Culture-negative endocarditis: contribution of bartonella infections

Blood culture negative endocarditis in the modern era of 16S rRNA sequencing

Blood culture negative endocarditis (BCNE) accounts for up to 20% of infective endocarditis. While the most common cause of BCNE remains the initiation of antibiotics prior to culture, intracellular organisms such as Coxiella and Bartonella spp account for a significant proportion of cases. Identifying the infecting organism remains important to ensure optimal antimicrobial treatment. However, these organisms can be difficult to diagnose. We outline a systematic approach to BCNE. Over half of patients with infective endocarditis now undergo early surgery and 16S ribosomal ribonucleic acid (rRNA) polymerase chain reaction (PCR) of excised tissue can be vitally important to secure a diagnosis. Molecular testing is likely to become a key tool in improving outcomes from BCNE and contribute to an improved understanding of the aetiology. We advocate modifying the Duke criteria to incorporate organisms identified on molecular testing, including 16S rRNA PCR, in particular from explanted tissue.

Detection of Bartonella quintana infection among the Homeless Population in Tokyo, Japan, from 2013-2015

Several outbreaks of trench fever caused by Bartonella quintana, occurred in soldiers during World Wars I and II. Although the number of trench fever cases has been decreasing worldwide, the disease has been reported among the homeless population in both developing and developed countries. The current prevalence of B. quintana infection in Japan is unclear. We collected blood and body louse (Pediculus humanus humanus) samples from homeless inpatients who had body lice at the time of emergency hospitalization in Tokyo from January 2013 to March 2015. Patients were tested for B. quintana infections using culture method, polymerase chain reaction, and indirect immunofluorescence assay (IFA). Among the 29 patients tested, the presence of Bartonella spp. was confirmed by genomic sequencing of DNA extracted from the samples from 2 patients (blood culture performed for 13 out of 15 patients), and from body louse samples of 20 patients (69%). Immunoglobulin G against B. quintana was detected in 10 patients (34.5%) at a cut-off titer of 1:256 in IFA. B. quintana infection was detected in samples obtained between 2013 and 2015 in Tokyo and needs to be on the list of differential diagnoses performed for febrile homeless individuals.

Bartonellaspecies as a cause of infective endocarditis in the UK

Bartonellaspp. are increasingly implicated in infectious endocarditis cases in the UK. Herein, we attempted to quantify their role in this syndrome and explored the epidemiology ofBartonella-associated endocarditis in the UK. Between November 2005 and October 2010, samples from 685 endocarditis patients were submitted to the Health Protection Agency forBartonellaserology. Serological evidence of infection was obtained for 57 (8·3%) patients. PCR-based evidence of infection was obtained from 13 out of 14 patients for whom heart valve tissue was available, withBartonella quintanaimplicated in 12 cases andB. henselaein one. Six patients withB. quintanaendocarditis were recent immigrants into the UK, of whom four lived in poor socioeconomic conditions. These results indicate thatBartonellais a not uncommon cause of endocarditis in the UK and should be considered particularly in patients raised in eastern Europe and/or with a history of homelessness or alcoholism.

Guidelines for the diagnosis and antibiotic treatment of endocarditis in adults: a report of the Working Party of the British Society for Antimicrobial Chemotherapy

The BSAC guidelines on treatment of infectious endocarditis (IE) were last published in 2004. The guidelines presented here have been updated and extended to reflect developments in diagnostics, new trial data and the availability of new antibiotics. The aim of these guidelines, which cover both native valve and prosthetic valve endocarditis, is to standardize the initial investigation and treatment of IE. An extensive review of the literature using a number of different search criteria has been carried out and cited publications used to support any changes we have made to the existing guidelines. Publications referring to in vitro or animal models have only been cited if appropriate clinical data are not available. Randomized, controlled trials suitable for the development of evidenced-based guidelines in this area are still lacking and therefore a consensus approach has again been adopted for most recommendations; however, we have attempted to grade the evidence, where possible. The guidelines have also been extended by the inclusion of sections on clinical diagnosis, echocardiography and surgery.

Isolation and characterization of Bartonella quintana from the parotid gland of an immunocompetent man

We describe a case of the isolation of Bartonella quintana from the parotid gland of an apparently healthy man. Pathological examination showed intraparotid granulomatous abscessual lymphadenitis. Diagnosis was made on the basis of high titers of immunoglobulin G (IgG) and IgM antibodies and of culture isolation of a causative agent from parotid aspirate.

Do bartonella infections cause agitation, panic disorder, and treatment-resistant depression?

INTRODUCTION

Bartonella is an emerging infection found in cities, suburbs, and rural locations. Routine national labs offer testing for only 2 species, but at least 9 have been discovered as human infections within the last 15 years. Some authors discuss Bartonella cases having atypical presentations, with serious morbidity considered uncharacteristic of more routine Bartonella infections. Some atypical findings include distortion of vision, abdominal pain, severe liver and spleen tissue abnormalities, thrombocytopenic purpura, bone infection, arthritis, abscesses, heart tissue and heart valve problems. While some articles discuss Bartonella as a cause of neurologic illnesses, psychiatric illnesses have received limited attention. Case reports usually do not focus on psychiatric symptoms and typically only as incidental comorbid findings. In this article, we discuss patients exhibiting new-onset agitation, panic attacks, and treatment-resistant depression, all of which may be attributed to Bartonella.

METHODS

Three patients receiving care in an outpatient clinical setting developed acute onset personality changes and agitation, depression, and panic attacks. They were retrospectively examined for evidence of Bartonella infections. The medical and psychiatric treatment progress of each patient was tracked until both were significantly resolved and the Bartonella was cured.

RESULTS

The patients generally seemed to require higher dosing of antidepressants, benzodiazepines, or antipsychotics in order to function normally. Doses were reduced following antibiotic treatment and as the presumed signs of Bartonella infection remitted. All patients improved significantly following treatment and returned to their previously healthy or near-normal baseline mental health status.

DISCUSSION

New Bartonella species are emerging as human infections. Most do not have antibody or polymerase chain reaction (PCR) diagnostic testing at this time. Manual differential examinations are of unknown utility, due to many factors such as low numbers of infected red blood cells, the small size of the infecting bacteria, uncertainty of current techniques in viewing such small bacteria, and limited experience. As an emerging infection, it is unknown whether Bartonella occurrence in humans worldwide is rare or common, without further information from epidemiology, microbiology, pathology, and treatment outcomes research.

CONCLUSION

Three patients presented with acute psychiatric disorders associated with Bartonella-like signs and symptoms. Each had clear exposure to ticks or fleas and presented with physical symptoms consistent with Bartonella, eg, an enlarged lymph node near an Ixodes tick bite and bacillary angiomatosis found only in Bartonella infections. Laboratory findings and the overall general course of the illnesses seemed consistent with Bartonella infection. The authors are not reporting that these patients offer certain proof of Bartonella infection, but we hope to raise the possibility that patients infected with Bartonella can have a variety of mental health symptoms. Since Bartonella can clearly cause neurologic disorders, we feel the presence of psychiatric disorders is a reasonable expectation.

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.

Guidelines for the antibiotic treatment of endocarditis in adults: report of the Working Party of the British Society for Antimicrobial Chemotherapy

The BSAC Guidelines on Endocarditis were last published in 1998. The Guidelines presented here have been updated and extended to reflect changes in both the antibiotic resistance characteristics of causative organisms and the availability of new antibiotics. Randomized, controlled trials suitable for the development of evidenced-based guidelines in this area are still lacking, and therefore a consensus approach has again been adopted. The Guidelines cover diagnosis and laboratory testing, suitable antibiotic regimens and causative organisms. Special emphasis is placed on common causes of endocarditis, such as streptococci and staphylococci, however, other bacterial causes (such as enterococci, HACEK organisms, Coxiella and Bartonella) and fungi are considered. The special circumstances of prosthetic endocarditis are discussed.

Isolation of Bartonella washoensis from a dog with mitral valve endocarditis

We report the first documented case of Bartonella washoensis bacteremia in a dog with mitral valve endocarditis. B. washoensis was isolated in 1995 from a human patient with cardiac disease. The main reservoir species appears to be ground squirrels (Spermophilus beecheyi) in the western United States. Based on echocardiographic findings, a diagnosis of infective vegetative valvular mitral endocarditis was made in a spayed 12-year-old female Doberman pinscher. A year prior to presentation, the referring veterinarian had detected a heart murmur, which led to progressive dyspnea and a diagnosis of congestive heart failure the week before examination. One month after initial presentation, symptoms worsened. An emergency therapy for congestive heart failure was unsuccessfully implemented, and necropsy evaluation of the dog was not permitted. Indirect immunofluorescence tests showed that the dog was strongly seropositive (titer of 1:4,096) for several Bartonella antigens (B. vinsonii subsp. berkhoffii, B. clarridgeiae, and B. henselae), highly suggestive of Bartonella endocarditis. Standard aerobic and aerobic-anaerobic cultures were negative. However, a specific blood culture for Bartonella isolation grew a fastidious, gram-negative organism 7 days after being plated. Phenotypic and genotypic characterizations of the isolate, including partial sequencing of the citrate synthase (gltA), groEL, and 16S rRNA genes, indicated that this organism was identical to B. washoensis. The dog was seronegative for all tick-borne pathogens tested (Anaplasma phagocytophilum, Ehrlichia canis, and Rickettsia rickettsii), but the sample was highly positive for B. washoensis (titer of 1:8,192) and, according to indirect immunofluorescent-antibody assay, weakly positive for phase II Coxiella burnetii infection.

Blood culture negative endocarditis: analysis of 63 cases presenting over 25 years

OBJECTIVE

To analyse cases of blood culture negative endocarditis (BCNE) seen at St Thomas' Hospital, London, between 1975 and 2000.

METHODS

Data on all episodes of endocarditis with negative blood cultures seen at St Thomas' Hospital between 1975 and 2000 were collected prospectively and analysed retrospectively.

RESULTS

Sixty three patients with BCNE were seen during the study period: 48 (76%) with native and 15 (24%) prosthetic valve infection. BCNE accounted for 12.2% of the 516 cases of endocarditis seen at St Thomas' Hospital. The diagnosis of endocarditis was clinically definite by the Duke criteria in only 21% (7 of 34) of cases of pathologically proven native valve endocarditis but in 62% (21 of 34) of cases by the St Thomas' modifications of the criteria. Comparable figures for the 11 cases of pathologically proven prosthetic valve endocarditis were 45% and 73%. Despite negative blood cultures a causative organism was identified in 31 (49%) of the 63 cases: in 15 by serology (8 Coxiella burnetii, 6 Bartonella species, and 1 Chlamydia psittaci); in 9 cases by culture of the excised valve; in 3 by microscopy of the excised valve, on which large numbers of Gram positive cocci were seen although the culture was sterile; and in the other 4 by isolation from a site other than the excised valve (2 respiratory specimens, 1 from the pacemaker tip, and 1 from an excised embolus). In addition 5 of the 6 cases of Bartonella infection were confirmed by polymerase chain reaction study of the excised valve. Two thirds of the 32 patients for whom no pathogen was identified had received antibiotics before blood was cultured. Thus truly "negative" endocarditis was very uncommon (6% of the cases).

CONCLUSION

If blood cultures are negative in definite or suspected endocarditis, serum should be analysed for Bartonella, Coxiella, and Chlamydia species antibodies, and the excised valve or (rarely) embolus should be analysed by microscopy, culture, histology, and relevant polymerase chain reaction. Other specimens may be relevant. The Duke criteria performed poorly in BCNE; St Thomas' additional minor criteria gave more definite diagnoses.

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.

Prosthetic valve endocarditis caused by Bartonella quintana

We describe the first case of Bartonella quintana endocarditis affecting a prosthetic valve in a person with no known risk factors for this infection. Bartonella should be considered as a cause of endocarditis in any clinical setting.

Aortic valve endocarditis in a dog due to Bartonella clarridgeiae

We report the first documented case of endocarditis associated with Bartonella clarridgeiae in any species. B. clarridgeiae was identified as a possible etiological agent of human cat scratch disease. Infective vegetative valvular aortic endocarditis was diagnosed in a 2.5-year-old male neutered boxer. Historically, the dog had been diagnosed with a systolic murmur at 16 months of age and underwent balloon valvuloplasty for severe valvular aortic stenosis. Six months later, the dog was brought to a veterinary hospital with an acute third-degree atrioventricular block and was diagnosed with infective endocarditis. The dog died of cardiopulmonary arrest prior to pacemaker implantation. Necropsy confirmed severe aortic vegetative endocarditis. Blood culture grew a fastidious, gram-negative organism 8 days after being plated. Phenotypic and genotypic characterization of the isolate, including partial sequencing of the citrate synthase (gltA) and 16S rRNA genes indicated that this organism was B. clarridgeiae. DNA extraction from the deformed aortic valve and the healthy pulmonic valve revealed the presence of B. clarridgeiae DNA only from the diseased valve. No Borrelia burgdorferi or Ehrlichia sp. DNA could be identified. Using indirect immunofluorescence tests, the dog was seropositive for B. clarridgeiae and had antibodies against Ehrlichia phagocytophila but not against Ehrlichia canis, Ehrlichia ewingii, B. burgdorferi, or Coxiella burnetii.

Native valve endocarditis due to Bartonella henselae in a middle-aged human immunodeficiency virus-negative woman

We report the case of a human immunodeficiency virus-negative woman who developed native valve endocarditis of the aortic valve due to Bartonell henselae infection. The diagnosis was established using serology and PCR analysis of excised aortic valve tissue.

Bartonella henselae induces NF-kappaB-dependent upregulation of adhesion molecules in cultured human endothelial cells: possible role of outer membrane proteins as pathogenic factors

The endothelium is a specific target for Bartonella henselae, and endothelial cell infection represents an important step in the pathogenesis of cat scratch disease and bacillary angiomatosis. Mechanisms of Bartonella-endothelial cell interaction as well as signaling pathways involved in target cell activation were analyzed. B. henselae strain Berlin-1, isolated from bacillary angiomatosis lesions of a human immunodeficiency virus-infected patient, potently stimulated human umbilical cord vein endothelial cells (HUVEC), as determined by NF-kappaB activation and enhanced adhesion molecule expression. These effects were accompanied by increased PMN rolling on and adhesion to infected endothelial cell monolayers, as measured in a parallel-plate flow chamber assay. Monoclonal antibodies against E-selectin significantly reduced PMN rolling and adhesion. In our hands, B. henselae Berlin-1 was substantially more active than the typing strain B. henselae ATCC 49882. E-selectin and ICAM-1 upregulation occurred for up to 9 days, as verified by Northern blotting and cell surface enzyme-linked immunosorbent assay. Induction of adhesion molecules was mediated via NF-kappaB activation and could be blocked by a specific NF-kappaB inhibitor. Additional studies indicated that B. henselae-induced effects did not require living bacteria or Bartonella lipopolysaccharides. Exposure of HUVEC to purified B. henselae outer membrane proteins (OMPs), however, reproduced all aspects of endothelial cell activation. In conclusion, B. henselae, the causative agent of cat scratch disease and bacillary angiomatosis, infects and activates endothelial cells. B. henselae OMPs are sufficient to induce NF-kappaB activation and adhesion molecule expression followed by enhanced rolling and adhesion of leukocytes. These observations identify important new properties of B. henselae, demonstrating its capacity to initiate a cascade of events culminating in a proinflammatory phenotype of infected endothelial cells.

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.

Coyotes (Canis latrans) as the reservoir for a human pathogenic Bartonella sp.: molecular epidemiology of Bartonella vinsonii subsp. berkhoffii infection in coyotes from central coastal California

Bartonella vinsonii subsp. berkhoffii was originally isolated from a dog suffering infectious endocarditis and was recently identified as a zoonotic agent causing human endocarditis. Following the coyote bite of a child who developed clinical signs compatible with Bartonella infection in Santa Clara County, Calif., this epidemiological study was conducted. Among 109 coyotes (Canis latrans) from central coastal California, 31 animals (28%) were found to be bacteremic with B. vinsonii subsp. berkhoffii and 83 animals (76%) had B. vinsonii subsp. berkhoffii antibodies. These findings suggest these animals could be the wildlife reservoir of B. vinsonii subsp. berkhoffii. PCR-restriction fragment length polymorphism (PCR-RFLP) analysis of the gltA and 16S rRNA genes for these 31 isolates yielded similar profiles that were identical to those of B. vinsonii subsp. berkhoffii. Partial sequencing of the gltA and 16S rRNA genes, respectively, indicated 99.5 and 100% homology between the coyote isolate and B. vinsonii subsp. berkhoffii (ATCC 51672). PCR-RFLP analysis of the 16S-23S intergenic spacer region showed the existence of two different strain profiles, as has been reported in dogs. Six (19%) of 31 Bartonella bacteremic coyotes exhibited the strain profile that was identified in the type strain of a canine endocarditis case (B. vinsonii subsp. berkhoffii ATCC 51672). The other 25 bacteremic coyotes were infected with a strain that was similar to the strains isolated from healthy dogs. Based on whole bacterial genome analysis by pulsed-field gel electrophoresis (PFGE) with SmaI restriction endonuclease, there was more diversity in fingerprints for the coyote isolates, which had at least 10 major variants compared to the two variants described for domestic dog isolates from the eastern United States. By PFGE analysis, three Bartonella bacteremic coyotes were infected by a strain identical to the one isolated from three healthy dog carriers. Further studies are necessary to elucidate the mode of transmission of B. vinsonii subsp. berkhoffii, especially to identify potential vectors, and to determine how humans become infected.

Bartonella henselae invasion of feline erythrocytes in vitro

Bartonella henselae, the causative agent of cat scratch disease, establishes long-term bacteremia in cats, in which it attaches to and invades feline erythrocytes (RBC). Feline RBC invasion was assessed in vitro, based on gentamicin selection for intracellular bacteria or by laser confocal microscopy and digital sectioning. Invasion rates ranged from 2 to 20% of the inoculum, corresponding to infection of less than 1% of the RBC. Invasion was a slow process, requiring >8 h before significant numbers of intracellular bacteria were detected. Pretreatment of the bacteria with trypsin, or of the RBC with trypsin or neuraminidase, had no effect, but pronase pretreatment of RBC resulted in a slight increase in invasion frequency. The ability to model B. henselae invasion of feline RBC in vitro should permit identification of bacterial surface components involved in this process and elucidate the significance of RBC invasion to transmission and infection in cats.