10 Questions
What is the primary mode of transmission of B.henselae from cats to humans?
Cat bites or scratches
What is the characteristic of B.henselae in immunocompetent individuals?
It is a low virulence organism, causing self-limited disease
What is the characteristic of cat-scratch disease in immunocompetent individuals?
It is a self-limited disease, eventually resolving without antibiotics
What is the characteristic of Bacillary angiomatosis in immunocompromised individuals?
It is characterized by raised, cherry-red vascular lesions in the skin and visceral organs
What is the morphology of B.henselae?
It is a small, pleomorphic gram-negative rod
What is the primary location of lesions in bacillary peliosis?
Liver and spleen
How is the diagnosis of CSD typically made?
By detecting antibodies against B. henselae antigens in a patient's serum
What is the drug of choice for treating severe lymphadenitis in CSD?
Azithromycin
What is the purpose of the Warthin-Starry silver stain in diagnosing BA?
To distinguish BA from Kaposi's sarcoma
Why are antibiotics not recommended for people who have sustained a cat scratch?
Because the infection is usually self-limiting
Study Notes
Bartonella henselae
- Causes cat-scratch disease and bacillary angiomatosis
- Small, pleomorphic gram-negative rod
Transmission
- Main mode of transmission: cat scratches or bites, especially from kittens
- Can be transmitted from cats to humans by the bite of cat fleas
- Exposure to cat urine or feces does not pose a risk of transmission
- No person-to-person transmission
Pathogenesis and Epidemiology
- Low virulence organism, disease is self-limited in immunocompetent individuals
- Cat-scratch disease is one of the most common zoonotic diseases in the United States
Clinical Findings
- Immunocompetent individuals: fever and tender, enlarged lymph nodes, typically on the same side as the scratch
- Papule may precede lymphadenopathy
- Disease has a prolonged course but eventually resolves, even without antibiotics
- Small percentage of infected individuals develop systemic disease, such as endocarditis or encephalitis
Clinical Findings in Immunocompromised Individuals
- Bacillary angiomatosis (BA): raised, cherry-red vascular lesions in the skin and visceral organs
- Bacillary peliosis (peliosis hepatis): similar to BA, but lesions occur primarily in the liver and spleen
Laboratory Diagnosis
- Diagnosis of CSD is usually made serologically
- Antibodies against B. henselae antigens can be detected in a patient's serum
- Organism can be cultured on artificial media, but takes 5 days or longer to grow
- Diagnosis of BA is often made by finding pleomorphic rods in biopsy tissue using the Warthin-Starry silver stain
Treatment
- No antibiotic therapy is typically recommended for CSD
- Azithromycin is the drug of choice for severe lymphadenitis
- Treatment of BA with doxycycline or erythromycin is effective
- No significant antibiotic resistance
Prevention
- No antibiotics are recommended for people who have sustained a cat scratch
- No vaccine is available
Learn about Bartonella henselae, the cause of cat-scratch disease and bacillary angiomatosis, and its properties and transmission.
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