Test specification | COBAS TaqMan MTB | TB-LAMP | Xpert MTB/RIF | XpertMTB/RIF Ultra | GenoType MTBDRplus | GenoType MTBDRsl |
---|---|---|---|---|---|---|
Manufacturer | Roche Diagnostics | Eiken Chemical Co | Cepheid | Cepheid | Hain Lifescience | Hain Lifescience |
Technology | Real-time PCR | Loop-mediated Isothermal amplification (LAMP) | Real-time PCR (molecular beacons) | Real-time PCR (molecular beacons) | Multiplex PCR + reverse hybridization | Multiplex PCR + reverse hybridization |
Detects | MTB | MTB | MTB + RIF resistance | MTB + RIF resistance | MTB + resistance to RIF and INH | MTB diagnosis + resistance to FLQ and SLID |
Target | 16S rRNA | IS6110 | rpoB gene | rpoB gene | rpoB, katG, inh genes | gyrA, rpo, rrs, eis genes |
Time to results | 2.5 h | < 1 h [41] | 2 h [43] | < 90 min [58] | 5 h | 5 h |
Approval status | FDA | WHO | WHO | WHO | WHO | WHO |
Recommandations | As a confirmatory test, on smear-positive specimens | As a replacement for smear microscopy in adults or a follow-on test to smear microscopy in adults (when further testing of sputum smear-negative specimens is necessary) [41] | As the initial diagnostic test for tuberculosis in patients (adults and children) suspected of having active TB disease with either multidrug-resistant TB or HIV-associated TB [47] | As a replacement of Xpert MTB/RIF due to its greater sensitivity in detecting MTB [66] | As the initial test instead of phenotypic culture-based DST to detect resistance to RIF and INH, in persons with a sputum smear-positive specimen or a cultured isolate of MTBC, from both pulmonary and extrapulmonary sites [73]. | For patients with confirmed RIF-R TB and/or MDR TB as the initial test, instead of phenotypic culture-based DST, to detect resistance to FLQ and SLID [83] |
Benefits | − Does not require expensive instruments and laboratory environments | - Requires minimal expertise - Speed and cost effective | - Requires minimal expertise - Excellent sensitivity in tests of smear-positive sputum samples | − Improve detection of mutants at codon 533 [58] − Differentiate silent mutations at codons 513 and 514 [58]. - Detect a hetero-resistant sample [58] | - High sensitivity for detection of RIF resistance. | - High sensitivity and specificity for detection of FLQ and SLID resistance [84]. |
Limitations | - Exhibits heterogeneous performance from study to study [24] - Does not screen for any markers of drug resistance | − Requires several manual steps. − Inferior performance in smear negatives sputum samples [102] − False positives results due to aerosol contamination [29] − Does not screen for any markers of drug resistance | - High costs and sophisticated hardware. - Low sensitivity in smear-negative pulmonary samples and special populations (HIV-positives, children, extrapulmonary TB). - Do not accommodate all mutations conferring resistance to anti-TB agents [58] | − Low specificity in patients with a recent history of TB treatment or from high-incidence countries [61]. − Should not be used as a replacement test for culture in children [65] − Do not accommodate all mutations conferring resistance to anti-TB agents [61] | − Over diagnose the presence of MTB complex DNA in culture-negative samples [81]. − Low sensitivity to detect INH resistance. − Complexity, the number of steps. − Requires training for interpretation of results − Do not perform well when applied to paucibacillary clinical specimens − Do not accommodate all mutations conferring resistance to anti-TB agents | − Not optimal to detect resistance to KAN [84] and ethambutol [86]. − Low sensitivity in smear-negative samples [76]. − Do not accommodate all mutations conferring resistance to anti-TB agents [84]. |
Price per test | Not available | US$ 6 | US$ 9.98 | US$ 9.98 | US$10 | US$10 |