2001 Volume 76 Issue 10 Pages 657-662
The methods most widely used for susceptibility testing against anti-tuberculosis drug (AST) are the proportion method on LOwenstein-Jensen egg (L-J), Ogawa egg or Middlebrookagar media, and BACTEC TB 460 system. Recently, drug concentrations have beenestablished for AST using the automated BACTEC MGIT 960 system (aMGIT). We haveevaluated the BACTEC MGIT 960 SIRE kit for AST of Mycobacterium tuberculosis toisoniazid, rifampin, streptomycin and ethambutol. Also we compared the results with theproportion methods on Middlebrook 7H 10 agar (7H 10), L-J and Ogawa egg, and themanual MGIT system (mMGIT). Overall concordance rates among aMGIT and theproportion method on 7H 10 or Ogawa media were 98.3 % and 96.9 % for 4 first-linedrugs, respectively. Rates were particularly high for isoniazid and rifampin betweena MGIT and 7H 10 (efficiency of 100%). On the other hand, overall concordance ratesamong two egg media, L-J and Ogawa were 99.9 %. Agreement between aMGIT and mMGIT was high for the AST to isoniazid and rifampin, but lower for the AST toethambutol (90.9 %), which relates to a lower specificity of mMGIT. The mean times toaMGIT and mMGIT results of susceptibility were 7 and 6 days, respectively, contrastedwith 3 weeks in 7H 10 and 4 weeks in L-J and Ogawa, indicating that both MGITsystems have the potential to consistently meet the turnaround time suggested by Centersfor Disease Control and Prevention (CDC) of the United States. These results demonstratethat the fully automated BACTEC MGIT 960 SIRE system for AST is useful forrapid diagnosis of drug resistant tuberculosis.
