RESUMEN
BACKGROUND: To determine the most effective method for detecting mycobacteria in formalin- fixed paraffin-embedded (FFPE) tissue, we compared the results of Ziehl-Neelsen stain (ZNS) and mycobacterial culture with those of polymerase chain reaction (PCR) and real-time quantitative PCR (RQ-PCR). METHODS: We analyzed 54 cases diagnosed as chronic granulomatous inflammation. In all cases, ZNS and nested PCR using three different primers, IS6110, Mpb64 and IS6110/Rpobeta were done. RQ-PCR with the IS6110/Rpobeta primer was done in 51 cases. RESULTS: Mycobacteria were identified by ZNS in 15/54 (27.8%) cases. RQ-PCR had the highest sensitivity (80.0%) compared to PCR with IS6110 (73.3%), Mpb64 (60.0%) and IS6110/Rpobeta (73.3%). Specificity was higher in all PCR experiments (79.5-82.1%) than in RQ-PCR (69.4%) experiments. The false negative rate was lowest for RQ-PCR (20.0%) than for PCR with IS6110 (26.7%), Mpb64 (40.0%) and IS6110/Rpobeta (26.7%). The false positive rate was highest for RQ-PCR (30.6%) compared to PCR with IS6110 (20.5%), Mpb64 (17.9%) and IS6110/Rpobeta (20.5%). CONCLUSIONS: RQ-PCR had the highest sensitivity, and the lowest false negative rate, but it also had a higher false positive rate than PCR for detection of mycobacteria in FFPE tissues.