The Agent of Bacillary Angiomatosis

TLDR

Bacillary angiomatosis is an infectious disease that causes proliferation of small blood vessels in skin and visceral organs of HIV‑infected and other immunocompromised patients, and its causative agent is visualized by Warthin‑Starry staining but has not been cultured or identified. The study aimed to identify the uncultured bacillus responsible for bacillary angiomatosis—and possibly cat scratch disease—using polymerase chain reaction. Researchers amplified 16S ribosomal RNA gene fragments from tissue samples with primers targeting eubacterial 16S rRNA, sequenced the fragments, and performed phylogenetic analysis while comparing normal tissues in parallel. The 16S sequences from patients formed a unique, previously uncharacterized rickettsia‑like organism most closely related to Rochalimaea quintana, with only minor variation among patients and no detection in normal tissues.

Abstract

Bacillary angiomatosis is an infectious disease causing proliferation of small blood vessels in the skin and visceral organs of patients with human immunodeficiency virus infection and other immunocompromised hosts. The agent is often visualized in tissue sections of lesions with Warthin-Starry staining, but the bacillus has not been successfully cultured or identified. This bacillus may also cause cat scratch disease.In attempting to identify this organism, we used the polymerase chain reaction. We used oligonucleotide primers complementary to the 16S ribosomal RNA genes of eubacteria to amplify 16S ribosomal gene fragments directly from tissue samples of bacillary angiomatosis. The DNA sequence of these fragments was determined and analyzed for phylogenetic relatedness to other known organisms. Normal tissues were studied in parallel.Tissue from three unrelated patients with bacillary angiomatosis yielded a unique 16S gene sequence. A sequence obtained from a fourth patient with bacillary angiomatosis differed from the sequence found in the other three patients at only 4 of 241 base positions. No related 16S gene fragment was detected in the normal tissues. These 16S sequences associated with bacillary angiomatosis belong to a previously uncharacterized microorganism, most closely related to Rochalimaea quintana.The cause of bacillary angiomatosis is a previously uncharacterized rickettsia-like organism, closely related to R. quintana. This method for the identification of an uncultured pathogen may be applicable to other infectious diseases of unknown cause.