An Analysis of Lymph Node DNA for Possible Bacterial Agents of Cat-Scratch Disease

Recent investigations have implicated Afipia felis and Rochalimaea henselae as possible agents of cat-scratch disease (CSD). We studied lymph nodes with necrotizing granulomas characteristic of CSD for A. felis and R. henselae DNA so that the relationship of these organisms to lymph nodes with necrotizing granulomas of unknown etiology might be better defined. We examined formalin-fixed, paraffin-embedded lymph node biopsies with necrotizing granulomas suggestive of CSD from 28 children obtained over the last 10 years. None had identifiable bacteria, fungi, or acid-fast organisms on routine staining. Pleomorphic bacillary structures consistent with the CSD bacillus were seen with the Steiner stain in 17 cases. We performed the polymerase chain reaction (PCR) on the extracted lymph node DNA with DNA primers for these organisms after demonstrating the presence of amplifiable DNA with c-K-Ras primers. R. henselae was identified in two samples. A. felis DNA was found in just one specimen. These putative CSD bacteria are infrequently associated with necrotizing granulomas using standard PCR techniques. It is possible that some of the patients did not have clinical CSD. The preservation of DNA or numbers of bacteria in the extracted sections may be inadequate for demonstration by DNA amplification methods. These bacilli may be responsible for a small proportion of these characteristic lesions of unknown etiology, or the typical CSD histology, including the presence of pleomorphic bacillary structures, may be nonspecific.