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Accuracy of the Phenotypic 1G Test to Detect Mycobacterium tuberculosis and Drug Resistance From Sputa in the US-Mexico Border

Aguirre M, Ayala D, Garcia JI, Martinez-Lopez YE, Hicks AD, Chacon N, Gay-Cobb A, Schami A et al.

The Journal of infectious diseases, 2026

Abstract

BACKGROUND: With >10 million new tuberculosis (TB) cases per year, a limitation to TB control is the lack of simple and accurate tests for diagnosis and drug susceptibility testing (DST) in endemic regions. We evaluated the accuracy of the first-generation, low-complexity phenotypic TB test (1G test), designed for simultaneous Mycobacterium tuberculosis (Mtb) detection and resistance to isoniazid, rifampicin, and moxifloxacin, suitable for resource-limited settings.

METHODS: A cross-sectional study was conducted with sputa from 426 possible pulmonary TB cases from 2 small Mexican cities bordering Texas. The 1G test was compared against phenotypic TB detection tests in the region, specifically acid-fast bacilli smear microscopy and Mycobacteria Growth Indicator Tube (MGIT) culture, as well as MGIT-DST for resistance to isoniazid, rifampicin, and moxifloxacin.

RESULTS: The 1G test demonstrated ≥98% sensitivity for Mtb detection; 100% sensitivity and 91% (rifampicin), 94% (isoniazid), and 97% (moxifloxacin) specificity for DST; and less contamination than the MGIT (3.5% vs 8.1%, P < .05). The 1G test time to detection of Mtb and simultaneous DST was 17 days, while the MGIT-DST required 2 steps: 7 days for Mtb detection plus 14 more days for DST (21 days total). Our study site drug-resistant TB prevalence was 14% when testing all consecutively enrolled participants vs 6% by passive reporting.

CONCLUSIONS: The 1G test is a low-complexity phenotypic TB diagnostic method that is a…

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Evidence Hub reads this as a cross-sectional, done in people. Its evidence level is 4 of 5 (Low · observational). Observational designs can show an association but not prove cause.

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