Gupta Pushpa, Jadaun G P S, Das Ram, Gupta U D, Srivastava Kiran, Chauhan Aradhana, Sharma V D, Chauhan D S, Katoch V M
Department of Microbiology & Molecular Biology, National JALMA Institute for Leprosy & Other Mycobacterial Diseases (ICMR), Agra, India.
Indian J Med Res. 2006 Feb;123(2):125-30.
BACKGROUND & OBJECTIVE: There is a need to understand the nature of drug resistance patterns and predictors of emergence of drug resistance in Mycobacterium tuberculosis. There could be common factors/mechanisms for resistance to the drugs, isoniazid and ethambutol, both acting on cell wall. The present study was conducted to analyze the antimycobacterial susceptibility patterns of M. tuberculosis isolates to determine the minimum inhibitory concentrations (MICs) of ethambutol for M. tuberculosis; and to find out possible association of ethambutol resistance with isoniazid resistance.
A total of 380 M. tuberculosis isolates were tested for their susceptibilities to ethambutol at 2, 4, 6 microg/ml, isoniazid at 1 microg/ml and rifampicin at 64 microg/ml using MIC method.
44.21, 24.73 and 14.21 per cent isolates were resistant to ethambutol at concentrations of 2, 4 and 6 microg/ml respectively. At 6 microg/ml of ethambutol concentration, 85.18 per cent ethambutol resistant isolates were resistant to isoniazid also. At the same ethambutol concentration a fraction of 28.75 per cent isoniazid resistant isolates were ethambutol resistant.
INTERPRETATION & CONCLUSION: Ethambutol resistance was accompanied with isoniazid resistance in a large percentage of isolates whereas ethambutol resistance was weakly linked with multidrug resistance. On the other hand, association between isoniazid and ethambutol resistance was weak showing one way linkage.
有必要了解结核分枝杆菌耐药模式的本质以及耐药性出现的预测因素。对于作用于细胞壁的异烟肼和乙胺丁醇这两种药物，可能存在共同的耐药因素/机制。本研究旨在分析结核分枝杆菌分离株的抗分枝杆菌药敏模式，以确定乙胺丁醇对结核分枝杆菌的最低抑菌浓度（MIC）；并找出乙胺丁醇耐药与异烟肼耐药之间可能存在的关联。
采用MIC法对总共380株结核分枝杆菌分离株进行药敏试验，检测其对2、4、6微克/毫升乙胺丁醇、1微克/毫升异烟肼和64微克/毫升利福平的敏感性。
分别有44.21%、24.73%和14.21%的分离株对2、4和6微克/毫升浓度的乙胺丁醇耐药。在乙胺丁醇浓度为6微克/毫升时，85.18%的乙胺丁醇耐药分离株也对异烟肼耐药。在相同的乙胺丁醇浓度下，28.75%的异烟肼耐药分离株对乙胺丁醇耐药。
在很大比例的分离株中，乙胺丁醇耐药与异烟肼耐药同时存在，而乙胺丁醇耐药与多药耐药的关联较弱。另一方面，异烟肼与乙胺丁醇耐药之间的关联较弱，呈单向联系。
