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Erythrocyte parasitism, or hemotrophy, is not a common strategy for bacteria. However, Bartonella species are elegantly adapted to parasitize a variety of cell types including red blood cells. Bartonella bacilliformis, a useful model organism for the genus, has been used to study virulence determinants involved in colonization, attachment and invasion of host cells.
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.
Since the isolation of Bartonella vinsonii subspecies berkhoffii from a dog with endocarditis in 1993, this organism has emerged as an important pathogen in dogs and as an emerging pathogen in people. Current evidence indicates that coyotes, dogs and gray foxes potentially serve as reservoir hosts. Based upon sequence differences within the 16S-23S ITS region and Pap31 gene, we propose a classification scheme that divides B. vinsonii subsp. berkhoffii isolates into four distinct types. Two conserved sequences, of 37 and 18 bp, respectively, are differentially present within the ITS region of each of the four B. vinsonii subsp. berkhoffii types. To date, B. vinsonii berkhoffii types I, II, and III have been identified in the US, type III in Europe and type IV in Canada. Based upon the proposed genotyping scheme, the geographic distribution of B. vinsonii berkhoffii types needs to be more thoroughly delineated in future molecular epidemiological studies involving Bartonella infection in coyotes, dogs, gray foxes, human beings and potentially other animals or in arthropod vectors. Strain typing may help to better define the reservoir potential, carriership patterns, modes of transmission, and geographic distribution for each B. vinsonii berkhoffii type.
Bartonella henselae has been identified and characterized for the first time in Italy. A strain, designed Pavia-1, was isolated from the blood of a cat whose owner developed cat scratch disease (CSD). Pavia-1 and two American B. henselae strains (Houston-1, ATCC 49882, type I and strain 269608, UC Davis, type II) were compared by whole-cell fatty analysis (CFA), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein profiles, Western immunoblotting (WB) for reactivity with polyclonal antibodies, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), type-specific 16S rRNA PCRs, and pulsed-field gel electrophoresis (PFGE). Bartonella clarridgeiae (ATCC 51734) was also included for comparison. Pavia-1 was identified as a B. henselae type I. PFGE allowed differentiation between B. clarridgeiae and B. henselae and furthermore, between all the B. henselae strains. The fingerprints of PFGE observed for Pavia-1 were distinct from those of B. henselae type II and also of Houston-1, suggesting that the two type I strains derived from two different clones. These results show the capability of B. henselae to develop genotypic variability between genetically related strains.
Zoonotic transmission of sylvatic plague caused by Yersinia pestis occurs in California, USA. Human infections with various Bartonella species have been reported recently. Coyotes (Canis latrans) are ubiquitous throughout California and can become infected with both bacterial agents, making the species useful for surveillance purposes. This study examined the geographic distribution of 863 coyotes tested for Y. pestis and Bartonella vinsonii subsp. berkhoffii serologic status to gain insight into the natural history of B. vinsonii subsp. berkhoffii and to characterize the spatial distribution of the two agents. We found 11.7% of specimens positive to Y. pestis and 35.5% positive to B. vinsonii subsp. berkhoffii. The two pathogens had distinct spatial clusters: Y. pestis was more prevalent in eastern portions of the state and B. vinsonii subsp. berkhoffii in coastal regions. Prevalence of Y. pestis increased with increasing elevation, whereas prevalence of B. vinsonii subsp. berkhoffii decreased with increasing elevation. There were differences in the proportions of positive animals on a yearly basis to both pathogens.
Bartonella species are emerging human pathogens responsible for a wide range of clinical manifestations, including Carrion's disease, trench fever, cat-scratch disease, bacillary angiomatosis-peliosis, endocarditis and bacteraemia. During infection of their human or animal reservoir host(s), these arthropod-borne pathogens typically invade and persistently colonize mature erythrocytes. However, in both reservoir and incidentally infected hosts, endothelial cells are target cells for bartonellae. Endothelial interactions involve a unique mode of cellular invasion, the activation of a proinflammatory phenotype and the formation of vasoproliferative tumours. Based on the establishment of bacterial genetics and appropriate infection models, recent work has begun to elucidate the cell and molecular biology of these unusual pathogen-host cell interactions.
BACKGROUND: Bartonella (Rochalimaea) quintana is a fastidious gram-negative bacterium known to cause trench fever, cutaneous bacillary angiomatosis, and endocarditis. Between January and June 1993 in Seattle, we isolated B. quintana from 34 blood cultures obtained from 10 patients not known to be infected with the human immunodeficiency virus (HIV). METHODS: After identifying the isolates as B. quintana by direct immunofluorescence and DNA-hybridization studies, we determined strain hybridization with studies of restriction-fragment-length polymorphisms (RFLPs) of the intergenic spacer (noncoding) region of ribosomal DNA amplified by the polymerase chain reaction (PCR). To characterize the epidemiologic and clinical features of bartonella infections in these patients, we performed a retrospective case-control study using as controls 20 patients with blood cultures obtained at approximately the same time as those obtained from the index patients. RESULTS: B. quintana isolates from the 10 patients were indistinguishable by PCR-RFLP typing. All 10 patients had chronic alcoholism, and 8 were homeless (P = 0.001 for both comparisons with controls). The six patients who underwent HIV testing were seronegative. At the time of their initial presentation, seven patients had temperatures of at least 38.5 degrees C. Six patients had three or more blood cultures that were positive for B. quintana, and in four of these patients B. quintana was isolated from blood cultures obtained 10 or more days apart. Subacute endocarditis developed in two patients and required surgical removal of the infected aortic valve in one of them. Nine patients recovered; one died of sepsis from Streptococcus pneumoniae infection. CONCLUSIONS: B. quintana is a cause of fever, bacteremia, and endocarditis in HIV-seronegative, homeless, inner-city patients with chronic alcoholism.
Sera from 292 cats were analyzed by means of indirect immunofluorescence for antibodies to Bartonella henselae, B. quintana and B. elizabethae. The sera were sent to the Swedish National Institute of Veterinary Medicine for health monitoring and were tested retrospectively for antibodies to Bartonella. The most prevalent antibodies (25%) reacted with the B. elizabethae antigen. Cats with such antibodies were older than those without antibodies. The prevalence of antibodies to B. elizabethae was higher in the south of Sweden than in the north, with the highest prevalence (46%) being found in cats living in the Stockholm region. There was no difference in sex distribution. A low prevalence (1%) of antibodies to B. henselae was found and no sera reacted with B. quintana. The high prevalence of antibodies to B. elizabethae is consistent with previous findings in Swedish patients. The small number of cats with B. henselae antibodies observed in this study could be due to the cold climate and the low occurrence of cat fleas in Sweden.
Two genotypes (I and II) of Bartonella henselae are involved in cat-scratch disease (CSD). Lymph node biopsies were taken from 3 children suffering from CSD, and blood cultures were obtained from their pet cats. Cat-scratch disease was confirmed serologically, histologically and by detection of B. henselae DNA in all 3 lymph nodes by PCR. Bartonella henselae grew in all cats' blood cultures. The first 2 children were siblings. Both children and their pet cats were infected with B. henselae genotype II, and the third patient and her cat were infected with B. henselae genotype I. In all cases, there were no essential differences in the clinical manifestations of the infection caused by these 2 genotypes of B. henselae.
Bartonella quintana is a recently recognized cause of culture-negative left-sided endocarditis. We report a case of isolated tricuspid endocarditis caused by B. quintana in a 65-year-old alcoholic man, who also had immune-complex glomerulonephritis. B. quintana was established as the cause of the endocarditis based on serological tests and on failure of extensive efforts to isolate an alternative organism. The patient improved gradually on antibiotic therapy and did not require surgery. To our knowledge, this is the first report of isolated right-sided endocarditis caused by B. quintana. Although uncommon, Bartonella should be considered in patients with isolated right-sided culture-negative endocarditis.
Bartonella henselae can infect humans resulting in a wide range of disease syndromes including cat-scratch disease, fever with bacteremia, endocarditis, bacillary angiomatosis, and bacillary peliosis hepatis, among others. The nature and severity of the clinical presentation correlates well with the status of the hosts' immune system. Individuals with impaired immune function, including HIV infection, progress to systemic infections more often. Patients with intact immune function who become infected with B. henselae usually get cat-scratch disease, a disease that usually involves lymphadenopathy resulting from a strong cellular immune response to the bacterium. However, immunocompromised patients often progress to bacillary angiomatosis or bacillary peliosis hepatis. The reduced ability of the hosts immune response to control bacterial infection apparently results in a bacteremia of longer duration, and in some patients the presence of angiogenic lesions that are unique among bacterial infections to Bartonella. Recently, the role of immune effector cells that produce angiogenic cytokines upon stimulation with B. henselae has been proposed. Here, the current status of the role of the immune response in both controlling infection and in B. henselae-triggered immunopathogenesis is presented.
PURPOSE: To determine the role of Bartonella henselae in intraocular inflammatory disease and identify its clinical features. METHODS: We retrospectively determined the serum immunoglobulin (Ig)G and IgM antibodies against B. henselae and Bartonella quintana by enzyme immunoassays in stored sera of 138 consecutive newly referred patients with uveitis who, during the acute stage of their ocular disease, underwent a standardized screening protocol to determine the cause of uveitis. RESULTS: For the entire series, the frequency of high positive levels of IgG (above 1:900) or IgM (above 1:300) antibody against B. henselae was 6% (8/138) and 3% (4/138), respectively. Except for cross-reactions between B. henselae and B. quintana, we did not find additional evidence for cross-reactions among the various bacteria tested (Coxiella burnetii and Chlamydia pneumoniae). All patients with proven infectious uveitis (n = 21) and those with established uveitic entities (n = 37) had negative B. henselae serology. High positive IgG levels were observed in 9% of patients (5/54) with unknown cause of uveitis, in two subjects with human leukocyte antigen (HLA)-B27 positive uveitis, and in one with sarcoidosis. Five patients with uveitis of unknown origin and highly elevated IgG levels against B. henselae exhibited clinical features characterized by papillitis with surrounding retinal focal lesions or edema. CONCLUSIONS: The serologic and clinical data indicate that uveitis in seropositive cases may be caused by B. henselae. We do not recommend including testing for B. henselae in initial screening of patients with uveitis, but consider it worthwhile for those with papillitis and screening results within normal limits.
A high frequency of Bartonella elizabethae seropositivity (39%) was recorded among intravenous heroin addicts in Stockholm, Sweden, who died from a lethal injection. Some of the B. elizabethae-seropositive individuals also had antibodies to B. henselae Houston-1, B. grahamii, and B. quintana, but none had antibodies to B. henselae Marseille or B. vinsonii subsp. vinsonii. Hepatitis was a frequent finding but no case had peliosis hepatitis. There was no case of endocarditis, but in three persons active subacute-to-chronic myocarditis was found; two of these cases were Bartonella-positive and HIV-negative.
We assessed in vitro the antibiotic susceptibilities of 14 Bartonella isolates of the species B. quintana, B. vinsonii, B. henselae, and B. elizabethae. Columbia agar base supplemented with 5% horse blood was used as the antibiotic assay medium. Bacterial growth could be evaluated within 5 days after incubation of the plates at 37 degrees C in a 5% carbon dioxide atmosphere. The MICs at which 90% of isolates are inhibited (MIC90s) were 0.06 microgram/ml for penicillin G and amoxicillin and 0.25 microgram/ml for ticarcillin and cefotaxime. The MIC90s of oxacillin and cephalothin were 4 and 16 micrograms/ml, respectively. The MIC90s ranged from 1 to 4 micrograms/ml for aminoglycosides. Erythromycin, doxycycline, and rifampin displayed MIC90s of 0.12, 0.12, and 0.25 microgram/ml, respectively. MIC90s were 1 and 5 micrograms/ml for trimethoprim-and sulfamethoxazole, respectively, 64 micrograms/ml for fosfomycin, and 16 micrograms/ml for colistin and vancomycin. The study confirms the high levels of in vitro susceptibility of Bartonella agents to antibiotics.
Serologic testing for the presence of antibodies to Bartonella henselae is a widely accepted diagnostic procedure for laboratory confirmation of the diagnosis of cat scratch disease (CSD). In this study a commercially available indirect immunofluorescence assay (IFA) based on B. henselae-infected human larynx carcinoma cells (test A) was evaluated. Sera from 42 patients with CSD (20 confirmed by PCR) and 270 sera from healthy controls (consisting of 63 cat owners, 65 individuals whose last close contact with cats was >6 months previously, and 142 persons who had never been exposed to cats) were investigated for antibodies to B. henselae. All patients with CSD had titers of immunoglobulin G (IgG) to B. henselae of 128 or higher (test A; sensitivity, 100%). Of the 270 controls 189 (70%) were seronegative (titer, <64), 38 (14.1%) had titers of 64, 30 (11.1%) had titers of 128, 9 (3.3%) had titers of 256, and 4 (1.5%) had high titers, 512 (test A; specificity, 70%). Of the cat owners and individuals who had never had close contact with cats, 71.4 and 71.12%, respectively, were seronegative, and titers of 64, 128, 256, and 512 were found in 14.3 and 16.2%, 1.6 and 10.5%, 9.5 and 0.7%, and 3.2 and 1.4%, respectively. The sera from the patients and from the first 100 healthy adults without a history of close contact with cats were additionally tested with a second commercially available IFA, based on Vero cells infected with B. henselae and Bartonella quintana (test B). The sensitivity and specificity of test B were 93 and 73%, respectively. For patients with CSD the cross-reactivity between B. henselae and B. quintana in this test was 95%. Both systems are highly sensitive but less specific for detection of IgG antibodies to B. henselae in samples from patients with clinically apparent CSD. For detection of IgM antibodies, test A seems to be more sensitive (88%) and more specific (95%) than test B (sensitivity and specificity of 64 and 86%, respectively). The data show that the seroprevalence of antibodies to B. henselae in German individuals is high (30%). Low antibody levels are not sufficient evidence of active or prior infection.
Historically, disease manifestations in dogs seroreactive to Ehrlichia canis antigens by indirect immunofluorescent antibody testing have been attributed to infection with either E. canis or Ehrlichia ewingii. A 1996 study by Dawson and colleagues provided PCR evidence that healthy dogs from southeastern Virginia could be naturally infected with Ehrlichia chaffeensis. This observation stimulated us to determine which Ehrlichia spp. infected sick dogs that were referred to our hospital from the same region. Based upon PCR amplification with species-specific primers, sick dogs seroreactive to E. canis antigens were determined to be infected with four Ehrlichia species: E. canis, E. chaffeensis, E. equi, and E. ewingii. Coinfection with three Ehrlichia species (E. canis, E. ewingii, and E. equi) was documented for one dog. An additional canine pathogen presumed to be tick transmitted, Bartonella vinsonii subsp. berkhoffii, was identified in 7 of 12 dogs. Importantly, our results indicate that in naturally infected dogs, E. chaffeensis can cause severe disease manifestations that are clinically and serologically indistinguishable from disease manifestations of E. canis or E. ewingii. In addition, our findings support the efficacy of doxycycline for treatment of E. canis, E. equi, and E. ewingii infections but indicate that, based upon the persistence of E. chaffeensis DNA for 1 year following treatment, E. chaffeensis infection in dogs may be more refractory to doxycycline treatment. Undetected coinfection with Bartonella may also complicate the evaluation of treatment efficacy while resulting in disease manifestations that mimic ehrlichiosis.
We describe the clinical and laboratory features of a 55-year-old human immunodeficiency virus-negative female patient who presented with bilateral intraocular inflammatory disease (neuroretinitis type) and behavioral changes caused by a Bartonella grahamii infection. Diagnosis was based on the PCR analysis of DNA extracted from the intraocular fluids. DNA analysis of the PCR product revealed a 100% identity with the 16S rRNA gene sequence of B. grahamii. The patient was successfully treated with doxycycline (200 mg/day) and rifampin (600 mg/day) for 4 weeks. This is the first report that demonstrates the presence of a Bartonella species in the intraocular fluids of a nonimmunocompromised patient and that indicates that B. grahamii is pathogenic for humans.
We report a case of endocarditis in a human infected with Bartonella vinsonii subsp. berkhoffii, which causes bacteremia and endocarditis in dogs. Bacterial identification was established by PCR amplification and sequencing of an intergenic spacer region (ITS1), 16S ribosomal DNA, and a gene encoding citrate synthase (gltA). Bartonella antibodies were detected by immunofluorescence.