Bartonella species are responsible for a wide variety of clinical syndromes. Bacillary angiomatosis, an important manifestation of bartonellosis, is discussed in Chapter 31. A variety of atypical infections, including retinitis, encephalitis, osteomyelitis, and persistent bacteremia and endocarditis (especially consider in culture-negative endocarditis), have been described.
Trench fever is a self-limited, louse-borne relapsing febrile disease caused by B quintana. The disease has occurred epidemically in louse-infested troops and civilians during wars and endemically in residents of scattered geographic areas (eg, Central America). An urban equivalent of trench fever has been described among the homeless. Humans acquire infection when infected lice feces enter sites of skin breakdown. Onset of symptoms is abrupt and fever lasts 3–5 days, with relapses. The patient complains of weakness and severe pain behind the eyes and typically in the back and legs. Lymphadenopathy, splenomegaly, and a transient maculopapular rash may appear. Subclinical infection is frequent, and a carrier state is recognized. The differential diagnosis includes other febrile, self-limited states such as dengue, leptospirosis, malaria, relapsing fever, and typhus. Treatment is generally not required since spontaneous recovery occurs regularly.
Cat-scratch disease is an acute infection of children and young adults caused by Bartonella henselae. It is transmitted from cats to humans as the result of a scratch or bite. Within a few days, a papule or ulcer will develop at the inoculation site in one-third of patients. One to 3 weeks later, fever, headache, and malaise occur. Regional lymph nodes become enlarged, often tender, and may suppurate. Lymphadenopathy from cat scratches resembles that due to neoplasm, tuberculosis, lymphogranuloma venereum, and bacterial lymphadenitis. The diagnosis is usually made clinically. Special cultures for bartonellae, serology, or excisional biopsy, though rarely necessary, confirm the diagnosis. The biopsy reveals necrotizing lymphadenitis and is itself not specific for cat-scratch disease. Cat-scratch disease is usually self-limited, requiring no specific therapy. Encephalitis occurs rarely.
Disseminated forms of the disease—bacillary angiomatosis, peliosis hepatis, and retinitis—occur most commonly in immunocompromised patients such as persons with late stages of HIV or solid organ transplant recipients. The lesions are vasculoproliferative and histopathologically distinct from those of cat-scratch disease. Unexplained fever in patients with late stages of HIV infection is not uncommonly due to bartonellosis. B quintana, the agent of trench fever, can also cause bacillary angiomatosis and persistent bacteremia or endocarditis (which will be “culture-negative” unless specifically sought), the latter two entities being associated with homelessness. Due to the fastidious nature of the organism and its special growth requirements, serologic testing (eg, demonstration of a high antibody titer in an indirect immunofluorescence assay) or nucleic acid amplification tests are often required to establish a diagnosis.
The disseminated forms of the disease (bacillary angiomatosis, peliosis hepatis, and retinitis) require a prolonged course of antibiotic therapy often in combination with a second agent. Bacteremia and endocarditis can be effectively treated with a 6-week course of doxycycline (200 mg orally or intravenously in two divided doses per day) plus either gentamicin 3 mg/kg/day intravenously or rifampin 600 mg/day orally in two divided doses. Relapse may occur.
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