Rapid polymerase chain reaction-based detection of the causative agent of cat scratch disease (Bartonella henselae) in formalin-fixed, paraffin-embedded samples.

Bartonella (formerly Rochalimaea) henselae (Bh) plays a central role in cat scratch disease. A polymerase chain reaction (PCR)-based assay that can detect Bh DNA in formalin-fixed, paraffin-embedded (FF-PE) samples would have utility in the evaluation of processed lymph nodes suggestive of this disorder. Fresh or FF-PE cultures of Bh and related species were analyzed. Thirteen lymph nodes (12 FF-PE and one fresh cell suspension) with necrotizing suppurative granulomatous inflammation and seven FF-PE negative control lymph nodes were also evaluated. PCR was performed using a novel, hemi-nested protocol. Amplified products were analyzed by gel electrophoresis. The fresh and FF-PE Bh cultures showed a specific PCR product with an analytical sensitivity of 0.5 pg bacterial DNA. Seven (54%) of 13 clinical lymph node samples with morphological features suggestive of cat scratch disease also had detectable Bh DNA, whereas none of the seven negative control lymph nodes yielded positive results. We have designed a rapid and sensitive PCR test that can reliably detect Bh DNA in fresh and FF-PE samples. Our findings indicate that this assay has clinical utility in the diagnosis of cat scratch disease.