结核分枝杆菌接种菌量对异烟肼和利福平药敏试验的影响

The influence on Isoniazid and Rifampicin drug susceptibility of the different bacterium quantity in Mycobacterium tuberculosis

目的 比较接种不同菌量结核分枝杆菌（MTB）绝对浓度法药物敏感性（药敏）与比例法药敏的差异程度,为MTB药敏检测准确性提供参考.方法 选择临界敏感或临界耐药MTB菌株53株,用比浊法制作MTB菌悬液,10倍梯度稀释,10^-4、10^-5、10^-6mg/mL菌悬液0.1ml接种于改良L-J培养基上作活菌计数,10^-2、10^-3 mg/ml菌悬液0.1ml接种于含INH、RFP改良L-J培养基上作绝对浓度法药敏,10^-3、10^-5mg/ml菌悬液0.1ml接种于含INH、RFP改良L-J培养基上作比例法药敏.结果 MTB活菌计数值多在5×10^6～5×10^7CFU/ml.10^-2、10^-3mg/ml菌悬液绝对浓度法药敏一致率INH、RFP分别达98.1%、100.0%;绝对浓度法与比例法药敏符合率INH、RFP均达90.6%～100.0%.结论 不同菌量MTB绝对浓度法药敏结果与比例法药敏结果比较一致性好,在常规药敏检测中不会影响结果的准确性.

Objective To compare the difference of drug susceptibility of Mycobacterium tuberculosis （MTB） by using both absolute concentration method with different bacterium quantity and proportion method. Methods The 53 probable drug-susceptible or drug-resistant strains of MTB were selected. The bacterial suspensions of MTB were prepared using Mcfarland method. 0.1 ml of bacterial suspensions （including 10^-4, 10^-5,10^-6 mg/ml） was incubated for MTB CFU, respectively. 0.1 ml of bacterial suspensions （including 10^-2, 10^-3 mg/ml） was incubated for the drug susceptibility testing with absolute concentration method, respectively. 0.1 ml of bacterial suspensions （including 10^-3, 10^-5 mg/ml） was incubated for the drug susceptibility testing with proportion method, respectively. Results The number of MTB CFU was from 5 ×10^6 CFU/ml to 5 ×10^7 CFU/ml in Mcfarland method. The accordance rate of isoniazid and rifampicin drug susceptibility in 10^-2 and 10^-3 mg/ml of MTB was 98.1%, 100.0% using absolute concentration method, respectively. The accordance rate of isoniazid and rifampicin drug susceptibility of MTB was from 90.6% to 100.0% with absolute concentration method and proportion method. Conclusion The result of drug susceptibility of MTB using absolute concentration method and proportion method is accordant.