Comparison of Anti-mycobacterial Drug Susceptibility Test Results by Institutes and Methods / 대한임상미생물학회지

ABSTRACT

BACKGROUND: The purposes of the current study were to evaluate the concordant rates of anti-mycobacterial drug susceptibility test (DST) results in different solid media performed in different institutes, and to determine reliable susceptible testing methods. METHODS: One hundred and twenty two Mycobacterium tuberculosis strains were isolated from patients in A Hospital in 2005. DSTs were performed by the absolute concentration method using L?wenstein Jensen medium in both A Hospital (method A-1) and B Institute (method B-1) and by the proportion method using Middlebrook 7H10 agar in B Institute (method B-2). Nine drugs were used including isoniazid and rifampin. Sensitivity and specificity of each method were estimated by using the acceptable standard of 90% for isoniazid and rifampin and 80% for other drugs. The therapeutic outcomes of quinolone-administered patients were evaluated according to ofloxacin susceptibility results. RESULTS: Method B-1 showed sensitivity and specificity levels over the acceptable standard levels for all drugs. Method B-2 showed specificity lower than the acceptable levels for rifampin and cycloserine. Method A-1 showed specificity lower than the acceptable levels for isoniazid, streptomycin, p-aminosalicylic acid, and ofloxacin and sensitivity lower than the acceptable levels for prothionamide and cycloserine. The concordance rates of therapeutic outcomes with method B-1, method B-2, and method A-1 were 77%, 74%, and 65%, respectively. CONCLUSION: The drug susceptibility results for some drugs were discordant between the testing laboratories and media, requiring an urgent application of quality control programs to raise the reliability of anti-mycobacterial DST.