Laboratory diagnosis of Bartonella infections

Antibodies to Borrelia burgdorferi and Bartonella species in serum and synovial fluid from people with rheumatic diseases

Vector-borne infections may underlie some rheumatic diseases, particularly in people with joint effusions. This study aimed to compare serum and synovial fluid antibodies to B. burgdorferi and Bartonella spp. in patients with rheumatic diseases. This observational, cross-sectional study examined paired synovial fluid and serum specimens collected from 110 patients with joint effusion between October 2017 and January 2022. Testing for antibodies to B. burgdorferi (using CDC criteria) and Bartonella spp. via two indirect fluorescent antibody (IFA) assays was performed as part of routine patient care at the Institute for Specialized Medicine (San Diego, CA, USA). There were 30 participants (27%) with positive two-tier B. burgdorferi serology and 26 participants (24%) with IFA seroreactivity (≥1:256) to B. henselae and/or B. quintana. Both B. burgdorferi IgM and IgG were detected more frequently in synovial fluid than serum: 27% of patients were either IgM or IgG positive in synovial fluid, compared to 15.5% in serum (P = 0.048). Conversely, B. henselae and B. quintana antibodies were detected more frequently in serum than synovial fluid; overall only 2% of patients had positive IFA titers in synovial fluid, compared to 24% who had positive IFA titers in serum (P < 0.001). There were no significant associations between B. burgdorferi or Bartonella spp. seroreactivity with any of the clinical rheumatological diagnoses. This study provides preliminary support for the importance of synovial fluid antibody testing for documenting exposure to B. burgdorferi but not for documenting exposure to Bartonella spp.

IMPORTANCE

This study focuses on diagnostic testing for two common vector-borne diseases in an affected patient population. In it, we provide data showing that antibodies to B. burgdorferi, but not Bartonella spp., are more commonly found in synovial fluid than serum of patients with joint effusion. Since Lyme arthritis is a common-and sometimes difficult to diagnose-rheumatic disease, improving diagnostic capabilities is of utmost importance. While our findings are certainly not definitive for changes to practice, they do suggest that synovial fluid could be a useful sample for the clinical diagnosis of Lyme disease, and future prospective studies evaluating this claim are warranted.

Detection of invasive Bartonella infections with next-generation sequencing of microbial cell-free DNA

We report 9 patients with invasive Bartonella infections, including 5 with endocarditis, who were diagnosed with microbial cell-free DNA next-generation sequencing and Bartonella serology studies. Diagnosis with plasma mcfDNA NGS enabled a faster clinical and laboratory diagnosis in 8 patients. Prompt diagnosis impacted antibiotic management in all 9 patients.

Hidden Burden of Bartonella quintana on the African Continent: Should the Bacterial Infection Be Considered a Neglected Tropical Disease?

Bartonella quintana is a louse-borne gram-negative bacillus that remains a poorly characterized cause of bacteremia, fever, and infective endocarditis. Due to the link with pediculosis, B quintana transmission is tied to poverty, conflict, overcrowding, and inadequate water access to maintain personal hygiene. Although these risk factors may be present globally, we argue that a substantial burden of undocumented B quintana infection occurs in Africa due to the high prevalence of these risk factors. Here, we describe the neglected burden of B quintana infection, endocarditis, and vector positivity in Africa and evaluate whether B quintana meets criteria to be considered a neglected tropical disease according to the World Health Organization.

Etiologies of Zoonotic Tropical Febrile Illnesses That Are Not Part of the Notifiable Diseases in Colombia

In Colombia, tropical febrile illnesses represent one of the most important causes of clinical attention. Febrile illnesses in the tropics are mainly zoonotic and have a broad etiology. The Colombian surveillance system monitors some notifiable diseases. However, several etiologies are not monitored by this system. In the present review, we describe eleven different etiologies of zoonotic tropical febrile illnesses that are not monitored by the Colombian surveillance system but have scientific, historical, and contemporary data that confirm or suggest their presence in different regions of the country: Anaplasma, Arenavirus, Bartonella, relapsing fever group Borrelia, Coxiella burnetii, Ehrlichia, Hantavirus, Mayaro virus, Orientia, Oropouche virus, and Rickettsia. These could generate a risk for the local population, travelers, and immigrants, due to which they should be included in the mandatory notification system, considering their importance for Colombian public health.

Blood Supplementation Enhances Bartonella henselae Growth and Molecular Detection of Bacterial DNA in Liquid Culture

Bacteria of the genus Bartonella, a member of the Alphaproteobacteria, are fastidious, Gram-negative, aerobic bacilli that comprise numerous species, subspecies, and genotypes. Bartonella henselae, with a worldwide distribution, infects cats, dogs, horses, humans, and other mammals. Diagnostically, direct detection of Bartonella henselae in patient blood specimens by culture or molecular methods is required to confirm infection with this bacterium. Enrichment blood culture combined with quantitative PCR (qPCR) or ddPCR enhances the sensitivity of direct detection. The addition of sheep blood to liquid culture media increased the Bartonella henselae DNA concentration compared to controls, additionally improving PCR direct detection sensitivity. IMPORTANCE This study aims to improve diagnostic detection of Bartonella henselae. Patient samples are combined with enriched bacterial cultures aimed at growing Bartonella henselae for the best possible chance at detection. However, current Bartonella growth methods could be improved. The DNA extraction method used by most laboratories should also be optimized. Sheep blood was added to increase the growth of Bartonella henselae and multiple DNA extraction methods were to be compared to each other.

Bartonella Prevalence and Genome Sequences in Rodents in Some Regions of Xinjiang, China

In this study, we investigated Bartonella infection and its genetic diversity in rodents in Beitun, Xinjiang Uygur Autonomous Region, China. Small mammals were captured using snap traps at four sampling sites in 2018. Spleen and liver tissues were collected and cultured to isolate Bartonella strains. Whole-genome sequencing was performed on the strains identified as Bartonella by gltA gene PCR, and the average nucleotide identity (ANI) of the genomes was calculated by using FastANI v1.33. Phylogenetic trees were constructed for the samples positive for Bartonella spp. by the gltA PCR assay based on 1,290-bp gltA genes, 2,903-bp rpoB genes, and core-genome single nucleotide polymorphisms (SNPs). Among 66 rodents, 11 were positive for Bartonella, with an infection rate of 16.67%. The rodent infection rates in different tissues (χ2 = 2.133; P = 0.242), species (χ2 = 9.631; P = 0.141), and habitats (χ2 = 4.309; P = 0.312) did not show statistical differences. Bartonella spp. isolated from the rodents were phylogenetically divided into six clades (two different Bartonella species were detected in two rodents). By comparing phylogenetic trees based on gltA genes, rpoB genes, and SNPs, we found that the topological structures of several evolutionary trees are different. However, the Bartonella strains isolated in this study were clustered into six clusters in different phylogenetic trees. Broad distributions and high genetic diversity of Bartonella strains were observed among rodents in Beitun, Xinjiang. IMPORTANCE Rodent-borne Bartonella species have been associated with zoonotic diseases. Bartonella species such as Bartonella elizabethae, Bartonella grahamii, and Bartonella tribocorum can cause disease in humans. Humans can be infected by blood-sucking arthropods through the scratches and bites of an infected reservoir host or via contact with infectious rodents. Xinjiang is one of the provinces with the most abundant species of Bartonella in China, but there are few reports about the prevalence of Bartonella in the Beitun area. This research aims to investigate the occurrence and prevalence of Bartonella infection in rodents at these sampling sites and provide a basis for the prevention and control of rodent Bartonella species in Beitun and the surrounding areas of Xinjiang.

Limitations of Serological Diagnosis of Typical Cat Scratch Disease and Recommendations for the Diagnostic Procedure

Introduction

Cat scratch disease (CSD) is the most common cause of bacterial infectious lymphadenopathy, especially in children, but its diagnosis still remains challenging. Serological assays are widely applied due to their simplicity and the non-invasive sampling. However, these techniques present several limitations, including not well-defined antigen preparation, assay conditions and cutoff titers, severe cross-reactions with other species and organisms, and the notably ranging seroprevalence in the normal population. The objective of this study is to review the literature in order to determine the best diagnostic procedure for the diagnosis of CSD.

Methods

Databases including PubMed, Medline, Google Scholar, and Google were searched to determine the best diagnostic procedure for the diagnosis of CSD. A total of 437 papers were identified and screened, and after exclusion of papers that did not fulfill the including criteria, 63 papers were used.

Results

It was revealed that sensitivities of serological assays varied from 10% to 100%. Indeed, more than half of the studies reported a sensitivity lower than 70%, while 71% of them had a sensitivity lower than 80%. Moreover, specificities of serological assays ranged from 15% to 100%, with 25 assays reporting a specificity lower than 90%.

Conclusion

It is considered that molecular assays should be the gold standard technique for CSD confirmation, and physicians are reinforced to proceed to lymph node biopsy in suspicious CSD cases.

Haemophagocytic lymphohistiocytosis associated with bartonella peliosis hepatis following kidney transplantation in a patient with HIV

Bacillary peliosis hepatis is a well recognised manifestation of disseminated Bartonella henselae infection that can occur in immunocompromised individuals. Haemophagocytic lymphohistiocytosis is an immune-mediated condition with features that can overlap with a severe primary infection such as disseminated Bartonella spp infection. We report a case of bacillary peliosis hepatis and secondary haemophagocytic lymphohistiocytosis due to disseminated Bartonella spp infection in a kidney-transplant recipient with well controlled HIV. The patient reported 2 weeks of fever and abdominal pain and was found to have hepatomegaly. He recalled exposure to a sick dog but reported no cat exposures. Laboratory evaluation was notable for pancytopenia and cholestatic injury. The patient met more than five of eight clinical criteria for haemophagocytic lymphohistiocytosis. Pathology review of a bone marrow core biopsy identified haemophagocytosis. A transjugular liver biopsy was done, and histopathology review identified peliosis hepatis. Warthin-Starry staining of the bone marrow showed pleiomorphic coccobacillary organisms. The B henselae IgG titre was 1:512, and Bartonella-specific DNA targets were detected by peripheral blood PCR. Treatment with doxycycline, increased prednisone, and pausing the mycophenolate component of his transplant immunosuppression regimen resulted in an excellent clinical response. Secondary haemophagocytic lymphohistiocytosis can be difficult to distinguish from severe systemic infection. A high index of suspicion can support the diagnosis of systemic Bartonella spp infection in those who present with haemophagocytic lymphohistiocytosis, especially in patients with hepatomegaly, immunosuppression, and germane animal exposures.

Atlantoaxial instability secondary to Bartonella henselae osteomyelitis managed surgically by atlantoaxial instrumentation: A case report and systematic review

Cat scratch disease (CSD), caused by Bartonella henselae, may atypically present with vertebral osteomyelitis. Antibiotic regimens are tailored to presentation, which is markedly variable and not well defined for any atypical disease. In cases of spinal instability, the use of antibiotics alone may not be sufficient. Atlantoaxial instability caused by osteomyelitis is a rare complication of CSD. In this report, we describe the rare case of vertebral osteomyelitis complicated by atlantoaxial instability, requiring both antibiotics and atlantoaxial fusion. We discuss our case, surgical technique, rationale, and outcome. In addition, we conducted a systematic review of the literature of vertebral osteomyelitis in pediatric secondary to B. henselae. A 2-year-old child presented with a 2-month history of irritability, fever, and rigid neck pain along with a recent history of feline exposure. Physical examination revealed cervical tenderness and decreased range of motion. Computed tomography (CT) showed osteolysis of the right C1 lateral mass and pars articularis; T1-weighted magnetic resonance imaging with contrast showed enhancement around the right C1 lateral mass. The titer for B. henselae was high. A diagnosis of cat scratch osteomyelitis with cervical instability was made, for which the patient underwent surgery with atlantoaxial fusion. Postoperative imaging demonstrated resolution of the contrast-enhanced lesion. At 6-year follow-up, the patient showed no signs of residual complications from surgical intervention with a solid fusion. Our review revealed 44 cases of pediatric CSD vertebral osteomyelitis. Conservative management with antibiotic employed in 86% while antibiotics with surgical intervention in 14% of the cases. Surgical intervention was most often in the form of incision for drainage and decompression without fusion. Average follow-up 10 months with 86% achieved complete resolution. Cervical instability caused by osteolysis is a rare complication of CSD. This can subsequently lead to vertebral instability, requiring definitive surgical intervention.

Isolated hepatosplenic abscess from cat scratch disease in a patient with HIV

Bartonella henselae infection, or cat scratch disease, typically is a self-limiting disease presenting as lymphadenopathy and fever after a bite or scratch from a cat. The most commonly reported presentation in immunocompromised patients includes bacillary angiomatosis and peliosis hepatitis, which resemble Kaposi's sarcoma. Isolated hepatosplenic abscess without diffuse lymphadenopathy or vasoproliferative disease is seldom reported in adult immunocompromised patients. Although several advances have been made in identifying the organism and antibodies with serological tests, biopsy, and polymerase chain reaction, there is little information about treatment. We report a case of an isolated hepatosplenic abscess without lymphadenopathy or vasoproliferative disease caused by B. henselae in an adult immunocompromised patient with HIV.

Molecular Survey and Genetic Diversity of Bartonella spp. in Small Indian Mongooses (Urva auropunctata) and Their Fleas on Saint Kitts, West Indies

This study aimed to molecularly survey and evaluate the genetic diversity of Bartonella spp. in mongooses and their fleas from St. Kitts. Spleen (n = 54), blood (n = 71), and pooled flea samples, all identified as Ctenocephalides felis (n = 53), were submitted to TaqMan real-time quantitative PCR (qPCR) targeting Bartonella-nuoG fragment (84 bp). Positive samples underwent further conventional PCR assays targeting five loci (gltA, rpoB, fstZ, nuoG, and ITS), subsequent sequencing, and phylogenetic and haplotype analyses. The overall occurrence of Bartonella spp. in mongooses and fleas was 51.2% (64/125 [95% CI (42.1–60.2%)]) and 62.3% (33/53) [95% CI (47.9–75.2%)]), respectively. From samples sequenced across the five loci, 50.8% (33/65) were identified as Bartonella henselae, 26.2% (17/65) were 96.74–99.01% similar by BLAST analysis to an unidentified Bartonella sp. previously reported in Japanese badgers (Meles anakuma), and 23.1% (15/65) were co-infected with both species. Nucleotide polymorphism analysis showed low diversity amongst haplotypes but did concur with phylogenetic analysis, placing the unidentified species in a separate clade from B. henselae by multiple mutational events. Our data confirms that mongooses and Ctenocephalides felis fleas collected from them are not only potential reservoirs for B. henselae but also a novel Bartonella sp. which we propose be called ‘Candidatus Bartonella kittensis’.

First isolation and genotyping of Bartonella henselae from a cat living with a patient with cat scratch disease in Southeast Europe

Background

The bacterial genus Bartonella is distributed worldwide and poses a public health risk. Cat-scratch disease caused by B. henselae in Croatia was first described in 1957. It is present throughout the country: a survey of serum samples from 268 Croatian patients with lymphadenopathy showed that 37.7% had IgG antibodies. Despite this prevalence, we are unaware of reports of Bartonella culturing from infected humans or cats in Croatia or elsewhere in southeast Europe.

Case presentation

Here we describe the diagnosis of a 12-year-old child with lymphadenopathy in Croatia with cat-scratch disease based on antibody detection and clinical signs, and the subsequent culturing and genotyping of B.henselae from the cat’s blood. The B. henselae isolate was grown on different blood agar plates and its identity was confirmed based on polymerase chain reaction (PCR) amplification of 16S ribosomal deoxyribonucleic acid (16S rDNA) and sequencing. Multi-locus sequence typing (MLST) identified the strain genotype as sequence type 5, commonly found zoonotic B. henselae strain in cats. The child recovered after azithromycin therapy, and B. henselae in the cat was eliminated within three months after doxycycline treatment.

Conclusions

This is, to our knowledge, the first report of B. henselae culturing and MLST-based genotyping from cat’s blood in southeast Europe. Our ability to detect B. henselae in blood through culturing but not PCR suggests that the prevalence of infected cats with low bacteremia is very high, suggesting the need to develop faster, more sensitive detection assays.

Evaluation of cell culture-grown Bartonella antigens in immunofluorescent antibody assays for the serological diagnosis of bartonellosis in dogs

BACKGROUND

Because of poor sensitivity and questionable specificity of immunofluorescent antibody assays (IFAs), serological diagnosis of Bartonella species infections in dogs remains challenging. Despite limitations, IFA testing is the historical "gold standard" for Bartonella serodiagnosis in animals and humans. Because most diagnostic laboratories test against only 1 or 2 Bartonella spp., testing against a broader panel of Bartonella antigens may enhance diagnostic sensitivity and specificity.

OBJECTIVE

To evaluate the sensitivity and specificity of Bartonella IFA using 8 cell culture-grown Bartonella spp. isolates.

ANIMALS

Archived serum samples from 34 Bartonella spp. naturally exposed, polymerase chain reaction (PCR)-positive dogs and from 26 PCR-negative and IFA-negative dogs.

METHODS

Bartonella IFA sensitivity and specificity were assessed using cell culture-grown whole cell antigens derived from 3 Bartonella henselae (Bh) strains (Bh Houston 1, Bh San Antonio Type 2, Bh California 1), 3 Bartonella vinsonii subsp. berkhoffii genotypes (Bvb I, II, and III), Bartonella koehlerae (Bk), and Bartonella quintana (Bq).

RESULTS

Only 62% of 34 Bartonella spp. PCR-positive dogs were seroreactive to any of the 8 Bartonella IFA antigens, indicating low IFA sensitivity. PCR-positive dogs were most often IFA seroreactive to Bq (n = 15), to Bvb II (n = 13), or to both (n = 9) antigens. Of the 26 previously IFA-negative/PCR-negative dogs, 4 (15%) were seroreactive using the expanded antigen panel.

CONCLUSION AND CLINICAL IMPORTANCE

Despite IFA testing of dogs against 8 different Bartonella isolates, IFA sensitivity remained poor, and specificity was only 85%. Development of a reliable serological assay is needed to facilitate the diagnosis of Bartonella infection in dogs.

Pathologic Features of Infectious Gastritis

This manuscript presents a review of infectious causes of gastritis aimed at the practicing anatomic pathologist. We shall highlight unique histologic findings and clinical attributes that will assist those analyzing endoscopically obtained mucosal biopsies of the stomach or resection specimens.

Serologic Study of Bartonella henselae in Patients with Acute Undifferentiated Febrile Illness in Korea

BACKGROUND

Bartonella infection is an emerging cause of acute febrile illness; however, its significance has not been thoroughly investigated. We studied the antibody specific to Bartonella henselae in patients with various febrile diseases in Korea.

MATERIALS AND METHODS

A total of 177 patients with acute febrile illness who were managed at the Inha University Hospital from February 2012 to January 2013 were evaluated with an in-house immunofluorescent antibody test to detect B. henselae immunoglobulin G (IgG) antibody. The clinical features of the patients included fever of undetermined origin (n = 88 patients), lymphadenopathy (n = 28), febrile rash (n = 17), respiratory infection (n = 12), aseptic meningitis (n = 7), intra-abdominal infection (n = 5), arthritis (n = 4), and other conditions (n = 16). We reviewed the medical records of these patients and collected demographic data, clinical features, and their histories of animal exposure.

RESULTS

Among the 177 patients with acute febrile illness, 23.7% (42/177) had elevated levels of IgG antibodies to B. henselae (≥1:160). Of these seropositive patients, 32.4% (12/37) had contact with animals and had developed arthralgia (29.5%), headache (25%), or lymphadenopathy (15.9%). Seven (16.7%) of the 42 patients had higher IgG titers (≥1:640). Among them, four patients presented fourfold increase/decrease of IgG in convalescent serum. According to the clinical diagnosis, the antibody positivity rates were as follows: 24/88 with undifferentiated fever, 8/28 with lymphadenopathy, 4/17 with febrile rash, 2/12 with respiratory infection, 2/7 with aseptic meningitis, and 2/16 with other illnesses.

CONCLUSIONS

There was high prevalence of B. henselae in patients with undifferentiated fever in Korea, for which further research is needed.

Prevalence and clinical presentation of Rickettsia, Coxiella, Leptospira, Bartonella and chikungunya virus infections among hospital-based febrile patients from December 2008 to November 2009 in Bangladesh

BACKGROUND

We conducted a study to identify Rickettsia, Coxiella, Leptospira, Bartonella, and Chikungunya virus infections among febrile patients presenting at hospitals in Bangladesh.

METHODS

We collected blood samples from patients at six tertiary hospitals from December 2008 to November 2009 and performed laboratory tests at the United States Centers for Disease Control and Prevention (CDC).

RESULTS

Out of 720 enrolled patients, 263 (37%) were infected with Rickettsia; 132 patients had immunofluorescence antibody titer >64 against spotted fever, 63 patients against scrub typhus fever and 10 patients against typhus fever. Ten patients were identified with Coxiella. We isolated Leptospira from two patients and Bartonella from one patient. Ten patients had antibodies against Chikungunya virus. The proportion of patients who died was higher with rickettsial fever (5%) compared to those without a diagnosis of rickettsial infection (2%). None of the patients were initially diagnosed with rickettsial fever.

CONCLUSIONS

Rickettsial infections are frequent yet under-recognized cause of febrile illness in Bangladesh. Clinical guidelines should be revised so that local clinicians can diagnose rickettsial infections and provide appropriate drug treatment.

Bartonella species in fleas from Palestinian territories: prevalence and genetic diversity

Bartonellosis is an infectious bacterial disease. The prevalence and genetic characteristics of Bartonella spp. in fleas of wild and domestic animals from Palestinian territories are described. Flea samples (n=289) were collected from 121 cats, 135 dogs, 26 hyraxes and seven rats from northern (n=165), central (n=113), and southern Palestinian territories (n=11). The prevalent flea species were: Ctenocephalides felis (n=119/289; 41.2%), Ctenocephalides canis (n=159/289; 55%), and Xenopsylla sp. (n=7/289; 2.4%). Targeting the Intergenic Transcribed Spacer (ITS) locus, DNA of Bartonella was detected in 22% (64/289) of all fleas. Fifty percent of the C. felis and 57% of the Xenopsylla sp. contained Bartonella DNA. DNA sequencing showed the presence of Bartonella clarridgeiae (50%), Bartonella henselae (27%), and Bartonella koehlerae (3%) in C. felis. Xenopsylla sp. collected from Rattus rattus rats were infected with Bartonella tribocorum, Bartonella elizabethae, and Bartonella rochalimae. Phylogenetic sequence analysis using the 16S ribosomal RNA gene obtained four genetic clusters, B. henselae and B. koehlerae as subcluster 1, B. clarridgeiae as cluster 2, while the rat Bartonella species (B. tribocorum and B. elizabethae) were an outgroup cluster. These findings showed the important role of cat and rat fleas as vectors of zoonotic Bartonella species in Palestinian territories. It is hoped that this publication will raise awareness among physicians, veterinarians, and other health workers of the high prevalence of Bartonella spp. in fleas in Palestinian territories and the potential risk of these pathogens to humans and animals in this region.

A case report of seronegative cat scratch disease, emphasizing the histopathologic point of view

Abstract

Cat scratch disease, necrotizing granulomatous lymphadenitis caused by Bartonella henselae, usually benign and self-limited. However, various clinical manifestations and no pathognomonic histopathologic features can lead to misinterpretations and diagnostic disputes. We report a case of cat scratch disease in a 39-yr-old male patient with fever and left axillary lymphadenitis. He had a history of cat bite on the left hand dorsum. On excision, the lymph node showed follicular hyperplasia, stellate microabscesses with a rim of granulomatous inflammation. Warthin-Starry silver staining showed many clumps of silver-stained bacilli within the necrotic foci. Serological tests were negative. Diagnosis was established by PCR analysis.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1877499238123059

Bartonella henselae infections in solid organ transplant recipients: report of 5 cases and review of the literature

Bartonella henselae is the causative agent of cat scratch disease and bacillary angiomatosis-peliosis. The spectrum of disease, diagnosis, and management of B. henselae infection in solid organ transplant recipients has not been well characterized. We identified 29 cases of solid organ transplant recipients who had Bartonella infection, 24 by a review of the English-language literature and 5 from our institution. Localized cat scratch disease was found in 8 patients (28%), and disseminated infection was found in 21 patients (72%). The mean time after transplantation to development of Bartonella infection among those with cat scratch disease was 5.6 ± 5.3 years, and among those with disseminated infection was 2.7 ± 2.4 years. Prominent clinical features included cat exposure in 26 patients (90%), fever in 27 patients (93%), lymphadenopathy in 12 patients (41%), and skin lesions in 7 patients (24%). Methods used in establishing the diagnosis of Bartonella infection included culture, polymerase chain reaction (PCR) assay, serologic assays, and histopathologic examination. Culture was positive in 2 of only 4 patients in whom this was performed, and PCR was positive in 12 of 14 patients (86%) in whom this test was performed. Serologic assays were positive in all 23 patients who were tested. Histopathologic examination of tissues in all 8 patients who had cat scratch disease revealed granulomatous inflammation in 4 (50%) and bacillary angiomatosis-peliosis in 2 (25%). Among the 15 patients who had disseminated infection and who had tissue examined, 8 (53%) had only granulomatous inflammation, 4 had only bacillary angiomatosis-peliosis (27%), and 2 had both granulomas and bacillary angiomatosis-peliosis (13%). A positive Warthin-Starry or Steiner stain was noted in 12 of 19 patients (63%) who had 1 of these stains performed. All 8 patients with cat scratch disease and 19 of 21 patients with disseminated bartonellosis were cured with antimicrobial therapy. Two patients, both of whom had endocarditis, died. Among solid organ transplant recipients, infection with B. henselae is uncommon and has diverse disease manifestations including disseminated disease. Persistent fevers or lymphadenopathy in a transplant recipient who has been exposed to cats should prompt clinicians to maintain a high index of suspicion for B. henselae infection. Identifying B. henselae as the causative organism often requires multiple diagnostic studies. Once the diagnosis is established, most solid organ transplant recipients respond appropriately to antimicrobial treatment.

Persistence of Bartonella spp. stealth pathogens: from subclinical infections to vasoproliferative tumor formation

Bartonella spp. are facultative intracellular bacteria that typically cause a long-lasting intraerythrocytic bacteremia in their mammalian reservoir hosts, thereby favoring transmission by blood-sucking arthropods. In most cases, natural reservoir host infections are subclinical and the relapsing intraerythrocytic bacteremia may last weeks, months, or even years. In this review, we will follow the infection cycle of Bartonella spp. in a reservoir host, which typically starts with an intradermal inoculation of bacteria that are superficially scratched into the skin from arthropod feces and terminates with the pathogen exit by the blood-sucking arthropod. The current knowledge of bacterial countermeasures against mammalian immune response will be presented for each critical step of the pathogenesis. The prevailing models of the still-enigmatic primary niche and the anatomical location where bacteria reside, persist, and are periodically seeded into the bloodstream to cause the typical relapsing Bartonella spp. bacteremia will also be critically discussed. The review will end up with a discussion of the ability of Bartonella spp., namely Bartonella henselae, Bartonella quintana, and Bartonella bacilliformis, to induce tumor-like vascular deformations in humans having compromised immune response such as in patients with AIDS.

A mathematical epidemiological model of gram-negative Bartonella bacteria: does differential ectoparasite load fully explain the differences in infection prevalence of Rattus rattus and Rattus norvegicus?

We postulate that the large difference in infection prevalence, 24% versus 5%, in R. norvegicus and R. rattus, respectively, between these two co-occurring host species may be due to differences in ectoparasite and potential vector infestation rates. A compartmental model, representative of an infectious system containing these two Rattus species and two ectoparasite vectors, was constructed and the coefficients of the forces of infection determined mathematically. The maximum difference obtained by the model in the prevalence of Bartonella in the two Rattus species amounts to 4.6%, compared to the observed mean difference of 19%. Results suggest the observed higher Bartonella infection prevalence in Rattus norvegicus compared to Rattus rattus, cannot be explained solely by higher ectoparasite load. The model also highlights the need for more detailed biological research on Bartonella infections in Rattus and the importance of the flea vector in the spread of this disease.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Co-isolation of Bartonella henselae and Bartonella vinsonii subsp. berkhoffii from blood, joint and subcutaneous seroma fluids from two naturally infected dogs

This report describes the clinical presentation, isolation and treatment of two dogs naturally infected with Bartonella henselae and Bartonella vinsonii subsp. berkhoffii. Chronic and progressive polyarthritis was the primary complaint for dog #1, from which B. henselae and B. vinsonii subsp. berkhoffii were cultured on three independent occasions from blood and joint fluid samples, despite administration of nearly 4 months of non-consecutive antibiotic therapy. A clinically atypical and progressively severe trauma-associated seroma was the primary complaint for dog #2, from which B. henselae and B. vinsonii subsp. berkhoffii were isolated from serum, blood and seroma fluid. Dogs can be co-infected with two Bartonella spp. and infection with these organisms should not be ruled out if specific antibodies are not detected. Specialized culture techniques should be used for isolation and to assess antibiotic efficacy.

Evaluation of immunohistochemistry in identifying Bartonella henselae in cat-scratch disease

Cat-scratch disease (CSD) is largely due to infection with Bartonella henselae. Microbiologic detection is difficult, and molecular testing is not readily available. A monoclonal antibody (mAB) to B henselae has become commercially available. We evaluated the usefulness of immunohistochemical analysis (IHC) for diagnosing CSD on surgical specimens and compared these results with polymerase chain reaction (PCR) detection and serologic testing for B henselae. We studied 24 formalin-fixed, paraffin-embedded (FFPE) cases of lymphadenitis with histologic and/or clinical suspicion of CSD. Control cases included 14 cases of lymphadenopathy other than CSD. FFPE tissue sections were evaluated with an mAB to B henselae, Steiner silver stain (SSS), and PCR that targeted B henselae and Bartonella quintana. Positive cases were as follows: SSS, 11 (46%); PCR, 9 (38%); and IHC, 6 (25%). Only 2 cases (8%) were positive for all 3 studies. All control cases were negative for IHC and PCR. The diagnostic sensitivity of these 3 tests is low for CSD. SSS seems to be the most sensitive test but is the least specific. PCR is more sensitive than IHC and may, therefore, serve as a helpful second-line test on all IHC- cases.

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.

Native valve endocarditis due to Bartonella henselae in an immunocompetent man

Culture-negative endocarditis accounts for 2.5-31% of all endocarditis cases and remains a diagnostic and therapeutic challenge. Bartonella spp. has only recently been recognized as an important cause of culture-negative endocarditis. We report a case of Bartonella henselae endocarditis occurring in an immunocompetent man who owned a cat and had previously been diagnosed with valvulopathy. Diagnosis was made only after prolonged diagnostic work-up with serology and with PCR and subsequent sequencing to identify the microorganism in the excised valves. The duration of treatment in patients with bartonella endocarditis is not clearly defined, and we decided to treat our patient with a prolonged course of antibiotic. Surgical treatment is usually necessary and was also successful in our patient. To our knowledge, this is the first case of bartonella endocarditis occurring in our geographic area.

Lymphadenopathy in a novel mouse model of Bartonella-induced cat scratch disease results from lymphocyte immigration and proliferation and is regulated by interferon-alpha/beta

In immunocompetent humans, cat scratch disease (CSD) is elicited by the Gram-negative bacterium Bartonella henselae and is characterized by a benign regional lymphadenopathy, the pathogenesis of which is poorly understood. Here, we describe a novel mouse model of Bartonella-induced CSD-like disease that allowed us to investigate the mechanisms leading to lymphadenopathy in vivo. In wild-type mice, a subcutaneous inoculation of either viable or inactivated B. henselae led to a strong swelling of the draining lymph node, which was long-lasting despite the rapid elimination of the bacteria. Carboxyfluorescein- and bromodesoxyuridine-labeling experiments showed that lymph node enlargement resulted from modified immigration and enhanced proliferation of lymphocytes, preferentially of B cells. A comparative analysis of B. henselae and the rodent pathogen B. grahamii in wild-type versus interferon-alpha/beta-receptor I chain-deficient mice revealed that interferon-alpha/beta is not only differentially induced by these two Bartonella species but also exerts an inhibitory effect on the development of lymphadenopathy both in vitro and in vivo. These data demonstrate that the lymphadenopathy of human CSD can be reproduced and studied in a mouse model and provide the first insights into the underlying immunological mechanisms.

Bacterial Infections

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

Adult systemic cat scratch disease associated with therapy for hepatitis C

Background

We describe the first case of systemic cat scratch disease in a patient receiving peginterferon α-2a and ribavirin for treatment of hepatitis C. Cases of adult systemic CSD are extremely infrequent and immunomodulatory treatment for hepatitis C has been associated with aberrant host responses to common pathogens.

Case presentation

A 52 year old man being treated for hepatitis C presented with diffuse lymphadenopathy, weight loss, fevers and splenic lesions. Symptoms were initially confused with adverse effects of his regimen, delaying recognition of his infection. Diagnostic investigation, including histopathology, microbiology and serologic parameters, confirmed that his illness was due to disseminated cat scratch disease with Bartonella henselae.

Conclusion

Disseminated CSD is exceptionally rare in adults. We describe the first case of disseminated cat scratch disease associated with peginterferon α and ribavirin to alert clinicians of the need to be aware of unusual manifestations of common infections in this population.

An unusual outcome in a child with hepatosplenic cat-scratch disease

Typical cat-scratch disease (Bartonella henselae infection) in an immunocompetent child is usually associated with a history of scratch, bite or intimate contact with a cat. Most patients develop a non-tender papule in the scratch line after three to ten days. This may persist for only a few days or as long as two to three weeks. During the next two weeks or more, regional lymph nodes that drain the area gradually enlarge and then slowly resolve in more than 10% of patients. The nodes develop overlying erythema and may suppurate. Atypical forms of cat-scratch disease occur in a minority of cases and are characterized by ocular or neurological manifestations, hepatosplenic involvement, vertebral osteomyelitis, endocarditis etc. Immunocompromised individuals with B. henselae infection may develop bacillary angiomatosis, bacillary peliosis, and relapsing bacteremia. There have been several reports of hepatosplenic granulomas caused by B. henselae in immunocompetent children. We report a case of a 6-year-old boy with the hepatosplenic form of cat-scratch disease. Despite early diagnosis and long-term antimicrobial treatment, splenectomy could not be avoided.

New and emerging infectious diseases

New and emerging diseases present a constant challenge. Globalization of business, international adoption, immigration, and tourism have contributed to the rapid spread of diseases, such as severe acute respiratory syndrome (SARS). Infectious diseases that emerge in Africa or Asia may arrive on US shores within days. This article reviews the new and emerging pathogens important to dermatologists.

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.

Diagnosis of Cat Scratch Disease With Bartonella Henselae Infection in Formalin-Fixed Paraffin-Embedded Tissues by Two Different PCR Assays

Cat scratch disease (CSD) is commonly caused by Bartonella henselae infection. Clinical history and histologic findings are often insufficient to establish a definitive diagnosis of CSD. We retrospectively studied formalin-fixed, paraffin-embedded (FFPE) lymph nodes from 35 patients with histologically suspected CSD by 2 different PCR assays and immunohistochemistry (IHC). The first primer pair amplified a 163-bp fragment of the 16S rRNA gene in 19 of the 35 cases (54%). The second primer pair amplified a 191-bp fragment of the henselae citrate synthase (gltA) gene in 17 of the 35 cases (49%). IHC identified the organisms in 8 of 33 cases (24%). Fresh cultures of various Bartonella species showed a specific PCR product with an analytical sensitivity of 0.5 to 5 pg bacterial DNA. Bartonella species were identified by the unique size of the amplified PCR product. Twenty-two lymph nodes without morphologic evidence or a history of CSD were negative by PCR and immunostaining. Tissues from a patient with Legionella pneumophila were also negative by PCR and immunostaining for CSD supporting the specificity of the PCR reaction. The specific PCR products of the B. henselae were confirmed by sequencing. Human beta-actin for each case was amplified to check the integrity of the DNA. Our data indicate that detection of Bartonella DNA by PCR is useful to confirm the diagnosis of CSD.

[Optic neuritis in cat scratch disease]

Ocular and neuro-ophthalmic manifestations of cat scratch disease are not uncommon. The association of anterior optic neuritis with retinal lesions suggests neuroretinitis, which is highly suggestive of cat scratch disease. A new case is described.

Bartonellosis: light and shadows in diagnostic and therapeutic issues

Cat-scratch disease involves a prolonged and/or complicated course, and lymph node drainage is usually required. Culture and molecular techniques often yield negative results, but immunofluorescence assays may give early information, and elevated antibodies may persist for months. Cat-scratch disease should be suspected in patients with prominent swelling of lymph nodes draining from the upper limbs, limited systemic involvement, and typical epidemiological-clinical features. The temporal antibody response during the sub-acute course remains unknown. Although biomolecular assays are available, the time between onset and investigation is an obstacle to positive results. The role of surgical debridement and the unpredictable activity of antimicrobial agents warrant further investigation.

A review of bacterial pathogens inCtenocephalides felisin New Zealand

The cat flea, Ctenocephalides felis, is the recognised vector of Bartonella henselae, B. clarridgeiae and Rickettsia felis. Although these Gram-negative bacteria were only described in the last decade, they are already known to cause a variety of diseases in people, particularly children and the immunosuppressed. Such diseases include cat-scratch disease, bacillary angiomatosis, endocarditis, bacteraemia, encephalopathy, neuroretinitis, osteomyelitis and peliosis hepatis. Although most infections in cats and dogs appear to be subclinical, recent studies have provided growing evidence that the bartonellas can also cause serious problems in pets, including hepatitis, endocarditis, central nervous system (CNS) signs, lymphadenopathy, uveitis, cataracts and reproductive failure. In 2004, DNA of B. henselae, B. clarridgeiae and R. felis was demonstrated in cat fleas from New Zealand and pets and their owners in the country are thus at risk of infection. While flea control programmes have traditionally been advocated by veterinarians to prevent pruritus and tapeworms in pets, they should now also be recommended to prevent infections with the new flea-borne bacterial pathogens. To raise awareness of the organisms amongst veterinarians and animal health workers, this review describes: the biology of the organisms; clinical and laboratory features of infections in cats, dogs and people; diagnosis; and possible treatments and control of infections with these organisms.