TB Treatment Monitoring: Molecular Bacterial Load Assay vs Standard Testing

This article is part of Pulmonology Advisor‘s coverage of the American Thoracic Society International Conference, taking place in Dallas, Texas. Our staff will report on medical research related to asthma and other respiratory conditions, conducted by experts in the field. Check back regularly for more news from ATS 2019.

DALLAS — Compared with standard of care tests and most clinical signs, the molecular bacterial load assay demonstrated higher sensitivity and more rapid turnaround times for monitoring tuberculosis (TB) treatment, according to study results presented at the American Thoracic Society International Conference held May 17-22, in Dallas, Texas.

Researchers enrolled 59 patients with TB (median age, 37 years; 62.7% men), 45.6% of whom were HIV positive and 8.47% of whom were being retreated for TB, in the study. Sputum samples were collected at baseline prior to standard anti-TB therapy and at week 2, and 2, 5, and 6 months of treatment. Molecular bacterial load assay sputum analysis for Mycobacterium tuberculosis was compared with smear microscopy, culture, and clinical monitoring. Change in bacterial load was measured by molecular bacterial load assay, smear microscopy, culture positivity, and clinical sign resolution.

The mean bacterial load was 5.48±1.30 at baseline, 3.42±0.70 at month 2, and 3.51±0.62 log₁₀ CFU/mL at month 6. These values correspond to a molecular bacterial load assay positivity of 92.98%, 65.5%, and 7.84%, at baseline, month 2, and month 6, respectively. Meanwhile, from baseline to 6 months of treatment, smear microscopy and culture positivity were 78.95%, 9.62%, and 0%, and 85.96%, 25.0%, and 3.39%, respectively.

The decrease in positivity was reflected in the resolution of clinical signs (eg, night sweats, chest pain, and cough). Cough was the slowest symptom to resolve, unlike night sweats and chest pain, but was also consistent with bacterial load change. The molecular bacterial load assay tests results were available in 24 hours, whereas the liquid culture results took a median of 14.83 days.

The increased sensitivity and more rapid availability of results “demonstrates the potential of [molecular bacterial load assay] to offer real-time accurate results to inform clinical decision making,” the researchers concluded.

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Reference

Mtafya B, Sabiiti W, Sabi I, Msuya Y, Ntinginya NE, Gillespie SH. Clinical evaluation of the molecular bacterial load assay for real-time monitoring of tuberculosis treatment response. Presented at: the American Thoracic Society International Conference; May 21, 2019; Dallas, TX. Abstract A5172/P69.

This article originally appeared on Pulmonology Advisor