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Updated: Feb 22 2020

Bartonella henselae

  • Snapshot
    • A 26-year-old woman presents to the urgent care clinic because of fever, weight loss, night sweats, and a red rash on her trunk, legs, and arms for the past week. She has a past medical history of HIV infection and currently is not on any anti-retroviral medications. She recently adopted a cat from the shelter 3 months ago and has been training it to not scratch when approached; however, she has been sustaining scratches during the training process. On physical exam, she has generalized lymphadenopathy and multiple clusters of violaceous papules and plaques. Her CD4 count is 100 cells/mm3. A skin biopsy was done and shows a neutrophilic infiltrate and granulomatous changes.
  • Introduction
    • Classification
      • Bartonella henselae
        • facultative intracellular, gram-negative rod
        • transmission
          • scratch or bite from a cat (more common) or dog
        • clinical syndromes
          • bacillary angiomatosis, a vasoproliferative disease
            • benign capillary tumors of the skin
            • immunosuppressed patients
          • cat scratch disease
            • tender lymphadenopathy
          • bacterial endocarditis (culture-negative)
    • Epidemiology
      • incidence
        • more common in the southern US
      • demographics
        • bacillary angiomatosis
          • immunosuppressed patients
        • cat scratch disease
          • children and adolescents > adults
      • risk factors
        • HIV/AIDS
        • immunosuppression
        • cat scratch, bite, or lick
    • Pathogenesis
      • B. henselae replicates in red blood cells
      • granulomatous inflammation
        • mediated by CD4+ T-cells
        • secretes γ-interferon and activates macrophages
    • Associated conditions
      • culture-negative bacterial endocarditis
    • Prognosis
      • cat scratch disease typically resolves within a few months
      • bacillary angiomatosis typically resolves completely with treatment
  • Presentation
    • Cat scratch disease
      • tender lymphadenopathy 2 weeks after exposure
      • vesicle, wheal, or papule at site of trauma
      • systemic symptoms
        • low-grade fever
        • myalgias
        • fatigue
    • Bacillary angiomatosis
      • multiple clustered red or violaceous papules, plaques, or nodules on skin and mucosa
      • bone pain
      • systemic symptoms
        • fever
        • night sweats
        • weight loss
  • Studies
    • Labs
      • serologic detection of immunoglobulins
        • via enzyme-linked immunosorbent assay (ELISA) or indirect immunofluorescence assay (IFA)
      • detection of bacterial DNA on polymerase chain reaction (PCR)
      • culture is not useful as the bacteria is fastidious and hard to culture
    • Biopsy of skin lesions or lymph node
      • neutrophilic infiltrate
      • granulomatous changes
    • Making the diagnosis
      • based on clinical presentation and laboratory studies
  • Differential
    • Kaposi sarcoma
      • distinguishing factor
        • presents clinically similar to bacillary angiomatosis but biopsy reveals lymphocytic infiltrate
  • Treatment
    • Management approach
      • cat scratch disease is self-limited and guidelines for antibiotics is unclear
      • bacillary angiomatosis requires treatment with antibiotics
    • Medical
      • azithromycin
        • indication
          • cat scratch disease
      • erythromycin or doxycycline
        • indication
          • bacillary angiomatosis
  • Complications
    • Persistent lymphadenopathy
    • Aseptic meningitis
    • Disfigurement
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