Objectives: Extrapulmonary tuberculosis (TB) constitutes the main cause of classic fever of unknown origin (FUO) in many populations. The aim of this study was to improve the diagnostic field of the disease using a nested polymerase chain reaction (PCR) assay, specific for the IS6110 insertion element of Mycobacterium tuberculosis complex, in order to achieve a more timely diagnosis and treatment.
Setting: Twenty-four, HIV-negative classic FUO patients who were admitted to the Regional Hospital of Alexandroupolis between April 1997 and July 1999.
Subjects and design: The above patients were considered as putative extrapulmonary TB after 3 weeks of in-patient investigation and underwent exhaustive examination for diagnosis of the disease. For this purpose, specimens were obtained from peripheral blood and bone marrow from these patients, as well as from damaged tissues, and analysed by both PCR and conventional methods. Anti-tuberculous treatment was initiated in 16 out of 24 patients and the response to this regimen was considered as the final criterion for diagnosis of tuberculosis.
Results: Extrapulmonary TB was established in 11 patients. The PCR-based methodology, when applied to samples derived from bone marrow aspirations and suspected damaged tissues, was able to diagnose 10 of them, whereas the conventional methods were able to detect only two.
Conclusions: Our results confirm the diagnostic value of molecular detection of M. tuberculosis in cases of FUO, thus supporting the application of PCR in tissue samples suspected of bacillus infection. Furthermore, our studies demonstrate that bone marrow aspiration specimens constitute an alternative, easy, safe and reliable source for such PCR analysis.