An analysis of lymph node DNA for possible bacterial agents of cat-scratch disease
G P Jevon1, W M Dunne, M J Finegold
1Department of Pathology, Texas Children's Hospital, Houston, USA.
Abstract:
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.
Insights
Afipia felis and Rochalimaea henselae DNA were sought in cat-scratch disease (CSD) lymph nodes. These bacteria were infrequently detected using PCR, suggesting they may cause only a small proportion of these lesions.
Area of Science:
- Microbiology
- Pathology
- Infectious Diseases
Background:
- Cat-scratch disease (CSD) is typically caused by Bartonella henselae.
- Afipia felis has also been implicated as a potential agent of CSD.
- Necrotizing granulomas in lymph nodes are characteristic of CSD, but the causative agent is not always identified.
Purpose of the Study:
- To investigate the presence of Afipia felis and Rochalimaea henselae DNA in lymph node biopsies with necrotizing granulomas suggestive of CSD.
- To better define the relationship of these bacteria to CSD lesions of unknown etiology.
Main Methods:
- Analysis of formalin-fixed, paraffin-embedded lymph node biopsies from 28 children with necrotizing granulomas.
- Routine staining for bacteria, fungi, and acid-fast organisms.
- Steiner stain for pleomorphic bacillary structures.
- Polymerase chain reaction (PCR) for A. felis and R. henselae DNA after confirming amplifiable DNA with c-K-Ras primers.
Main Results:
- Pleomorphic bacillary structures, consistent with the CSD bacillus, were observed in 17 out of 28 cases using Steiner stain.
- Rochalimaea henselae DNA was identified in 2 samples.
- Afipia felis DNA was detected in only 1 sample.
- PCR failed to detect these bacteria in most cases with characteristic CSD histology.
Conclusions:
- Afipia felis and Rochalimaea henselae are infrequently associated with necrotizing granulomas suggestive of CSD when using standard PCR techniques.
- The low detection rates may be due to inadequate DNA preservation, low bacterial numbers, or the possibility that some cases were not clinical CSD.
- These bacteria might be responsible for a small subset of these lesions, or the observed histology may be nonspecific.
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