Department of Microbiology, Assam University, Silchar, India.
Department of Microbiology, Silchar Medical College and Hospital, Silchar, India.
Infect Genet Evol. 2019 Sep;73:332-336. doi: 10.1016/j.meegid.2019.05.024. Epub 2019 Jun 3.
Escherichia coli, one of the major pathogens, frequently exhibits carbapenem resistance. It would be of interest to investigate which of the mechanisms responds when a strain that carries both bla and over expressed AcrAB-TolC efflux pump system is exposed against carbapenem under differential concentration gradient stress. Four different sets of strains were used in the study; (i) Strain that have bla and over expressed AcrAB-TolC system (ii) Strain that harbour bla and express AcrAB-TolC at basal level (iii) the strain that is devoid of bla but having over expressed AcrAB-TolC systems and (iv) E. coli AG100A (ΔAcrAB) and E. coli HUE 1 (ΔAcrAB-TolC) where blawas cloned. The Quantitative Real time PCR showed bla was over expressed under meropenem and imipenem stress irrespective of concentration gradient. In case of ertapenem, at lower concentration AcrA were over expressed whereas, at higher concentration bla showed elevated expression. A consistent elevated expression of AcrA and AcrB was observed against all carbapenems in the strains devoid of bla where as in case of the strain with basal level expression of AcrA, no significant over expression could be observed for bla. In case of clones in group IV, expression of bla was elevated in the presence of carbapenem stress.
大肠杆菌是主要病原体之一，经常表现出碳青霉烯类耐药性。因此，研究在不同浓度梯度碳青霉烯类药物压力下，同时携带 bla 和过表达 AcrAB-TolC 外排泵系统的菌株，哪种机制会产生反应，这将是很有意义的。在这项研究中使用了四组不同的菌株：（i）携带 bla 和过表达 AcrAB-TolC 系统的菌株；（ii）携带 bla 并在基础水平表达 AcrAB-TolC 的菌株；（iii）缺乏 bla 但过表达 AcrAB-TolC 系统的菌株；（iv）克隆了 bla 的 E. coli AG100A（ΔAcrAB）和 E. coli HUE 1（ΔAcrAB-TolC）。实时定量 PCR 显示，bla 在美罗培南和亚胺培南压力下均过表达，而在厄他培南较低浓度下，AcrA 过表达，而在较高浓度下，bla 表达升高。在缺乏 bla 的菌株中，所有碳青霉烯类药物都观察到 AcrA 和 AcrB 的一致升高表达，而在 AcrA 基础水平表达的菌株中，对于 bla 则观察不到明显的过表达。在第四组克隆中，在碳青霉烯类药物压力下，bla 的表达升高。
