Direct detection and identification of Mycobacterium tuberculosis in smear-positive sputum samples by fluorescence in situ hybridization (FISH) using peptide nucleic acid (PNA) probes
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Updated: Oct 19, 2026

Identification of Mycobacterium Species by DNA Microarray Chip Method
Published on: June 24, 2025
H Stender1, T A Mollerup, K Lund
1DAKO A/S, Glostrup, Denmark.
Setting:
Peptidenucleic acid (PNA) probesdesigned for specific detection of mycobacteria of the Mycobacterium tuberculosis complex (MTC) and other non-tuberculous mycobacterium species (NTM) are shown to be able to penetrate the mycobacterial cell wall and subsequently hybridize in situ to complementary rRNA.
Objective:
To demonstrate the use of fluorescein-labelled PNA probes for detection and identification of M. tuberculosis in smear-positive sputum samples.
Design:
The sensitivity and specificity of the PNA probes were investigated by fluorescence in situ hybridization (FISH) using cultures of mycobacterium strains representing species of the MTC and NTM, respectively.
Results:
M. tuberculosis strains were detected by FISH using specific fluorescein-labelled PNA probes directly in smear-positive sputum samples without changing the morphology of the cells.
Conclusion:
PNA probes allow for rapid diagnosis of tuberculosis in smear-positive cases.
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