title: Inconsistencies in drug susceptibility testing of Mycobacterium tuberculosis: Current riddles and recommendations.
abstract: Drug susceptibility testing (DST) of Mycobacterium tuberculosis is a crucial procedure to determine the effective drug regimen for patients' treatment. Reporting of erroneous DST results to the treating physician has adulterous effects on patients. As a first study of its type, the inconsistencies in reporting DST results of rifampicin and isoniazid from Saudi Arabia were assessed. An automated liquid culture-based DST and a molecular mutation detection technique were used. Performance of first-line drug susceptibility testing of 1904 clinical isolates showed 44 inconsistent results. The majority of the cases reported as MDR-TB from the referral laboratories could not reproduce the same results at a different site (Mycobacteriology Research Section). Of the 44 cases, 16 (36.3%) showed false resistance to isoniazid and rifampicin and on the other hand, 14 (31.8%) cases showed false susceptibility to the same drugs. The possible causes for the inconsistencies and recommendations to overcome the biases based on this experience are discussed.
authors.affiliation: Mycobacteriology Research Section, Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia. Electronic address: bvarghese99@kfshrc.edu.sa.
authors.forename: Bright
authors.initials: B
authors.lastname: Varghese
authors.affiliation: Mycobacteriology Research Section, Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia. Electronic address: Rujaka_12@hotmail.com.
authors.forename: Ruba
authors.initials: R
authors.lastname: Al-Omari
authors.affiliation: Mycobacteriology Research Section, Department of Infection and Immunity, King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia. Electronic address: hajoj@kfshrc.edu.sa.
authors.forename: Sahal
authors.initials: S
authors.lastname: Al-Hajoj
keywords: Drug susceptibility testing; Genotyping; Tuberculosis