[Molecular pathology of tuberculosis : Status, methodology, and limits]

Area of Science:

• Medical Microbiology
• Pathology
• Infectious Diseases

Background:

• Mycobacterioses diagnosis relies on culture and antibiogram, the gold standard.
• Formalin-fixed paraffin-embedded (FFPE) and other fixed samples pose challenges for standard microbiological methods.

Purpose of the Study:

• To evaluate diagnostic approaches for mycobacterioses, especially in fixed tissues.
• To emphasize the importance of molecular pathology in diagnosing mycobacterial infections.
• To highlight the critical need for accurate species identification and resistance determination for effective therapy.

Main Methods:

• Microscopic pathogen detection (ZN/Fite/rhodamine-auramine) on fixed samples.
• Molecular pathological examination for mycobacterial gene sequences in fixed materials.
• Discussing rebiopsy for native material when diagnosis is uncertain.

Main Results:

• Microscopy and molecular methods can detect or rule out mycobacterial infection in fixed samples, despite limitations.
• A negative molecular result does not exclude mycobacteriosis but may suggest alternative diagnoses.
• Accurate species and resistance detection are vital for guiding tuberculosis and nontuberculous mycobacterial (NTM) disease therapy.

Conclusions:

• Molecular pathology is essential for diagnosing mycobacteriosis in FFPE and other fixed samples.
• Accurate diagnosis is paramount to avoid therapeutic misadventures in mycobacterial diseases.
• Consider rebiopsy for microbiological testing if initial diagnosis remains uncertain.