Foongladda S, Banu S, Pholwat S, Gratz J, O-Thong S, Nakkerd N, Chinli R, Ferdous SS, Rahman SMM, Rahman A, Ahmed S, Heysell S, Sariko M, Kibiki G, Houpt E. Comparison of TaqMan(®) Array Card and MYCOTB(TM) with conventional phenotypic susceptibility testing in MDR-TB.
Int J Tuberc Lung Dis 2016;
20:1105-12. [PMID:
27393547 PMCID:
PMC4937751 DOI:
10.5588/ijtld.15.0896]
[Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 03/27/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND
Although phenotypic drug susceptibility testing (DST) is endorsed as the standard for second-line drug testing of Mycobacterium tuberculosis, it is slow and laborious.
METHODS
We evaluated the accuracy of two faster, easier methodologies that provide results for multiple drugs: a genotypic TaqMan(®) Array Card (TAC) and the Sensititre(®) MYCOTB(TM) plate. Both methods were tested at three central laboratories in Bangladesh, Tanzania, and Thailand with 212 multidrug-resistant tuberculosis (MDR-TB) isolates and compared with the laboratories' phenotypic method in use.
RESULTS
The overall accuracy for ethambutol, streptomycin, amikacin, kanamycin, ofloxacin, and moxifloxacin vs. the phenotypic standard was 87% for TAC (range 70-99) and 88% for the MYCOTB plate (range 76-98). To adjudicate discordances, we re-defined the standard as the consensus of the three methods, against which the TAC and MYCOTB plate yielded 94-95% accuracy, while the phenotypic result yielded 93%. Some isolates with genotypic mutations and high minimum inhibitory concentration (MIC) were phenotypically susceptible, and some isolates without mutations and low MIC were phenotypically resistant, questioning the phenotypic standard.
CONCLUSIONS
In our view, the TAC, the MYCOTB plate, and the conventional phenotypic method have similar performance for second-line drugs; however, the former methods offer speed, throughput, and quantitative DST information.
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