What conditions are caused by Bartonella henselae?

Conditions Caused by Bartonella henselae

Bartonella henselae causes several clinical conditions including cat scratch disease, bacillary angiomatosis, bacillary peliosis hepatis, endocarditis, osteomyelitis, and neuroretinitis, with cat scratch disease being the most common manifestation in immunocompetent hosts. 1, 2

Primary Conditions

In Immunocompetent Hosts:

• Cat Scratch Disease (CSD)

  • Most common manifestation
  • Characterized by regional lymphadenopathy that develops approximately 3 weeks after inoculation
  • Lymphadenopathy typically resolves within 1-6 months
  • Suppuration occurs in about 10% of cases
  • Often begins with a papule or pustule at the site of inoculation (3-30 days after scratch/bite) 1

• Parinaud Oculoglandular Syndrome

  • Conjunctival granuloma with preauricular lymphadenopathy 3

• Neuroretinitis

  • Stellate neuroretinitis causing visual impairment 4

• Other Extranodal Manifestations (occur in ≤2% of cases)

  • Central nervous system involvement (encephalopathy)
  • Hepatosplenic infection
  • Osteomyelitis
  • Endocarditis
  • Persistent fever without localizing signs 1, 3, 4

In Immunocompromised Hosts (particularly HIV patients with CD4+ <100 cells/µL):

• Bacillary Angiomatosis (BA)

  • Vascular proliferative lesions affecting nearly every organ system
  • Cutaneous lesions most commonly identified
  • Can be clinically indistinguishable from Kaposi's sarcoma
  • Often accompanied by systemic symptoms (fever, night sweats, weight loss) 1

• Bacillary Peliosis Hepatis

  • Blood-filled cystic spaces in the liver
  • Only caused by B. henselae (not B. quintana) 1

• Relapsing Bacteremia

  • Chronic illness lasting months to years
  • Major cause of unexplained fever in late-stage AIDS patients 1, 3

Clinical Presentation

Cat Scratch Disease:

• Regional lymphadenopathy (hallmark finding)
• Low-grade fever
• Malaise
• Self-limiting in most immunocompetent hosts 2, 4

Bacillary Angiomatosis:

• Two clinical presentations:
  1. Red papules varying from millimeters to several centimeters in size (can number from 1 to >1000)
  2. Subcutaneous, painful nodules with normal or dusky overlying skin 1

Diagnosis

• Histopathology: Warthin-Starry silver stain of infected tissue shows characteristic bacilli 1
• Serology: Primary diagnostic method, though antibodies may not be detectable for up to 6 weeks after infection 1, 2
• PCR: Available for identification and speciation but not widely accessible 1
• Culture: Difficult due to fastidious nature of the organism; blood should be collected in EDTA tubes 1, 5

Treatment

Cat Scratch Disease:

• Azithromycin is the recommended first-line treatment:
  • Patients >45 kg: 500 mg on day 1 followed by 250 mg for 4 additional days
  • Patients <45 kg: 10 mg/kg on day 1 and 5 mg/kg for 4 more days 1, 2

Bacillary Angiomatosis and Other Severe Infections in Immunocompromised Patients:

• Erythromycin 500 mg four times daily OR
• Doxycycline 100 mg twice daily
• Treatment duration: 2 weeks to 2 months (minimum 3 months recommended) 1
• For CNS involvement: Doxycycline with or without rifampin 1

Prevention

• Control of cat flea infestation (cats are the main reservoir)
• Avoid cat scratches, especially from kittens and feral cats
• Immunocompromised individuals should consider risks of cat ownership
• If acquiring a cat, choose one >1 year old and in good health 1, 2, 6

Key Considerations

• Lymphadenopathy may persist for 1-6 months despite appropriate treatment 2
• Uncomplicated cat scratch disease in immunocompetent hosts may not require antibiotic therapy as it's often self-limiting 3, 4
• Bartonella infection should be considered in the differential diagnosis for unexplained fever in HIV patients with CD4+ <100 cells/µL 1