The contribution of the placenta to the diagnosis of congenital tuberculosis

[摘要] ENGLISH ABSTRACT: The aim of this pilot project was to determine whether mothers with laboratory confirmed or clinicallysuspected tuberculosis (TB)had evidence of TB in the placenta. A secondary objective was to correlateevidence of placental TB with neonatal outcome. A total of 56 placentas were examined to determine if there were any specific histopathological features predictive of tuberculosis together with Ziehl-Neelsen (ZN) staining. A total of 30 cases were positive for maternal TB and one case was a false positive maternal diagnosis of TB, whilst 25 cases were negative for maternal TB. Biopsies from these 56 placentas were collected for conventional PCR from the paraffin embedded tissue blocks. The performance of these two diagnostic modalities (histopathology and PCR) was assessed coll ectively and individually, and compared to the neonatal outcome (presence or absence of active clinical mycobacterial tuberculosis infection) and evidence of maternal pulmonary and extra pulmonary tuberculosis.The recognition of specific sites of lesions in the placenta (e.g. membranes vs. intervillous space) may lead to an understanding of the pathogenic mechanisms involved in maternalfetal transmission of tuberculosis, and thereby pave the way for further studies in understanding the pathogenesis of congenital TB.Invaluable knowledge was obtained in thediagnoses of M.tuberculosis in the placenta as it was found that micro abscesses and intervillositis were strong indicators of TBinfection in the placenta, however, ZNstaining still remains the gold standard for diagnosing M.tuberculosis infection in the placenta. PCR is found to have limitations, because only M.tuberculosis DNA is amplifiedand does not distinguish live from dead bacteria.The conclusion reached is that PCR is of limited value in the diagnosis of active M.tuberculosisinfection in the placenta using FFPE tissue, while certain histological changes may be indicative of such infection; however confirmation of the organism by ZN staining is still essential.

[发布机构] Stellenbosch University