Infections associated with Bartonella species in persons infected with human immunodeficiency virus

The Clinical Profile of Cat-Scratch Disease’s Neuro-Ophthalmological Effects

Cat-scratch disease is an illness caused by Bartonella henselae that occurs as a result of contact with an infected kitten or dog, such as a bite or scratch. It is more prevalent in children and young adults, as well as immunocompromised individuals. There are limited publications examining the features of CSD in patients. As such, the purpose of this research was to assess the clinical neuro-ophthalmological consequences of CSD reported in the literature. Among the ophthalmologic disorders caused by cat-scratch disease in humans, Parinaud oculoglandular syndrome, uveitis, vitritis, retinitis, retinochoroiditis and optic neuritis are the most prevalent. The neurological disorders caused by cat-scratch disease in humans include encephalopathy, transverse myelitis, radiculitis, and cerebellar ataxia. The current review addresses the neuro-ophthalmological clinical manifestations of cat-scratch disease, as described in papers published over the last four decades (1980–2022). All the data gathered were obtained from PubMed, Medline and Google Scholar. The current descriptive review summarizes the most-often-encountered clinical symptomatology in instances of cat-scratch disease with neurological and ocular invasion. Thus, the purpose of this review is to increase knowledge of cat-scratch disease’s neuro-ophthalmological manifestations.

Epidemiological of cat scratch disease among inpatients in the Spanish health system (1997-2015)

Cat scratch disease, whose causative agent is Bartonella henselae, is an anthropozoonosis with a worldwide distribution that causes significant public health problems. Although it is an endemic disease in Spain, the available data are very limited. The aim of our study was to describe cat scratch disease inpatients in the National Health System (NHS) of Spain. This was a retrospective descriptive study using the minimum basic data set (CMBD in Spanish) in patients admitted to hospitals of the NHS between 1997 and 2015 with a diagnosis of cat scratch disease (ICD-9: 078.3). We found 781 hospitalized patients diagnosed with cat scratch disease. The mean age (± SD) was 30.7 ± 25.3 years old. The male/female ratio was 1.1:1. The incidence rate over the study period was 0.93 (95% CI, 0.86-0.99) cases per million person-years. The incidence rate in men was 0.98 cases per million person-years and that in women was 0.88 cases per million person-years. The cases were more frequent from September to January. A total of 652 (83.5%) cases were urgent hospital admissions. The average hospital stay was 8.4 ± 8.9 days. The overall lethality rate of the cohort was 1.3%. We have demonstrated that CSD causes a substantial burden of disease in Spain, affecting both adult and pediatric patients with a stable incidence rate. Our data suggest that CSD is benign and self-limited, with low mortality, and its incidence is possibly underestimated. Finally, there is a need for a common national strategy for data collection, monitoring, and reporting, which would facilitate a more accurate picture and the design of more strategic control measures. Hospital discharge records (HDRs) could be a good database for the epidemiological analysis of the hospital management of CSD.

The Many Faces of Bacterium-Endothelium Interactions during Systemic Infections

A wide variety of pathogens reach the circulatory system during viral, parasitic, fungal, and bacterial infections, causing clinically diverse pathologies. Such systemic infections are usually severe and frequently life-threatening despite intensive care, in particular during the age of antibiotic resistance. Because of its position at the interface between the blood and the rest of the organism, the endothelium plays a central role during these infections. Using several examples of systemic infections, we explore the diversity of interactions between pathogens and the endothelium. These examples reveal that bacterial pathogens target specific vascular beds and affect most aspects of endothelial cell biology, ranging from cellular junction stability to endothelial cell proliferation and inflammation.

Seroprevalence of six pathogens transmitted by the Ixodes ricinus ticks in asymptomatic individuals with HIV infection and in blood donors

The objective of our study was to estimate the seroprevalence of six pathogens transmitted by ticks in HIV-infected persons and blood donors in Poland (B. burgdorferi s.l., A. phagocytophilum, Ehrlichia spp., Babesia spp., Rickettsia spp. Bartonella henselae) to assess the frequency of exposure to such microorganisms in immunocompetent and immunocompromised individuals in endemic regions for I. ricinus ticks. Serum samples were collected from 227 HIV-infected patients and 199 blood donors. All samples were analyzed for antibodies against six tick-borne pathogens and seroprevalence rates were statistically compared between two tested group as well as age, sex and lymphocyte T CD4+ level in HIV infected patients. The seroprevalence of tick-borne infections in HIV-infected patients is higher than that of the healthy population in Poland, although no association between serological status of patients and lymphocyte CD4+ T cell level has been observed. The frequency of tick-borne coinfections and doubtful results of serological tests were significantly higher in HIV-positive individuals. In Poland, the possibility of tick-borne diseases transmission with blood is rather negligible.

Cat-Scratch Disease in the United States, 2005-2013

Each year, this preventable disease affects about 12,500 persons, mostly those who live in the South and are 5–9 years of age.

Cat-scratch disease (CSD) is mostly preventable. More information about the epidemiology and extent of CSD would help direct prevention efforts to those at highest risk. To gain such information, we reviewed the 2005–2013 MarketScan national health insurance claims databases and identified patients <65 years of age with an inpatient admission or outpatient visit that included a CSD code from the International Classification of Diseases, Ninth Revision, Clinical Modification. Incidence of CSD was highest among those who lived in the southern United States (6.4 cases/100,000 population) and among children 5–9 years of age (9.4 cases/100,000 population). Inpatients were significantly more likely than outpatients to be male and 50–64 years of age. We estimate that each year, 12,000 outpatients are given a CSD diagnosis and 500 inpatients are hospitalized for CSD. Prevention measures (e.g., flea control for cats) are particularly helpful in southern states and in households with children.

Dynamics of Co-Infection with Bartonella henselae Genotypes I and II in Naturally Infected Cats: Implications for Feline Vaccine Development

Bartonella henselae is an emerging bacterial pathogen causing cat-scratch disease and potentially fatal bacillary angiomatosis in humans. Bacteremic cats constitute a large reservoir for human infection. Although feline vaccination is a potential strategy to prevent human infection, selection of appropriate B. henselae strains is critical for successful vaccine development. Two distinct genotypes of B. henselae (type I, type II) have been identified and are known to co-infect the feline host, but very little is known about the interaction of these two genotypes during co-infection in vivo. To study the in vivo dynamics of type I and type II co-infection, we evaluated three kittens that were naturally flea-infected with both B. henselae type I and type II. Fifty individual bloodstream isolates from each of the cats over multiple time points were molecularly typed (by 16S rRNA gene sequencing), to determine the prevalence of the two genotypes over 2 years of persistent infection. We found that both B. henselae genotypes were transmitted simultaneously to each cat via natural flea infestation, resulting in mixed infection with both genotypes. Although the initial infection was predominately type I, after the first 2 months, the isolated genotype shifted to exclusively type II, which then persisted with a relapsing pattern. Understanding the parameters of protection against both genotypes of B. henselae, and the competitive dynamics in vivo between the two genotypes, will be critical in the development of a successful feline vaccine that can ultimately prevent B. henselae transmission to human contacts.

Disseminated cat-scratch disease presenting as nausea, diarrhea, and weight loss without fever in a heart transplant recipient

We report the case of an afebrile 59-year-old heart transplant recipient presenting with nausea, vomiting, diarrhea, weight loss, and diffuse lymphadenopathy. Lymph node biopsies revealed non-caseating granulomatous inflammation. Cat-scratch disease was confirmed by serologic studies, Warthin-Starry staining, and polymerase chain reaction testing of lymph node tissue. The patient's symptoms resolved with 3 months of doxycycline. We review clinical presentations of Bartonella henselae infection and review diagnostic approaches for B. henselae in this patient population.

Pyogenic Granuloma: Pyogenic Again? Association between Pyogenic Granuloma and Bartonella

Background:

Pyogenic granulomas (PG) are benign vascular lesions which were thought to have an infectious etiology, yet none has been found. Bacillary angiomatosis (BA), which presents as disseminated vascular lesions in immunosuppressed patients, and verruga peruana (VP), which presents as crops of vascular nodules in immunocompetent persons, are caused by infection with Bartonella. Thus, the question was raised whether Bartonella could be associated with the development of PG, also a vasoproliferative lesion like BA and VP. The objective of this study was to determine through a case-control study whether such an association exists.

Methods:

Patients who presented with PG and age and sex-matched controls with capillary hemangiomas and senile (cherry) angiomas were tested for serum IgG antibodies against Bartonella using an immunofluorescence antibody method. The prevalence of positive serology was compared between the groups.

Results:

Twenty PG patients and 20 control patients with hemangiomas or angiomas were studied. Six out of 20 PG patients tested positive (30%), while none of the 20 control patients tested positive (0%). The difference between the proportions of seropositivity in the two groups reached statistical significance ( p = 0.02, df= 1).

Conclusions:

Pyogenic granuloma patients were determined to have a statistically higher prevalence of Bartonella seropositivity compared with control patients. Further studies are needed to confirm the association and establish a possible etiological link. Such an association could have potential therapeutic importance. A nonsurgical approach with antibiotics may be possible and may decrease the recurrence rate and occurrence of satellite lesions.

Bartonella spp. infection in HIV positive individuals, their pets and ectoparasites in Rio de Janeiro, Brazil: serological and molecular study

BACKGROUND

Bartonella is the agent of cat-scratch disease, but is also responsible for more severe conditions such as retinitis, meningoencephalitis, endocarditis and bacillary angiomatosis. Its seroprevalence is unknown in Brazil.

METHODS

Patients in an AIDS clinic, asymptomatic at the time of the study, were enrolled prospectively. They answered a structured questionnaire and had blood taken for serological and molecular assays. Cat breeder's pets were tested serologically and collected ectoparasites were tested by molecular biology techniques. Blood donors, paired by age and sex, were tested for Bartonella IgG antibodies.

RESULTS

125 HIV positive patients with a median age of 34 were studied; 61 were male and 75% were on HAART. Mean most recent CD4 count was 351-500 cells/mm(3). A high rate of contact with ticks, fleas and lice was observed. Bartonella IgG seroreactivity rate was 38.4% in HIV positive individuals and breeding cats was closely associated with infection (OR 3.6, CI 1.1-11.9, p<0.05). No difference was found between the sexes. Titers were 1:32 in 39 patients, 1:64 in seven, 1:128 in one and 1:256 in one. In the control group, IgG seroreactivity to Bartonella spp. was 34%, and female sex was correlated to seropositivity. Fourteen of 61 (23%) males vs 29/64 (45.3%) females were seroreactive to Bartonella (OR 2.8, CI 1.2-6.5, p<0.01). Titers were 1:32 in 29 patients, 1:64 in ten and 1:128 in four.

CONCLUSIONS

Bartonella spp. seroprevalence is high in HIV positive and in blood donors in Rio de Janeiro. This may be of public health relevance.

Bartonella quintana in body lice and head lice from homeless persons, San Francisco, California, USA

Bartonella quintana is a bacterium that causes trench fever in humans. Past reports have shown Bartonella spp. infections in homeless populations in San Francisco, California, USA. The California Department of Public Health in collaboration with San Francisco Project Homeless Connect initiated a program in 2007 to collect lice from the homeless to test for B. quintana and to educate the homeless and their caregivers on prevention and control of louse-borne disease. During 2007-2008, 33.3% of body lice-infested persons and 25% of head lice-infested persons had lice pools infected with B. quintana strain Fuller. Further work is needed to examine how homeless persons acquire lice and determine the risk for illness to persons infested with B. quintana-infected lice.

[Bacterial, mycobacterial and fungal opportunistic infections in HIV-infected immigrants: diagnosis and treatment]

The number of HIV infected immigrants has increased sharply in Spain. These patients are prone to contracting several different types of opportunistic infections, including bacterial, mycobacterial, fungal and parasitic infections. The present article provides an in-depth review of bacterial and fungal infections, with particular emphasis on those not endemic in our country.

Seroprevalence of Bartonella spp. infection in HIV patients in Catalonia, Spain

Background

Although the first clinical descriptions of Bartonella infection were associated with immunocompromised patient with bacillary angiomatosis, we currently know that this organism is directly involved in diseases affecting a large number of patients, regardless of their immune status. Cat scratch disease, hepatic peliosis, and some cases of bacteraemia and endocarditis, are directly caused by some species of the genus Bartonella. The purpose of this study was to determinate the prevalence of IgG antibodies against Bartonella henselae and B. quintana in HIV patients and to identify the epidemiological factors involved.

Methods

Serum samples were collected from HIV patients treated at Hospital de Sabadell. Antibodies to B. henselae and B. quintana from 340 patients were examined by indirect immunofluorescence assay (IFA). Significance levels for univariate statistical test were determined by the Mann-Whitney U test and χ² test.

Results

Of 340 patients, 82 were women and 258 men, with a median age of 42.21 ± 10.35 years (range 16–86 years). Seventy-six (22.3%) patients reacted with one or more Bartonella antigens. Of all the factors concerning the seroprevalence rate being studied (age, sex, intravenous drugs use, alcohol consumption, CD4 levels, AIDS, HCV, HBV, residential area), only age was statistically significant.

Conclusion

A high percentage of HIV patients presents antibodies to Bartonella and is increasing with age.

Emerging zoonoses and vector-borne infections affecting humans in Europe

The purpose of this study was to assess and describe the current spectrum of emerging zoonoses between 2000 and 2006 in European countries. A computerized search of the Medline database from January 1966 to August 2006 for all zoonotic agents in European countries was performed using specific criteria for emergence. Fifteen pathogens were identified as emerging in Europe from 2000 to August 2006: Rickettsiae spp., Anaplasma phagocytophilum, Borrelia burgdorferi, Bartonella spp., Francisella tularensis, Crimean Congo Haemorrhagic Fever Virus, Hantavirus, Toscana virus, Tick-borne encephalitis virus group, West Nile virus, Sindbis virus, Highly Pathogenic Avian influenza, variant Creutzfeldt-Jakob disease, Trichinella spp., and Echinococus multilocularis. Main risk factors included climatic variations, certain human activities as well as movements of animals, people or goods. Multi-disciplinary preventive strategies addressing these pathogens are of public health importance. Uniform harmonized case definitions should be introduced throughout Europe as true prevalence and incidence estimates are otherwise impossible.

HIV-1 infection of mononuclear phagocytic cells: the case for bacterial innate immune deficiency in AIDS

HIV-1 infection of mononuclear phagocytic cells, comprising monocytes, macrophages, and dendritic cells, has been the subject of extensive research over the past 20 years. The roles of mononuclear phagocytic cells in transmission of HIV-1 infection and as reservoirs of actively replicating virus have received particular attention. Experimental data have also accumulated about the effects of HIV-1 on the physiological function of mononuclear phagocytic cells, particularly their role in innate immunity to bacteria. The effects of HIV-1 on bacterial innate immune responses by mononuclear phagocytic cells are discussed here together with reports of direct interactions between HIV-encoded products and bacterial innate immune signalling pathways. These reports demonstrate mechanisms for HIV-mediated disruption of innate immune responses by mononuclear phagocytic cells that could provide novel therapeutic targets in HIV-infected patients. The clinical urgency is highlighted by greatly increased risk of invasive bacterial disease in this population, even in the era of highly active antiretroviral therapy. HIV-mediated injury to bacterial innate immunity provides an experimental paradigm that could broaden our overall understanding of innate immunity and be used to study responses to pathogens other than bacteria.

A study on forensic samples of Bartonella spp antibodies in Swedish intravenous heroin addicts

Infection with Bartonella, an emerging bacterial pathogen which often affects immunodeficient patients, has been reported in Sweden over the past few years, with a high seroprevalence of B. elizabethae. A high prevalence of antibodies against B. elizabethae has also been found in urban intravenous drug users in the USA. Using immunofluorescence, we retrospectively examined serum samples taken at autopsy from 59 Swedish intravenous drug addicts from the Stockholm area for evidence of antibodies against 6 pathogenic strains of Bartonella. The 59 addicts died following heroin injection during the years 1987-1992 and include 24 individuals (41%) who were additionally HIV-positive. An overall seropositivity rate for Bartonella spp. of 39% (23/59) was found with the following antigenic reactivities: B. elizabethae, 39% (23/59); B. grahamii, 3% (2/59); B. henselae (Houston-1), 14% (8/59); and B. quintana, 3% (2/59). There were no positive reactions for B. henselae (Marseille) or B. vinsonii subsp. vinsonii. The Bartonella-seropositive cases included 11/23 (48%) individuals who were HIV-positive. Subacute to chronic myocarditis was seen in 2/11 microscopically investigated Bartonella-seropositive cases that were HIV-negative and in 1/14 seronegative cases. No cases of endocarditis or other common manifestations of Bartonella infection were found. An overall Bartonella seropositivity of 21% (9/44) was observed in control forensic autopsy samples.

Laboratory diagnosis of Bartonella infections

Bartonella species are pathogens of emerging and reemerging significance, causing a wide array of clinical syndromes. In North America and Europe, they are increasingly recognized as a cause of culture negative endocarditis, neuroretinitis, and disease among homeless, HIV-infected, and other immunosuppressed individuals. In South America, bartonellosis continues to plague those in endemic regions and poses a significant threat to travelers in these areas. As the clinician is increasingly faced with these illnesses, which may be difficult to diagnose, laboratory techniques to confirm or refute the diagnosis are becoming increasingly important. Culture methods have improved over the past decade demonstrating increased sensitivity, but still require prolonged periods before isolation of the organism. Specimen handling, media selection, and growth conditions all may affect results and must be optimized in order to provide the highest likelihood of recovering the organism. Pure culture of the bacteria not only provides morphologic information, but also provides material for further diagnostic testing. Work with liquid media, which may provide a more rapid means of cultivation has shown some promise and should continue to be pursued. Improved blood culture techniques were a primary factor in the discovery of Bartonella endocarditis and continued improvements will likely demonstrate further clinical insights. Serologic testing for B henselae infections has become the cornerstone of clinical diagnosis, replacing the skin test that was poorly standardized and posed a potential risk to the patient. Immunofluorescence assays have been well characterized and validated in clinical trials, however they are not universally available. Vero cell cocultivated antigens appear to provide higher sensitivity and specificity when compared with agar-derived antigens. IFA assays are inherently difficult to perform, requiring significant expertise to provide reproducible results. On the contrary, enzyme immunoassays offer ease of use and a high level of reproducibility, however ideal antigens for use in the diagnosis of Bartonella infections have not been clearly identified. Continued work to define antigenic targets of the human response to infection and incorporation of these into a widely available EIA will provide a cost-effective tool for the clinician and epidemiologist alike. Due to the close phylogenetic relationship of B henselae and B quintana, differentiation between these species by serologic means may prove difficult. Molecular techniques including PCR offer high sensitivity and specificity, rapid availability of information, and the ability to differentiate Bartonella organisms at the highest level. Results of studies to date are promising and as methods are refined it will be important to conduct clinical studies to define the role of these assays. In disseminated Bartonella infections such as bacillary angiomatosis, peliosis, endocarditis, and urban trench fever, PCR currently offers the ability to establish the diagnosis when other tests may be unrevealing. For CSD, this technique should be used as a confirmatory technique when the diagnosis is unclear by other means. PCR analysis of blood specimens offers a minimally invasive approach to diagnosis, but clinical data are scarce and further studies are needed. As DNA microarrays move into the clinical arena, specific hybridization probes may allow improved identification and differentiation of Bartonellae at the molecular level.

Serodiagnosis of Bartonella bacilliformis infection by indirect fluorescence antibody assay: test development and application to a population in an area of bartonellosis endemicity

Bartonella bacilliformis causes bartonellosis, a potentially life-threatening emerging infectious disease seen in the Andes Mountains of South America. There are no generally accepted serologic tests to confirm the disease. We developed an indirect fluorescence antibody (IFA) test for the detection of antibodies to B. bacilliformis and then tested its performance as an aid in the diagnosis of acute bartonellosis. The IFA is 82% sensitive in detecting B. bacilliformis antibodies in acute-phase blood samples of laboratory-confirmed bartonellosis patients. When used to examine convalescent-phase sera, the IFA is positive in 93% of bartonellosis cases. The positive predictive value of the test is 89% in an area of Peru where B. bacilliformis is endemic and where the point prevalence of infection is 45%.

Bartonella infection in animals: carriership, reservoir potential, pathogenicity, and zoonotic potential for human infection

Recent observations have begun to support a role for Bartonella spp. as animal as well as human pathogens. Bartonella spp. are vector-transmitted, blood-borne, intracellular, gram-negative bacteria that can induce prolonged infection in the host. Persistent infections in domestic and wild animals result in a substantial reservoir of Bartonella organisms in nature that can serve as a source for inadvertent human infection. The prevalence of bacteremia can range from 50 to 95% in selected rodent, cat, deer, and cattle populations. Dogs infected with Bartonella spp. can develop lameness, endocarditis, granulomatous lymphadenitis, and peliosis hepatis, lesions that have also been reported in association with human infection. Understanding the role of Bartonella spp. as pathogens in cats and other wild or domestic animals awaits the results of additional studies. Considering the extensive animal reservoirs and the large number of insects that have been implicated in the transmission of Bartonella spp., both animal and human exposure to these organisms may be more substantial than is currently believed.

Bartonella infection in animals: carriership, reservoir potential, pathogenicity, and zoonotic potential for human infection

Recent observations have begun to support a role for Bartonella spp. as animal as well as human pathogens. Bartonella spp. are vector-transmitted, blood-borne, intracellular, gram-negative bacteria that can induce prolonged infection in the host. Persistent infections in domestic and wild animals result in a substantial reservoir of Bartonella organisms in nature that can serve as a source for inadvertent human infection. The prevalence of bacteremia can range from 50 to 95% in selected rodent, cat, deer, and cattle populations. Dogs infected with Bartonella spp. can develop lameness, endocarditis, granulomatous lymphadenitis, and peliosis hepatis, lesions that have also been reported in association with human infection. Understanding the role of Bartonella spp. as pathogens in cats and other wild or domestic animals awaits the results of additional studies. Considering the extensive animal reservoirs and the large number of insects that have been implicated in the transmission of Bartonella spp., both animal and human exposure to these organisms may be more substantial than is currently believed.

Ocular manifestations of cat-scratch disease

Bartonella henselae has only recently been isolated, characterized, and found to be the principal cause of cat-scratch disease (CSD). The availability of specific serologic investigations has allowed the recognition of a spectrum of ocular CSD syndromes that previously were ill defined and considered idiopathic. The primary inoculation complex causing regional lymphadenopathy is represented in the eye by Parinaud's oculoglandular syndrome; B. henselae is the most common cause. Leber's neuroretinitis has been identified for 80 years, and new data suggest that it is commonly a manifestation of CSD; the extent of the association remains to be determined. CSD optic neuritis is also described. The vitreoretinal manifestations include anterior uveitis, vitritis, pars planitis, focal retinal vasculitis, a characteristic retinal white spot syndrome, Bartonella retinitis, branch retinal arteriolar or venular occlusions, focal choroiditis, serous retinal detachments, and peripapillary angiomatous lesions. The pattern of ocular disease in AIDS-associated B. henselae infections is poorly delineated; unusual manifestations include conjunctival and retinal bacillary angiomatosis. The benefit of antimicrobial therapy for CSD in immunocompetent individuals has been difficult to establish, partly because most infections are self limited. Empirically, azithromycin, ciprofloxacin, rifampin, parenteral gentamicin, or trimethoprim-sulfamethoxazole provide the best therapeutic choices to minimize damage to the eye.

Serious waterborne and wilderness infections

Serious waterborne and wilderness infections are common and usually treatable if diagnosed early. The differential diagnosis for these infections requires a careful and thorough history and physical examination. Common clinical presentations include acute febrile illnesses, altered mental status, diarrhea, or pneumonia. Pathogens causing serious infections include bacteria, fungi, viruses, and protozoa. Epidemiologic help can be obtained from local or state health departments as well as the Centers for Disease Control.

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.

Current knowledge of Bartonella species

Bartonella species are now considered emerging pathogens. Of the 11 currently recognized species, four have been implicated in human disease, although only two have been encountered in Europe. Bartonella quintana infections are now being diagnosed among the urban homeless and deprived, manifesting as trench fever, and Bartonella henselae has been shown to be the causative agent of cat scratch disease. Both species also cause a variety of HIV-associated infections, including bacillary anglomatosis. However, perhaps the most significant presentation of bartonellae infection is culture-negative endocarditis. The epidemiologies of Bartonella infections are poorly understood; most Bartonella henselae infections are probably acquired from infected cats, either directly by contact with a cat or indirectly via fleas. No animal reservoir has been implicated for Bartonella quintana; however, infection can be transmitted via the human body louse. Diagnosis of Bartonella infections can be made using histological or microbiological methods. The demonstration of specific antibodies may be useful in some instances, although certainly not in all. Cultivation of Bartonella is difficult, as the bacteria are extremely fastidious. Polymerase chain reaction-based or immunological methods for the detection of bartonella in infected tissues have proven useful. Clinical relapse is often associated with Bartonella infections despite a wide range of prescribed regimens. Only aminoglycosides display in vitro bactericidal activity against intracellular Bartonella species; therefore, they are recommended for treatment of Bartonella infections.

The expanding spectrum of Bartonella infections: II. Cat-scratch disease

Recent advancements and developments in molecular biotechnology have allowed more precise reclassification of many microorganisms. With the use of these new taxonomy tools, several organisms previously thought to belong to other genera have been recently described as bartonellae. Of the 11 organisms now described as Bartonella spp., only four have been shown to be pathogenic for humans. Table 1 lists the four Bartonella human pathogens along with the their known epidemiology and the scope and range of disease associated with each. All are now considered to be bacteria and can be grown on blood-enriched agar although primary isolation in some may best be achieved in cell tissue culture. B. bacilliformis infection is limited to certain geographic regions in South America where the only human reservoir and the sandfly vector(s) that spreads the disease reside together. Specific antibiotic treatment is dramatically effective in treating the highly fatal, acute intraerythrocytic hemolytic form of the disease, but their effectiveness in treating the vascular proliferative forms (verruga peruana) or the chronic asymptomatic, bacteremic, carrier state of the disease has not been effective. This disease should remain confined to its present endemic geographic areas in South American unless asymptomatic bacteremic persons from these areas migrate to areas where sandflies and humans exist that are capable of establishing this infection in new endemic areas. B. quintana and B. henselae cause a wide range of clinical diseases in humans, the type and extent of which varies significantly with the immune status of the host. In immunocompetent hosts the pathologic response is granulomatous, suppurative, extracellular and intracellular, generally self-limited and usually unresponsive to antibiotic treatment, even to those drugs to which the organism is shown to be sensitive in vitro. In contrast, in immunocompromised hosts the pathologic response is vasculoproliferative, organisms may be seen intracellularly but they are often seen in abundance in extracellular clumps and infection is usually progressive and fatal unless treated. In these patients clinical response to treatment with drugs that are effective in vitro against these organisms has usually been dramatic. Of these agents those that penetrate cells and are found in high concentrations intracellularly, such as erythromycin, clarithromycin, azithromycin, rifampin, doxycycline and gentamicin, appear to be most effective. These agents not only appear to provide the most dramatic treatment response in patients with BA, BP and PRFB and other manifestations of B. henselae (and B. quintana as well) in immunocompromised persons, they appear to be the most promising agents for treatment of persons with both typical and atypical CSD. Further studies will be necessary to more clearly elucidated the mechanisms responsible for the diverse clinical presentations of infection with these organisms in human hosts relative to their immune status. In addition clarification of the epidemiology of B. elizabethae infections in humans may be helpful in understanding the nature of infection with Bartonella organisms.

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.