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

In the diagnosis of mycobacterioses, microbiological examination with culture and antibiogram, possibly in combination with molecular biological testing of the fresh material, still represents the gold standard. However, these methods are not available for formalin-fixed paraffin-embedded (FFPE) material or other fixed samples. For this reason, the first step in pathology is to attempt microscopic pathogen detection (ZN/Fite/rhodamine-auramine). Subsequently, molecular pathological examination for the detection of mycobacterial gene sequences should also be considered mandatory today. Although this has clear limits due to the material, it is nevertheless well suited, if carried out correctly, to detect a mycobacterial infection or make it unlikely. A negative result may favor an alternative diagnosis but does not completely rule out mycobacteriosis.For the therapy of tuberculosis or nontuberculous mycobacterial (NTM) disease, the reliable detection of the species and the determination of resistance is of utmost importance. With regard to therapy, the clinician cannot afford to make a false diagnosis. In case of doubt, a rebiopsy for sampling native material, particularly for microbiological testing, should be discussed.