questions 2

Bartonella henselae

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Topic updated on 02/13/17 9:57am

Snapshot
  • A 23-year-old female presents to the infectious disease clinic with a 3-week history of fever, unintentional weight loss, and dark nodules on her face, trunk, and legs. She was diagnosed with HIV a year ago but was lost to follow up. She lives alone with three cats. On exam, the patient has generalized lymphadenopathy, oral thrush, and widespread dome-shaped purplish nodules varying from 0.5 to 4 cm in diameter. Her CD4 count is 76 cells/mm3. A wedge biopsy of one the nodules was taken and sent for H&E stain as well as Warthin-Starry silver stain.
Introduction
  • Classification
    • gram-negative, zoonotic bacteria
      • Bartonella henselae
  • Pathogenesis
    • transmission
      • cat and dog bites and scratches
    • predisposing factors
      • cats and dogs as pets
      • children (more likely to be scratched)
      • HIV patients
    • molecular biology
      • granulomatous inflammmation
        • mediated by CD4 TH cells
        • secretes γ-interferon and activates macrophages
        • forms non-caseating granulomas
Presentation
  • Cat-scratch disease 
    • symptoms
      • swollen lymph nodes near the bite site
      • headaches
      • low-grade fever
    • physical exam
      • lymphadenopathy
  • Bacillary angiomatosis 
    • seen in AIDS and immunosuppression
    • commonly presents in the skin, bone, and liver
    • symptoms
      • fever
      • unintentional weight loss
      • dark-colored lesions on skin and mucosa
      • bone pain (if bone involvement)
      • abdominal pain and swelling
      • nausea and vomitting
    • physical exam
      • cutaneous lesions
        • dark red/purplish papules, nodules, or plaques
      • visceral lesions
        • hepatosplenomegaly
        • jaundice
  • Endocarditis
    • culture-negative
    • symptoms
      • unexplained fever
    • physical exam
      • new-onset or changing murmur
Evaluation
  • Serologic testing for cat-scratch disease
    • indirect fluorescence assay commonly used
  • Wedge biopsy of nodule for bacillary angiomatosis
    • followed by staining
      • Haematoxylin and eosin stain
        • bacillary angiomatosis has a neutrophilic infiltrate
        • Kaposi sarcoma has a lymphocytic infiltrate
      • Warthin-Starry silver stain
Differential
  • Kaposi sarcoma 
    • lymphocytic infiltrate on H&E stain
Treatment
  • Azithromycin
  • Doxycycline
Prognosis, Prevention, and Complications
  • Prognosis
    • cat-scratch disease usually self-limiting
    • bacillary angiomatosis good if treated
  • Complications
    • bacillary angiomatosis can cause
      • disfigurement
      • biliary obstruction and jaundice
      • GI bleeding


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(M1.MC.1) A 16-year-old female presents to her pediatrician complaining of 2 weeks of fever and 1 week of swollen lumps in her left armpit. Upon examination of the left upper extremity, her physician notes the presence of a single papule which the patient claimed appeared one week ago. The patient started her first job at a pet store 2.5 weeks ago. Which of the following is the vector of transmission of the causative agent? Topic Review Topic
FIGURES: A          

1. Animal Urine
2. Cats
3. Parrots
4. Armadillos
5. Rabbits

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