Bartonella henselae

From IDWiki
Bartonella henselae


  • Causes cat-scratch disease


  • Present worldwide
  • Main reservoir is cats, and especially kittens
  • Infections are more common in children, likely due to increased exposure to kittens
  • Transmitted to humans by inoculation of cat flea (Ctenocephalides felis) feces into a cat scratch or bite

Clinical Manifestations

Cat Scratch Disease

  • Typical cat-scratch disease is a self-limited febrile illness with regional lymphadenopathy
    • Following an incubation period of 3 to 10 days, and initial pustule develops at site of inoculation which may last for up to 3 weeks
    • Usually a history of cat exposure (adult or kitten), but 5-10% have no known exposure
    • This is followed in 1 to 7 weeks by ipsilateral lymphadenopathy (usually the head or neck)
      • May involve one or more lymph nodes
      • May drain pus
      • Will eventually resolve, over months or longer
    • There may be a concurrent low-grade fever for several days, with malaise or fatigue
    • May have headache, sore throat, transient rash, or, rarely, erythema nodosum
    • May have mild leukocytosis (neutrophils or eosinophils), mildly elevated C-reactive protein or ESR
  • CSD may be complicated by encephalopathy in 2 to 4% of cases
    • Headache is common, and they may develop seizures and neurologic deficits
    • Resolves over weeks to months (to as long as a year)
    • CSF is usually normal, although lymphocytic pleiocytosis and elevated protein are seen in one third
    • MRI brain is almost always normal
    • EEG is nonspecific
    • Proportionally less common in children

Other Syndromes


  • Histopathology of node aspirate shows nonspecific inflammation, with granulomas and stellate ncerosis
    • Microabscesses are classic finding
    • Bacilli may be seen with Warthin-Starry staining
  • Culture
    • Fastidious organism which may not be detected by automated blood culture systems
    • If suspected, cultures should be held for 21 days
  • Molecular
    • PCR of node aspirate (or blood) is the best and most sensitive test
  • Serology
    • 1:64 is suggestive, 1:256 is strongly suggestive, and a four-fold rise from acute to convalescent titres is diagnostic
    • Cross-reacts with other Bartonella species, but possibly also with Chlamydia and Coxiella burnetii


Cat-Scratch Disease

  • Disease is usually self-limited in immunocompetent patients
  • May wish to treat if extensive lymphadenitis
  • First-line: azithromycin 500 mg po on day 1 followed by 250 mg po daily for 4 more days (10 mg/kg and 5 mg/kg for children)
  • Hepatosplenic CSD in children may respond to combination azithromycin ± rifampin for 14 days