Bacillary angiomatosis is a skin condition in immunocompromised patients (especially patients with AIDS and/or CD4 count < 100) characterized by vascular proliferation that results in lesions on the skin and potentially other organs (e.g., GI tract, respiratory tract). It is caused primarily by Bartonella henselae, which is most commonly transmitted via cat scratches. Skin manifestations include red papules and nodules that bleed easily. Diagnosis is confirmed on biopsy. Antibiotics are used to treat bacillary angiomatosis, and patients with HIV should be started on ART.
- Biopsy of lesion (first-line test) 
- The following studies may provide supportive evidence but are not widely available/used: 
- Initiate ART (if not already started) in patients with HIV.
- Antibiotic therapy 
- In seropositive patients, serial IgG antibody titers (every 6–8 weeks) can be used to monitor response to therapy.
- Management of recurrences
Bartonella henselae 
- Limit cat ownership to cats > 1 year old and in good condition; provide regular flea treatment.
- Reduce the risk of cat scratches: Avoid petting stray cats and playing roughly with cats.
- Clean any scratches promptly with soap and clean water.
Bartonella quintana 
- Advise patients to avoid sharing clothes or bedding; wash clothes and bedding in hot water (> 50°C/120°F).
- Provide treatment to patients affected by body lice.