Cat Scratch Disease

Cat-scratch disease is caused by the bacterium Bartonella henselae and begins with a cutaneous papule or pustule at the site of inoculation, usually a kitten scratch or bite, within a week of the injury. A regional adenopathy involving the head, neck, and upper extremity follows in 1 to 7 weeks. Fever and malaise occurs in approximately one third of patients. The diagnosis is made by demonstrating pleomorphic bacilli by Warthin-Starry silver stain of a lymph node biopsy or by polymerase chain reaction (PCR) amplification techniques on lymph node tissue. The neurological and ophthalmological manifestations associated with cat-scratch disease include (1) encephalopathy (in 2 to 4 percent of patients with cat-scratch disease) characterized by headache, restlessness, irritability, focal or generalized seizure activity, confusion, disorientation, and coma. Focal neurological deficits including disturbances of language, cranial nerve palsies, hemiplegia, and ataxia can occur; and (2) neuroretinitis, characterized by a painless, unilateral, sudden loss of visual acuity. On examination, papilledema is associated with macular exudates in a star formation. There is mounting evidence implicating B. henselae in HIV dementia and HIV-associated focal brain lesions, aseptic meningitis and neuropsychiatric disease. The serological test for anti-Bartonella antibodies cannot discriminate between anti-Bartonella henselae and anti-Bartonella quintana (the etiological agent of trench fever) antibodies. Examination of the CSF in cases of cat-scratch disease encephalopathy demonstrate an elevation of the protein concentration, a lymphocytic and rarely a leukocytic pleocytosis, and a normal glucose concentration. CSF cultures for B. henselae are negative. In patients with lymphadenopathy, biopsy of a lymph node may reveal the typical features of cat-scratch disease. Skin tests with the Hanger-Rose cat-scratch disease antigen are positive in the majority of patients. In a few patients with neuroretinitis associated with cat-scratch disease, B. henselae has been isolated from blood. Gram's stain reveals small, gram-negative, slightly curved rods. The physician should question the patient about the history of a scratch by a kitten or a cat and the appearance of any skin lesion. No clear guidelines exist for which patients should be treated and what antibiotic should be used. The majority of patients with cat-scratch disease without an associated neurological manifestation have a self-limited illness. The demonstration of B. henselae bacteremia associated with neuroretinitis has led to the recommendation that antimicrobial therapy be considered in these patients with either erythromycin, doxycycline, azithromycin, clarithromycin, or ofloxacin. As stated earlier, an increasing amount of evidence exists for B. henselae as an etiological agent in a small proportion of cases of HIV- associated dementia, neuropsychiatric illness, focal brain lesions, and aseptic meningitis. Antimicrobial therapy may benefit these patients, but firm recommendations cannot be made at this time. y

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Eliminating Stress and Anxiety From Your Life

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