AID TB resistance line probe assay for rapid detection of resistant Mycobacterium tuberculosis in clinical samples

Summary Objectives To determine the sensitivity and specificity of AID TB Resistance line probe assay (AID Diagnostika, Germany) to detect Mycobacterium tuberculosis and its resistance to first- and second-line drugs in clinical samples using BACTEC 460TB as the reference standard. Methods The test consists on three strips to detect resistance to isoniazid/rifampicin, fluoroquinolones/ethambutol, and kanamycin/amikacin/capreomycin/streptomycin, respectively. This test was performed on 65 retrospectively selected clinical samples corresponding to 32 patients. Results A valid result was obtained for 92.3% (60/65), 90.8% (59/65) and 78.5% (51/65) of the samples tested, considering the three strips, respectively. Global concordance rates between AID and BACTEC for detecting resistance to isoniazid, rifampicin, fluoroquinolones, ethambutol, kanamycin/capreomycin and streptomycin were 98.3% (59/60), 100% (60/60), 91.5% (54/59), 72.9% (43/59), 100% (51/51) and 98.0% (50/51), respectively. Regarding the discordant results obtained between AID and BACTEC, the alternative molecular methods performed (GenoType MTBDR plus , GenoType MTBDR sl [Hain Lifescience, Germany] and/or pyrosequencing) confirmed the genotypic result in 90.9% (20/22) of the cases. Conclusions AID line probe assay is a useful tool for the rapid detection of drug resistance in clinical samples enabling an initial therapeutic approach. Nevertheless, for a correct management of drug resistant tuberculosis patients, molecular results should be confirmed by a phenotypic method.