Bartonella sp are gram-negative bacteria previously classified as Rickettsiae. They cause several uncommon diseases: cat-scratch disease, an acute febrile anemia, a chronic cutaneous eruption, and disseminated disease in immunocompromised hosts (see Table 1: Gram-Negative Bacilli: Some Bartonella Infections).
Cat-scratch disease is infection caused by Bartonella henselae. Symptoms are a local papule and regional lymphadenitis. Diagnosis is clinical and confirmed by biopsy. Treatment is with local heat application and analgesics.
The domestic cat is a major reservoir for B. henselae. The prevalence of B. henselae antibodies in US cats is 14 to 50%. About 99% of patients report contact with cats, most of which are healthy. The cat flea may be an additional vector. Children are most often affected.
Symptoms and Signs
Within 3 to 10 days after a scratch, most patients develop an erythematous, crusted papule (rarely, a pustule) at the scratch site. Regional lymphadenopathy develops within 2 wk. The nodes are initially firm and tender, later becoming fluctuant, and may drain with fistula formation. Fever, malaise, headache, and anorexia may accompany lymphadenopathy.
Unusual manifestations occur in 5 to 14% of patients: Parinaud's oculoglandular syndrome (conjunctivitis associated with palpable preauricular nodes) in 6%, neurologic manifestations (encephalopathy, seizures, neuroretinitis, myelitis, paraplegia, cerebral arteritis) in 2%, and hepatosplenic granulomatous disease in < 1%. Severe disseminated illness may occur in patients with AIDS.
Lymphadenopathy subsides spontaneously within 2 to 5 mo. Complete recovery is usual, except in severe neurologic or hepatosplenic disease, which may be fatal or have residual effects.
Diagnosis is confirmed by positive serum Ab titers or PCR testing of samples from lymph node aspirates. Immunocompromised patients and patients with systemic symptoms should also have blood cultures. Lymph node aspirates are rarely culture-positive.
Treatment in immunocompetent patients is local heat application and analgesics. If a lymph node is fluctuant, needle aspiration usually relieves the pain.
Antibiotic treatment is not clearly beneficial and generally should not be given for localized infection. Ciprofloxacin, gentamicin, or doxycycline may be used for bacteremia in AIDS patients. Prolonged therapy is usually necessary (eg, weeks to months) for bacteremia to clear. In vitro antibiotic susceptibilities often do not correlate with clinical results; testing often shows sensitivity to trimethoprim/sulfamethoxazole (TMP/SMX) and cephalosporins, but these drugs are clinically ineffective.
Oroya Fever and Verruga Peruana
Oroya fever and verruga peruana are infections caused by Bartonella bacilliformis. Oroya fever occurs after initial exposure; verruga peruana occurs after recovery from the primary infection.
Endemic only to the Andes Mountains in Colombia, Ecuador, and Peru, both diseases are passed from human to human by the Phlebotomus sandfly.
Symptoms include fever and profound anemia, which may be sudden or indolent in onset. The anemia is primarily hemolytic, but myelosuppression also occurs. Muscle and joint pain, severe headache, and often delirium and coma may occur. Superimposed bacteremia caused by Salmonella or other coliform organisms may occur. Mortality rates may exceed 50% in untreated patients.
Diagnosis is confirmed by blood cultures. Because Oroya fever is often complicated by Salmonella bacteremia, chloramphenicol 500 to 1000 mg po q 6 h for 7 days is the treatment of choice; some clinicians add another antibiotic, typically a β-lactam, but TMP/SMX, macrolides, and fluoroquinolones have also been used successfully.
This disorder manifests as multiple skin lesions that strongly resemble bacillary angiomatosis, usually occurring on the limbs and face. The lesions may persist for months to years and may be accompanied by pain and fever.
Verruga peruana is diagnosed by its appearance and sometimes by biopsy showing dermal angiogenesis. Treatment with most antibiotics produces remission, but relapse is common and requires prolonged therapy. Typical treatment is streptomycin 15 to 20 mg/kg IM once/day for 10 days or rifampin 10 mg/kg po once/day for 10 to 14 days. Ciprofloxacin 500 mg po bid for 7 to 10 days has been used successfully, as has azithromycin.
Bacillary angiomatosis is skin infection caused by Bartonella henselae or B. quintana.
Bacillary angiomatosis almost always occurs in immunocompromised people and is characterized by protuberant, reddish, berrylike lesions on the skin, often surrounded by a collar of scale. Lesions bleed profusely if traumatized. They may resemble Kaposi's sarcoma or pyogenic granulomas. Infection is spread by lice and ticks and probably by fleas from household cats. Disease may spread throughout the reticuloendothelial system, particularly in AIDS patients.
Diagnosis relies on histopathology of the skin lesions, cultures, and PCR analysis. The laboratory should be notified that Bartonella is suspected because special stains and prolonged culture growth are necessary.
Treatment is with erythromycin 500 mg po q 6 h or doxycycline 100 mg po q 12 h, continued for at least 3 mo.
(Wolhynia, Shin Bone, or Quintan Fever)
Trench fever is a louse- or tick-borne disease caused by Bartonella quintana or B. henselae and observed originally in military populations during World Wars I and II. Symptoms are an acute, recurring febrile illness, occasionally with a rash. Diagnosis is by blood culture. Treatment is with a macrolide or doxycycline.
Humans are the only reservoir. B. quintana is transmitted to humans when feces from infected lice are rubbed into abraded skin or the conjunctiva. B. henselae is transmitted by tick bites. Trench fever is endemic in Mexico, Tunisia, Eritrea, Poland, and the former Soviet Union and is reappearing in the homeless population in the US.
After a 14- to 30-day incubation period, onset is sudden, with fever, weakness, dizziness, headache, and severe back and leg pains. Fever may reach 40.5° C and persist for 5 to 6 days. In about half the cases, fever recurs 1 to 8 times at 5- to 6-day intervals. A transient macular or papular rash and, occasionally, hepatomegaly and splenomegaly occur. Relapses are common and have occurred up to 10 yr after the initial attack.
Trench fever should be suspected in people living where louse infestation is heavy. Leptospirosis, typhus, relapsing fever, and malaria must be considered.
The organism is identified by blood culture, although growth may take 1 to 4 wk. The disease is marked by persistent bacteremia during the initial attack, during relapses, and throughout the asymptomatic periods between relapses.
Although recovery is usually complete in 1 to 2 mo and mortality is negligible, bacteremia may persist for months after clinical recovery, and prolonged (> 1 mo) macrolide or doxycycline treatment may be needed. Body lice must be controlled (see Parasitic Skin Infections: Body lice). Patients with chronic bacteremia should be monitored for signs of endocarditis.
Last full review/revision August 2009 by Burke A. Cunha, MD