Rochalimaea's Role in Cat Scratch Disease and Bacillary Angiomatosis

The pathogens responsible for cat scratch disease and bacillary angiomatosis have been difficult to identify. New technologies, including analysis of the 16S ribosomal gene of DNA isolated from bacteria associated with these diseases, have helped to solve these diagnostic dilemmas. Both disorders appear to result from Rochalimaea species infection, including the recently identified R. henselae, a slow-growing, fastidious, gram-negative bacillus. Despite shared causes, cat scratch disease and bacillary angiomatosis are distinguished by differing host ranges, clinical manifestations, responses to antibiotic therapy. The tools are available now to understand these differences and to characterize more fully the natural history of infection with Rochalimaea.

This issue of Annals includes two articles describing different manifestations of infection caused by Rochalimaea species, a slow-growing, fastidious, gram-negative bacillus [1]. Rochalimaea species play a significant role in two syndromes, cat scratch disease (R. henselae) and bacillary angiomatosis (R. henselae and R. quintana), for which, until recently, attempts to isolate and culture the responsible pathogen(s) have been difficult. Application of new technologies that analyze the 16S rDNA present in bacteria has helped solve these diagnostic dilemmas. This is possible because the genes for rRNA contain sequences that have changed only slightly over time, along with moderately conserved sequences and highly variable ones. The DNA from bacteria in tissue can be isolated and the 16S rDNA sequence amplified using the polymerase chain reaction. The similarities of the organisms can then be deduced by comparing their sequences.

Cat scratch disease was recognized as a clinical syndrome in the 1930s, but the first report was not until 1950 [2, 3]. A history of contact with cats is found in 90% of patients and antecedent cat scratch in 60% [4]. Often the initial symptom is …