Endocarditis caused by Rochalimaea henselae

Adhesion of Bartonella henselae to Fibronectin Is Mediated via Repetitive Motifs Present in the Stalk of Bartonella Adhesin A

Adhesion to host cells is the first and most crucial step in infections with pathogenic Gram-negative bacteria and is often mediated by trimeric autotransporter adhesins (TAAs). Bartonella henselae targets the extracellular matrix glycoprotein fibronectin (Fn) via the Bartonella adhesin A (BadA) attaching the bacteria to the host cell. The TAA BadA is characterized by a highly repetitive passenger domain consisting of 30 neck/stalk domains with various degrees of similarity. To elucidate the motif sequences mediating Fn binding, we generated 10 modified BadA constructs and verified their expression via Western blotting, confocal laser scanning, and electron microscopy. We analyzed their ability to bind human plasma Fn using quantitative whole-cell enzyme-linked immunosorbent assays (ELISAs) and fluorescence microscopy. Polyclonal antibodies targeting a 15-mer amino acid motif sequence proved to reduce Fn binding. We suggest that BadA adheres to Fn in a cumulative effort with quick saturation primarily via unpaired β-strands appearing in motifs repeatedly present throughout the neck/stalk region. In addition, we demonstrated that the length of truncated BadA constructs correlates with the immunoreactivity of human patient sera. The identification of BadA-Fn binding regions will support the development of new "antiadhesive" compounds inhibiting the initial adherence of B. henselae and other TAA-expressing pathogens to host cells. IMPORTANCE Trimeric autotransporter adhesins (TAAs) are important virulence factors and are widely present in various pathogenic Gram-negative bacteria. TAA-expressing bacteria cause a wide spectrum of human diseases, such as cat scratch disease (Bartonella henselae), enterocolitis (Yersinia enterocolitica), meningitis (Neisseria meningitis), and bloodstream infections (multidrug-resistant Acinetobacter baumannii). TAA-targeted antiadhesive strategies (against, e.g., Bartonella adhesin A [BadA], Yersinia adhesin A [YadA], Neisseria adhesin A [NadA], and Acinetobacter trimeric autotransporter [Ata]) might represent a universal strategy to counteract such bacterial infections. BadA is one of the best characterized TAAs, and because of its high number of (sub)domains, it serves as an attractive adhesin to study the domain-function relationship of TAAs in the infection process. The identification of common binding motifs between TAAs (here, BadA) and their major binding partner (here, fibronectin) provides a basis toward the design of novel "antiadhesive" compounds preventing the initial adherence of Gram-negative bacteria in infections.

Bartonella endocarditis and diffuse crescentic proliferative glomerulonephritis with a full-house pattern of immune complex deposition

Background

Bartonella endocarditis is often a diagnostic challenge due to its variable clinical manifestations, especially when it is first presented with involvement of organs other than skin and lymph nodes, such as the kidney.

Case presentation

This was a 13-year-old girl presenting with fever, chest and abdominal pain, acute kidney injury, nephrotic-range proteinuria and low complement levels. Her kidney biopsy showed diffuse crescentic proliferative glomerulonephritis with a full-house pattern of immune complex deposition shown by immunofluorescence, which was initially considered consistent with systemic lupus erythematous-associated glomerulonephritis (lupus nephritis). After extensive workup, Bartonella endocarditis was diagnosed. Antibiotic treatment and valvular replacement surgery were undertaken with subsequent return of kidney function to normal range.

Conclusion

This case demonstrates the importance of considering the full clinical picture when interpreting clinical, laboratory and biopsy findings, because the treatment strategy for infective endocarditis versus lupus nephritis is drastically different.

Comparison of Serological and Molecular Assays for Bartonella Species in Dogs with Hemangiosarcoma

Currently, a gold standard diagnostic test for Bartonella infection in dogs is lacking. This represents a critical limitation for the development and evaluation of new diagnostic tests, as well as for the diagnosis of, and research on, bartonellosis in dogs. This retrospective observational study aims to compare the results of commonly performed and newly-reported Bartonella spp. diagnostic tests in banked clinical specimens from 90 dogs with hemangiosarcoma (HSA) using composite reference standard (CRS) and random effects latent class analysis (RE-LCA) techniques. Samples from each dog were tested using six serological or molecular diagnostic assays, including indirect fluorescent antibody (IFA) and Western blot (WB) for the detection of antibodies in serum, and qPCR and droplet digital PCR (ddPCR) in blood and fresh frozen tissue biopsy samples (mainly splenic HSA tumors and histopathologically normal spleen or skin/adipose tissue). Bartonella infection prevalence was estimated to be 78% based on the CRS (parallel testing with all six assays), and 64% based on the RE-LCA model. The assay with the highest diagnostic accuracy was qPCR performed on fresh frozen tissue biopsy samples (sensitivity: 94% by RE-LCA and 80% by CRS; specificity: 100%). When comparing newly-reported to traditional Bartonella diagnostic assays, ddPCR was more sensitive for the detection of Bartonella DNA than qPCR when testing blood samples (36% vs. 0%, p < 0.0001). Dogs that were positive on serological assays alone with negative molecular assays were highly unlikely (<3%) to be classified as infected by the RE-LCA model. These data indicate that Bartonella spp. DNA can be PCR amplified from fresh frozen tissues from a majority of dogs with HSA using both qPCR and ddPCR, supporting the use of these methods for future controlled studies comparing the prevalence of Bartonella spp. DNA in the tissue of dogs with HSA to that of unaffected controls.

A case report on death from acute bacterial cholangitis accompanied by von Meyenburg complexes: Use of 16S rRNA gene sequencing to identify pathogenic microbes from postmortem formalin-fixed, paraffin-embedded tissue

RATIONALE

In some cases, autopsy is the first opportunity to find a previously unrecognized critical infection. Pathogens are identified by various methods, such as microscopic examination, special stains, culture tests, and immunohistochemistry. Here, we report a case of 16S ribosomal RNA (rRNA) gene sequencing using a postmortem formalin-fixed, paraffin-embedded (FFPE) tissue, which was useful for identifying pathogenic microbes.

PATIENT CONCERNS

Autopsy was performed on an 87-year-old man who had chronic renal failure and had developed sepsis from a central venous catheter infection 10 days before his death. Prior to these events, von Meyenburg complexes (VMCs) were also found during regular checkups.

DIAGNOSIS

Postmortem microscopic examination revealed acute purulent cholangitis with numerous microabscesses, accompanied by VMCs. Gram-negative rods were observed in some microabscesses, which were considered causative pathogens.

INTERVENTIONS

16S rRNA gene sequencing using postmortem FFPE tissue.

OUTCOMES

Pseudomonas aeruginosa was identified, different from the one detected in the central venous catheter culture while alive.

LESSONS

16S rRNA gene sequencing is a useful tool for identifying pathogenic microbes in postmortem FFPE tissues. This technique may be useful for amplicon sizes of approximately 100 bp or less.

What Is in a Cat Scratch? Growth of Bartonella henselae in a Biofilm

Bartonella henselae (B. henselae) is a gram-negative bacterium that causes cat scratch disease, bacteremia, and endocarditis, as well as other clinical presentations. B. henselae has been shown to form a biofilm in vitro that likely plays a role in the establishment and persistence of the bacterium in the host. Biofilms are also known to form in the cat flea vector; hence, the ability of this bacterium to form a biofilm has broad biological significance. The release of B. henselae from a biofilm niche appears to be important in disease persistence and relapse in the vertebrate host but also in transmission by the cat flea vector. It has been shown that the BadA adhesin of B. henselae is critical for adherence and biofilm formation. Thus, the upregulation of badA is important in initiating biofilm formation, and down-regulation is important in the release of the bacterium from the biofilm. We summarize the current knowledge of biofilm formation in Bartonella species and the role of BadA in biofilm formation. We discuss the evidence that defines possible mechanisms for the regulation of the genes required for biofilm formation. We further describe the regulation of those genes in the conditions that mimic both the arthropod vector and the mammalian host for B. henselae. The treatment for persistent B. henselae infection remains a challenge; hence, a better understanding of the mechanisms by which this bacterium persists in its host is critical to inform future efforts to develop drugs to treat such infections.

Pediculosis capitis y transmisión potencial de enfermedades infecciosas reemergentes en Colombia. Revisión de la literatura

Introducción. La infestación por piojos de la cabeza en humanos (Pediculus humanus capitis) se conoce como pediculosis capitis. Estos parásitos pueden ser vectores de enfermedades infecciosas con potencial reemergente.Objetivos. Revisar la literatura actual sobre las enfermedades infecciosas transmitidas por piojos de la cabeza y realizar una breve descripción de sus manifestaciones clínicas.Materiales y métodos. Se realizó una revisión de la literatura en PubMed, ScienceDirect, SciELO y Redalyc mediante la siguiente estrategia de búsqueda: años de publicación: 1938 a 2019; idioma: inglés y español; términos de búsqueda: “Pediculus”, “lice infestations”, “bacteria”, “emerging communicable diseases”, “Rickettsia”, “Bartonella”, “Borrelia”, “Acinetobacter”, “Yersinia“, and “Colombia”, y sus equivalentes en español.Resultados. De los 110 artículos incluidos, la mayoría correspondió a investigaciones originales (48.2%). A nivel mundial, numerosos estudios han reportado la transmisión de Rickettsia prowazekii, Bartonella quintana, Borrelia recurrentis, Staphylococcus aureus, Acinetobacter baumannii y Yersinia pestis, entre otras bacterias, por los piojos de la cabeza y del cuerpo en humanos.Conclusiones. Aunque las enfermedades infecciosas transmitidas por piojos de la cabeza son raras, guardan potencial reemergente en poblaciones afectadas por migraciones humanas, crisis sociopolíticas, indigencia e inmunosupresión. En Colombia no se han realizado investigaciones sobre la transmisión de estas enfermedades por Pediculus spp., por lo que se sugiere que en estudios futuros se determine la prevalencia y los aspectos epidemiológicos de las enfermedades transmitidas por piojos de la cabeza en población colombiana.

A broad-range PCR technique for the diagnosis of infective endocarditis

Infective endocarditis (IE) remains a severe and potentially fatal disease demanding sophisticated diagnostic strategies for detection of the causative microorganisms. The aim of the present study was to develop a broad-range 16S ribosomal RNA gene polymerase chain reaction in the routine diagnostic of IE for the early diagnosis of fatal disease. A broad-range PCR technique was selected and evaluated in terms of its efficiency in the diagnosis of endocarditis using 19 heart valves from patients undergoing cardiovascular surgeries at the Habib Bourguiba Hospital of Sfax, Tunisia, on the grounds of suspected IE. The results demonstrated the efficiency of this technique particularly in cases involving a limited number of bacteria since it helped to increase detection sensitivity. The technique proved to be efficient, particularly, in the bacteriological diagnosis of IE in contexts involving negative results from conventional culture methods and other contexts involving bacterial species that were not amenable to identification by phenotypic investigations. Indeed, the sequencing of the partial 16S ribosomal RNA gene revealed the presence of Bartonella henselae, Enterobacter sp., and Streptococcus pyogenes in three heart valves with the negative culture. It should be noted that the results obtained from the polymerase chain reaction-sequencing identification applied to the heart valve and the strain isolated from the same tissue were not consistent with the ones found by the conventional microbiological methods in the case of IE caused by Gemella morbillorum. In fact, the results from the molecular identification revealed the presence of Lactobacillus jensenii. Overall, the results have revealed that the proposed method is sensitive, reliable and might open promising opportunities for the early diagnosis of IE.

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.

Bartonella spp. - a chance to establish One Health concepts in veterinary and human medicine

Infectious diseases remain a remarkable health threat for humans and animals. In the past, the epidemiology, etiology and pathology of infectious agents affecting humans and animals have mostly been investigated in separate studies. However, it is evident, that combined approaches are needed to understand geographical distribution, transmission and infection biology of “zoonotic agents”. The genus Bartonella represents a congenial example of the synergistic benefits that can arise from such combined approaches: Bartonella spp. infect a broad variety of animals, are linked with a constantly increasing number of human diseases and are transmitted via arthropod vectors. As a result, the genus Bartonella is predestined to play a pivotal role in establishing a One Health concept combining veterinary and human medicine.

Clinicocytopathologic correlation in an atypical presentation of lymphadenopathy with review of literature

OBJECTIVES

To present a clinicocytopathologic correlation of an atypical case of cat scratch disease (CSD) involving retroperitoneal lymph nodes, with emphasis on communication between service teams for managing lymphadenopathy of unknown origin. We consider clinical and cytologic differential diagnoses and review the literature on atypical cases of CSD, with emphasis on abdominal presentation and cytologic findings.

METHODS

Clinical services met with the cytology service to review clinical and pathologic features. Literature was reviewed via PubMed search (Harbor-UCLA subscriptions). Immunohistochemistry and Steiner silver stains were performed by Harbor-UCLA Department of Pathology. Enzyme-linked immunosorbent assay IgG and IgM Bartonella henselae titers were carried out by Quest Nichols Institute.

RESULTS

Fine-needle aspirate Diff-Quik and Papanicolaou smears and H&E-stained cell block showed abundant histiocytes, monocytoid B cells, and numerous neutrophils associated with necrosis corresponding to a late stage of CSD infection. Silver stain was positive for clumps of pleomorphic organisms. IgM and IgG antibody titers were elevated.

CONCLUSIONS

The cytologic findings of CSD in an atypical abdominal presentation are similar to those of a classic presentation. Laboratory workup for atypical CSD should include at least two other modalities aside from cytomorphologic features. Close clinical and cytologic correlation avoided potentially unnecessary and harmful surgery and enabled timely treatment.

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.

Oroya fever and verruga peruana: bartonelloses unique to South America

Bartonella bacilliformis is the bacterial agent of Carrión's disease and is presumed to be transmitted between humans by phlebotomine sand flies. Carrión's disease is endemic to high-altitude valleys of the South American Andes, and the first reported outbreak (1871) resulted in over 4,000 casualties. Since then, numerous outbreaks have been documented in endemic regions, and over the last two decades, outbreaks have occurred at atypical elevations, strongly suggesting that the area of endemicity is expanding. Approximately 1.7 million South Americans are estimated to be at risk in an area covering roughly 145,000 km2 of Ecuador, Colombia, and Peru. Although disease manifestations vary, two disparate syndromes can occur independently or sequentially. The first, Oroya fever, occurs approximately 60 days following the bite of an infected sand fly, in which infection of nearly all erythrocytes results in an acute hemolytic anemia with attendant symptoms of fever, jaundice, and myalgia. This phase of Carrión's disease often includes secondary infections and is fatal in up to 88% of patients without antimicrobial intervention. The second syndrome, referred to as verruga peruana, describes the endothelial cell-derived, blood-filled tumors that develop on the surface of the skin. Verrugae are rarely fatal, but can bleed and scar the patient. Moreover, these persistently infected humans provide a reservoir for infecting sand flies and thus maintaining B. bacilliformis in nature. Here, we discuss the current state of knowledge regarding this life-threatening, neglected bacterial pathogen and review its host-cell parasitism, molecular pathogenesis, phylogeny, sand fly vectors, diagnostics, and prospects for control.

Detection of Bartonella spp. DNA in clinical specimens using an internally controlled real-time PCR assay

Bartonella henselae is the causative agent of cat-scratch disease (CSD), usually presenting itself as a -self-limiting lymphadenopathy. In this chapter an internally controlled Taqman probe-based real-time PCR targeting the groEL gene of Bartonella spp. is described. This assay allows for the rapid, sensitive, and simple detection of Bartonella spp. in samples from CSD or endocarditis suspects, and it is suitable for implementation in the diagnostic microbiology laboratory.

Bartonella infection: treatment and drug resistance

Bartonella species, which belong to the α-2 subgroup of Proteobacteria, are fastidious Gram-negative bacteria that are highly adapted to their mammalian host reservoirs. Bartonella species are responsible for different clinical conditions affecting humans, including Carrion's disease, cat scratch disease, trench fever, bacillary angiomatosis, endocarditis and peliosis hepatis. While some of these diseases can resolve spontaneously without treatment, in other cases, the disease is fatal without antibiotic treatment. In this article, we discuss the antibiotic susceptibility patterns of Bartonella species, detected using several methods. We also provide an overview of Bartonella infection in humans and animals and discuss the antibiotic treatment recommendations for the different infections, treatment failure and the molecular mechanism of antibiotic resistance in these bacteria.

Feline bartonellosis

Bartonella infection is common among domestic cats, but the role of Bartonella species as feline pathogens requires further study. Most Bartonella species that infect cats are zoonotic. Cats are the mammalian reservoir and vector for Bartonella henselae, an important zoonotic agent. Cat fleas transmit Bartonella among cats, and cats with fleas are an important source of human B henselae infections. New information about Bartonella as feline pathogens has recently been published, and this article summarizes much of that information. Issues surrounding diagnosis and treatment of feline Bartonella infections are described, and prevention of zoonotic transmission of Bartonella is discussed.

Genetic diversity of Bartonella henselae in human infection detected with multispacer typing

This techniqueis a suitable tool for evaluating the genetic diversity of B. henselae human isolates.

We applied multispacer typing (MST) by incorporating 9 variable intergenic spacers to Bartonella henselae DNA detected in lymph node biopsy specimens from 70 patients with cat-scratch disease (CSD), in cardiac valve specimens from 2 patients with endocarditis, and in 3 human isolates from patients with bacillary angiomatosis, CSD, and endocarditis. Sixteen MST genotypes were found, 5 previously identified in cats and 11 new. Of the studied DNA, 78.7% belonged to 2 genotypes, which were phylogenetically organized into 4 lineages. Human strains were mostly grouped within 2 lineages, previously identified as Marseille and Houston-1. Our results suggest a greater genetic diversity in human-infecting B. henselae than what has previously been evaluated by using other genotyping methods. However, the diversity is not significantly different from that of cat strains. MST is thus a suitable genotyping tool for evaluating the genetic heterogeneity of B. henselae among isolates obtained from human patients.

Multispacer typing to study the genotypic distribution of Bartonella henselae populations

Bartonella henselae, a worldwide fastidious bacterium, has a feline reservoir and is pathogenic for humans. However, the relationship between human and cat isolates of B. henselae, as well as its population dynamics and geographic heterogeneity, is not fully understood, in part because of the absence of appropriate typing methods. Multilocus sequence typing (MLST), the most discriminatory genotyping method for B. henselae, identified seven genotypes and suggested that human isolates arose from a limited number of cat isolates. Herein, we estimated the discriminatory power of multispacer typing (MST) by studying 126 B. henselae cat isolates from various areas of Europe, Asia, and the United States. We identified the nine most variable intergenic spacers conserved by both B. henselae and Bartonella quintana genomes. By comparing the sequences obtained from these nine spacers for each studied isolate, we identified 39 MST genotypes. The distribution of isolates into MST genotypes matched their phylogenetic organization into four clusters. MST showed that European and Asian isolates were different, in contrast with American isolates, but failed to identify pandemic strains. Our study demonstrated that MST is a powerful method for genotyping B. henselae at the strain level and may serve in studying the population dynamics of this bacterium and understanding the relationships between cat and human isolates. Finally, we provide a free-access MST-Rick online software program (http://ifr48.timone.univ-mrs.fr/MST_BHenselae/mst) that investigators may use to compare their own MST sequences to our database.

Isolation of Bacteriophages from Bartonella vinsonii subsp. berkhoffii and the Characterization of Pap31 Gene Sequences from Bacterial and Phage DNA

Bacteriophages enhance bacterial survival, facilitate bacterial adaptation to new environmental conditions, assist in the adaptation to a new host species, and enhance bacterial evasion or inactivation of host defense mechanisms. We describe the detection and purification of a novel tailed bacteriophage from Bartonella vinsonii subsp. berkhoffii, which was previously described as a bacteriophage-negative species. We also compare B. vinsonii subsp. berkhoffi Pap31 bacteriophage gene sequences to B. henselae (Houston I), and B. quintana (Fuller) bacteriophage Pap31 sequences. Negative staining electron microscopy of log phase culturesof B. vinsonii subsp. berkhoffii identified bacteriophages, possessing a 50-nm icosahedric head diameter and a 60- to 80-nm contractile tail. Sequence analysis of the bacteriophage Pap31 gene from B. vinsonii subsp. berkhoffii showed three consensus sequences and a 12-bp insertion when compared with Pap31 gene sequences from B. henselae (Houston I) and B. quintana (Fuller) bacteriophages. Isolation of B. vinsonii subsp. berkhoffii bacteriophages containing a Pap31 gene suggests that this heme-binding protein gene might play an important role in bacterial virulence through the genetic exchange of DNA within this subspecies. Defining phage-associated genes may also contribute to the enhanced understanding of the evolutionary relationships among members of the genus Bartonella.

Novel chemically modified liquid medium that will support the growth of seven bartonella species

Bacteria of the genus Bartonella, a member of the Alphaproteobacteria, are fastidious, gram-negative, aerobic bacilli that comprise numerous species, subspecies, and subtypes. In human and veterinary medicine, species isolation remains a vital component of the diagnostic and therapeutic management of Bartonella infection. We describe a novel, chemically modified, insect-based liquid culture medium that supports the growth of at least seven Bartonella species. This medium will also support cocultures consisting of different Bartonella species, and it facilitated the primary isolation of Bartonella henselae from blood and aqueous fluid of naturally infected cats. This liquid growth medium may provide an advantage over conventional direct blood agar plating for the diagnostic confirmation of bartonellosis.

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.

Potential limitations of the 16S-23S rRNA intergenic region for molecular detection of Bartonella species

PCR targeting the 16S-23S rRNA gene intergenic transcribed spacer (ITS) region has been proposed as a rapid and reliable method for the detection of Bartonella species DNA in clinical samples. Because of variation in ITS sequences among Bartonella species, a single PCR amplification can be used to detect different species within this genus. Therefore, by targeting the ITS region, multiple PCRs or additional sample-processing steps beyond the primary amplification can be avoided when attempting to achieve molecular diagnostic detection of Bartonella species. Although PCR amplification targeting this region is considered highly sensitive, amplification specificity obviously depends on primer design. We report evidence of nonspecific PCR amplification of Mesorhizobium species with previously published primers that were designed to amplify the Bartonella consensus ITS region. Use of these or other, less species-specific, primers could lead to a false-positive diagnostic test result when evaluating clinical samples. We also report the presence of Mesorhizobium species DNA as a contaminant in molecular-grade water, a series of homologous sequences in the ITS region that are common to Bartonella and Mesorhizobium species, the amplification of Mesorhizobium DNA with unpublished primers designed in our laboratory targeting the ITS region, and the subsequent design of unambiguous ITS primers that avoid nonspecific amplification of Mesorhizobium species. Our results define some potential limitations associated with the molecular detection of Bartonella species in patient samples and indicate that primer specificity is of critical importance if the ITS region is used as a diagnostic target for detection of Bartonella species.

Prevalence, risk factors, and genetic diversity of Bartonella henselae infections in pet cats in four regions of the United States

Blood was collected from a convenience sample of 271 pet cats aged 3 months to 2 years (mean age, 8 months, median and mode, 6 months) between May 1997 and September 1998 in four areas of the United States (southern California, Florida, metropolitan Chicago, and metropolitan Washington, D.C.). Sixty-five (24%) cats had Bartonella henselae bacteremia, and 138 (51%) cats were seropositive for B. henselae. Regional prevalences for bacteremia and seropositivity were highest in Florida (33% and 67%, respectively) and California (28% and 62%, respectively) and lowest in the Washington, D.C. (12% and 28%, respectively) and Chicago (6% and 12%, respectively) areas. No cats bacteremic with B. clarridgeiae were found. The 16S rRNA type was determined for 49 B. henselae isolates. Fourteen of 49 cats (28.6%) were infected with 16S rRNA type I, 32 (65.3%) with 16S rRNA type II, and three (6.1%) were coinfected with 16S rRNA types I and II. Flea infestation was a significant risk factor for B. henselae bacteremia (odds ratio = 2.82, 95% confidence interval, 1.1 to 7.3). Cats >or=13 months old were significantly less likely to be bacteremic than cats <or=6 months old (odds ratio = 0.18, 95% confidence interval, 0.05 to 0.61). Flea infestation, adoption from a shelter or as a stray cat, hunting, and being from Florida or California were significant risk factors for B. henselae seropositivity. DNA fingerprint was significantly associated with region (P = 0.03) and indoor/outdoor status of cats (P = 0.03).

Clinicopathological Abnormalities and Treatment Response in 24 Dogs Seroreactive to Bartonella vinsonii (berkhoffii) Antigens

Bartonella vinsonii (B. vinsonii) subspecies berkhoffii is a recently recognized cause of endocarditis, myocarditis, and granulomatous disease in dogs. In an effort to elucidate other potential disease manifestations, the case records of 24 dogs that were seroreactive to B. vinsonii (berkhoffii) antigens were studied retrospectively. Diagnoses included immune-mediated hemolytic anemia, neutrophilic or granulomatous meningoencephalitis, neutrophilic polyarthritis, cutaneous vasculitis, and uveitis. Repeated B. vinsonii (berkhoffii) antibody titers became negative after treatment. This study indicates that a diverse spectrum of disease manifestations and clinicopathological abnormalities can be detected in dogs that are seroreactive to B. vinsonii (berkhoffii) antigens.

Fatal case of endocarditis associated with Bartonella henselae type I infection in a domestic cat

We report the first feline case of Bartonella henselae endocarditis. Despite negative blood cultures, the cat had high Bartonella antibody titers and B. henselae type I DNA was detected in the damaged aortic valve. Microscopic examination of the valve revealed endocarditis with small silver positive coccoid structures in endothelial cells.

Clinical impact of persistent Bartonella bacteremia in humans and animals

Bartonella spp. are emerging vector-borne pathogens that cause persistent, often asymptomatic bacteremia in their natural hosts. As our knowledge progresses, it appears that chronic infection may actually predispose the host to mild, insidious nonspecific manifestations or induce, in selected instances, severe diseases. Persistent asymptomatic bacteremia is most common in animals that serve as the main reservoir for the specific Bartonella. In humans, these organisms are B. bacilliformis and B. quintana. Other Bartonella species, for which humans are not the natural reservoir, tend to cause persistent bacteremia only in immunodeficient individuals. In some of these individuals, endothelial cell proliferation may create lesions such as bacillary angiomatosis or bacillary peliosis. In cats, bacteremia of variable level and continuity may last for years. Some strains of B. henselae may induce clinical manifestations, including fever, mild neurological signs, reproductive disorders, whereas others do not induce clinically obvious disease. Reproductive disorders have also been reported in mice experimentally infected with B. birtlesii. Finally, canids constitute the most interesting naturally occurring animal model for the human disease. Like immunocompetent people, healthy dogs only occasionally demonstrate long-term bacteremia when infected with Bartonella spp. However, some dogs develop severe clinical manifestations, such as endocarditis, and the pathologic spectrum associated with Bartonella spp. infection in domestic dogs is rapidly expanding and resembles the infrequently reported clinical entities observed in humans. In coyotes, persistent bacteremia is more common than in domestic dogs. It will be of interest to determine if coyotes develop clinical or pathological indications of infection.

Urban zoonoses caused by Bartonella, Coxiella, Ehrlichia, and Rickettsia species

The last half of the 20th Century witnessed an increase in the occurrence and recognition of urban zoonoses caused by members of the genera Bartonella, Coxiella, Ehrlichia, and Rickettsia, all traditionally considered to be members of the family Rickettsiaceae. In recent years, new human pathogens (Bartonella elizabethae, Bartonella henselae, and Rickettsia felis) have been recognized in urban environments. Other newly recognized pathogens (Ehrlichia chaffeensis and Ehrlichia phagocytophila in the United States) have sylvan zoonotic cycles but are present in urban areas because their vertebrate hosts and associated ectoparasitic arthropod vectors are able to survive in cities. Still other agents, which were primarily of historical importance (Bartonella quintana) or have not traditionally been associated with urban environments (Rickettsia rickettsii), have been recognized as causes of human disease in urban areas. Some diseases that have traditionally been associated with urban environments, such as rickettsialpox (caused by Rickettsia akari) and murine typhus (caused by Rickettsia typhi), still occur in large cities at low or undetermined frequencies and often go undetected, despite the availability of effective measures to diagnose and control them. In addition, alternate transmission cycles have been discovered for Coxiella burnetii, Rickettsia prowazekii, and R. typhi that differ substantially from their established, classic cycles, indicating that the epidemiology of these agents is more complex than originally thought and may be changing. Factors leading to an increase in the incidence of illnesses caused by these bacteria in urban areas include societal changes as well as intrinsic components of the natural history of these organisms that favor their survival in cities. Transovarial and transstadial transmission of many of the agents in their arthropod hosts contributes to the highly focal nature of many of the diseases they cause by allowing the pathogens to persist in areas during adverse times when vertebrate amplifying hosts may be scarce or absent. Domesticated animals (primarily cats, dogs, and livestock) or commensal rodents [primarily Norway rats (Rattus norvegicus) and house mice (Mus musculus)] can serve as vertebrate amplifying hosts and bring these agents and their ectoparasitic arthropod vectors into direct association with humans and help maintain transmission cycles in densely populated urban areas. The reasons for the increase in these urban zoonoses are complex. Increasing population density worldwide, shifts in populations from rural areas to cities, increased domestic and international mobility, an increase in homelessness, the decline of inner-city neighborhoods, and an increase in the population of immunosuppressed individuals all contribute to the emergence and recognition of human diseases caused by these groups of agents. Due to the focal nature of infections in urban areas, control or prevention of these diseases is possible. Increased physician awareness and public health surveillance support will be required to detect and treat existing urban infections caused by these agents, to determine the disease burden caused by them, to design and implement control programs to combat and prevent their spread, and to recognize emerging or resurging infections caused by members of these genera as they occur.

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.

Diagnosis of Bartonella endocarditis by a real-time nested PCR assay using serum

Bartonella endocarditis is a severe disease for which blood cultures frequently remain negative. We tested three PCR assays by using specimens of serum sampled early during the disease from 43 patients diagnosed in our laboratory as having Bartonella endocarditis on the basis of serological, culture, and/or valvular molecular detection. We tested a two-step nested PCR (TSN-PCR), a one-step nested PCR (OSN-PCR) with a regular thermal cycler, and a one-step nested PCR with the LightCycler (LCN-PCR). These assays were performed with primers derived from the riboflavin synthase-encoding gene ribC, never before amplified in our laboratory. Due to contamination of negative controls, the results of the TSN-PCR were not interpretable, and this technique was no longer considered. The LCN-PCR had a specificity of 100% and a sensitivity of 58.1%, higher than those of the OSN-PCR (18.6%; P < 0.01) and prolonged blood culturing (7.1%; P < 0.01). The LCN-PCR results correlated strictly with those of other direct diagnostic tests, when available, and identified the causative species for six patients previously diagnosed on the basis of serological analysis only. The efficacy of the LCN-PCR was not influenced by antibiotics (P = 0.96) but was altered by prolonged storage of serum specimens at -20 degrees C (P = 0.04). Overall, the LCN-PCR is specific and more sensitive than traditional methods (i.e., culturing and/or PCR with EDTA-treated blood). It can easily be applied to the diagnosis of patients with suspected Bartonella endocarditis, especially when only serum is available.

Value of microimmunofluorescence for diagnosis and follow-up of Bartonella endocarditis

Bartonella endocarditis is a disease of emerging importance that causes serious complications and high rates of mortality. Due to the fastidious nature of Bartonella species and their high degrees of antibiotic susceptibility, cultures of clinical samples most often remain sterile and valvular biopsy specimens, the best specimens for PCR amplification, are seldom available. Therefore, serology appears to be the easiest diagnostic tool. In order to determine the best cutoff value for serology and its predictive values for the detection of Bartonella endocarditis, we studied 48 patients with culture- and/or PCR-confirmed Bartonella endocarditis. We also applied these serological criteria to 156 patients with blood culture-negative endocarditis. Furthermore, we compared the kinetics of the antibody responses to Bartonella spp. in order to estimate the value of serology for prediction of the occurrence of relapses. A titer of > or = 1:800 for immunoglobulin G antibodies to either Bartonella henselae or B. quintana has a positive predictive value of 0.810 for the detection of chronic Bartonella infections in the general population and a value of 0.955 for the detection of Bartonella infections among patients with endocarditis. When this cutoff was applied to 156 patients with blood culture-negative endocarditis, we were able to diagnose Bartonella infections in an additional 45 patients with definite endocarditis for whom a positive Bartonella serology was the only evidence of infection. On follow-up, the kinetics of the decrease in antibody titers were significantly delayed in two patients with relapses. In conclusion, we recommend the determination of antibodies to both B. quintana and B. henselae and the use of a cutoff value of 1:800 for the diagnosis of Bartonella endocarditis. We propose that this criterion, which may also help with the detection of late relapses, be included as a major criterion in the Duke criteria for the diagnosis of infective endocarditis.

Diagnostic methods current best practices and guidelines for histologic evaluation in infective endocarditis

Infective endocarditis (IE) often presents diagnostic and therapeutic challenges and continues to cause high morbidity and mortality. Confirmation of the diagnosis of IE is important for the purposes of epidemiologic and clinical studies and is crucial for patient management. Despite recent advances in diagnostic techniques, about 10% of IE cases remain culture-negative. Because pathological examination of cardiac valves to demonstrate vegetations and valvular inflammation remains the gold standard for the diagnosis of IE, the role of the pathologist is often decisive, especially when bacteriologists fail to isolate a microorganism or when a microorganism that has been isolated may be a contaminant. Furthermore, the pathologist may play an important role in identification of previously unknown infectious agents.

16S/23S rRNA intergenic spacer regions for phylogenetic analysis, identification, and subtyping of Bartonella species

Species of the genus Bartonella are currently recognized in growing numbers and are involved in an increasing variety of human diseases, mainly trench fever, Carrion's disease, bacillary angiomatosis, endocarditis, cat scratch disease, neuroretinitis, and asymptomatic bacteremia. Such a wide spectrum of infections makes it necessary to develop species and strain identification tools in order to perform phylogenetic and epidemiological studies. The 16S/23S rRNA intergenic spacer region (ITS) was sequenced for four previously untested species, B. vinsonii subsp. arupensis, B. tribocorum, B. alsatica, and B. koehlerae, as well as for 28 human isolates of B. quintana (most of them from French homeless people), six human or cat isolates of B. henselae, five cat isolates of B. clarridgeiae, and four human isolates of B. bacilliformis. Phylogenetic trees inferred from full ITS sequences of the 14 recognized Bartonella species using parsimony and distance methods revealed high statistical support, as bootstrap values were higher than those observed with other tested genes. Five well-supported lineages were identified within the genus and the proposed phylogenetic organization was consistent with that resulting from protein-encoding gene sequence comparisons. The ITS-derived phylogeny appears, therefore, to be a useful tool for investigating the evolutionary relationships of Bartonella species and to identify Bartonella species. Further, partial ITS amplification and sequencing offers a sensitive means of intraspecies differentiation of B. henselae, B. clarridgeiae, and B. bacilliformis isolates, as each strain had a specific sequence. The usefulness of this approach in epidemiological investigations should be highlighted. Among B. quintana strains, however, the genetic heterogeneity was low, as only three ITS genotypes were identified. It was nevertheless sufficient to show that the B. quintana population infecting homeless people in France was not clonal.

Use of rpoB gene analysis for detection and identification of Bartonella species

Identification of Bartonella species is of increasing importance as the number of infections in which these bacteria are involved increases. To date, these gram-negative bacilli have been identified by various serological, biochemical, and genotypic methods. However, the development of alternative tools is required, principally to circumvent a major risk of contamination during sample manipulation. The aim of our study was to investigate the possible identification of various Bartonella species by comparison of RNA polymerase beta-subunit gene (rpoB) sequences. This approach has previously been shown to be useful for the identification of members of the family Enterobacteriaceae (C. M. Mollet, M. Drancourt, and D. Raoult, Mol. Microbiol. 26:1005-1011, 1997). Following PCR amplification with specific oligonucleotides, a 825-bp region of the rpoB gene was sequenced from 13 distinct Bartonella strains. Analysis of these sequences allowed selection of three restriction enzymes (ApoI, AluI, and AflIII) useful for discerning the different strains by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. To confirm the potential value of such an approach for identification of Bartonella, the rpoB PCR was then applied to 94 clinical samples, and the results obtained were identical to those obtained by our reference PCR method. Twenty-four isolates were also adequately identified by PCR-RFLP analysis. In all cases, our results were in accordance with those of the reference method. Moreover, conserved regions of DNA were chosen as suitable primer targets for PCR amplification of a 439-bp fragment which can be easily sequenced.

Endocarditis due to rare and fastidious bacteria

The etiologic diagnosis of infective endocarditis is easily made in the presence of continuous bacteremia with gram-positive cocci. However, the blood culture may contain a bacterium rarely associated with endocarditis, such as Lactobacillus spp., Klebsiella spp., or nontoxigenic Corynebacterium, Salmonella, Gemella, Campylobacter, Aeromonas, Yersinia, Nocardia, Pasteurella, Listeria, or Erysipelothrix spp., that requires further investigation to establish the relationship with endocarditis, or the blood culture may be uninformative despite a supportive clinical evaluation. In the latter case, the etiologic agents are either fastidious extracellular or intracellular bacteria. Fastidious extracellular bacteria such as Abiotrophia, HACEK group bacteria, Clostridium, Brucella, Legionella, Mycobacterium, and Bartonella spp. need supplemented media, prolonged incubation time, and special culture conditions. Intracellular bacteria such as Coxiella burnetii cannot be isolated routinely. The two most prevalent etiologic agents of culture-negative endocarditis are C. burnetti and Bartonella spp. Their diagnosis is usually carried out serologically. A systemic pathologic examination of excised heart valves including periodic acid-Schiff (PAS) staining and molecular methods has allowed the identification of Whipple's bacillus endocarditis. Pathologic examination of the valve using special staining, such as Warthin-Starry, Gimenez, and PAS, and broad-spectrum PCR should be performed systematically when no etiologic diagnosis is evident through routine laboratory evaluation.

Quantitative analysis of valvular lesions during Bartonella endocarditis

Cardiac valve pathology was evaluated in 15 patients with confirmed diagnosis of Bartonella endocarditis. Ten were infected by Bartonella quintana and 5 by Bartonella henselae. Histologic features of these cases, including fibrosis, calcification, vegetation, pattern of inflammation, and vascularization, were compared with those of valves from 25 cases of non-Bartonella endocarditis as controls using a computerized quantitative image analysis. Pathologic and immunohistologic testing for localization of Bartonella species in resected valves included Warthin-Starry stain and polyclonal antibody-based immunodetection. Compared with other cases of infective endocarditis, cases of Bartonella endocarditis are more fibrotic and calcified, less vascularized, with less extensive vegetation and chronic inflammation. These pathologic changes are suggestive of a prolonged infection. Warthin-Starry stain and immunohistologic testing demonstrated the presence of the organism, respectively, in 11 and 10 of the 13 tested valves. Results of both staining methods showed microorganisms in extracellular locations and in regions unaccompanied by inflammation. Pathology and immunohistology may contribute to the etiologic diagnosis of Bartonella endocarditis when serology and molecular techniques are not available.

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.

Differentiation of Bartonella species by a microimmunofluorescence assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western immunoblotting

Bartonella species can be differentiated by microimmunofluorescence assay, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and immunoblotting with murine polyclonal antisera to Bartonella henselae, B. quintana, B. elizabethae, and B. bacilliformis. A pairwise comparison on the basis of SDS-PAGE protein profiles demonstrated similarity values for proteins of different Bartonella species ranging from 28.6 to 86.4%. Antigenic relationships revealed by immunoblotting with murine antisera were equivalent to those of proteins observed by SDS-PAGE. A dendrogram obtained on the basis of protein bands of SDS-polyacrylamide gels showed that Bartonella species could be divided into three groups. B. bacilliformis was distinct from all other Bartonella species; B. grahamii, B. taylorii, B. doshiae, and B. vinsonii formed a cluster, as did B. henselae, B. quintana, B. elizabethae, and B. clarridgeiae. These relationships were consistent with those revealed by parsimony trees derived from 16S rRNA and gltA gene sequencing. SDS-PAGE analysis showed that 120-, 104-, 85-, 71-, 54-, 47-, 40-, 33-, 30-, and 19-kDa proteins were present in all species, with the 54-kDa protein being the most dominant. Proteins with a molecular mass of less than 54 kDa allow the differentiation of species and are a possible target for future species-specific antibodies and antigens.