Dawan Jirapat, Ahn Juhee
Department of Biomedical Science and Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea.
Department of Biomedical Science and Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea.
Microb Pathog. 2021 Aug;157:104973. doi: 10.1016/j.micpath.2021.104973. Epub 2021 May 23.
This study was designed to investigate the cooperative resistance in the mixed culture of antibiotic-sensitive and antibiotic-resistant Salmonella Typhimurium. Strains of S. Typhimurium ATCC 19585 (ST) and clinically isolated antibiotic-resistant S. Typhimurium CCARM 8009 (ST) grown in single and mixture with 1 × MIC ceftriaxone (CEF) were used to determine the viability, β-lactamase activity, and gene expression. The MIC values of ST to CEF was increased by more than 5-fold with increasing inoculum densities from 10 to 10 CFU/mL. ST was resistant to 1 × MIC CEF in the mixed culture of ST and ST, showing the more than 10 CFU/mL after 20 h of incubation at 37 °C. The highest β-lactamase activity was 18 μmol/min/mL in the mixed culture, corresponding to the highest relative expression of β-lactamase-related genes (bla). These results shed new light on the cooperative resistance of antibiotic-sensitive bacteria within a heterogeneous population including β-lactamase-producing bacteria.
本研究旨在调查抗生素敏感型和耐药型鼠伤寒沙门氏菌混合培养物中的协同耐药性。使用鼠伤寒沙门氏菌ATCC 19585（ST）菌株和临床分离的耐药型鼠伤寒沙门氏菌CCARM 8009（ST）菌株，分别进行单菌培养以及与1×MIC头孢曲松（CEF）混合培养，以测定其活力、β-内酰胺酶活性和基因表达。随着接种密度从10⁶增至10⁸CFU/mL，ST对CEF的MIC值增加了5倍以上。在ST与ST的混合培养物中，ST对1×MIC CEF耐药，在37℃孵育20小时后显示出超过10⁸CFU/mL的菌量。混合培养物中最高的β-内酰胺酶活性为18μmol/min/mL，这与β-内酰胺酶相关基因（bla）的最高相对表达相对应。这些结果为包括产β-内酰胺酶细菌在内的异质群体中抗生素敏感菌的协同耐药性提供了新的见解。
