Bartonella henselae: Difference between revisions

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Bartonella henselae
(Created page with "* Causes '''cat-scratch disease''' {{DISPLAYTITLE:''Bartonella henselae''}} Category:Gram-negative bacilli")
 
 
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==Background==
* Causes '''cat-scratch disease'''

*Causes '''cat-scratch disease'''

===Epidemiology===

*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 (''[[Vector::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 [[Causes::regional lymphadenopathy]]
**Following an incubation period of [[Usual incubation period::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 [[Causes::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 [[Causes::fever]] for several days, with [[Causes::malaise]] or [[Causes::fatigue]]
**May have [[Causes::headache,]] sore throat, transient rash, or, rarely, [[Causes::erythema nodosum]]
**May have mild leukocytosis (neutrophils or eosinophils), mildly elevated C-reactive protein or ESR
*CSD may be complicated by [[Causes::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 ===

*Other syndromes include:
**[[Causes::Parinaud oculoglandular syndrome]], with granulomatous conjunctivitis and ipsilateral (usually preauricular) lymphadenopathy
**[[Causes::Neuroretinitis]] and other ophthalmic complications
**[[Causes::Fever of unknown origin]], in children
**Culture-negative [[Causes::endocarditis]] in patients with existing valve abnormalities
**Chronic endocarditis, with [[Causes::vasculitis]] and [[Causes::glomerulonephritis]]
*Disseminated disease is possible in immunocompromised patients, including bacteremia, disseminated skin lesions, and hepatosplenic lesions

==Diagnosis==

*Histopathology of node aspirate shows nonspecific inflammation, with granulomas and stellate necrosis
**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]]''

==Management==
===Cat-Scratch Disease===

*Disease is usually self-limited in immunocompetent patients
*May wish to treat if extensive lymphadenitis
*First-line: [[Is treated by::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 [[Is treated by::azithromycin]] ± [[Is treated by::rifampin]] for 14 days

===Endocarditis===

*[[Is treated by::Doxycycline]] and [[Is treated by::gentamicin]] for 14 days followed by [[doxycycline]] alone for three months, or until 6 weeks after valve replacement (if done)


{{DISPLAYTITLE:''Bartonella henselae''}}
{{DISPLAYTITLE:''Bartonella henselae''}}

Latest revision as of 15:23, 17 October 2024

Background

  • Causes cat-scratch disease

Epidemiology

  • 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

Diagnosis

  • Histopathology of node aspirate shows nonspecific inflammation, with granulomas and stellate necrosis
    • 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

Management

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

Endocarditis