frequently exposed to sub-minimal inhibitory concentrations (sub-MICs) of antimicrobials that can trigger diverse adaptive responses such as biofilm formation. Biofilms can promote bacterial defense to external and internal harsh conditions. This study aimed to investigate the effect of sub-MICs of cefotaxime, one of the third-generation cephalosporins, on biofilm formation by non-clinical S. enterica strains. Crystal violet staining demonstrated that cefotaxime at 1/8 MIC enhanced biofilm formation by two monophasic S. Typhimurium strains. Confocal laser scanning microscopy and enzymatic treatment assay revealed that cellulose was the most dominant extracellular matrix component contributing to Salmonella biofilm formation. Scanning electron microscopy demonstrated that cefotaxime treatment led to bacterial incomplete cell division and filamentous morphology during the whole process of biofilm formation. Our study is the first to report the enhancement effect of cefotaxime on non-clinical, monophasic S. Typhimurium by affecting bacterial morphology. The results will contribute to conducting risk assessments of Salmonella in the pork production chain and guiding the rational use of antimicrobial agents to reduce the risk of biofilm formation.
沙门氏菌是最重要的食源性和动物源性致病菌之一，单相鼠伤寒沙门氏菌是全球导致动物和人类感染的五大沙门氏菌血清型之一。沙门氏菌对第三代和更高代头孢菌素的耐药性引起了极大关注。细菌经常暴露于低于最低抑菌浓度（sub-MICs）的抗菌药物中，这会引发多种适应性反应，如生物膜形成。生物膜可以促进细菌对外界和内部恶劣条件的防御。本研究旨在研究第三代头孢菌素头孢噻肟的亚抑菌浓度对非临床鼠伤寒沙门氏菌菌株生物膜形成的影响。结晶紫染色表明，头孢噻肟在 1/8 MIC 时增强了两种单相鼠伤寒沙门氏菌菌株的生物膜形成。共聚焦激光扫描显微镜和酶处理试验表明，纤维素是形成沙门氏菌生物膜的最主要的细胞外基质成分。扫描电子显微镜表明，头孢噻肟处理导致细菌在生物膜形成的整个过程中不完全细胞分裂和丝状形态。本研究首次报道了头孢噻肟通过影响细菌形态来增强非临床单相鼠伤寒沙门氏菌的作用。研究结果将有助于对猪肉生产链中沙门氏菌进行风险评估，并指导合理使用抗菌药物以降低生物膜形成的风险。
