Epithelioid haemangioma-like vascular proliferation in AIDS: manifestation of cat scratch disease bacillus infection?

Kaposi's Sarcoma: A Clinico-Pathologic Overview

A careful overview of the classical appearances of Kaposi's sarcoma (KS) as well as of its variants were reviewed from the clinical and pathological point of view. The growth phases (stages) and the cellular patterns were histopathologically compared with emphasis on the developmental progression of disease as well as mitotic activity. Other morphological aspects were also assessed such as the features of the early phases and the incidence of hyaline bodies. One hundred and forty-three lesions from 96 patients mostly of the Italian sporadic type were investigated. A complete list of those entities which should be considered in differential diagnosis is shown and the dilemma of whether KS is a neoplasia or a hyperplasia is discussed.

Surgical Pathologic Diagnosis

Surgical pathology results can play a crucial role in the management of immunocompromised patients. Here we highlight factors that differ between immunocompromised and immunocompetent hosts, such as variation in inflammatory response. Conditions that are covered include drug reactions, disease within solid organ allografts, immune reconstitution inflammatory syndrome, specific immunodeficiency syndromes, neoplasms related to viral infections, and viral, bacterial, fungal, and parasitic infections. Special techniques including immunohistochemistry, in situ hybridization and molecular detection of pathogen nucleic acid from formalin-fixed, paraffin-embedded tissue are discussed.

Accuracy of Clinical Suspicion and Pathologic Diagnosis of Kaposi Sarcoma in East Africa

BACKGROUND

HIV-associated Kaposi sarcoma (KS) is one of the most common malignancies in sub-Saharan Africa. The diagnosis is often based on clinical suspicion, without histopathologic confirmation. When biopsies are performed, the accuracy of interpretation by local pathologists is poorly understood. We assessed the accuracy of clinical suspicion and pathologic diagnosis of KS in 2 East African countries.

METHODS

At 2 large HIV care sites in Uganda and Kenya, we evaluated consecutive biopsies performed from October 2008 to January 2013 on HIV-infected adults with clinically suspected KS. Biopsies were interpreted by both local African pathologists and a group of US-based dermatopathologists from a high volume medical center. For the purpose of this analysis, the US-based dermatopathologist interpretation was used as the gold standard. Positive predictive value was used to characterize accuracy of local African clinical suspicion of KS, and concordance, sensitivity, and specificity were used to characterize accuracy of local pathologic diagnosis.

RESULTS

Among 1106 biopsies, the positive predictive value of clinical suspicion of KS was 77% (95% confidence interval: 74% to 79%). When KS was not histopathologically diagnosed, clinically banal conditions were found in 35%, medically significant disorders which required different therapy in 59% and life-threatening diseases in 6%. Concordance between African pathologists and US-based dermatopathologists was 69% (95% confidence interval: 66% to 72%). Sensitivity and specificity of African pathologic diagnoses were 68% and 89%, respectively.

CONCLUSIONS

Among East African HIV-infected patients, we found suboptimal positive predictive value of clinical suspicion of KS and specific, but not sensitive, histopathologic interpretation. The findings call for abandonment of isolated clinical diagnosis of KS in the region and augmentation of local dermatopathologic services.

Selected Zoonoses

Human risks of acquiring a zoonotic disease from animals used in biomedical research have declined over the last decade because higher quality research animals have defined microbiologic profiles. Even with diminished risks, the potential for exposure to infectious agents still exists, especially from larger species such as nonhuman primates, which may be obtained from the wild, and from livestock, dogs, ferrets, and cats, which are generally not raised in barrier facilities and are not subject to the intensive health monitoring performed routinely on laboratory rodents and rabbits. Additionally, when laboratory animals are used as models for infectious disease studies, exposure to microbial pathogens presents a threat to human health. Also, with the recognition of emerging diseases, some of which are zoonotic, constant vigilance and surveillance of laboratory animals for zoonotic diseases are still required.

Intruders below the radar: molecular pathogenesis of Bartonella spp

Bartonella spp. are facultative intracellular pathogens that employ a unique stealth infection strategy comprising immune evasion and modulation, intimate interaction with nucleated cells, and intraerythrocytic persistence. Infections with Bartonella are ubiquitous among mammals, and many species can infect humans either as their natural host or incidentally as zoonotic pathogens. Upon inoculation into a naive host, the bartonellae first colonize a primary niche that is widely accepted to involve the manipulation of nucleated host cells, e.g., in the microvasculature. Consistently, in vitro research showed that Bartonella harbors an ample arsenal of virulence factors to modulate the response of such cells, gain entrance, and establish an intracellular niche. Subsequently, the bacteria are seeded into the bloodstream where they invade erythrocytes and give rise to a typically asymptomatic intraerythrocytic bacteremia. While this course of infection is characteristic for natural hosts, zoonotic infections or the infection of immunocompromised patients may alter the path of Bartonella and result in considerable morbidity. In this review we compile current knowledge on the molecular processes underlying both the infection strategy and pathogenesis of Bartonella and discuss their connection to the clinical presentation of human patients, which ranges from minor complaints to life-threatening disease.

Ocular bacillary angiomatosis in an immunocompromised man

An immunocompromised man presented with an inflammatory eyelid lesion. Biopsy was performed; histopathology and special staining confirmed a diagnosis of bacillary angiomatosis. The man was treated with oral erythromycin, and the lesion resolved. The etiologic agents of bacillary angiomatosis are Bartonella henselae and Bartonella quintana, Gram-negative coccobacilli. The organisms stain positively with the Warthin-Starry silver stain. Lesions can be cutaneous or visceral and have been commonly described in immunocompromised patients. Histopathologic examination of lesions reveals angiogenesis and cellular proliferation. Bacillary angiomatosis can be treated with oral antibiotics.

[Bartonella henselae, an ubiquitous agent of proteiform zoonotic disease]

Bartonella henselae is the causative agent of cat scratch disease, a human infection usually characterized by persistent regional lymphadenopathy. It is transmitted to humans by cat scratches or bites. Cats are the major reservoir for this bacterium thus B. henselae has a worldwide distribution. The bacterial pathogenicity may bay emphasized by the immune status of the infected host. Angiomatosis or hepatic peliosis are the most frequent clinical manifestations in immunocompromised patients. B. henselae is also responsible for endocarditis in patients with valvular diseases, and may induce various clinical presentations such as: bacteriemia, retinitis, musculoskeletal disorders, hepatic or splenic diseases, encephalitis, or myocarditis. Several diagnostic tools are available; they may be combined and adapted to every clinical setting. B. henselae is a fastidious bacterium; its diagnosis is mainly made by PCR and blood tests. No treatment is required for the benign form of cat scratch disease. For more severe clinical presentations, the treatment must be adapted to every clinical presentation.

Bacterial Infections

In Osier’s time, bacterial pneumonia was a dreaded event, so important that he borrowed John Bunyan’s characterization of tuberculosis and anointed the pneumococcus, as the prime pathogen, “Captain of the men of death.”1 One hundred years later much has changed, but much remains the same. Pneumonia is now the sixth most common cause of death and the most common lethal infection in the United States. Hospital-acquired pneumonia is now the second most common nosocomial infection.2 It was documented as a complication in 0.6% of patients in a national surveillance study,3 and has been reported in as many as 20% of patients in critical care units.4 Furthermore, it is the leading cause of death among nosocomial infections.5 Leu and colleagues6 were able to associate one third of the mortality in patients with nosocomial pneumonia to the infection itself. The increase in hospital stay, which averaged 7 days, was statistically significant. It has been estimated that nosocomial pneumonia produces costs in excess of $500 million each year in the United States, largely related to the increased length of hospital stay.

Bartonella-induced endothelial cell proliferation is mediated by release of calcium from intracellular stores

The facultative intracellular bacterium Bartonella henselae induces unique angiogenic lesions in immunocompromised hosts. To determine the role of intracellular calcium pools in B. henselae-induced endothelial cell proliferation, we generated B. henselae-conditioned medium (BCM) and tested the ability of these cell-free proteins to induce human umbilical vein endothelial cell (HUVEC) proliferation, CXCL8 production, and intracellular Ca2+ signals. HUVECs incubated with BCM for 3 days had higher cell numbers than controls. In addition, HUVECs produced increased amounts of CXCL8 in response to BCM when compared to medium controls. When BCM was added to HUVECs and the intracellular Ca2+ response measured with the calcium-sensitive dye fura-2/AM, a Ca2+ rise was demonstrated. It was determined that this Ca2+ rise originated from intracellular Ca2+ stores through the use of the Ca2+ ATPase inhibitor thapsigargin. Further, it was demonstrated that BCM enhanced CXCL8 production and HUVEC proliferation in a Ca2+-dependent manner. Conditioned medium from B. henselae causes an intracellular Ca2+ rise in HUVECs, which is involved in B. henselae-induced HUVEC proliferation and CXCL8 production. These results implicate intracellular Ca2+ pools in B. henselae-induced angiogenesis and may lead to increased understanding of the mechanisms of pathogen-induced angiogenesis.

Bacillary Angiomatosis Associated With Pseudoepitheliomatous Hyperplasia

Bacillary angiomatosis is an opportunistic bacterial infection caused by either Bartonella henselae or B. quintana. The classic histologic presentation of bacillary angiomatosis involves three components: a lobular proliferation of capillaries with enlarged endothelial cells, neutrophilic debris, and clumps of finely granular material identified as bacteria with staining techniques. Pseudoepitheliomatous hyperplasia is a histologic reaction pattern characterized by epithelial proliferation in response to a variety of stimuli, including mycobacterial, fungal, and bacterial infections. We describe a case of bacillary angiomatosis associated with pseudoepitheliomatous hyperplasia in an immunocompromised patient with Acquired Immunodeficiency Syndrome. Histologic examination of a finger lesion demonstrated a capillary proliferation with neutrophilic debris and characteristic amorphous granular deposits. Warthin-Starry and Giemsa staining revealed clumps of coccobacilli. Cervical lymph node tissue also revealed organisms identified as Bartonella with PCR techniques. Stains and cultures for acid fast bacilli, fungus, and bacteria were negative. To our knowledge, there has been only one other report of bacillary angiomatosis presenting with pseudoepitheliomatous hyperplasia. We conclude that the differential diagnosis of entities associated with pseudoepitheliomatous hyperplasia should be expanded to include bacillary angiomatosis.

Interaction of Bartonella henselae with endothelial cells promotes monocyte/macrophage chemoattractant protein 1 gene expression and protein production and triggers monocyte migration

Bacillary angiomatosis (BA), one of the many clinical manifestations resulting from infection with the facultative intracellular bacterium Bartonella henselae, is characterized by angiogenic lesions. Macrophages have been identified as important effector cells contributing to the angiogenic process during B. henselae infection by infiltrating BA lesions and secreting vascular endothelial growth factor. Monocyte-macrophage chemoattractant protein 1 (MCP-1) recruits macrophages to sites of inflammation. In this study, we investigated the ability of B. henselae to upregulate MCP-1 gene expression and protein production in the human microvascular endothelial cell line HMEC-1. MCP-1 mRNA was induced at 6 and 24 h after treatment with bacteria, whereas protein production was elevated at 6, 24, and 48 h. This induction was not dependent on the presence of bacterial lipopolysaccharide or endothelial cell toll-like receptor 4. However, MCP-1 production was dependent on NF-kappaB activity. Outer membrane proteins of low molecular weight were able to upregulate MCP-1 production. Furthermore, supernatants from B. henselae-infected HMEC-1 were able to induce chemotaxis of THP-1 monocytes. These data suggest a mechanism by which the macrophage effector cell is recruited to the endothelium during B. henselae infection and then contributes to bacterial-induced angiogenesis.

Induction of a potential paracrine angiogenic loop between human THP-1 macrophages and human microvascular endothelial cells during Bartonella henselae infection

Bartonella henselae is responsible for various disease syndromes that loosely correlate with the immune status of the host. In the immunocompromised individual, B. henselae-induced angiogenesis, or bacillary angiomatosis, is characterized by vascular proliferative lesions similar to those in Kaposi's sarcoma. We hypothesize that B. henselae-mediated interaction with immune cells, namely, macrophages, induces potential angiogenic growth factors and cytokines which contribute in a paracrine manner to the proliferation of endothelial cells. Vascular endothelial growth factor (VEGF), a direct inducer of angiogenesis, and interleukin-1beta (IL-1beta), a potentiator of VEGF, were detected within 12 and 6 h, respectively, in supernatants from phorbol 12-myristate 13-acetate-differentiated human THP-1 macrophages exposed to live B. henselae. Pretreatment of macrophages with cytochalasin D, a phagocytosis inhibitor, yielded comparable results, suggesting that bacterium-cell attachment is sufficient for VEGF and IL-1beta induction. IL-8, an angiogenic cytokine with chemotactic properties, was induced in human microvascular endothelial cells (HMEC-1) within 6 h of infection, whereas no IL-8 induction was observed in infected THP-1 cells. In addition, conditioned medium from infected macrophages induced the proliferation of HMEC-1, thus demonstrating angiogenic potential. These data suggest that Bartonella modulation of host or target cell cytokines and growth factors, rather than a direct role of the bacterium as an endothelial cell mitogen, is the predominant mechanism responsible for angiogenesis. B. henselae induction of VEGF, IL-1beta, and IL-8 outlines a broader potential paracrine angiogenic loop whereby macrophages play the predominant role as the effector cell and endothelial cells are the final target cell, resulting in their proliferation.

Unsuspected extralymphocutaneous dissemination in febrile cat scratch disease

Cat scratch disease (CSD) commonly manifests as regional self-limited lymphadenitis. However, dissemination of the infection to distant multiple sites may occur even in immunocompetent patients. We report a series of 11 children with fever and extralymphocutaneous manifestations of CSD, in order to highlight potential multiorgan involvement in patients with febrile CSD. To be eligible for enrollment, patients had to present with involvement of sites other than regional lymph nodes. The diagnosis was based on suggestive clinical criteria, histological findings and positive serology. The utilization of ultrasound imaging revealed hepatic lesions in 3 children and splenic lesions in 8 children, whereas osteolytic lesions were observed in 4 children by bone scan. Hepatic or splenic involvement was not suggested by clinical signs or biochemical investigation in 2/3 and 6/8 children, respectively. Bone involvement was supported either by relative symptoms or signs. Our findings indicate that, in the presence of fever, extralymphocutaneous manifestations have to be anticipated in patients with clinically suspected CSD. The systematic use of imaging modalities in patients with serologically documented Bartonella henselae infection could contribute to a better understanding of the clinical spectrum of CSD.

Imaging of musculoskeletal and spinal infections in AIDS

The diagnosis of common and opportunistic infections in patients with HIV begins with clinical suspicion and involves relatively standard methodology. Musculoskeletal infection is sometimes the first manifestation of an HIV infection. In patients with HIV, the infections tend to be more advanced at presentation, occur in unusual sites, are caused by a wider spectrum of pathogens, and tend to show an inadequate or delayed response to therapy. The index of suspicion for musculoskeletal infections should be high when reviewing imaging studies of patients with HIV.

Bartonella henselae, B. quintana, and B. bacilliformis: historical pathogens of emerging significance

Bartonella species were virtually unrecognized as modern pathogens of humans until the last decade. However, identification of Bartonella species as the agents of cat-scratch disease, bacillary angiomatosis, urban trench fever, and possible novel presentations of Carrion's disease has left little doubt of the emerging medical importance of this genus of organisms. The three primary human pathogenic bartonellae, Bartonella bacilliformis (Carrion's disease), B. henselae (cat-scratch disease), and B. quintana (trench fever), present noteworthy comparisons in the epidemiology, natural history, pathology, and host-microbe interaction that this review will briefly explore.

Species-specific monoclonal antibodies for rapid identification of Bartonella quintana

Seven species-specific monoclonal antibodies (MAbs) to Bartonella quintana were produced and characterized. The MAbs were of the immunoglobulin G class and reacted only with 13 B. quintana strains in indirect microimmunofluorescence and Western immunoblotting assays. They did not react with eight other Bartonella spp., including Bartonella henselae, the most closely related species, and a selected MAb did also not react with nine other strains of gram-negative bacteria. The MAbs reacted mainly with a 34-kDa protein epitope of B. quintana which was shown to be species specific by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four of five body lice experimentally infected with B. quintana were found to be positive for the organism in microimmunofluorescence assays with one MAb. These MAbs may provide a specific, simple, rapid, and low-cost tool for the identification of B. quintana and the diagnosis of infections due to the microorganism.

Bacillary angiomatosis in immunocompromised patients

OBJECTIVES

To report seven cases of bacillary angiomatosis; to evaluate the most useful diagnostic tools; to analyse the clinical and epidemiological features associated with Bartonella quintana or Bartonella henselae infections.

DESIGN

Clinical, diagnostic and epidemiological evaluation of 37 speciated bacillary angiomatosis cases in the literature, including the seven patients in our study.

METHODS

Pathological examination of tissue samples, including Warthin-Starry staining and immunohistology; titre of antibodies to Bartonella sp.; detection of Bartonella sp. in blood and biopsy materials by culture or PCR; and statistical analysis of clinical and epidemiological features associated with B. quintana or B. henselae bacillary angiomatosis cases.

RESULTS

Seven immunocompromised patients (six with AIDS and one patient with acute leukaemia) had bacillary angiomatosis confirmed by histology. B. quintana was cultured in three patients, whereas B. henselae DNA was amplified by PCR in the remaining four patients. Serum from only one patient reacted with Bartonella antigens. Amongst the 14 B. quintana and 23 B. henselae bacillary angiomatosis cases now reported in the literature, lymphadenopathies were significantly more frequent in B. henselae-infected patients, and neurological disorders of the central nervous system in B. quintana-infected patients. Risk factors were contact with cats, and homelessness or poor socioeconomic status in B. henselae and B. quintana bacillary angiomatosis cases, respectively.

CONCLUSIONS

Although diagnosis of bacillary angiomatosis often remains solely based upon histology, culture or PCR-based methods are useful for the detection of Bartonella sp., and allow identification of the species involved, which is necessary to further characterize clinical and epidemiological features associated with B. quintana or B. henselae infections.

Bartonella-associated infections

Bartonella-associated infections occur in immunocompetent and immunocompromised patients. The spectrum of diseases caused by Bartonella species has expanded and now includes cat-scratch disease, bacillary angiomatosis, bacillary peliosis, bacteremia, endocarditis, and trench fever. Most Bartonella-associated infections that occur in North America and Europe are caused by B. henselae or B. quintana. The domestic cat serves as the major reservoir for B. henselae; the reservoir for the modern day B. quintana infection remains unknown. Methods used to diagnose Bartonella-associated infections include histopathologic analysis of biopsy specimens, culture of tissue samples, blood culture, and serology. Available data on treatment of Bartonella-associated infections remain relatively sparse but would suggest that erythromycin or doxycycline provide the best responses.

Seroprevalence of Bartonella henselae in cattery cats: association with cattery hygiene and flea infestation

We attempted to determine what factors were common to catteries with high Bartonella henselae antibody prevalence compared with catteries with low prevalence, in order to contribute to better guidelines for the choice of a safe pet cat. The overall seroprevalence in 11 catteries from diverse geographical locations in North America in the present study was 35.8%. There was evidence of B. henselae exposure in all 11 homes tested, with 5 catteries being heavily infected. The distribution of B. henselae exposure was bimodal in catteries: either most or all cats in the home had been exposed, or very few or no cats had been exposed. Prevalence per home was also correlated with the home mean antibody titre. Flea infestation was the most important risk factor for high B. henselae seroprevalence in the catteries we surveyed. Individual cat titres were comparable for male and female cats, cats of various ages, and cats with concurrent infectious diseases. There was no association of B. henselae with cattery size, husbandry practices, presence or absence of rescued cats, dog ownership, attending cat shows, routine visits to a veterinarian, and outside travel. In summary, cattery cats can be easily identified as high or low risk to new potential cat owners.

Cutaneous vascular proliferation. Part II. Hyperplasias and benign neoplasms

This second part of our review about vascular proliferations summarizes the clinicopathologic features of the cutaneous vascular hyperplasias and benign neoplasms. Hyperplasias comprise a heterogeneous group of vascular proliferations that eventually show a tendency to regression. Angiolymphoid hyperplasia with eosinophilia is included within the group of hyperplasias because of its historical denomination and its reactive nature, probably as a consequence of an arteriovenous shunt, although usually the lesions do not regress. Pyogenic granuloma, bacillary angiomatosis, intravascular papillary endothelial hyperplasia, and pseudo-Kaposi's sarcoma qualify as vascular hyperplasias because they regress when the stimulus that initiated them is removed. Benign neoplasms form a large group of hemangiomas with distinctive clinicopathologic characteristics, although some of them are of recent description and may produce diagnostic difficulties. We classified cutaneous benign vascular neoplasms according to their cell lineage of differentiation, for example, endothelial, glomus cell, and pericytic differentiation. Subsequent categories are established according to the size of the involved vessels (capillaries, venules and arterioles, or veins and arteries) or the nature of the proliferating vessels (blood or lymphatic vessels). Capillary and cavernous hemangiomas have been the terms classically used to name the most common variants of benign vascular neoplasms (i.e., infantile hemangiomas), but they are not the most appropriate denominations for these lesions. First, these names are not contrasting terms. Furthermore, most of the socalled "cavernous" hemangiomas are not hemangiomas (neoplasms) at all, but venous malformations. The most important conceptual issue is that, at any point in time, a particular hemangioma has its own histopathologic pattern throughout the depth of the lesion. For these reasons, we classified hemangiomas into superficial and deep categories. Some of the lesions reviewed have been recently described in the literature, and they may histopathologically mimic lesions of Kaposi's sarcoma; these include targetoid hemosiderotic hemangioma, microvenular hemangioma, tufted hemangioma, glomeruloid hemangioma, kaposiform hemangioendothelioma, spindle-cell hemangioendothelioma, and benign lymphangioendothelioma. In each of these lesions, we update and emphasize those clinical and histopathologic features that are helpful for differential diagnosis with lesions of authentic Kaposi's sarcoma in any of its three stages of development (patch, plaque, or nodule).

Bacillary angiomatosis and other Bartonella species infections

Infections with organisms of the genus Bartonella, for many years important only in South and Central America, have assumed significance in developing countries, especially in conjunction with the advent of the pandemic of the human immunodeficiency virus infection. New molecular and culture techniques have determined that these organisms cause new diseases such as bacillary angiomatosis as well as diseases the etiology of which have been unknown such as cat scratch disease. In this article, the microbiology, pathogenesis, histopathology and clinical manifestations of diseases caused by these organisms are discussed.

Bartonella spp. as emerging human pathogens

Members of the genus Bartonella (formerly Rochalimaea) were virtually unknown to modern-day clinicians and microbiologists until they were associated with opportunistic infections in AIDS patients about 6 years ago. Since that time, Bartonella species have been associated with cat scratch disease, bacillary angiomatosis, and a variety of other disease syndromes. Clinical presentation of infection with Bartonella ranges from a relatively mild lymphadenopathy with few other symptoms, seen in cat scratch disease, to life-threatening systemic disease in the immunocompromised patient. In some individuals, infection manifests as lesions that exhibit proliferation of endothelial cells and neovascularization, a pathogenic process unique to this genus of bacteria. As the spectrum of disease attributed to Bartonella is further defined, the need for reliable laboratory methods to diagnose infections caused by these unique organisms also increases. A brief summary of the clinical presentations associated with Bartonella infections is presented, and the current status of laboratory diagnosis and identification of these organisms is reviewed.

Bacterial infections

Non-opportunistic bacterial infections are an important cause of morbidity and mortality for HIV-infected adults and children. Factors associated with increased risk of these include altered B- and T-cell function; altered phagocytic cell function; skin and mucous membrane defects; and use of indwelling vascular catheters, antibiotics, or cytotoxic agents. The pathogens encountered most frequently are S. aureus, S. pneumoniae, H. influenzae, Salmonella sp., and Pseudomonas aeruginosa. Less commonly encountered organisms include Rhodococcus equi, Listeria monocytogenes, Shigella sp., and Nocardia asteroides, Strategies for prevention as well as diagnosis and treatment of these are discussed.

Cat scratch disease: The story continues

OBJECTIVE

To present a perspective on the current state of knowledge of cat scratch disease (CSD), including the evidence for Bartonella henselae as the etiological agent, epidemiological and clinical characteristics of the disease, available diagnostic tests and current therapeutic options.

DATA SOURCES

MEDLINE search of the literature published from 1966 to 1995 using 'cat scratch disease', 'Bartonella henselae', 'Rochalimaea henselae' as key words and bibliographies of selected papers.

DATA EXTRACTION

Selected studies reporting data on etiology, epidemiology, clinical characteristics, diagnosis and therapy of CSD were evaluated.

DATA SYNTHESIS AND CONCLUSIONS

Evidence accumulated to date supports B henselae as the etiological agent of CSD. The most significant risk factors for CSD are being licked on the face, scratched or bitten by a kitten and owning a kitten with fleas. Available serological tests can confirm classic CSD and identify B henselae as the cause of more atypical presentations, such as fever of unknown origin, granulomatous hepatitis, encephalitis and osteomyelitis. Symptomatic management is appropriate for isolated lymphadenopathy caused by CSD in healthy individuals; however, antibiotic therapy may be indicated for patients with more severe manifestations of the disease and immunocompromised hosts. Further study of CSD, in particular the epidemiology and therapy, is warranted. A better understanding of the pathogenesis of B henselae infection will have important implications in both immunocompetent and immunocompromised individuals.

Bacillary angiomatosis in an HIV seronegative patient on systemic steroid therapy

Bacillary angiomatosis is an unusual systemic vascular proliferation seen predominantly in patients with the acquired immunodeficiency syndrome. These vascular lesions are due to infection with a Bartonella species, most commonly B. henselae, but sometimes B. quintana. It is treatable and often curable, but without therapy may be life-threatening. Clinically, the disorder often resembles several different vascular disorders, particularly pyogenic granuloma and Kaposi's sarcoma. We now report a clinically typical patient with bacillary angiomatosis who was HIV seronegative, but who had idiopathic thrombocytopenic purpura, was status-post splenectomy and to whom long-term systemic prednisone had been administered.

Will the real agent of cat-scratch disease please stand up?

Cat-scratch disease has been recognized since 1889 in association with the oculoglandular syndrome of Parinaud. The epidemiologic association with cats was first made in 1931 and further substantiated throughout the years, refining the interaction predominantly to kittens. Putative infectious agents have included numerous species of bacteria, chlamydiae, and viruses. The cultivation of Afipia spp. in the late 1980s appeared to answer the mystery of the identity of the agent. However, even more recent analysis, which has combined traditional microbiology, molecular methods, and additional epidemiology, has demonstrated that Bartonella (Rochalimaea) henselae is the definitive agent of cat-scratch disease. Our understanding of the pathogenesis of cat-scratch disease and other diseases caused by Bartonella species is incomplete and the spectrum of diseases continues to emerge. We review historic and modern efforts to understand the etiology of cat-scratch disease and related syndromes.

Bartonella (Rochalimaea) quintana infections

Bartonella (formerly Rochalimaea) quintana is the etiological agent of trench fever, a disease extensively reported during the World Wars. Recent molecular biology approaches have allowed dramatic extension of the spectrum of Bartonella infections. B. quintana is now also recognized as an etiological agent of fever and bacteremia, endocarditis, bacillary angiomatosis, and chronic lymphadenopathy. Human immunodeficiency virus-infected patients and/or homeless people are the most vulnerable to infection. Poverty and louse infestation were the main epidemiological factors associated with B. quintana infections during wartime. Although poverty and chronic alcoholism have been associated with modern cases of trench fever and bacteremia due to B. quintana in Europe and the United States, vectors for B. quintana have not been clearly identified and B. quintana has not been isolated from modern-day lice. Microscopic bacillary angiomatosis lesions are characterized by tumor-like capillary lobules, with proliferating endothelial cells. In vitro experiments have shown that B. quintana survives within endothelial cells and stimulates cell proliferation. These observations, together with the finding that lesions may regress when antibiotic therapy is administered, strongly suggest that B. quintana itself stimulates angiogenesis. Bartonella infections are characterized by a high frequency of relapses after brief courses of antibiotic therapy. It is to be noted that in vitro, although Bartonella species are highly susceptible to antibiotics, only the aminoglycosides have proved to be bactericidal. However, the most effective antibiotic regimen for Bartonella infections remains to be established.

Molecular approaches to the identification of unculturable infectious agents

New molecular biologic techniques, particularly representational difference analysis, consensus sequence-based polymerase chain reaction, and complementary DNA library screening, have led to the identification of several previously unculturable infectious agents. New agents have been found in tissues from patients with Kaposi's sarcoma, non-A, non-B hepatitis, hantavirus pulmonary syndrome, bacillary angiomatosis, and Whipple's disease by using these techniques without direct culture. The new methods rely on identifying subgenomic fragments from the suspected agent. After a unique nucleic acid fragment belonging to an agent is isolated from diseased tissues, the fragment can be sequenced and used as a probe to identify additional infected tissues or obtain extended portions of the agent's genome. For agents that cannot be cultured by standard techniques, these approaches have proved invaluable for identification and characterization studies. Applying these techniques to other human diseases of suspected infectious etiology may rapidly elucidate novel candidate pathogens.

Intra-abdominal mass associated with gastrointestinal hemorrhage: a new manifestation of bacillary angiomatosis

Bacillary angiomatosis is a recently described vascular proliferative lesion that occurs most commonly in individuals infected with human immunodeficiency virus. Cutaneous lesions are the most frequently described manifestations of bacillary angiomatosis. However, as culture techniques and disease recognition have improved, additional manifestations have been identified in human immunodeficiency virus-infected individuals, including bacillary peliosis hepatis and isolated bacteremia. Two species of the genus Bartonella (formerly Rochalimaea), Bartonella henselae or Bartonella quintana, have been cultured from the cutaneous lesions of bacillary angiomatosis. A new manifestation of Bartonella infection is reported: an intra-abdominal mass presenting with massive gastrointestinal hemorrhage in a patient with human immunodeficiency virus infection. B. quintana was cultured from a percutaneous needle-biopsy specimen obtained from the highly vascularized intra-abdominal mass. The bacillary angiomatosis lesion resolved after 3 months of tetracycline treatment. Recognition of Bartonella infection is extremely important because it is readily treatable with antibiotic therapy.

Characterization of a 17-kilodalton antigen of Bartonella henselae reactive with sera from patients with cat scratch disease

A library of Bartonella (Rochalimaea) henselae DNA was constructed in the cloning vector lambda ZAPII and screened for expression of antigenic proteins by using a pool of sera from patients who had been diagnosed with cat scratch disease (CSD) and had antibodies to Bartonella spp., as determined by indirect fluorescent-antibody (IFA) assay. Ten immunoreactive phages were subcloned as recombinant plasmids by in vivo excision. All 10 recombinants expressed a protein of approximately 17 kDa when they were examined by immunoblot with the pool of human sera. Restriction endonuclease digestion of each recombinant plasmid indicated seven profiles, suggesting that cloning bias was not the reason for repeated isolation of clones expressing the 17-kDa antigen. The gene coding for the 17-kDa antigen was sequenced and shown to code for an open reading frame of 148 amino acids with a predicted molecular mass of 16,893 Da. The amino terminus of the deduced amino acid sequence was hydrophobic in nature and similar in size and composition to signal peptides found in gram-negative bacteria. The remainder of the deduced amino acid sequence was more hydrophilic and may represent surface-exposed epitopes. Further subcloning of the 17-kDa antigen as a biotinylated fusion protein in the expression vector PinPoint Xa-2 resulted in a 30-kDa protein that was highly reactive on immunoblots with individual serum samples from patients with CSD. The agreement between reactivity with the 30-kDa fusion protein on immunoblot analysis and the results obtained by IFA assay was 92% for IFA-positive sera and 88% for IFA-negative sera. The recombinant-expressed 17-kDa protein should be of value as an antigen for serologic diagnosis of CSD and Bartonella infections and warrants further study in attempts to develop a subunit vaccine to prevent long-term Bartonella infection in cats and the potential for further spread of these organisms to humans.

Bacillary Angiomatosis: A Unique Cutaneous Complication of Hiv Infection

As the prevalence of human immunodeficiency virus (HIV) infection increases, so does the recognition of unusual manifestations of this syndrome. This study describes two patients who presented with a unique, rare, cutaneous manifestion of HIV infection. One patient developed an aggressive atypical cellulitis and ascending lymphangitis of the hand, which failed to improve following multiple courses of several different antibiotics. The other patient presented with multiple, vascular, nodular lesions, clinically resembling Kaposi's sarcoma. Routine biopsies and wound cultures were not helpful for diagnosis. A definitive diagnosis of bacillary angiomatosis (BA) was made using a special silver-staining (Warthin-Starry) histological technique and electron microscopy. Both patients responded completely to oral erythromycin therapy. BA is a newly recognized bacterial infection caused by bacteria of the genus Bartonella. It is seen primarily in patients with acquired immunodeficiency syndrome (AIDS), and less commonly in patients with other immunosuppressed conditions. The term BA describes the lesion's pathogenesis (infective-bacillary) and clinico-histology (angiomatosis). The causal organism cannot be cultured reliably and is resistant to most antibiotics. This study reviews these two patients, the differential diagnosis of BA, specific confirmatory tests used in diagnosis, and the treatment outcome of this condition. It is important for the plastic surgeon to understand BA, because it can resemble other common presentations, but it can also be associated with internal involvement leading to mortality. However, when recognized, it can usually be cured by oral erythromycin therapy (500 mg qid) for several weeks.

Unraveling mysteries associated with cat-scratch disease, bacillary angiomatosis, and related syndromes

The search for the infectious agents responsible for cat-scratch disease, bacillary angiomatosis, and related syndromes has a long and often circuitous history. Recognition of the etiologic agents and a new understanding of the fundamental features of the epidemiology and natural history of modern day Bartonella (formerly Rochalimaea)-associated diseases culminate a multipartite story that combines clinical medicine, traditional microbiology, and novel technological approaches to solve a long-standing enigma.