MGIT-seq for the Identification of Nontuberculous Mycobacteria and Drug Resistance: a Prospective Study

Current Trends in Identification and Susceptibility Testing of Mycobacteria

While Mycobacterium species cause various infections, extrapulmonary tuberculosis (EPTB) and nontuberculous mycobacterial (NTM) infections were overlooked in the past. However, the incidence rates of these infections have increased over time. Similarly, there are limited testing modalities for diagnosing NTM and EPTB. In this review, we described the contemporary testing methods and associated challenges and benefits for NTM and EPTB.

Evaluation of the GenoType NTM-DR line probe assay for nontuberculous mycobacteria using whole genome sequences as reference standard

Pulmonary nontuberculous mycobacteria (NTM) disease is an emerging public health challenge that is especially problematic in people with cystic fibrosis (CF). Effective treatment depends on accurate species and subspecies identification and antimicrobial susceptibility status. We evaluated the GenoType NTM-DR VER 1.0 assay using biobanked NTM isolates with whole genome sequence (WGS) data and control isolates (total n=285). Species and subspecies detection sensitivity and specificity were 100 % for all species and subspecies except for two subspecies of M. intracellulare, that demonstrated a small degree of discrepant identification between M. intracellulare subspecies intracellulare and subspecies chimaera. All antimicrobial resistance markers were identified with 100 % sensitivity and specificity. We conclude that the GenoType NTM-DR assay offers a rapid and accurate option for identifying the most frequently encountered pathogenic NTM taxa and drug resistance markers. SUPPORT: Colorado CF Research Development Program and Colorado CF National Resource Centers funded by the Cystic Fibrosis Foundation, NJH Advanced Diagnostics Laboratories, Colorado Advanced Industries Accelerator Grant.

Integrating Paper-Based Microfluidics and Lateral Flow Strip into Nucleic Acid Amplification Device toward Rapid, Low-Cost, and Visual Diagnosis of Multiple Mycobacteria

Efficient diagnosis of mycobacterial infections can effectively manage and prevent the transmission of infectious diseases. Unfortunately, existing diagnostic strategies are challenged by long assay times, high costs, and highly specialized expertise to distinguish between pulmonary tuberculosis (PTB) and nontuberculous mycobacterial pulmonary diseases (NTM-PDs). Herein, in this study, an optimized 3D paper-based analytical device (µPAD) is incorporated with a closed lateral flow (LF) strip into a loop-mediated isothermal amplification (LAMP) device (3D-µPAD-LF-LAMP) for rapid, low-cost, and visual detection of pathogenic mycobacteria. The platform's microfluidic feature enhanced the nucleic acid amplification, thereby reducing the costs and time as compared to boiling, easyMAG, and QIAGEN techniques. Moreover, the LF unit is specifically designed to minimize aerosol contamination for a user-friendly and visual readout. 3D-µPAD-LF-LAMP is optimized and assessed using standard strains, demonstrating a limit of detection (LOD) down to 10 fg reaction-1. In a cohort of 815 patients, 3D-µPAD-LF-LAMP displays significantly better sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and diagnostic accuracy than conventional bacterial culture and Xpert techniques. Collectively, 3D-µPAD-LF-LAMP demonstrates enhanced accessibility, efficiency, and practicality for the diagnosis of multiple pathogenic mycobacteria, which can be applied across diverse clinical settings, thereby ultimately improving public health outcomes.

Tuberculosis Diagnosis: Current, Ongoing, and Future Approaches

Tuberculosis (TB) remains an impactful infectious disease, leading to millions of deaths every year. Mycobacterium tuberculosis causes the formation of granulomas, which will determine, through the host-pathogen relationship, if the infection will remain latent or evolve into active disease. Early TB diagnosis is life-saving, especially among immunocompromised individuals, and leads to proper treatment, preventing transmission. This review addresses different approaches to diagnosing TB, from traditional methods such as sputum smear microscopy to more advanced molecular techniques. Integrating these techniques, such as polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP), has significantly improved the sensitivity and specificity of M. tuberculosis identification. Additionally, exploring novel biomarkers and applying artificial intelligence in radiological imaging contribute to more accurate and rapid diagnosis. Furthermore, we discuss the challenges of existing diagnostic methods, including limitations in resource-limited settings and the emergence of drug-resistant strains. While the primary focus of this review is on TB diagnosis, we also briefly explore the challenges and strategies for diagnosing non-tuberculous mycobacteria (NTM). In conclusion, this review provides an overview of the current landscape of TB diagnostics, emphasizing the need for ongoing research and innovation. As the field evolves, it is crucial to ensure that these advancements are accessible and applicable in diverse healthcare settings to effectively combat tuberculosis worldwide.