Real-time PCR strategy and detection of bacterial agents of lymphadenitis

The aim of this study was to compare 16 S rRNA gene amplification and sequencing with a systematic real-time PCR assay screening strategy that includes all common known pathogens recovered from lymph node biopsy specimens. Lymph node biopsy samples sent to our laboratory from January 2007 to December 2008 were tested in the study. Lymph nodes were screened for the presence of any bacteria by PCR amplification and sequencing targeting the 16 S rRNA gene and also by a specific real-time PCR strategy that includes Bartonella henselae, mycobacteria, Francisella tularensis, and Tropheryma whipplei. By testing 491 lymph nodes, we found that the sensitivity of our specific real-time PCR assay strategy was significantly higher than 16 S rRNA PCR amplification and sequencing for the detection of Bartonella henselae (142 vs 98; p < 10(-4)), Francisella tularensis (16 vs 10, p < 10(-4)), and mycobacteria (8 versus 3, p < 10(-4)). None of the samples was positive for Tropheryma whipplei. Our study demonstrates the usefulness and specificity of a systematic real-time PCR strategy for molecular analysis of lymph node biopsy specimens and the higher sensitivity compared with standard 16 S rRNA gene amplification and sequencing.