Bartonella henselae: Difference between revisions
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Bartonella henselae
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==Diagnosis== |
==Diagnosis== |
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− | *Histopathology of node aspirate shows nonspecific inflammation, with granulomas and stellate |
+ | *Histopathology of node aspirate shows nonspecific inflammation, with granulomas and stellate necrosis |
**Microabscesses are classic finding |
**Microabscesses are classic finding |
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**Bacilli may be seen with Warthin-Starry staining |
**Bacilli may be seen with Warthin-Starry staining |
Latest revision as of 10:23, 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
- Other syndromes include:
- Parinaud oculoglandular syndrome, with granulomatous conjunctivitis and ipsilateral (usually preauricular) lymphadenopathy
- Neuroretinitis and other ophthalmic complications
- Fever of unknown origin, in children
- Culture-negative endocarditis in patients with existing valve abnormalities
- Chronic endocarditis, with vasculitis and 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: 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
- Doxycycline and gentamicin for 14 days followed by doxycycline alone for three months, or until 6 weeks after valve replacement (if done)