Immunohistochemical diagnosis of abdominal and lymph node tuberculosis by detecting Mycobacterium tuberculosis complex specific antigen MPT64.

Abstract

BACKGROUND:

The aim of this study was to evaluate the diagnostic potential of immunohistochemistry using an antibody to the secreted mycobacterial antigen MPT64, in abdominal and lymph node tuberculosis.

METHODS:

We used formalin-fixed histologically diagnosed abdominal tuberculosis (n = 33) and cervical tuberculous lymphadenitis (n = 120) biopsies. These were investigated using a combination of Ziehl-Neelsen method, culture, immunohistochemistry with an antibody to MPT64, a specific antigen for Mycobacterium tuberculosis complex organisms. Abdominal and cervical lymph node biopsies from non-mycobacterial diseases (n = 50) were similarly tested as negative controls. Immunohistochemistry with commercially available anti-BCG and nested PCR for IS6110 were done for comparison. Nested PCR was positive in 86.3% cases and the results of all the tests were compared using nested PCR as the gold standard.

RESULTS:

In lymph node biopsies, immunohistochemistry with anti-MPT64 was positive in 96 (80%) cases and 4 (12.5%) controls and with anti-BCG 92 (76.6%), and 9 (28%) respectively. The results for cases and controls in abdominal biopsies were 25 (75.7%) and 2 (11.1%) for anti-MPT64 and 25 (75.7%) and 4 (22%) for anti-BCG. The overall sensitivity, specificity, positive and negative predictive values of immunohistochemistry with anti-MPT64 was 92%, 97%, 98%, and 85%, respectively while the corresponding values for anti-BCG were 88%, 85%, 92%, and 78%.

CONCLUSION:

Immunohistochemistry using anti-MPT64 is a simple and sensitive technique for establishing an early and specific diagnosis of M. tuberculosis infection and one that can easily be incorporated into routine histopathology laboratories.

• Authors: Manju R Purohit, Tehmina Mustafa, Harald G Wiker, Odd Mørkve, Lisbet Sviland
• Journal: Diagnostic pathology (Diagn Pathol) Vol. 2 Pg. 36 (Sep 25 2007) ISSN: 1746-1596 [Electronic] England
• PMID: 17894882 (Publication Type: Journal Article)