Rapid detection of mycobacteria in inflammatory necrotizing granulomas from formalin-fixed, paraffin-embedded tissue by PCR in clinically high-risk patients with acid-fast stain and culture-negative tissue biopsies.
A collection of inflammatory necrotizing granulomas (INGs) negative by acid-fast stain and culture (AFSC) were analyzed by polymerase chain reaction (PCR) for the presence of mycobacteria. Forty-two paraffin-embedded specimens with INGs were collected from patients at high risk for contracting tuberculosis. Twenty biopsies were positive and 22 were negative for mycobacteria by AFSC. Two universal primers specific for all mycobacteria were used to detected a 414 base pair (bp) fragment of 16S rRNA gene. Twenty of 20 biopsies were positive for mycobacteria by both AFSC and PCR (100%), whereas 19 of 22 biopsies negative by AFSC were positive by PCR (86%). Follow-up of patients who were PCR positive but AFSC negative identified nine patients who had subsequent biopsies. Specimens from eight of these nine patients eventually grew Mycobacterium tuberculosis. Our results demonstrate that the detection of mycobacterial DNA by this method should be used in conjunction with AFSC for the initial diagnosis of mycobacterial infection.