cat scratch disease

Introduction

Inoculation of Bartonella henselae from the scratch or bite of an infected cat, generally a infected kitten. Bartonella henselae may also be transmitted by fleas of kitten. Kitten may be bacteremic with B henselae for months while appearing healthy. Cases after exposure to dogs & monkeys have been reported. The disease is more common in children.

Pathology

• granulomas surrounding stellate microabscesses
• skin lesions are designated bacillary angiomatosis
• liver & spleen lesions are designated bacillary peliosis

Clinical manifestations

• malaise (30%)
• headaches (13%)
• fever
• splenomegaly (12%)
• conjunctivitis (5%)
• scratch with papule or vesicle 4-6 days (3-10 days) post exposure
  • often gone when patient presents to physician
• regional, painful lymphadenopathy with overlying erythema
  • 1-8 weeks after papule appearance
  • 80% of nodes involve upper extremities, neck & head
  • preauricular lymphadenitis
• 80% of patients are < 21 years of age & have self-limited regional disease
• episodes frequently resolve spontaneously in 2-4 months
• 2% of patients suffer complications
  • bacteremia
  • involvement of liver, spleen, lung, bone, CNS, retina conjunctiva, skin
  • encephalitis, seizures
  • immunocompromised hosts especially susceptible

Laboratory

• skin testing with antigen
• cultures
  • blood culture or culture of skin lesions
  • 9-15 days required for growth
• Warthin-Starry silver stain
• serology
  • Bartonella henselae antibody in serum
  • indirect fluorescent antibody tests
• electron microscopy for organisms
• WBC generally within normal limits
• erythrocyte sedimentation rate (ESR) commonly elevated

Differential diagnosis

• regional lymphadenopathy
  • suppurative bacterial lymphadenitis
  • atypical mycobacteria
  • sporotrichosis
  • tularemia
  • toxoplasmosis
  • infectious mononucleosis
  • tumors
  • sarcoidosis
  • lymphogranuloma venereum
  • coccidioidomycosis
• other infections associated with cats
  • Capnocytophaga spp. (bite/infection)
  • Microsporum canis (dermatophytosis)
  • Toxocara cata (larva migrans)
  • Dirofilaria repens (subcutaneous nodules)

Management

• generally symptomatic, but self-limited
• pharmacologic agents
  • azithromycin
  • rifampin
  • ciprofloxacin
  • trimethoprim/sulfamethoxazole
  • clarithromycin
  • doxycycline
  • erythromycin (drug of choice for bacillary angiomatosis)
• relapses may occur
• surgical drainage of suppurative node may be indicated

More general terms

• bacterial infection

Additional terms

• Bartonella henselae (Rochalimaea henselae)