Cost-effective identification of Mycobacterium tuberculosis complex using microscopic morphology and rapid tests

Area of Science:

• Microbiology
• Clinical Diagnostics
• Infectious Diseases

Background:

• Rapid diagnosis of tuberculosis (TB) relies on identifying Mycobacterium tuberculosis complex (MTC) in clinical isolates.
• Current methods for MTC identification can be time-consuming or expensive.

Purpose of the Study:

• To propose a cost-effective laboratory protocol for MTC identification.
• To evaluate the performance of rapid diagnostic tests for MTC.

Main Methods:

• Compared microscopic morphology, two immunochromatographic assays (ICAs) (Tibilia and MeDiPro), and strand displacement amplification (SDA) (ProbeTec) for MTC identification.
• Evaluated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for each method.

Main Results:

• Cord-like microscopic morphology demonstrated high sensitivity (99.3%) and negative predictive value (99.1%), with the lowest cost.
• The Tibilia ICA showed high sensitivity (98.7%) and specificity (98.4%), comparable to the SDA method.
• Tibilia performed better than MeDiPro ICA, and ICA offered cost-effective screening compared to SDA.

Conclusions:

• A combination of microscopic morphology and the Tibilia ICA is recommended for improved sensitivity and PPV in MTC identification.
• This combined approach offers a cost-effective strategy for rapid MTC identification in clinical laboratories.
• Microscopic morphology alone is a valuable, inexpensive tool for initial MTC screening.