The role of the host immune response in pathogenesis of Bartonella henselae

Adult systemic cat scratch disease associated with therapy for hepatitis C

Background

We describe the first case of systemic cat scratch disease in a patient receiving peginterferon α-2a and ribavirin for treatment of hepatitis C. Cases of adult systemic CSD are extremely infrequent and immunomodulatory treatment for hepatitis C has been associated with aberrant host responses to common pathogens.

Case presentation

A 52 year old man being treated for hepatitis C presented with diffuse lymphadenopathy, weight loss, fevers and splenic lesions. Symptoms were initially confused with adverse effects of his regimen, delaying recognition of his infection. Diagnostic investigation, including histopathology, microbiology and serologic parameters, confirmed that his illness was due to disseminated cat scratch disease with Bartonella henselae.

Conclusion

Disseminated CSD is exceptionally rare in adults. We describe the first case of disseminated cat scratch disease associated with peginterferon α and ribavirin to alert clinicians of the need to be aware of unusual manifestations of common infections in this population.

Prevalence of Bartonella henselae antibodies in serum of cats with and without clinical signs of central nervous system disease

Bartonella henselae is occasionally associated with neurological dysfunction in people and some experimentally infected cats. The purpose of this study was to determine whether B henselae seroprevalence or titer magnitude varies among cats with neurological disease, cats with non-neurological diseases, and healthy cats while controlling for age and flea exposure. There was no difference in B henselae seroprevalence rates between cats with seizures and cats with other neurological diseases. Cats with non-neurological disease and healthy cats were more likely than cats with neurological disease to be seropositive. While the median B henselae antibody titer was greater in cats with seizures than in cats with other neurological disease, the median B henselae antibody titer was also greater in healthy cats than cats with seizures. The results suggest that titer magnitude cannot be used alone to document clinical disease associated with B henselae infection and that presence of B henselae antibodies in serum of cats with neurological disease does not prove the clinical signs are related to B henselae.

Genome rearrangements, deletions, and amplifications in the natural population of Bartonella henselae

Cats are the natural host for Bartonella henselae, an opportunistic human pathogen and the agent of cat scratch disease. Here, we have analyzed the natural variation in gene content and genome structure of 38 Bartonella henselae strains isolated from cats and humans by comparative genome hybridizations to microarrays and probe hybridizations to pulsed-field gel electrophoresis (PFGE) blots. The variation in gene content was modest and confined to the prophage and the genomic islands, whereas the PFGE analyses indicated extensive rearrangements across the terminus of replication with breakpoints in areas of the genomic islands. We observed no difference in gene content or structure between feline and human strains. Rather, the results suggest multiple sources of human infection from feline B. henselae strains of diverse genotypes. Additionally, the microarray hybridizations revealed DNA amplification in some strains in the so-called chromosome II-like region. The amplified segments were centered at a position corresponding to a putative phage replication initiation site and increased in size with the duration of cultivation. We hypothesize that the variable gene pool in the B. henselae population plays an important role in the establishment of long-term persistent infection in the natural host by promoting antigenic variation and escape from the host immune response.

Characterization of Th1 activation by Bartonella henselae stimulation in BALB/c mice: Inhibitory activities of interleukin-10 for the production of interferon-gamma in spleen cells

This study was conducted to analyze cytokine production mechanisms in mice after Bartonella henselae stimulation. BALB/c mice were inoculated intraperitoneally with 3 x 10(6) colony forming units of B. henselae (Houston-1 strain) twice at 10-day interval. Spleen cells were harvested from the mice and stimulated with the organisms. Following the stimulation, interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), IL-10, IL-12 and tumor necrosis factor-alpha (TNF-alpha) were measured in the culture supernatants of the spleen cells by ELISA. The spleen cells specifically secreted IFN-gamma, but not IL-4, indicating that T helper 1 (Th1) cells were activated following B. henselae stimulation. In addition, IL-10 and TNF-alpha productions were also detected in the culture supernatants of spleen cells. Neutralization of IL-10 in the culture supernatants significantly enhanced the production of IFN-gamma from the spleen cells stimulated with B. henselae. These results indicate that B. henselae predominantly stimulated Th1 cells and resulted in secreting IFN-gamma, however the production was partially inhibited by IL-10, which was produced simultaneously.

Disseminated Bartonella infection following liver transplantation*

Bartonella henselae has not only been identified as the causative agent of cat scratch disease, but it is also associated with other significant infectious syndromes in the immunocompromised population. We describe two cases of B. henselae associated diseases in liver transplant recipients who both had contact with cats. The first recipient developed localized skin manifestation of bacillary angiomatosis in association with granulomatous hepatitis. He tested positive for Immunoglobulin G (IgG) antibodies against B. henselae. The second patient developed axillary lymphadenopathy, with biopsy showing necrotizing granulomatous inflammation and polymerase chain reaction studies were positive for B. henselae DNA. Her serology for bartonellosis showed a fourfold rise in antibody titers during her hospitalization. Both patients responded to treatment with Azithromycin in combination with Doxycycline. These were the only cases within a series of 467 consecutive liver transplants performed in 402 patients performed during a 4-year period. Although bartonellosis is a rare infection in liver transplantation recipients, it should always be included in the differential diagnosis of patients presenting with fever, central nervous system (CNS) symptoms, skin lesions, lymphadenopathy, and hepatitis especially if prior contact with cats is reported.

Broad-range polymerase chain reaction for the diagnosis of Bartonella henselae endocarditis

We present a case of subacute bacterial endocarditis in a 10-year-old girl with Di-George syndrome, congenital heart disease, and mild immunodeficiency. She was afebrile at initial presentation but was found to have massive splenomegaly, and signs of congestive heart failure. No causative organism could be identified on routine blood and tissue cultures. A detailed clinical history revealed a history that she had been scratched by a cat and developed intermittant fevers over 3 months. Bartonella henselae was identified by broad-range 16S r-DNA polymerase chain reaction on valvular tissue specimens.

Okuloglanduläres Syndrom nach Parinaud

Two cases of Parinaud's oculoglandular syndrome, which represents an ocular manifestation of cat-scratch disease, are reported. The symptoms are subacute and include unilateral conjunctivitis and pre-auricular lymphadenopathy. Diagnosis primarily relies on the recognition of suggestive clinical signs in conjunction with positive serologic testing. In most cases, therapy is not necessary.

Primary Left Ventricular Angiomatosis First Description of a Rare Vascular Tumor in the Left Heart

A 24 year-old male who presented with palpitations and presyncopal attacks had monomorphic ventricular tachycardia and a well-defined huge mass within the inferoposterior wall of the left ventricle proved by transthoracic echocardiography. The mass was completely resected and shown to be proliferative angiomatosis by histopathologic examination. This is the first reported case of primary left ventricular angiomatosis in the literature.

Cat-scratch disease in elderly patients

BACKGROUND

Cat-scratch disease (CSD) is mostly contracted by children and young adults. To our knowledge, CSD in elderly patients has never been characterized, and it may be underrecognized in this age group.

METHODS

The study population included all patients with CSD diagnosed at our reference laboratory during 1991-2002. Demographic, clinical, and laboratory data for patients with CSD aged >or=60 years (elderly group) were compared with data for patients with CSD aged <60 years (nonelderly group).

RESULTS

There were 846 immunocompetent patients with CSD included in this study. Fifty-two patients (6%) were >or=60 years old. Lymphadenopathy was less common in elderly patients than in nonelderly patients (76.5% vs. 94.4%; P<.001), and general malaise was more frequent in elderly patients (70.8% vs. 51.4%; P=.009). Atypical CSD was more common in elderly patients than in nonelderly patients (32.7% vs. 13.6%), including endocarditis (odds ratio [OR], 61.6; P<.001), encephalitis (OR, 6.3; P=.013), and fever of unknown origin (OR, 7.3; P<.001). The time period from onset of symptoms to diagnosis was >6 weeks for 29.5% of elderly patients versus 13.3% of nonelderly patients (P=.003).

CONCLUSIONS

CSD affects elderly persons as well as nonelderly persons, but clinical features differ between the patient groups. Atypical CSD, including endocarditis, is more frequent in elderly than in nonelderly patients. Conversely, lymphadenitis, the hallmark of typical CSD, is often absent in elderly patients. Lack of awareness among clinicians may delay the diagnosis of CSD in elderly persons and result in unnecessary and often invasive diagnostic procedures.

Bartonellosis: light and shadows in diagnostic and therapeutic issues

Cat-scratch disease involves a prolonged and/or complicated course, and lymph node drainage is usually required. Culture and molecular techniques often yield negative results, but immunofluorescence assays may give early information, and elevated antibodies may persist for months. Cat-scratch disease should be suspected in patients with prominent swelling of lymph nodes draining from the upper limbs, limited systemic involvement, and typical epidemiological-clinical features. The temporal antibody response during the sub-acute course remains unknown. Although biomolecular assays are available, the time between onset and investigation is an obstacle to positive results. The role of surgical debridement and the unpredictable activity of antimicrobial agents warrant further investigation.

Molecular and Cellular Basis ofBartonellaPathogenesis

The genus Bartonella comprises several important human pathogens that cause a wide range of clinical manifestations: cat-scratch disease, trench fever, Carrion's disease, bacteremia with fever, bacillary angiomatosis and peliosis, endocarditis, and neuroretinitis. Common features of bartonellae include transmission by blood-sucking arthropods and the specific interaction with endothelial cells and erythrocytes of their mammalian hosts. For each Bartonella species, the invasion and persistent intracellular colonization of erythrocytes are limited to a specific human or animal reservoir host. In contrast, endothelial cells are target host cells in probably all mammals, including humans. Bartonellae subvert multiple cellular functions of human endothelial cells, resulting in cell invasion, proinflammatory activation, suppression of apoptosis, and stimulation of proliferation, which may cumulate in vasoproliferative tumor growth. This review summarizes our understanding of Bartonella-host cell interactions and the molecular mechanisms of bacterial virulence and persistence. In addition, current controversies and unanswered questions in this area are highlighted.