Experience of using TB test kit for the rapid drug susceptibility testing of M. tuberculosis.

Abstract

The results of the comparative testing of the susceptibility of M. tuberculosis clinical strains to isoniazid, streptomycin, rifampicin and ethambutol using the TB test kit, developed in SCRAMB, (Obolensk) and the absolute concentrations method; the TB test kit and the BACTEC MGIT 960 automated system are presented in the study. A total of 629 and 220 strains, respectively, were tested. A high degree of agreement of the results was shown: 89.1-98.6% for isoniazid, 96.2-98.0% for rifampicin, 91.5-98.2% for streptomycin and 89.1-95.9% for ethambutol. The smallest number of discrepancies in the results was obtained when comparing the TB test kit and BACTEC MGIT 960. The discrepant results analysis was performed by the proportion method, PCR sequencing, or re-testing on new lots of the TB test kit and Lowenstein-Jensen medium with anti-tuberculosis drugs, after which the sensitivity, the specificity and the efficiency of the TB test kit have exceeded 95 % for all anti-tuberculosis drugs. The turnaround time with the TB test kit (median 9.25-9.9 days, ranged from 8 to13 days) was significantly shorter than that with the absolute concentration method (median 21-23 days, ranged from 20 to 28 days) and is commensurate with the turnaround time with BACTEC MGIT 960 (average 7.2 days, ranged from 5 to 12 days). The TB test kit is easy to use, does not require expensive equipment and special staff training.