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Nucleic acid amplification testing (NAAT) enables rapid and sensitive diagnosis of tuberculosis (TB), which facilitates treatment and mitigates transmission. Nucleic acid extraction from sputum constitutes the greatest technical challenge in TB NAAT for near-patient settings. This report presents preliminary data for a semi-automated sample processing method, wherein sputum is disinfected and liquefied, followed by PureLyse® mechanical lysis and solid-phase nucleic acid extraction in a miniaturized, battery-operated bead blender. Sputum liquefaction and disinfection enabled a >104 fold reduction in viable load of cultured Mycobacterium tuberculosis (M.tb) spiked into human sputum, which mitigates biohazard concerns. Sample preparation via the PureLyse® method and a clinically validated manual method enabled positive PCR-based detection for sputum spiked with 104 and 105 colony forming units (cfu)/mL M.tb. At 103 cfu/mL sputum, four of six and two of six samples amplified using the comparator and PureLyse® method, respectively. For clinical specimens from TB cases and controls, the two methods provided 100% concordant results for samples with "Equation missing"1 mL input volume (N = 41). The semi-automated PureLyse® method therefore performed similarly to a validated manual comparator method, but is faster, minimally instrumented and can be integrated into TB molecular diagnostic platforms designed for near-patient low-resource settings.

Diagnosis of pulmonary tuberculosis (TB) usually includes laboratory analysis of sputum, a viscous material derived from deep in the airways of patients with active disease. As a diagnostic sample matrix, sputum can be difficult to collect and analyze by microbiological and molecular techniques. An alternative, less invasive sample matrix could greatly simplify TB diagnosis. We hypothesized that Mycobacterium tuberculosis cells or DNA accumulate on the oral epithelia of pulmonary TB patients and can be collected and detected by using oral (buccal) swabs. To test this hypothesis, 3 swabs each were collected from 20 subjects with active pulmonary TB and from 20 healthy controls. Samples were tested by using a polymerase chain reaction (PCR) specific to the M. tuberculosis IS6110 insertion element. Eighteen out of 20 confirmed case subjects (90%) yielded at least 2 positive swabs. Healthy control samples were 100% negative. This case-control study supports past reports of M. tuberculosis DNA detection in oral swabs. Oral swab samples are non-invasive, non-viscous and easy to collect with or without active TB symptoms. These characteristics may enable simpler and more active TB case finding strategies.