DIFFERENTIATION OF BCG-INDUCED LYMPHADENITIS FROM TUBERCULOSIS IN LYMPH-NODE BIOPSY SPECIMENS BY MOLECULAR ANALYSES OF PNCA AND OXYR

Without culture, differentiation of bacille Calmette-Guerin-induced ly mphadenitis (BCG-LA) from tuberculosis (TB) is sometimes difficult by histology, but is important because of different treatment schemes, Th e purpose of this study was to investigate the feasibility of differen tiating BCG-LA from TB in lymph nodes (LNs) by molecular analyses of t wo recently identified genes, pncA and oxyR. In both genes, a single n ucleotide difference exists between Mycobacterium bovis and M. tubercu losis. M. tuberculosis complex (MTC) DNA was first detected in nine of ten formalin-fixed, paraffin-embedded LNs from patients aged under 20 years with suspected mycobacterial infections, using polymerase chain reaction (PCR) for IS6110, an insertion sequence specific for MTC spe cies, PCR, together with direct DNA sequencing and PCR-restriction fra gment length polymorphism (RFLP) assay, was then performed to identify polymorphic nucleotide in pncA and oxyR, respectively. For comparison , 37 adult cases of tuberculous lymphadenitis were also analysed by PC R-single strand conformation polymorphism (SSCP) assay for pncA and by PCR-RFLP for oxyR. The results revealed that five of the nine IS6110- positive child cases had a G residue at nucleotide 169 in pncA, and al so had a three-band pattern after digesting the amplified oxyR segment with AluI, suggesting BCG-LA. The remaining four child cases, as well as all adult cases with detectable IS6110, showed no motility shift i n pncA PCR-SSCP and had the same one-band pattern as M. tuberculosis i n oxyR PCR-RFLP, suggesting TB lymphadenitis, The data from molecular analyses showed a good correlation with the vaccination history and cl inicopathological findings, except for one case, This study indicates that molecular assay of either oxyR or pncA could be a rapid and usefu l tool to distinguish BCG-LA from TB. (C) 1998 John Wiley & Sons, Ltd.