Western immunoblotting for Bartonella endocarditis

Epidemiology and treatment of invasive Bartonella spp. infections in the United States

OBJECTIVES

Bartonella spp., renowned for cat-scratch disease, has limited reports of dissemination. Tissue and blood cultures have limitations in detecting this fastidious pathogen. Molecular testing (polymerase chain reaction, PCR) and cell-free DNA have provided an avenue for diagnoses. This retrospective observational multicenter study describes the incidence of disseminated Bartonella spp. and treatment-related outcomes.

METHODS

Inclusion criteria were diagnosis of bartonellosis via diagnosis code, serology testing of blood, polymerase chain reaction (PCR) of blood, 16/18S tests of blood or tissue, cultures of blood or tissue, or cell-free DNA of blood or tissue from January 1, 2014, through September 1, 2021. Exclusions were patients who did not receive treatment, insufficient data on treatment course, absence of dissemination, or retinitis as dissemination.

RESULTS

Patients were primarily male (n = 25, 61.0%), white (n = 28, 68.3%), with mean age of 50 years (SD 14.4), and mean Charlson comorbidity index of 3.5 (SD 2.1). Diagnosis was primarily by serology (n = 34, 82.9%), with Bartonella henselae (n = 40, 97.6%) as the causative pathogen. Treatment was principally doxycycline with rifampin (n = 17, 41.5%). Treatment failure occurred in 16 (39.0%) patients, due to escalation of therapy during treatment (n = 5, 31.3%) or discontinuation of therapy due to an adverse event or tolerability (n = 5, 31.3%).

CONCLUSIONS

In conclusion, this is the largest United States-based cohort of disseminated Bartonella spp. infections to date with a reported 39% treatment failure. This adds to literature supporting obtaining multiple diagnostic tests when Bartonella is suspected and describes treatment options.

Bartonella Endocarditis in Spain: Case Reports of 21 Cases

Blood culture negative endocarditis (BCNE) is frequent in infective endocarditis (IE). One of the causes of BCNE is fastidious microorganisms, such as Bartonella spp. The aim of this study was to describe the epidemiologic, clinical characteristics, management and outcomes of patients with Bartonella IE from the “Spanish Collaboration on Endocarditis-Grupo de Apoyo al Manejo de la Endocarditis infecciosa en España (GAMES)”cohort. Here we presented 21 cases of Bartonella IE. This represents 0.3% of a total of 5590 cases and 2% of the BCNE from the GAMES cohort. 62% were due to Bartonella henselae and 38% to Bartonella quintana. Cardiac failure was the main presenting form (61.5% in B. hensalae, 87.5% in B. quintana IE) and the aortic valve was affected in 85% of the cases (76% in B. henselae, 100% in B. quintana IE). Typical signs such as fever were recorded in less than 40% of patients. Echocardiography showed vegetations in 92% and 100% of the patients with B. henselae and B. quintana, respectively. Culture was positive only in one patient and the remaining were diagnosed by serology and PCR. PCR was the most useful tool allowing for diagnosis in 16 patients (100% of the studied valves). Serology, at titers recommended by guidelines, only coincided with PCR in 52.4%. Antimicrobial therapy, in different combinations, was used in all cases. Surgery was performed in 76% of the patients. No in-hospital mortality was observed. One-year mortality was 9.4%. This article remarks the importance for investigating the presence of Bartonella infection as causative agent in all BCNE since the diagnosis needs specific microbiological tools and patients could benefit of a specific treatment.

Glomerulonephritis Caused by Bartonella spp. Infective Endocarditis: The Difficulty and Importance of Differentiation from Anti-neutrophil Cytoplasmic Antibody-related Rapidly Progressive Glomerulonephritis

A 65-year-old man with valvular disorder presented to his physician because of widespread purpura in both lower extremities. Blood tests showed elevated serum creatinine levels and proteinase 3-anti-neutrophil cytoplasmic antibody (ANCA) with hematuria, suggesting ANCA-related rapidly progressive glomerulonephritis (RPGN). Although multiple blood cultures were negative, transthoracic echocardiography revealed warts in the valves, and a renal biopsy also showed findings of glomerular infiltration by mononuclear leukocytes and C3 deposition in the glomeruli, suggesting infection-related glomerulonephritis. Later, Bartonella antibody turned positive. Antimicrobial treatment improved the purpura and renal function without any recurrence. ANCA-positive RPGN requires the exclusion of infective endocarditis, especially that induced by Bartonella spp.

Bartonella infections diagnosed in the French reference center, 2014-2019, and focus on infections in the immunocompromised

We studied retrospectively 651 PCR-confirmed Bartonella infections diagnosed at the French reference center for bartonellosis from 2014 to 2019. The most common form was cat-scratch disease (89%) followed by endocarditis (9%). Disseminated forms (2%) mainly presented as bacillary angiomatosis or peliosis hepatis in solid organ transplant recipients.

Western Immunoblotting for the Diagnosis of Enterococcus faecalis and Streptococcus gallolyticus Infective Endocarditis

Blood culture-negative endocarditis (BCNE) remains a diagnostic challenge. In our center, despite a systematic and exhaustive microbiological diagnostics strategy, 22% of patients with BCNE remain without an identified etiology. In an effort to determine the relevance of using Western blot (WB) for the etiological diagnosis of BCNE in patients with early antibiotic use, we developed specific assays for the major infective endocarditis (IE) causative agents, namely, Staphylococcus aureus, Enterococcus faecalis, Streptococcus anginosus, and Streptococcus gallolyticus. Our technique was effective to identify the antigenic profiles of the four tested agents, but cross-reactions with S. aureus and S. anginosus antigens were frequent. A scoring method was developed for the diagnosis of E. faecalis and S. gallolyticus IE using the presence of reactivity to at least two antigenic bands for each bacterium and the positivity to at least one of the Ef300, Ef72, or Ef36 proteic bands for E. faecalis, and positivity for the two Sg75 and Sg97 proteic bands for S. gallolyticus. We tested these diagnostic criteria in a prospective cohort of 363 patients with suspected IE. Immunoblotting for the diagnosis of E. faecalis IE showed a sensitivity of 100% and a specificity of 99%. The positive and negative predictive values were 73 and 100%, respectively. Regarding S. gallolyticus infection, immunoblot had a sensitivity of 100% and a specificity of 95%. However, the positive predictive value was 22%, whereas the predictive negative value was 100%. Using WB, we identified a potential etiological agent in 4 of 14 BCNE cases with no identified pathogen. In conclusion, WB constitutes a promising and helpful method to diagnose E. faecalis or S. gallolyticus IE in patients with early antibiotic uptake and negative blood cultures.

An unexpected case of Bartonella alsatica prosthetic vascular graft infection

Bartonella alsatica is a wild rabbit pathogen causing bacteremia rarely reported in humans, with only three cases published so far, including one lymphadenitis and two endocarditis cases. Here, we report the case of a 66-year-old man who suffered from acute renal failure due to a membranoproliferative glomerulonephritis. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) showed diffuse FDG uptake around the aortobifemoral graft with no indication of infection. A white blood cell scan showed an accumulation of labeled neutrophils on the left femoral part of the graft. The patient underwent surgery and an abscess around the left iliac part of the graft was found intraoperatively. Intraoperative samples were all negative, but 16S rRNA gene-based PCR was positive, and the sequence was positioned among the Bartonella species cluster. Specific PCRs targeting groEL/hsp60, rpoB and gltA genes were performed and led to the identification of B. alsatica. Accordingly, indirect immunofluorescence serological analyses were positive for Bartonella henselae and Bartonella quintana. The patient had a history of regularly hunting wild rabbits. He was treated with 100 mg of doxycycline twice a day for six months and his renal function significantly improved with no sign of persistent infection. This case highlights the contribution of serology assays and molecular-based methods in prosthetic vascular graft infection diagnosis.

Bartonella quintana, an Unrecognized Cause of Infective Endocarditis in Children in Ethiopia

Bartonella quintana endocarditis, a common cause of culture-negative endocarditis in adults, has rarely been reported in children. We describe 5 patients 7-16 years of age from Ethiopia with heart defects and endocarditis; 4 cases were caused by infection with B. quintana and 1 by Bartonella of undetermined species. All 5 patients were afebrile and oligosymptomatic, although 3 had heart failure. C-reactive protein was normal or slightly elevated, and erythrocyte sedimentation rate was high. The diagnosis was confirmed by echocardiographic demonstration of vegetations, the presence of high Bartonella IgG titers, and identification of B. quintana DNA in excised vegetations. Embolic events were diagnosed in 2 patients. Our data suggest that B. quintana is not an uncommon cause of native valve endocarditis in children in Ethiopia with heart defects and that possible B. quintana infection should be suspected and pursued among residents of and immigrants from East Africa, including Ethiopia, with culture-negative endocarditis.

Marseille scoring system for empiric treatment of infective endocarditis

Despite advances in medical, surgical, and critical care, infective endocarditis (IE) remains associated with considerable morbidity and mortality. We evaluated the performance of the Marseille score, including clinical data and biological tests obtained within 2 h, to identify patients at high risk of IE in order to initiate early antimicrobial treatment. This was secondarily confirmed using modified ESC criteria combined with molecular testing and ⁽¹⁸⁾fluorodeoxyglucose-positron emission tomography/computed tomography as diagnostic tools. In a prospective cohort study, we enrolled 484 patients with cardiovascular predisposition and clinical suspicion of IE from 2011 to 2013. The final diagnosis was definite IE in 123 patients and possible IE in 107. Marseille score was calculated adding one point for each present parameter (range 0-9). This score includes clinical, epidemiological (male, fever, splenomegaly, clubbing, vascular disease and stroke) and biological criteria (Leucocytes >10,000/mm3, sedimentation rate (SR) > 50/mm or C reactive protein >10 mg/L and hemoglobin <100 g/l). A score of 2 or more performed best in predicting IE in patients with predisposing heart lesions. Sensitivity was better on left-side heart lesions (94%) than on right-side heart lesions (85%) (p = 0.04) and better for valvulopathy (94%) than intra cardiac devices (84%) (p = 0.02). The predictive positive value of prosthetic valves was greater than that of native valves (p = 0.02). Using our simple Marseille score combined with our standardized diagnostic procedures would help improve IE management by focusing on early empiric treatment within 2 h of admission for patients with cardiac predisposition factors.

Bartonella Species, an Emerging Cause of Blood-Culture-Negative Endocarditis

Since the reclassification of the genus Bartonella in 1993, the number of species has grown from 1 to 45 currently designated members. Likewise, the association of different Bartonella species with human disease continues to grow, as does the range of clinical presentations associated with these bacteria. Among these, blood-culture-negative endocarditis stands out as a common, often undiagnosed, clinical presentation of infection with several different Bartonella species. The limitations of laboratory tests resulting in this underdiagnosis of Bartonella endocarditis are discussed. The varied clinical picture of Bartonella infection and a review of clinical aspects of endocarditis caused by Bartonella are presented. We also summarize the current knowledge of the molecular basis of Bartonella pathogenesis, focusing on surface adhesins in the two Bartonella species that most commonly cause endocarditis, B. henselae and B. quintana. We discuss evidence that surface adhesins are important factors for autoaggregation and biofilm formation by Bartonella species. Finally, we propose that biofilm formation is a critical step in the formation of vegetative masses during Bartonella-mediated endocarditis and represents a potential reservoir for persistence by these bacteria.

Blood culture-negative endocarditis: Improving the diagnostic yield using new diagnostic tools

Blood culture-negative endocarditis (BCNE) may represent up to 70% of all endocarditis cases, depending on series. From 2001 to 2009, we implemented in our laboratory a multimodal diagnostic strategy for BCNE that included systematized testing of blood, and when available, valvular biopsy specimens using serological, broad range molecular, and histopathological assays. A causative microorganism was identified in 62.7% of patients.In this study from January 2010 to December 2015, in an effort to increase the number of identified causative microorganisms, we prospectively added to our diagnostic protocol specific real-time (RT) polymerase chain reaction (PCR) assays targeting various endocarditis agents, and applied them to all patients with BCNE admitted to the 4 public hospitals in Marseille, France.A total of 283 patients with BCNE were included in the study. Of these, 177 were classified as having definite endocarditis. Using our new multimodal diagnostic strategy, we identified an etiology in 138 patients (78.0% of cases). Of these, 3 were not infective (2.2%) and 1 was diagnosed as having Mycobacterium bovis BCG endocarditis. By adding specific PCR assays from blood and valvular biopsies, which exhibited a significantly greater sensitivity (P < 10) than other methods, causative agents, mostly enterococci, streptococci, and zoonotic microorganisms, were identified in an additional 27 patients (14 from valves only, 11 from blood only, and 2 from both). Finally, in another 107 patients, a pathogen was detected using serology in 37, valve culture in 8, broad spectrum PCR from valvular biopsies and blood in 19 and 2, respectively, immunohistochemistry from valves in 3, and a combination of several assays in 38.By adding specific RT-PCR assays to our systematic PCR testing of patients with BCNE, we increased the diagnostic efficiency by 24.3%, mostly by detecting enterococci and streptococci that had not been detected by other diagnostic methods, but also agents requiring specific management such as Mycoplasma hominis and Tropheryma whipplei.

Prosthetic Valve Endocarditis Caused by Bartonella henselae: A Case Report of Molecular Diagnostics Informing Nonsurgical Management

Identifying the pathogen responsible for culture-negative valve endocarditis often depends on molecular studies performed on surgical specimens. A patient with Ehlers-Danlos syndrome who had an aortic graft, a mechanical aortic valve, and a mitral anulloplasty ring presented with culture-negative prosthetic valve endocarditis and aortic graft infection. Research-based polymerase chain reaction (PCR)/electrospray ionization mass spectrometry on peripheral blood samples identified Bartonella henselae. Quantitative PCR targeting the16S-23S ribonucleic acid intergenic region and Western immunoblotting confirmed this result. This, in turn, permitted early initiation of pathogen-directed therapy and subsequent successful medical management of B henselae prosthetic valve endocarditis and aortic graft infection.

Evaluation of empirical treatment for blood culture-negative endocarditis

OBJECTIVES

Much progress has been made in understanding the main causes of blood culture-negative endocarditis (BCNE). Few studies concerning BCNE treatment (due to previous antibiotics used or fastidious pathogens) are available. We performed this study to evaluate the effectiveness of our therapeutic protocol in BCNE, based on compliance with the protocol, outcome and 1 year mortality.

PATIENTS AND METHODS

We collected prospectively and analysed retrospectively cases of BCNE between 2002 and 2014, using a simplified and standardized protocol developed by our multidisciplinary team. We apply two kinds of protocols to treat BCNE, which include only four intravenous antimicrobial agents: amoxicillin, vancomycin, gentamicin and amphotericin B.

RESULTS

We had 177 patients with definite BCNE. There were 154 (87.0%) patients treated with both appropriate antimicrobial agents and appropriate duration of treatment. We analysed the causes of inappropriate treatment in 13 (7.3%) cases and inappropriate duration in 10 (5.6%) cases. The treatment changes were justified in all cases except one of discharge against medical advice. The fatality rate was 5.1% (nine cases) and all deaths occurred in the group of patients who were treated with appropriate treatment; however, four deaths were not attributable to empirical treatment failure. Concerning the other deaths, the lack of surgical management, in association with empirical treatment, could explain our protocol's failure, such as poorly tolerated surgery.

CONCLUSIONS

Our protocol is efficient and our mortality rate was low, compared with the literature review. This may result from a strategy that uses a sampling procedure and a standardized protocol at the same time.

Development of fluorogenic probe-based and high-resolution melting-based polymerase chain reaction assays for the detection and differentiation of Bartonella quintana and Bartonella henselae

Bartonella henselae and Bartonella quintana are the major etiological agents of infective endocarditis, which pose a serious threat to human health. To simultaneously detect and differentiate B. henselae and B. quintana, a reliable and fast method to simultaneously detect and differentiate B. henselae and B. quintana is required. In this study, we developed and validated two rapid, highly sensitive and specific, duplex, real-time polymerase chain reaction (PCR) assays-one based on high-resolution melting (HRM) analysis, and the other on TaqMan probes-to simultaneously detect and differentiate B. henselae and B. quintana. The sensitivity of developed assays were found 100 times more sensitive than that of conventional PCR. The specificity of the assays were validated by the absence of any cross reaction with the other Bartonella species, non-Bartonella bacteria and other animals. The results indicate that the duplex HRM-based and TaqMan probe-based assays have high specificity and sensitivity, and good reproducibility for simultaneous the detection of B. henselae and B. quintana. They are cost-effective, sensitive and reliable methods; and are thus suitable for clinical diagnosis, epidemiological surveys, and disease surveillance.

[Proliferative glomerulonephritis and erythroblastopenia associated with Bartonella quintana endocarditis]

Bartonella quintana is a facultative intracellular bacteria responsible of negative blood culture endocarditis whose diagnosis is often delayed. The occurrence of renal involvement has been exceptionally described in this context. We report the case of a 54-year-old man presenting with Bartonella quintana endocarditis complicated by proliferative glomerulonephritis with acute kidney injury and erythroblastopenia.

Bartonella, a common cause of endocarditis: a report on 106 cases and review

Bartonella spp. are fastidious bacteria that cause blood culture-negative endocarditis and have been increasingly reported. In this study, we included all patients retrospectively and prospectively diagnosed with Bartonella endocarditis in our French reference center between 2005 and 2013. Our diagnosis was based on the modified Duke criteria and microbiological findings, including serological and PCR results. To review the published literature, we searched all human Bartonella endocarditis cases published in the PubMed database between January 2005 and October 2013. We report here a large series of 106 cases, which include 59 cases that had not previously been reported or mentioned. Indirect immunofluorescence assays, Western blotting, and real-time PCR from total blood, serum, and valve tissue exhibited sensitivities of 58%, 100%, 33%, 36%, and 91%, respectively. The number of cases reported in the literature between 2005 and 2013 increased to reach a cumulative number of 196 cases. The number of cases reported in the literature by other centers is increasing more rapidly than that reported by our French reference center (P < 10(-2)). Currently, there is a lack of criteria for the diagnosis of Bartonella endocarditis. We suggest that a positive PCR result from a cardiac valve or blood specimen, an IgG titer of ≥800 using an immunofluorescence assay, or a positive Western blot assay be considered major Duke criteria for Bartonella endocarditis. There is no real increase in the incidence of these infections but rather a better understanding and interest in the disease resulting from the improvement of diagnostic tools.

Bartonella henselae endocarditis in Laos - 'the unsought will go undetected'

Background

Both endocarditis and Bartonella infections are neglected public health problems, especially in rural Asia. Bartonella endocarditis has been described from wealthier countries in Asia, Japan, Korea, Thailand and India but there are no reports from poorer countries, such as the Lao PDR (Laos), probably because people have neglected to look.

Methodology/Principal Findings

We conducted a retrospective (2006–2012), and subsequent prospective study (2012–2013), at Mahosot Hospital, Vientiane, Laos, through liaison between the microbiology laboratory and the wards. Patients aged >1 year admitted with definite or possible endocarditis according to modified Duke criteria were included. In view of the strong suspicion of infective endocarditis, acute and convalescent sera from 30 patients with culture negative endocarditis were tested for antibodies to Brucella melitensis,Mycoplasma pneumoniae,Bartonella quintana,B. henselae,Coxiella burnetii and Legionella pneumophila. Western blot analysis using Bartonella species antigens enabled us to describe the first two Lao patients with known Bartonella henselae endocarditis.

Conclusions/Significance

We argue that it is likely that Bartonella endocarditis is neglected and more widespread than appreciated, as there are few laboratories in Asia able to make the diagnosis. Considering the high prevalence of rheumatic heart disease in Asia, there is remarkably little evidence on the bacterial etiology of endocarditis. Most evidence is derived from wealthy countries and investigation of the aetiology and optimal management of endocarditis in low income countries has been neglected. Interest in Bartonella as neglected pathogens is emerging, and improved methods for the rapid diagnosis of Bartonella endocarditis are needed, as it is likely that proven Bartonella endocarditis can be treated with simpler and less expensive regimens than “conventional” endocarditis and multicenter trials to optimize treatment are required. More understanding is needed on the risk factors for Bartonella endocarditis and the importance of vectors and vector control.

Infection of heart valves (endocarditis) with bacteria is an important condition, especially afflicting those with rheumatic heart disease, and has a high mortality if untreated. Most of the evidence for optimal antibiotic and surgical management comes from wealthy countries. There are no published data from poorer countries in SE Asia despite a high burden of rheumatic heart disease. We investigated the bacterial infections of heart valves in the Lao PDR (Laos) through heart ultrasound scans and analysis of patients' blood. We provide evidence of infection with the poorly understood bacteria Bartonella henselae (the cause of cat scratch disease) in two patients from Laos. We argue that it is likely that Bartonella endocarditis is more widespread than appreciated, as there are few laboratories in Asia able to make the diagnosis. This is important as it is likely that proven Bartonella endocarditis can be treated with simpler and less expensive regimens than “conventional” endocarditis. There have been great advances in the wealthy world in the diagnosis and treatment of endocarditis but these have not been assessed or implemented in poorer countries. More evidence on the causes and optimal management of endocarditis in low income countries is needed.

Infective endocarditis in the Lao PDR: clinical characteristics and outcomes in a developing country

INTRODUCTION

Data on infective endocarditis (IE) in Southeast Asia are scarce.

OBJECTIVES

To describe the clinical epidemiology of IE in Lao PDR, a lower middle-income country.

METHODS

A single centre retrospective study at Mahosot Hospital, Vientiane. Patients aged over 1year of age admitted 2006-2012 to Mahosot Hospital with definite or possible IE by modified Duke criteria were included.

RESULTS

Thirty-six patients fulfilled the inclusion criteria; 33 (91.7%) had left-sided IE. Eleven (30.6%) had definite IE and 25 (69.4%) possible left-sided IE. Median age was 25years old [IQR 18-42]. Fifteen patients (41.7%) were males. Underlying heart diseases included: rheumatic valve disease in 12 (33.3%), congenital heart disease in 7 (19.4%), degenerative valve disease in 3 (8.3%), and of unknown origin in 14 (38.9%) patients. Native valve IE was present in 30 patients (83.3%), and prosthetic valve IE in 6 patients (16.7%). The most frequent pathogens were Streptococcus spp. in 7 (19.4%). Blood cultures were negative in 22 patients (61.1%). Complications included: heart failure in 11 (30.6%), severe valve regurgitation in 7 (19.4%); neurological event in 7 (19.4%); septic shock or severe sepsis in 5 (13.9%); and cardiogenic shock in 3 patients (8.3%). No patient underwent heart surgery. Fourteen (38.9%) had died by follow-up after a median of 2.1years [IQR 1-3.2]; and 3 (8.3%) were lost to follow-up.

CONCLUSIONS

Infective endocarditis, a disease especially of young adults and mainly caused by Streptococcus spp., was associated with rheumatic heart disease and had high mortality in Laos.

Bartonella vinsonii endocarditis in an adolescent with congenital heart disease

We report the second human case of Bartonella vinsonii subsp. berkhoffii endocarditis in a 19-year-old male with congenital heart disease. Diagnosis was established by Bartonella antibodies detected by immunofluorescence, and polymerase chain reaction amplification and sequencing from blood.

Identification of candidate proteins for the diagnosis of Bartonella henselae infections using an immunoproteomic approach

Bartonella henselae is an emerging gram-negative facultative intracellular pathogen transmitted via Ctenocephalides felis (cat fleas) or cat scratches. Bartonellosis is present mainly in the form of cat scratch disease (CSD), bacillary angiomatosis and infective endocarditis (IE). The methods used to diagnose B. henselae rely on culturing, immunofluorescent assays and molecular techniques. The objective of the present study was to identify candidate proteins for the serodiagnosis of bartonellosis with the differential discrimination of both clinical scenarios: CSD and IE. For this, an immunoproteomic approach combined with 2-DE, immunoblotting and matrix-assisted laser desorption/ionization time-of-flight MS has been developed. Immunoproteomic profiles of sera collected from patients with CSD and IE were compared with those of blood donors. We identified several candidate proteins as phage-encoding Pap31 protein and an outer membrane protein of BH11510 that, in our view, might be useful for the serodiagnosis of bartonellosis.

[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.

Fatal myocarditis-associated Bartonella quintana endocarditis: a case report

Introduction

Bartonella spp. infection is not rare and must be considered with great care in patients with suspected infective endocarditis, particularly if regular blood cultures remain sterile. Management of these infections requires knowledge of the identification and treatment of these bacteria.

Case presentation

A 50-year-old Senegalese man was admitted to our Department of Cardiac Surgery with a culture-negative endocarditis. Despite valvular surgery and adequate antibiotic treatment, recurrence of the endocarditis was observed on the prosthetic mitral valve. Heart failure required circulatory support. Weaning off the circulatory support could not be attempted owing to the absence of heart recovery. Bacteriological diagnosis of Bartonella quintana endocarditis was performed by molecular methods retrospectively after the death of the patient.

Conclusions

This case report underlines the severity and difficulty of the diagnosis of Bartonella quintana endocarditis. The clinical picture suggested possible Bartonella quintana associated myocarditis, a feature that should be considered in new cases.

High Bartonella spp. seroprevalence in a Swedish homeless population but no evidence of trench fever

Blood samples and epidemiological data were collected from 50 homeless patients in central Stockholm, Sweden. Sera were analysed for antibodies to B. henselae, B. quintana, B. elizabethae and B. grahamii. Whole blood was cultured and used as substrate for a newly developed quantitative real time polymerase chain reaction (QPCR) specifically targeting Bartonella spp. DNA. 61 matched blood donor sera were used as controls. Homeless patients were significantly more often seropositive to Bartonella spp. than controls (OR 7.58 (3.30-17.39), p<0.05). Reactivity to the B. elizabethae antigen was dominating, although the difference between patients and controls was most significant in seroreactivity to the B. henselae antigen. There was no evidence of an ongoing B. quintana epidemic. The absence of louse infestation could explain the lack of B. quintana bacteraemia and the failure to amplify Bartonella DNA.

Zoonoses of dermatologic interest

Zoonoses are infectious diseases that can be transmitted from animals to humans. Transmission occurs directly or through vectors such as ticks, mosquitoes, or flies. The causative agents include bacteria, parasites, viruses, and fungi. Domestic pets and livestock, as well as wild animals, can be the source of disease. In this summary, we will focus on a number of dermatologically relevant examples.

Multiplexed whole bacterial antigen microarray, a new format for the automation of serodiagnosis: the culture-negative endocarditis paradigm

The serological diagnosis of blood culture-negative endocarditis due to Coxiella burnetii, Bartonella spp., Brucella melitensis and Legionella pneumophila is based on a manual immunofluorescence assay (IFA), which is taken to be the reference method. The automated IFA InoDiag multiplexed antigenic microarray, which includes a slide with all the above bacteria and four internal controls, an incubator, a fluorescent reader and software with an algorithm of interpretation for infectious endocarditis (IE) was evaluated. A single serum dilution at 1/128 was used. Eleven patients with Bartonella spp. IE and ten with C. burnetii IE, diagnosed using the modified Duke criteria, as well as one patient with B. melitensis infection and three patients with L. pneumophila IE were tested. In total, 236 sera were used as negative controls, with the reference method. The results of IgG detection were: C. burnetii phase I, 'sensitivity (Se) = 88% and specificity (Sp) = 99%', and C. burnetii phase II, Se = 88% and Sp = 99%; for Bartonella henselae, Se = 100% and Sp = 100%; for Bartonella quintana, Se = 78% and Sp = 96%; for B. melitensis, Se = 100% and Sp = 99%; and for L. pneumophila, Se = 100% and Sp = 99%. With the algorithm interpretation, the negative and positive predictive values of the test 'were 100% for the diagnosis of IE caused by the four bacteria tested. These results were confirmed by two other assays, one using triplicate testing and one blind testing performed by another centre. This multiplexed test is therefore a valuable tool for the rapid diagnosis of blood-culture negative IE.

[Infective endocarditis due to Bartonella henselae following a rupture of a cerebral aneurysm]

We report a case of severe aortic bicuspid valve endocarditis, revealed by global cardiac failure without fever, in a 38-year-old man who had developed cerebral mycotic aneurysms nine months earlier. PCR analysis of the excised aortic valve and serological tests (even 9 months earlier) were positive for Bartonella henselae. A combination of intravenous then oral doxycyclin at 200mg/day and intravenous gentamycin at 90mg/day was given for 6 and 2 weeks respectively. The evolution was favorable on follow-up, 12 months after completion of the therapy. Only 49 cases of B. henselae endocarditis have been reported to date, none with associated mycotic aneurysm but most often located on the bicuspid aortic valve, and usually with severe valvular damage due to late diagnosis.

High prevalence of fastidious bacteria in 1520 cases of uveitis of unknown etiology

The etiologic evaluation of uveitis is frequently unsuccessful when noninvasive methods are used. We conducted a prospective study to evaluate systematic screening for pathogens of uveitis. All patients with uveitis referred to the participating tertiary ophthalmology departments from January 2001 to September 2007 underwent intraocular and serum specimen collection. The standardized protocol for laboratory investigations included universal polymerase chain reaction (PCR)-based detection of any bacteria and mycoses, specific PCR-based detection of fastidious (difficult-to-grow) bacteria and herpes viruses, and culture of vitreous fluid. Sera were tested for fastidious bacteria. Among the 1321 included patients (1520 specimens), infection was diagnosed in 147 (11.1%) patients: 78 (53%) were caused by fastidious bacteria that included spirochetes, Bartonella species, intracellular bacteria (Chlamydia species, Rickettsia species, Coxiella burnetii), and Tropheryma whipplei; 18 by herpes viruses; and 9 by fungi. Bartonella quintana, Coxiella burnetii, Paracoccus yeei, Aspergillus oryzae, and Cryptococcus albidus were found to be associated with uveitis for the first time, to our knowledge. We recommend applying a 1-step diagnostic procedure that incorporates intraocular, specific microbial PCR with serum analyses in tertiary centers to determine the etiology of uveitis.

A view on Bartonella quintana endocarditis—confirming the molecular diagnosis by specific fluorescence in situ hybridization

Culture-negative endocarditis is a frequent problem in cardiology, especially if caused by fastidious organisms. Among these, the diagnostic tools for the detection of Bartonella quintana are still unsatisfactory. In a culture-negative case of suspected endocarditis undergoing aortic valve replacement, polymerase chain reaction amplification and sequencing of the 16S rRNA gene indicated B. quintana infection. To develop a new diagnostic tool, independent from culture and amplification techniques, we designed and optimized an oligonucleotide fluorescence in situ hybridization (FISH) probe specific for B. quintana and suitable for FISH. FISH succeeded in simultaneous visualization and identification of vital microorganisms directly within the aortic valve tissue and in fast and univocal diagnosis of B. quintana endocarditis.

Microfluidic chip analysis of outer membrane proteins responsible for serological cross-reaction between three Gram-negative bacteria: Proteus morganii O34, Escherichia coli O111 and Salmonella Adelaide O35

Bacterial strains have complex and individual antigenic structure, which provides basis for their serological identification. However, serological cross-reaction may occur when antibodies against a certain strain recognize other strains too. The molecular basis of this phenomenon is the expression of similar or identical antigenic epitopes on the surface of different bacterial cells. Such cross-reactions might harden the serological diagnosis of pathogenic bacteria. But it can be also advantageous, when antigens of non-pathogenic strains can be used in the serological examinations. Serological cross-reaction between three taxonomically different strains--Proteus morganii O34 (8662/64), Escherichia coli O111 and Salmonella Adelaide O35--have been described. It has been proven that it is based partially on the similar lipopolysaccharide structures of these pathogens. In this study the involvement of the outer membrane proteins of these strains in the serological cross-reaction is presented. Microfluidic chip technology was applied for the detection of common proteins, which provided fast and quantitative data about the proteins that might be responsible for serological cross-reaction. Two outer membrane proteins with apparent molecular mass of 36 and 41 kDa, respectively, could be detected in the profile of each strain, while individual dominating protein peaks have also appeared in the protein profiles. The presence of common protein antigens was proven by Western blotting.

From cat scratch disease to endocarditis, the possible natural history of Bartonella henselae infection

Background

Most patients with infectious endocarditis (IE) due to Bartonella henselae have a history of exposure to cats and pre-existing heart valve lesions. To date, none of the reported patients have had a history of typical cat scratch disease (CSD) which is also a manifestation of infection with B. henselae.

Case presentation

Here we report the case of a patient who had CSD and six months later developed IE of the mitral valve caused by B. henselae.

Conclusion

Based on this unique case, we speculate that CSD represents the primary-infection of B. henselae and that IE follows in patients with heart valve lesions.

Chronic nasal infection caused by Klebsiella rhinoscleromatis or Klebsiella ozaenae: two forgotten infectious diseases

OBJECTIVES

Klebsiella rhinoscleromatis and Klebsiella ozaenae are associated with chronic diseases of the upper airways: rhinoscleroma and ozena, respectively. These have become uncommon in developed countries. We report herein one case of each disease in patients living in Marseilles, France, and include a review of the literature.

METHODS

Diagnosis was made by direct evidence of bacteria (specific cultures and autoimmunohistochemistry on nasal biopsy) and using an indirect method (serology). In addition, the literature review showed that the majority of publications were old, confirming the fact that these diseases have been long forgotten.

RESULTS

The specific and original methods used have allowed us to confirm the pathogenic role of K. ozaenae in ozena and confirmed rhinoscleroma in a granulomatous lesion. In the literature, K. rhinoscleromatis is only associated with rhinoscleroma whereas K. ozaenae is also associated with clinical diseases other than chronic rhinitis.

CONCLUSIONS

In cases of chronic rhinitis, ozena and rhinoscleroma should be kept in mind, even in developed countries, and systematically screened for, especially as there are specific diagnostic tools and effective treatments available.

New insight into the diagnosis of fastidious bacterial endocarditis

Sterile blood cultures are noted in one third of patients with infectious endocarditis. Although in half of cases this is due to previous antibiotic therapy, in the other half, the aetiology of culture-negative endocarditis is intracellular bacteria such as Coxiella burnetii or fastidious growing bacteria. Although it was previously considered that the prevalence of such organisms was identical throughout the world, recent investigations on Bartonella endocarditis clearly showed that the aetiology of culture-negative endocarditis is likely to be strongly related to epidemiology of the agent in each country. During the past decade the use of molecular techniques such as PCR with subsequent sequencing to detect or to identify bacteria in valves from patients with infectious endocarditis have considerably improved the aetiological diagnosis. This is especially true in the case of culture-negative endocarditis following earlier antibiotic therapy. However, the fact that DNA remnants of past endocarditis can be detected some time after the acute episode, when the patient has been cured, suggests that the predictive value of these techniques along with the traditional histology and culture need to be evaluated closely.

Production of recombinant Bartonella henselae 17-kDa protein for antibody-capture enzyme-linked immunosorbent assay

The Bartonella henselae 17-kDa protein was expressed in a prokaryotic expression system as a histidine-tagged fusion protein and was purified. The target gene was cloned into a recombinant expression construct, pTri-17kd. The expressed protein was purified to near homogeneity by a nickel-agarose column chromatography. Protein recovery was estimated to be 2.9 mg from 100 mL of bacterial culture. The purified 17-kDa protein was recognized by serum from patients infected with B. henselae and Bartonella quintana, suggesting antigenic integrity. The sensitivity and specificity of the IgG enzyme-linked immunosorbent assay (ELISA) relative to immunofluorescent antibody assay testing were 71.1% and 93.0%, respectively. According to the receiver operating characteristic curve analysis, the area under the curve was 0.823. These results indicate that the expressed 17-kDa protein is a suitable source of antigen for development of an antibody-capture ELISA for the detection of antibodies to B. henselae.

Bartonella quintana characteristics and clinical management

The pathogen is reemerging in the United States and Europe and is responsible for a number of clinical conditions.

Bartonella quintana, a pathogen that is restricted to human hosts and louse vectors, was first characterized as the agent of trench fever. The disease was described in 1915 on the basis of natural and experimental infections in soldiers. It is now recognized as a reemerging pathogen among homeless populations in cities in the United States and Europe and is responsible for a wide spectrum of conditions, including chronic bacteremia, endocarditis, and bacillary angiomatosis. Diagnosis is based on serologic analysis, culture, and molecular biology. Recent characterization of its genome allowed the development of modern diagnosis and typing methods. Guidelines for the treatment of B. quintana infections are presented.

First isolation of Bartonella alsatica from a valve of a patient with endocarditis

We report the first documented case of endocarditis in a man infected with Bartonella alsatica, which causes bacteremia in healthy wild rabbits. B. alsatica was identified by serology and culture and by PCR of an aortic valve specimen. B. alsatica should be added to the list of zoonotic agents of blood culture-negative endocarditis.

Contribution of systematic serological testing in diagnosis of infective endocarditis

Despite progress with diagnostic criteria, the type and timing of laboratory tests used to diagnose infective endocarditis (IE) have not been standardized. This is especially true with serological testing. Patients with suspected IE were evaluated by a standard diagnostic protocol. This protocol mandated an evaluation of the patients according to the modified Duke criteria and used a battery of laboratory investigations, including three sets of blood cultures and systematic serological testing for Coxiella burnetii, Bartonella spp., Aspergillus spp., Legionella pneumophila, and rheumatoid factor. In addition, cardiac valvular materials obtained at surgery were subjected to a comprehensive diagnostic evaluation, including PCR aimed at documenting the presence of fastidious organisms. The study included 1,998 suspected cases of IE seen over a 9-year period from April 1994 to December 2004 in Marseilles, France. They were evaluated prospectively. A total of 427 (21.4%) patients were diagnosed as having definite endocarditis. Possible endocarditis was diagnosed in 261 (13%) cases. The etiologic diagnosis was established in 397 (93%) cases by blood cultures, serological tests, and examination of the materials obtained from cardiac valves, respectively, in 348 (81.5%), 34 (8%), and 15 (3.5%) definite cases of IE. Concomitant infection with streptococci and C. burnetii was seen in two cases. The results of serological and rheumatoid factor evaluation reclassified 38 (8.9%) possible cases of IE as definite cases. Systematic serological testing improved the performance of the modified Duke criteria and was instrumental in establishing the etiologic diagnosis in 8% (34/427) cases of IE.

Blood culture-negative endocarditis in a reference center: etiologic diagnosis of 348 cases

To identify the current etiologies of blood culture-negative infective endocarditis and to describe the epidemiologic, clinical, laboratory, and echocardiographic characteristics associated with each etiology, as well as with unexplained cases, we tested samples from 348 patients suspected of having blood culture-negative infective endocarditis in our diagnostic center, the French National Reference Center for Rickettsial Diseases, between 1983 and 2001. Serology tests for Coxiella burnettii, Bartonella species, Chlamydia species, Legionella species, and Aspergillus species; blood culture on shell vial; and, when available, analysis of valve specimens through culture, microscopic examination, and direct PCR amplification were performed. Physicians were asked to complete a questionnaire, which was computerized. Only cases of definite infective endocarditis, as defined by the modified Duke criteria, were included. A total of 348 cases were recorded-to our knowledge, the largest series reported to date. Of those, 167 cases (48%) were associated with C. burnetii, 99 (28%) with Bartonella species, and 5 (1%) with rare, fastidious bacterial agents of endocarditis (Tropheryma whipplei, Abiotrophia elegans, Mycoplasma hominis, Legionella pneumophila). Among 73 cases without etiology, 58 received antibiotic drugs before the blood cultures. Six cases were right-sided endocarditis and 4 occurred in patients who had a permanent pacemaker. Finally, no explanatory factor was found for 5 remaining cases (1%), despite all investigations.Q fever endocarditis affected males in 75% of cases, between 40 and 70 years of age. Ninety-one percent of patients had a previous valvulopathy, 32% were immunocompromised, and 70% had been exposed to animals. Our study confirms the improved clinical presentation and prognosis of the disease observed during the last decades. Such an evolution could be related to earlier diagnosis due to better physician awareness and more sensitive diagnostic techniques. As for Bartonella species, B. quintana was recorded more frequently than B. henselae (53 vs 17 cases). For 18 patients with Bartonella endocarditis, the responsible species was not identified. Species determination was achieved through culture and/or PCR in 49 cases and through Western immunoblotting in 22. Comparison of B. quintana and B. henselae endocarditis revealed distinct epidemiologic patterns. The 2 cases due to T. whipplei reflect the emerging role of this agent as a cause of infective endocarditis. Because identification of the bacterium was possible only through analysis of excised valves by histologic examination, PCR, and culture on shell vial, the prevalence of the disease might be underestimated. Among patients who received antibiotic drugs before blood cultures, 4 cases (7%) were found to be associated with Streptococcus species (2 S. bovis and 2 S. mutans) through 16S rDNA gene amplification directly from the valve, which shows the usefulness of this technique in overcoming the limitations of previous antibiotic treatment. Right-sided endocarditis occurred classically in young patients (mean age, 36 yr), intravenous drug users in 50% of cases, and suffering more often from embolic complications. Finally, 5 cases without etiology or explaining factors were all immunocompetent male patients with previous aortic valvular lesions, and 3 of the 5 presented with an aortic abscess. Further investigations should be focused on this group to identify new agents of infective endocarditis.

Bacterial zoonoses and infective endocarditis, Algeria

Blood culture–negative endocarditis is common in Algeria. We describe the etiology of infective endocarditis in this country. Samples from 110 cases in 108 patients were collected in Algiers. Blood cultures were performed in Algeria. Serologic and molecular analysis of valves was performed in France. Infective endocarditis was classified as definite in 77 cases and possible in 33. Causative agents were detected by blood cultures in 48 cases. All 62 blood culture–negative endocarditis cases were tested by serologic or molecular methods or both. Of these, 34 tested negative and 28 had an etiologic agent identified. A total of 18 infective endocarditis cases were caused by zoonotic and arthropodborne bacteria, including Bartonella quintana (14 cases), Brucella melitensis (2 cases), and Coxiella burnetii (2 cases). Our data underline the high prevalence of infective endocarditis caused by Bartonella quintana in northern Africa and the role of serologic and molecular tools for the diagnosis of blood culture–negative endocarditis.

Bartonella vinsonii subsp. arupensis as an agent of blood culture-negative endocarditis in a human

We report the case of a patient hospitalized with endocarditis. The etiological diagnosis of Bartonella was suggested by detection of high titers of antibodies by immunofluorescence and Western blotting. Two different nested PCRs performed on sera identified Bartonella vinsonii subsp. arupensis by sequencing.

Ectoparasitism and vector-borne diseases in 930 homeless people from Marseilles

Homeless people are particularly exposed to ectoparasites, but their exposure to arthropod-borne diseases has not been evaluated systematically. A medical team of 27 persons (7 nurses, 6 infectious disease residents or fellows, 2 dermatologists, and 12 infectious disease specialists) visited the 2 shelters in Marseilles, France, for 4 consecutive years. Homeless volunteers were interviewed, examined, and received care; and blood was sampled for cell counts and detection of bacteremia, antibodies to louse-borne (Rickettsia prowazekii, Bartonella quintana, and Borrelia recurrentis), flea-borne (R. typhi, R. felis), mite-borne (R. akari), and tick-borne (R. conorii) bacterial agents. We selected sex- and age-adjusted controls among healthy blood donors. Over 4 years, 930 homeless people were enrolled. Lice were found in 22% and were associated with hypereosinophilia (odds ratio, 5.7; 95% confidence intervals, 1.46-22.15). Twenty-seven patients (3%) with scabies were treated with ivermectin. Bartonella quintana was isolated from blood culture in 50 patients (5.3%), 36 of whom were treated effectively. The number of bacteremic patient increased from 3.4% to 8.4% (p = 0.02) over the 4 years of the study. We detected a higher seroprevalence to Borrelia recurrentis, R. conorii, and R. prowazekii antibodies in the homeless. Our study shows a high prevalence of louse-borne infections in the homeless and a high degree of exposure to tick-borne diseases and scabies. Despite effective treatment for Bartonella quintana bacteremia and the efforts made to delouse this population, Bartonella quintana remains endemic, and we found hallmarks of epidemic typhus and relapsing fever. The uncontrolled louse infestation of this population should alert the community to the possibility of severe re-emerging louse-borne infections.

Culture-negative endocarditis due to Houston Complex Bartonella henselae acquired in Noumea, New Caledonia

A 44-year-old man with a bioprosthetic aortic valve suffered destructive endocarditis with severe embolic disease due to Bartonella henselae infection. Multilocus sequence typing was successfully performed with crude preparations of operative tissue as templates, and the infecting organism was determined to be typical of the Houston clonal group, although it was never cultured from blood or tissue. This is the first report of B. henselae infection in the South Pacific, and it reminds one that B. henselae is a cause of potentially lethal culture-negative endocarditis which may respond poorly to conventional empirical therapy. Nothing is known of the epidemiology of the infection in this region, but it is likely to be common and to contain representatives of both major clonal complexes. This study emphasizes the ease with which multilocus sequence typing can be used directly with tissue, which is important because of suggestions of strain-dependent clinical outcomes.

Pericardial effusion in a homeless man due to Bartonella quintana

Bartonella quintana may cause trench fever, endocarditis, bacillary angiomatosis, and chronic bacteremia, and a reemergence among homeless populations in cities has been noted. Pericarditis from Rickettsia conorii and Coxiella burnetii infection has been described, but there have been no reports of pericarditis due to Bartonella spp. We report a case of pericardial effusion due to Bartonella quintana in a homeless man, diagnosed on the basis of PCR detection of Bartonella quintana in a pericardial biopsy sample and a fourfold rise in antibody titers. The patient recovered within 2 weeks with antibiotics active against bartonellae.