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目的亚最小抑菌浓度(MIC)剂量的某些抗生素能够诱导和促进艰难梭菌毒力编码基因及其毒素的表达,但具体机制不明。本文从艰难梭菌的毒力调控基因(tcdC、tcdE、tcdR)着手来试图解释亚MIC剂量的抗生素对艰难梭菌毒力编码基因和毒素的影响。方法中国株艰难梭菌BJ08分别生长在含有1/2 MIC剂量的克雷霉素或头孢噻肟或无抗生素的脑心浸液肉汤(BHI)液体培养基中。每4h,取一定量的艰难梭菌,通过实时荧光定量PCR检测其毒力调控基因(tcdC、tcdE、tcdR)mRNA的表达。结果 BJ08在1/2 MIC剂量的克雷霉素存在的情况下,对毒力调控基因mRNA表达的影响不大;但是在1/2 MIC剂量的头孢噻肟存在的情况下,tcdCmRNA的表达在培养早期和中期低于对照组,tcdE和tcdR的表达比起对照组都增高且提前,但两者增加幅度不同,高峰期也不同。结论在某些亚MIC剂量的抗生素存在的情况下,艰难梭菌毒力编码基因和毒素表达的变化可能是通过调节调控基因而实现的。
Some antibiotics that target sub-minimum inhibitory concentration (MIC) doses induce and promote the expression of virulence-coding genes and toxins in C. difficile, but the exact mechanism is unknown. This article attempts to explain the effect of submicrobial doses of antibiotics on C. difficile virulence genes and toxins from the virulence regulatory genes of C. difficile (tcdC, tcdE, tcdR). Methods China strain of C. difficile BJ08 was grown in liquid medium of brain heart infusion broth (BHI) with ½ MIC dose of either crylomycin or cefotaxime, respectively, or without antibiotics. Every 4h, a certain amount of C. difficile was taken and the expression of tCDC, tcdE, tcdR mRNA was detected by real-time fluorescence quantitative PCR. Results BJ08 had little effect on the expression of virulence-regulated genes in the presence of 1/2-MIC doses of crylomycin, but in the presence of cefotaxime at ½-MIC, the expression of tcdC mRNA was Compared with the control group, the expression of tcdE and tcdR in the early and middle stages were lower than those in the control group, but the amplitude of tcdE and tcdR increased at different stages. Conclusions Changes in the expression of C. difficile virulence-encoding genes and toxins may be mediated through the regulation of regulatory genes in the presence of some submicrobial doses of antibiotics.