Cat scratch disease

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Cat scratch disease
Classification and external resources
OMIM 115470
DiseasesDB 2173


Cat-scratch disease (CSD) is an infectious disease consisting of gradually progressive regional lymphadenopathy, often occurring after contact with a feline animal (often a scratch). Atypical presentations are characterized by a variety of neurologic manifestations as well as granulomatous involvement of the eye, liver, spleen, and bone. The disease is usually self-limiting, and recovery is typically complete; however, patients with atypical presentations, especially if immunocompromised, may suffer significant morbidity and even mortality.

Disease

There are generally two forms of CSD as it relates to the eye:

  1. Parinauds Ocularglanduar Syndrome: consisting mostly of lymphadenopathy and conjunctivitis
  2. Neuroretinitis due to Cat scratch disease: consisting mostly of lymphadenopathy and granulomatous inflammation of the retina and optic nerve with classic optic nerve swelling and macular star (neuroretinitis), and possible vasculitis.

Etiology

Major cause: Bartonella henselae, possibly Afipia felis and Bartonella clarrigeiae. To be clear, there are other causes of neuroretinitis which would not be strictly considered CSD. The definition of CSD is based on the organism primarily, in combination with the presenting findings.

General Pathology

Bartonella species are a gram-negative bacillus that has been associated with a clinical syndrome of a self-limited lymphadenopathy associated with a cat scratch or bite or transmission through vectors such as fleas or flies. Mode of transmission: predominantly by direct inoculation through the scratch, bite, or lick of a cat, especially a kitten.

Pathophysiology

Bartonella organisms typically invade, and colonize mature erythrocytes. However, endothelial cells are also a target for Bartonella organisms, and appear to be the target host cells in humans. Endothelial invasion leads to a pro-inflammatory response and vasoproliferation.

Diagnosis

Diagnosis of CSD is straight forward in the presence of typical neuro­retinitis, and macular star formation, in addition to labratory t.esting pointing to Bartonella infection (typically blood test/titers) Additionally, recognition of isolated discrete white retinal, and chorioretinal lesions may aid in diagnosis.

History

Approximately 1-3 weeks after inoculation of the bacteria into the host, regional lymphatic tissues begin to display granulomatous infiltration associated with gradual hypertrophy.

Signs

The most common presentation is regional lymphadenopathy. Pre-auricular, submandibular, or cervical lymph nodes are typically affected. Conjunctival epithelium ulcerations, and necrosis are commonly seen producing a purulent discharge in severe cases. Erythematous overlying skin, showing signs of suppuration from involved lymph nodes. Careful examination; evidence of cutaneous inoculation in the form of a nonpruritic, slightly tender pustule or papule.

Typical intraocular presentation includes neuroretinitis with macular star formation, and discrete white retinal or choroidal lesions. Vascular leakage from the optic nerve head results in the macular star formation, which may persist for months despite resolution of the neuroretinitis. In more recent studies, discrete white retinal, and chorioretinal lesions were a more common finding than the ‘classic’ macular star, and neuroretinitis. Additionally, an afferent pupillary defect is typically present in unilateral cases, and a cecocentral scotoma is present on visual field testing. More sight-threatening presentation includes retinal vasculitis, and vascular occlusions. Less common posterior segment findings include Branch retinal artery, and vein occlusion, and local serous retinal detachments.

Parinaud oculoglandular syndrome (conjunctival inflammation with preauricular adenopathy) may be seen in about 7% of patients with cat-scratch disease.

Symptoms

Patients typically present with unilateral decline in vision (20/80) with systemic symptoms present in 67%. Unilateral conjunctiva injection, foreign body sensation, and epiphora. Malaise and headache in fewer than one third of patients.

Clinical diagnosis

Typical history of prodromal symptoms, lymphadenopathy, and cat exposure helps strengthen the diagnosis, especially when presenting in young adults or children.

Diagnostic procedures

Visual field testing sometimes shows cecocentral scotoma. Fluorescine angiography often shows optic nerve leakage.

Although rarely required, in the presence of typical presentation and blood titer, lymph node biopsy or culture may be performed.

  • Biopsy: classically shows granulomatous inflammation. Warthin-Starry silver stain on biopsy can identify the bacteria.
  • Culture: B. henselae is a fastidious, slow-growing, gram-negative rod that requires specific culture techniques for tissue or blood.

Laboratory test

Serologies: An IFA or EIA Bartonella serology (titer ≥1:64) is diagnostic, with sensitivity, and specificity of 62%, and 100% respectively. A PCR assay on tissue or blood is also available.

Routine laboratory findings: Mild leukocytosis or leukopenia, infrequent eosinophilia and elevated ESR or CRP. Abnormalities of bilirubin excretion and elevated hepatic transaminases are usually secondary to hepatic obstruction by granuloma, mass, or lymph node. In patients with neurologic manifestations, lumbar puncture usually reveals normal CSF, although there may be a mild pleocytosis and modest elevation in protein.

Differential diagnosis

Etiologies that must be differentiated include other causes of optic nerve head swelling such as optic neuritis, and sarcoid papillitis. Also, infectious etiologies such as syphilitic perineuritis, and rarely toxoplasmosis can produce a similar clinical appearance. Pseudotumor cerebri can mimic the less frequent appearance of bilateral CSD.

Granulomas of this syndrome must be differentiated from those associated with:

  • Tularemia
  • Tuberculosis or other myobacterial infections
  • Brucellosis
  • Sarcoidosis
  • Sporotrichosis or other fungal diseases
  • Toxoplasmosis
  • Lymphogranuloma venereum
  • Benign and malignant tumors such as lymphoma

Management

CSD tends to be a self-limiting disease. Usually no treatment is recommended. However, patients with severe ocular or systemic complications, a course of antibiotics may be initiated. In immunocompromised patients, antibiotic treatment has lead to dramatic clinical responses

General treatment

Antipyretics and NSAIDs may also be used. Warm compresses to the affected nodes. In cases of encephalitis or coma, antibiotics and supportive care are indicated.

Medical therapy

Doxycycline (100 mg twice daily) has good intraocular, and central nervous system penetration. However, in patients less than 12  years of age, erythromycin is recommended due to the risk of tooth discoloration. Azithromycin has been observed to cause rapid resolution of lymphadenopathy. However, the distribution of azithromycin to the eye appears higher for conjunctival tissue but lower in intraocular fluids.

Prognosis

The visual prognosis is good with or without treatment.

Additional Resources

References

1. Windsor JJ: Cat-scratch disease: epidemiology, aetiology and treatment. Br J Biomed Sci 2001; 58: pp. 101-110.

2. Ormerod LD, and Dailey JP: Ocular manifestations of cat-scratch disease. Curr Opin Ophthalmol 1999; 10: pp. 209-216.

3. Solley WA, Martin DF, Newman NJ, et al: Cat scratch disease: posterior segment manifestations. Ophthalmology 1999; 106: pp. 1546-1553.

4. Zacchei AC, Newman NJ, and Sternberg P: Serous retinal detachment of the macula associated with cat scratch disease. Am J Ophthalmol 1995; 120: pp. 796-797.

5. Cunningham ET, and Koehler JE: Ocular bartonellosis. Am J Ophthalmol 2000; 130: pp. 340-349.

6. Suhler EB, Lauer AK, and Rosenbaum JT: Prevalence of serologic evidence of cat scratch disease in patients with neuroretinitis. Ophthalmology 2000; 107: pp. 871-876.

7. Tsuneoka H, Fujii R, Fujisawa K, et al: [Clinical evaluation of commercial serological test for Bartonella infection]. Kansenshogaku Zasshi 2000; 74: pp. 387-391.

8. Curi AL, Machado D, Heringer G, et al: Cat-scratch disease: ocular manifestations and visual outcome. Int Ophthalmol 2010; 30: pp. 553-558.

9. Dehio C: Molecular and cellular basis of . Annu Rev Microbiol 2004; 58: pp. 365-390.

10. Gray AV, Michels KS , Lauer AK, Samples JR. Bartonella henselae infection associated with neuroretinitis, central retinal artery and vein occlusion, neovascular glaucoma, and severe vision loss. Am J Ophtha/mol. 2004;137:187-1 89.

11. Brazis PW, Stokes HR, Ervin FR. Optic neuritis in cat scratch disease. J Clin Neuroophthalmol. 1986;6;172-174.

12. Batts and Demers, 2004. Batts S., and Demers D.M.: Spectrum and treatment of cat-scratch disease. Pediatr Infect Dis J 2004; 23: pp. 1161.

13. Klotz et al., 2011. Klotz S.A., et al: Cat-scratch disease. Am Fam Physician 2011; 83: pp. 152-155