鲍曼不动杆菌Ⅰ类整合酶基因在生物被膜内的表达及耐药分析

Expression of Class Ⅰ integrase gene in Acinetobacter baumannii and drug-resistance

目的:研究携带Ⅰ类整合子的鲍曼不动杆菌在生物被膜状态和普通液相培养状态下Ⅰ类整合酶基因(Class Ⅰ integrase gene,intI 1)mRNA的表达,并分析Ⅰ类整合子阳性菌耐药情况。方法:收集鲍曼不动杆菌临床株,并经过基因扩增筛选出携带Ⅰ类整合子的阳性菌株。提取携带Ⅰ类整合子的鲍曼不动杆菌在生物被膜和液相培养2种生长状态下的总RNA,采用半定量RT-PCR方法分析2种生长状态下细菌的Ⅰ类整合酶表达情况。并用纸片扩散法对携带Ⅰ类整合子的临床分离鲍曼不动杆菌进行药敏试验。结果:携带Ⅰ类整合子的鲍曼不动杆菌在生物被膜状态和液相培养状态下均有intI 1基因mRNA表达。但生物被膜生长状态下的intI 1mRNA表达量高于液相培养状态下表达量约4倍。在收集的64株鲍曼不动杆菌中有46株携带intI 1基因,而且Ⅰ类整合子基因盒阳性菌株的部分耐药率高于整合子基因阴性的菌株。结论:鲍曼不动杆菌在生物被膜状态intI 1mRNA的表达上调,Ⅰ类整合子在细菌耐药中发挥作用。提示整合子在生物被膜状态下可进行更活跃的基因捕获。

Objective To explore the expression level of class Ⅰ integrase （ intl 1 ） mRNA in Acinetobacter baumannii from biofilm cells and planktonic cultured cells , and to analyze the drug-resistance of Class Ⅰ integron positive strains. Methods Acinetobacter baumannii were collected from hospitals, and Class Ⅰ integron strains were screened by gene amplification. Total RNA of Class Ⅰ integron positive strains was extracted, and the int11 mRNA expression in the bioflim cells and planktonic cultured cells was measured by RT-PCR. Susceptibilities to antibiotics of Class Ⅰ integron positive strains were also examined. Results The int11 gene mRNA was expressed under 2 conditions, and the mRNA expressed in the biofilm ceils was about 4 times higher than that in the planktonic cultured cells. Among the 64 strains of Acinetobacter baumannii, 46 strains were Class Ⅰ integron positive strains. The antibiotic resistance of int11 gene cassette-positive strains was higher than that of gene cassette-negative strains. Conclusion The int11 gene mRNA can be up-regulated in Acinetobacter baumannii biofilm cells. Class Ⅰ integron plays an important role in drug resistance. It is much easier to capture gene cassettes for bacteria under biofilm condition.