BARTONELLA-ASSOCIATED INFECTIONS

Although descriptions of infections caused by Bartonella (formerly Roc halimaea), such as Oroya fever, trench fever, and cat-scratch disease (CSD), have existed for more than 50 years, much of the current unders tanding of Bartonella-associated infections has resulted from the AIDS epidemic. In 1983, Stoler et al(94) provided the first report of a Ba rtonella-associated infection in an HIV-infected individual. This repo rt described an AIDS patient from New York who developed multiple subc utaneous vascular nodules that contained numerous bacillary organisms visualized by electron microscopy. Additional reports in the late 1980 s described patients with similar cutaneous lesions, and these vascula r proliferative lesions became known as bacillary angiomatosis (BA).(5 2) During this time, however, investigators could not cultivate an org anism from these lesions, and the cause remained unidentified. In a De cember 1990 issue of the New England Journal of Medicine, separate gro ups of investigators respectively described three key new findings: (1 ) the close relationship of a DNA sequence from the bacillus in BA tis sue to the agent of trench fever, Rochalimaea quintana; (2) the isolat ion of a small, fastidious, gramnegative rod from patients with relaps ing bacteremia; and (3) the association of a small bacillus with the u nusual histopathologic entity of peliosis hepatis in the livers of HIV -infected patients.(76, 81, 88) These three research groups soon reali zed that their separate findings involved the same organism. This newl y-recognized bacillary organism, which was subsequently named Rochalim aea henselae,(79 102) was initially presumed to be the sole agent of B A. In 1992, however, Kcehler et al(47) became the first group to isola te organisms from BA lesions, and in this process demonstrated that ei ther R. quintana or R. henselae can cause BA. The four species belongi ng to the genus of Rochalimaea were moved to the genus of Bartonella i n 1993 after genetic studies showed the close relationship between the Rochalimaea species and B. bacilliformis, the original member of the genus Bartonella.(14) More recently, the genus of Grahamella was merge d with the genus of Bartonella, and at present, nine cultivated specie s belong to the genus Bartonella.(11) Four of these species, B. bacill iformis, B. henselae, B, quintana, and B. elizabethne, have been docum ented to be pathogenic in humans. Four species, B. vinsonii, B. graham ii, B, taylorii, and B. doshine, were isolated from small wild mammals , and B. clarridgeiae was isolated from a domestic cat.(3, 10, 26, 51) In addition, one group recently isolated a subspecies of B. vinsonii from a dog with endocarditis.(13) The spectrum of diseases caused by B artonella has rapidly expanded to include BA(47, 81) bacillary peliosi s,(76, 102) relapsing bacteremia,(59, 88) endocarditis,(28, 33) (90, 9 1) and ''urban trench fever.''(92) Moreover, in 1995 Regnery et al(80) demonstrated antibodies to Bartonella species in a panel of banked se ra from immunocompetent patients with a clinical diagnosis of CSD, thu s contradicting the initial belief that Afipia felis was the causative agent of CSD. Subsequently, B. henselae was isolated from the lymph n odes of two patients with apparent CSD and B. henselae DNA was detecte d by polymerase chain reaction (PCR) in specimens from patients with C SD.(2, 31) In addition, the domestic cat was identified as the major r eservoir for B. henselae.(45) Taken together, these data from 1992 to 1994 convincingly identified B. henselae, not A. felis, as the predomi nant causative organism of CSD. Bartonella species represent a fascina ting group of emerging pathogens. This article presents a summary of t he manifestations of human Bartonella infections identified at present in North America and in Europe, but will not discuss B. bacilliformis , an infection predominantly limited to South America. Although consid erable knowledge of Bartonella-associated infections has been gained, much data remain to be gathered to better define disease spectrum, pre valence, maintenance, and mode of transmission.