Adhesion and host cell modulation: critical pathogenicity determinants of Bartonella henselae

Bartonella henselae, the agent of cat scratch disease and the vasculoproliferative disorders bacillary angiomatosis and peliosis hepatis, contains to date two groups of described pathogenicity factors: adhesins and type IV secretion systems. Bartonella adhesin A (BadA), the Trw system and possibly filamentous hemagglutinin act as promiscous or specific adhesins, whereas the virulence locus (Vir)B/VirD4 type IV secretion system modulates a variety of host cell functions. BadA mediates bacterial adherence to endothelial cells and extracellular matrix proteins and triggers the induction of angiogenic gene programming. The VirB/VirD4 type IV secretion system is responsible for, e.g., inhibition of host cell apoptosis, bacterial persistence in erythrocytes, and endothelial sprouting. The Trw-conjugation system of Bartonella spp. mediates host-specific adherence to erythrocytes. Filamentous hemagglutinins represent additional potential pathogenicity factors which are not yet characterized. The exact molecular functions of these pathogenicity factors and their contribution to an orchestral interplay need to be analyzed to understand B. henselae pathogenicity in detail.

Molecular epidemiology of Bartonella henselae infection in human immunodeficiency virus-infected patients and their cat contacts, using pulsed-field gel electrophoresis and genotyping

Bartonella henselae causes severe disease in immunocompromised individuals. B. henselae was isolated from 12 human immunodeficiency virus (HIV)-infected individuals with bacillary angiomatosis and/or peliosis hepatis and from their 15 cat contacts. Specific associations between the 2 B. henselae genotypes, individual pulsed-field gel electrophoresis (PFGE) patterns, and different clinical syndromes and pathogenicity were investigated. The role of cat contacts as the source of human infection was also examined. Three of the 4 patients with B. henselae genotype I infection, but none of the 8 patients with genotype II infection, had hepatosplenic vascular proliferative lesions (P=.018). Four of 5 human-cat pairs had closely-related PFGE patterns and concordant results by 16S rDNA typing, which strongly suggests that human infection was caused by the cat contact. These results corroborate the major role of cats in the transmission of B. henselae to humans and suggest that B. henselae genotypes may induce different pathological features in HIV-infected patients.

Peliosis hepatis in a dog infected with Bartonella henselae

A 6-year-old spayed female Golden Retriever was examined because of generalized weakness and abdominal distention. Abdominal ultrasonography revealed a large quantity of peritoneal fluid. In addition, the liver appeared larger than normal and contained multiple, small, nodular masses and cyst-like structures. Abdominal exploratory surgery was performed, and 5 L of serosanguineous peritoneal fluid was removed. Gross lesions were not found in the stomach, kidneys, intestines, adrenal glands, or urinary bladder. There were diffuse cystic nodules in all liver lobes. The dog did not recover from anesthesia. A diagnosis of peliosis hepatis was made on the basis of gross and histologic appearance of the liver. A polymerase chain reaction assay revealed Bartonella henselae DNA in liver specimens. To our knowledge, this is the first report of molecular evidence of B henselae infection in a dog with peliosis hepatis.

Absence of Kaposi's sarcoma-associated herpesvirus DNA in bacillary angiomatosis-peliosis lesions

Bartonella henselae and B. quintana induce an unusual vascular proliferative tissue response known as bacillary angiomatosis (BA) and bacillary peliosis (BP) in some human hosts. The mechanisms of Bartonella-associated vascular proliferation remain unclear. Although host factors probably play a role, microbial coinfection has not been ruled out. Because of the vascular proliferative characteristics noted in both Kaposi's sarcoma (KS) and BA and occasional colocalization of KS and BA, the possibility was explored that KS-associated herpesvirus (KSHV) might be associated with BA lesions. Tissues with BA and positive and negative control tissues were tested for the presence of KSHV DNA by a sensitive polymerase chain reaction assay. Only 1 of 10 BA tissues, a splenic biopsy, was positive in this assay; this tissue was from a patient with concomitant KS of the skin. Thus, KSHV is probably not involved in the vascular proliferative response seen in BA-BP.

Peloisis hepatis due to Bartonella henselae in transplantation: a hemato-hepato-renal syndrome

BACKGROUND

Bacillary peliosis hepatis is an uncommon but well recognized disease due to disseminated Bartonella infections occurring predominantly in immunocompromised individuals infected with human immunodeficiency virus, type 1. A similar condition in the absence of Bartonella infection when described in organ transplant patients was felt to be secondary to azathioprine and/or cyclosporine.

METHODS

Herein, we report the first case of bacillary peliosis hepatis due to systemic Bartonella henselae infection in a patient after kidney transplant. The patient presented with severe anemia, persistent thrombocytopenia, and hepato-renal syndrome. DNA-based polymerase chain reactions (PCR), which allowed direct detection of both B henselae and quintana DNA in patient's peripheral blood and liver tissue, were used. Indirect immunofluorescence assay for Bartonella serology was performed on peripheral blood.

RESULTS

Histopathology of the liver biopsy demonstrated peliosis hepatis. Indirect immunofluorescence assay for Bartonella serology was positive, and B henselae DNA was identified by PCR in the peripheral blood and liver tissue. Treatment with a 3-month course of oral erythromycin resulted in an excellent clinical response.

CONCLUSIONS

The present case suggests that although various anti-rejection therapies and opportunistic infections are associated with hepatic and renal dysfunction along with bone marrow suppression, the diagnostic evaluation in this situation should include liver biopsy and a careful search for evidence of systemic Bartonella infection, e.g., exposure to cats, Bartonella serology, and Bartonella DNA by PCR. A reduction in immunosuppression and prolonged therapy with antibiotics such as erythromycin will often result in early recovery.

Molecular epidemiology of bartonella infections in patients with bacillary angiomatosis-peliosis

BACKGROUND

Bacillary angiomatosis and bacillary peliosis are vascular proliferative manifestations of infection with species of the genus bartonella that occur predominantly in patients infected with the human immunodeficiency virus. Two species, B. henselae and B. quintana, have been associated with bacillary angiomatosis, but culture and speciation are difficult, and there has been little systematic evaluation of the species-specific disease characteristics. We studied 49 patients seen over eight years who were infected with bartonella species identified by molecular techniques and who had clinical lesions consistent with bacillary angiomatosis-peliosis.

METHODS

In this case-control study, a standardized questionnaire about exposures was administered to patients with bacillary angiomatosis-peliosis and to 96 matched controls. The infecting bartonella species were determined by molecular techniques.

RESULTS

Of the 49 patients with bacillary angiomatosis-peliosis, 26 (53 percent) were infected with B. henselae and 23 (47 percent) with B. quintana. Subcutaneous and lytic bone lesions were strongly associated with B. quintana, whereas peliosis hepatis was associated exclusively with B. henselae. Patients with B. henselae infection were identified throughout the study period and were epidemiologically linked to cat and flea exposure (P< or =0.004), whereas those with B. quintana were clustered and were characterized by low income (P=0.003), homelessness (P = 0.004), and exposure to lice (P= 0.03). Prior treatment with macrolide antibiotics appeared to be protective against infection with either species.

CONCLUSIONS

B. henselae and B. quintana, the organisms that cause bacillary angiomatosis-peliosis, are associated with different epidemiologic risk factors and with predilections for involvement of different organs.

[A new bacterium: Rochalimaea]

Originally limited to trench fever, infections due to Rochalimaea now comprise manifestations particular to patients with human immunodeficiency virus (bacillary angiomatosis and hepatic peliosis), but also manifestations as diverse as isolated fever, septicaemia, endocarditis, lymphocytic meningitis, or central neurological disorders, in immunodepressed or immunocompetent subjects. The involvement of Rochalimaea in cat-scratch fever remains debated. Microbiological analysis used for diagnosis has been modified to allow isolation of these new bacteria, whose culture is slow and difficult, in the course of the above-cited clinical manifestations, which should further extend the range of Rochalimaea infections.

The epidemiology of bacillary angiomatosis and bacillary peliosis

OBJECTIVE

To determine environmental risk factors for bacillary angiomatosis-bacillary peliosis (BAP), and to confirm infection with Rochalimaea species.

DESIGN

Case-control study.

SETTING

Community and university hospitals and clinics.

PATIENTS

Case patients (N = 48) had biopsy-confirmed BAP. Controls (N = 94) were matched to patients by institution and by human immunodeficiency virus (HIV) serological status.

MAIN OUTCOME MEASURES

Clinical information was obtained from medical records. Subjects were queried about environmental exposures. Univariate odds ratios (ORs) with 95% confidence intervals (CIs) were determined. Bivariate analyses were performed on variables associated with disease by univariate analysis. DNA from 22 available case-patient tissues and from 22 control tissues was amplified with the polymerase chain reaction (PCR) using primers designed to detect Rochalimaea species.

RESULTS

We identified five HIV-negative, immunocompetent case patients; one HIV-negative, immunodeficient case patient; and 42 HIV-positive case patients. There were no significant differences between case patients and controls by race, sex, age, or risk factors for HIV infection. Owning a cat (OR, 2.8; CI, 1.4 to 5.8) and history of a recent cat lick (OR, 1.95; CI, 1.0 to 3.8), cat scratch (OR, 3.7; CI, 1.7 to 8.0), or cat bite (OR, 3.9; CI, 1.8 to 8.9) were associated with disease in the univariate analysis. In bivariate analyses, only the variables representing traumatic contact with a cat (bite or scratch) remained associated with disease. No other environmental exposure was associated with disease. The PCR amplified a DNA fragment of the size expected for Rochalimaea species in all 22 case-patient tissue specimens.

CONCLUSIONS

These data suggest that BAP is a new zoonosis associated with both traumatic exposure to cats and infection with Rochalimaea species or a closely related organism.

The epidemiology of bacillary angiomatosis and bacillary peliosis

OBJECTIVE

To determine environmental risk factors for bacillary angiomatosis-bacillary peliosis (BAP), and to confirm infection with Rochalimaea species.

DESIGN

Case-control study.

SETTING

Community and university hospitals and clinics.

PATIENTS

Case patients (N = 48) had biopsy-confirmed BAP. Controls (N = 94) were matched to patients by institution and by human immunodeficiency virus (HIV) serological status.

MAIN OUTCOME MEASURES

Clinical information was obtained from medical records. Subjects were queried about environmental exposures. Univariate odds ratios (ORs) with 95% confidence intervals (CIs) were determined. Bivariate analyses were performed on variables associated with disease by univariate analysis. DNA from 22 available case-patient tissues and from 22 control tissues was amplified with the polymerase chain reaction (PCR) using primers designed to detect Rochalimaea species.

RESULTS

We identified five HIV-negative, immunocompetent case patients; one HIV-negative, immunodeficient case patient; and 42 HIV-positive case patients. There were no significant differences between case patients and controls by race, sex, age, or risk factors for HIV infection. Owning a cat (OR, 2.8; CI, 1.4 to 5.8) and history of a recent cat lick (OR, 1.95; CI, 1.0 to 3.8), cat scratch (OR, 3.7; CI, 1.7 to 8.0), or cat bite (OR, 3.9; CI, 1.8 to 8.9) were associated with disease in the univariate analysis. In bivariate analyses, only the variables representing traumatic contact with a cat (bite or scratch) remained associated with disease. No other environmental exposure was associated with disease. The PCR amplified a DNA fragment of the size expected for Rochalimaea species in all 22 case-patient tissue specimens.

CONCLUSIONS

These data suggest that BAP is a new zoonosis associated with both traumatic exposure to cats and infection with Rochalimaea species or a closely related organism.

Immunocytochemical identification of Rochalimaea henselae in bacillary (epithelioid) angiomatosis, parenchymal bacillary peliosis, and persistent fever with bacteremia

We report the immunocytochemical identification of Rochalimaea henselae, a newly recognized fastidious, Gram-negative, Warthin-Starry-positive organism, as the common pathogen in bacillary angiomatosis (BA), bacillary peliosis (BP) of the liver and spleen, and persistent fever with bacteremia in immunocompromised patients. Immunogenic proteins of the R. henselae strain isolated from the blood of a febrile immunocompromised patient with BP of the liver were used to produce primary immune serum in rabbits. Using immunocytochemical procedures, the polyclonal antiserum reacted strongly not only with the immunizing strain of the bacteria, but also with other blood isolates of R. henselae (five cases) from both immunocompromised and immunocompetent patients and with the organisms present in the tissue lesions of cutaneous BA (five cases) and BP of the liver (two cases) and spleen (one case). The blood isolates and BA and BP tissue samples were obtained from widely separated geographic areas. The antiserum was weakly cross-reactive with cultures of Rochalimaea quintana, an organism closely related to R. henselae, but this reactivity was eliminated by specific adsorption. The antiserum did not cross-react with the Warthin-Starry-positive organisms associated with cat scratch disease (Afipia felis), syphilis (Treponema pallidum), Lyme disease (Borrelia burgdorferi) or chronic active gastritis (Helicobacter pylori). Likewise, the antiserum did not identify organisms in eight cases of Kaposi's sarcoma, a disorder of immunocompromised patients that is clinically similar to BA. Further studies are needed to determine the prevalence of this newly recognized organism as well as its possible involvement in other angioproliferative diseases.

Bacillary peliosis hepatis as a cause of acute anemia in a patient with the acquired immunodeficiency syndrome

A 33-year-old white homosexual man, infected with the human immunodeficiency virus, presented with acute anemia and thrombocytopenia not responsive to transfusions or to treatment with steroids and intravenous gamma-globulin. Hematologic workup was compatible with peripheral sequestration or loss of blood cells; however, there was no evidence of gastrointestinal or other sources of hemorrhage, and the only significant finding was a progressive liver enlargement. An abdominal computerized tomographic scan showed a massive homogeneous liver without focal lesions, a very small amount of ascites, and no retroperitoneal fluid collections. A transjugular liver biopsy specimen showed the cystic, blood-filled cavities characteristic of peliosis hepatis. Cavities varied in size, all contained pooled erythrocytes, and some had areas suggestive of thrombi in various stages of organization. Bacteria similar in morphology to those described in bacillary peliosis hepatis were seen in the peliotic spaces. The clinical picture began resolving shortly after treatment with zidovudine and ampicillin/sulbactam was started and had totally resolved 6 months after presentation. This case shows that bacillary peliosis hepatis is a reversible entity that may produce acute sequestration of blood in the liver.

Rochalimaea henselae causes bacillary angiomatosis and peliosis hepatis

BACKGROUND

Recent studies have demonstrated that a newly described agent of persistent bacteremia, Rochalimaea henselae, and the agent of bacillary angiomatosis are both closely related to Rochalimaea quintana. Bacillary peliosis hepatis seemed likely to have the same etiologic agent as bacillary angiomatosis. We sought these pathologic changes in patients from whom R henselae was cultivated.

METHODS

For two patients whose histopathologic findings we reviewed, additional light and electron microscopy were performed. Their bacterial isolates were compared by electrophoretic patterns of outer membrane proteins, restriction endonuclease digestion patterns of DNA, and reaction with murine antiserum.

RESULTS

A previously reported human immunodeficiency virus-infected man with persistent bacteremia due to R henselae was found to have bacillary peliosis hepatis. Rochalimaea henselae was also isolated from the spleen of a woman receiving immunosuppressive therapy after allogeneic renal transplantation. She had developed fever, liver and spleen nodules, and periaortic lymphadenopathy. Bacillary peliosis of her liver and spleen, as well as bacillary angiomatosis of liver, spleen, and a lymph node, were found. The bacterial isolates had comparable electrophoretic patterns of outer membrane proteins and of restriction endonuclease-digested DNA, which differed from the respective patterns of R quintana. Murine antisera raised to the first isolate reacted strongly with the second by means of immunoblot and immunofluorescence techniques, while reacting only weakly with R quintana.

CONCLUSION

Rochalimaea henselae, recently recognized to cause persistent fever and bacteremia in immunocompetent and immunocompromised persons, also causes bacillary angiomatosis and parenchymal bacillary peliosis.

Rochalimaea henselae sp. nov., a cause of septicemia, bacillary angiomatosis, and parenchymal bacillary peliosis

Nine strains of Rochalimaea spp. that were isolated from patients over a period of 4.5 years were characterized for their enzyme activities, cellular fatty acid compositions, and DNA interrelatedness among Rochalimaea spp., Bartonella bacilliformis, and Afipia felis (cat scratch disease bacillus). All except one isolate, which was Rochalimaea quintana, were determined to belong to a newly proposed species, Rochalimaea henselae sp. nov. After recovery from clinical material, colonies required 5 to 15 days of incubation to become apparent. Cells were small, gram-negative, curved bacilli and displayed twitching motility. Enzyme specificities for amino acid and carbohydrate substrates showed that R. henselae could be distinguished from Rochalimaea vinsonii by L-arginyl-L-arginine and L-lysyl-L-alanine peptidases, but not all strains could be distinguished from R. quintana on the basis of peptidases or carbohydrate utilization. R. henselae also closely resembled R. quintana in cellular fatty acid composition, with both consisting mainly of C18:1, C18:0, and C16:0 fatty acids. However, the strains of R. henselae all contained C18:0 in amounts averaging greater than or equal to 22%, in contrast to R. quintana, which contained this cellular fatty acid in amounts averaging 16 and 18%. DNA hybridization confirmed the identification of one clinical isolate as R. quintana and showed a close interrelatedness (92 to 100%) among the other strains. Under optimal conditions for DNA reassociation, R. henselae showed approximately 70% relatedness to R. quintana and approximately 60% relatedness to R. vinsonii. Relatedness with DNA from B. baciliformis was 43%. R. henselae was unrelated to A. felis. R. henselae is the proposed species of a newly recognized member of the family Rickettsiaceae, which is a pathogen that may be encountered in immunocompromised or immunocompetent patients. Prolonged fever with bacteremia or vascular proliferative lesions are clinical manifestations of the agent.