Garima Kushal, Pathak Rakesh, Tandon Rashmi, Rathor Nisha, Sinha Rajesh, Bose Mridula, Varma-Basil Mandira
Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India.
Department of Biochemistry, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India.
Tuberculosis (Edinb). 2015 Mar;95(2):155-61. doi: 10.1016/j.tube.2015.01.005. Epub 2015 Jan 21.
Several reports have elaborated on the role of efflux pumps in drug resistance in Mycobacterium tuberculosis by analysing the mRNA expression profiles. However, there is no uniformity in the subinhibitory concentrations of drugs chosen in these studies. Some investigators studied the expression of efflux pumps under a drug concentration of 1/2 minimum inhibitory concentration (MIC), while others used 1/3, 1/4 or 1/8MIC. The present study was planned to understand the effect of different concentrations of antituberculosis drugs on the expression of efflux pump genes. Log phase culture of the laboratory strain M. tuberculosis H37Rv was exposed to rifampicin (RIF), isoniazid (INH), streptomycin (SM) and ethambutol (EMB) at different drug concentrations (1/2MIC, 1/3MIC and 1/4MIC). The expression of 10 putative efflux pump genes was studied using quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). We observed an optimal expression of efflux pumps at higher concentrations of INH; and at lower concentrations of RIF and EMB. However, in the presence of SM, a decreased expression of efflux genes with increasing concentrations of the drug was confounded by a significant reduction in Colony Forming Units (CFU).
通过分析mRNA表达谱，已有多篇报道阐述了流出泵在结核分枝杆菌耐药性中的作用。然而，这些研究中所选用的药物亚抑制浓度并不统一。一些研究者研究了在1/2最低抑菌浓度（MIC）的药物浓度下流出泵的表达，而其他研究者则使用了1/3、1/4或1/8 MIC。本研究旨在了解不同浓度的抗结核药物对流出泵基因表达的影响。将实验室菌株结核分枝杆菌H37Rv的对数期培养物暴露于不同药物浓度（1/2 MIC、1/3 MIC和1/4 MIC）的利福平（RIF）、异烟肼（INH）、链霉素（SM）和乙胺丁醇（EMB）中。使用定量实时聚合酶链反应（qRT-PCR）研究了10个假定的流出泵基因的表达。我们观察到，在较高浓度的INH下，流出泵有最佳表达；在较低浓度的RIF和EMB下也有最佳表达。然而，在存在SM的情况下，随着药物浓度的增加，流出基因表达的降低与菌落形成单位（CFU）的显著减少相混淆。
