Current knowledge of Bartonella species

Prevalencia de anticuerpos séricos frente a Bartonella spp. en una polación sana del área sur de la provincia de Sevilla

OBJECTIVE

To know the prevalence of serum antibodies against Bartonella spp. in a healthy population from south of Spain.

PATIENTS AND METHODS

A clinical-epidemiological survey was conducted among 146 healthy individuals. An indirect immunofluorescence commercial technique was used in a sample of serum from each individual to detect the present of IgG type serum antibodies against Bartonella spp., considering a result equal to or greater than 1:128 as positive.

RESULTS

Thirty six (24.7%) of all the subjects studied were asymptomatic carriers of antibodies against Bartonella spp. No crossed reactions against Chlamydia trachomatis, C. pneumoniae or Coxiella burnetti were observed. No significant association was found between the presence of seropositivity for Bartonella spp. and other factors.

CONCLUSION

There is an elevated frequency of asymptomatic carriers of antibodies against Bartonella spp. among the healthy population of our area. This suggests that most of the infections by Bartonella are subclinical.

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

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

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

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

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

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

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

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

In vitro model of Bartonella henselae-induced angiogenesis

Bartonella henselae is a gram-negative pathogen that causes angiogenesis. Here, I establish in vitro models to study Bartonella-induced blood vessel formation. I found that B. henselae induces long-term endothelial survival and tubular differentiation within type I collagen matrix.

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.

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.

Molecular Detection of Bartonella henselae DNA in the Dental Pulp of 800-Year-Old French Cats

Bartonella species are responsible for chronic bacteremia in domestic cats, which raises a question about the antiquity of the relationship between Bartonella species and cats that act as reservoirs for the organism. The sequencing of Bartonella pap31 and groEL genes from the dental pulp of cats dating from the 13th to 16th centuries identified the presence of B. henselae genotype Houston; the observation of a unique mutation in the results of PCR assays for Bartonella species ruled out modern DNA contamination of the dental pulp samples. We conclude that cats had bacteremia due to B. henselae 800 years ago.

Rapid detection and differentiation of Bartonella spp. by a single-run real-time PCR

A Real-time PCR for the identification and differentiation of Bartonella spp. based on the detection of mutations in an internal region of the gltA gene by thermal analysis was developed. The assay included a simultaneous detection of the amplicons by direct hybridization of LCRed and fluorescein-labelled probes coupled with melting curve analysis by the use of fluorescence resonance energy transfer technology. The protocol allowed establishing genospecie identity in less than 1 h without a need for restriction enzyme digestion or gel electrophoresis. The method is simple, reproducible, rapid, specific and potentially transferable to clinical samples.

Seroprevalence of and risk factors for Bartonella henselae and Bartonella quintana infections among pet cats in Jordan

To determine the seroprevalences of Bartonella henselae and Bartonella quintana antibodies in Jordanian pet cats, serum samples from 153 cats from three geographical regions were analyzed. Seroprevalences were determined by indirect immunofluorescence. The true seroprevalences to B. henselae and B. quintana were 32 and 1.5%, respectively. The seroprevalence of B. henselae-specific antibodies in cats from northern Jordan was significantly higher than in cats from the central or southern parts of Jordan. The seroprevalence to B. henselae increased to age 2 years. Odds of seropositivity were higher in cats living outdoors, showing hunting behavior, having a flea infestation and of a mixed breed. No association was detected with sex.

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

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

Predominant outer membrane antigens of Bartonella henselae

A hallmark of Bartonella henselae is persistent bacteremia in cats despite the presence of a vigorous host immune response. To understand better the long-term survival of B. henselae in cats, we examined the feline humoral immune response to B. henselae outer membrane (OM) proteins in naturally and experimentally infected cats. Initially, a panel of sera (n = 42) collected throughout North America from naturally infected cats was used to probe B. henselae total membranes to detect commonly recognized antigens. Twelve antigens reacted with sera from at least 85% of cats, and five were recognized by sera from all cats. To localize these antigens further, OMs were purified on discontinuous sucrose density step gradients. Each membrane fraction (OM, hybrid or inner membrane [IM]) contained less than 1% of the total malate dehydrogenase activity (soluble marker), indicating very little contamination by cytoplasmic proteins. FtsI, an integral IM cell division protein, was used to identify the low-density fraction (rho = 1.13 g/cm3) as putative IM (<5% of the total FtsI localized to the high-density fraction) while lipopolysaccharide (LPS) and Pap31, a homolog of the Bartonella quintana heme-binding protein A (HbpA), defined the high-density fraction (rho = 1.20 g/cm3) as putative OM. Additionally, little evidence of cross-contamination between the IM and OM was evident by two-dimensional gel electrophoresis. When purified OMs were probed with feline sera, antigenic proteins profiles were very similar to those observed with total membranes, indicating that many, but not all, of the immunoreactive proteins detected in the initial immunoblots were OM components. Interestingly, two-dimensional immunoblots indicated that B. henselae LPS and members of the Hbp family of proteins did not appear to stimulate an humoral response in any infected cats. Seven proteins were recognized by at least 70% of sera tested, but only three were recognized by all sera. Nanospray-tandem mass spectrometry was used to identify OM components, including the immunodominant OM proteins. Recognition of the nonimmunogenic nature of the major OM components, such as LPS, and identification of the predominant immunogens should elucidate the mechanisms by which B. henselae establishes persistent bacteremic infections within cats. Additionally, the common antigens may serve as potential feline vaccine candidates to eliminate the pathogen from its animal reservoir.

ECTOPARASITES OF GRAY SQUIRRELS IN TWO DIFFERENT HABITATS AND SCREENING OF SELECTED ECTOPARASITES FOR BARTONELLAE

Gray squirrels, Sciurus carolinensis, were livetrapped in 2 different habitat types, woodland (67 squirrels) and parkland (53 squirrels), in southeastern Georgia. Ectoparasites were recovered from anesthetized squirrels and compared between hosts from the 2 habitats. Because of the absence of low vegetation in parkland habitats, it was hypothesized that the ectoparasite fauna, especially ticks and chiggers, would be more diverse on woodland squirrels. The results were generally in agreement with this hypothesis. Seventeen species of ectoparasites were recovered from woodland squirrels, compared with 6 species from parkland squirrels. Five species of ticks and 3 species of chiggers parasitized the woodland squirrels compared with no ticks or chiggers on the parkland squirrels. Significantly higher infestation prevalences were recorded on woodland compared with parkland squirrels for the flea Orchopeas howardi, the tick Amblyomma americanum, and the mesostigmatid mite Androlaelaps fahrenholzi. The mean intensity for O. howardi also was significantly higher on woodland than on parkland squirrels. Because a new strain of Bartonella sp. was isolated recently from S. carolinensis in Georgia, selected ectoparasites from this study were screened for bartonellae by polymerase chain reaction (PCR). Some of the fleas and lice, but none of the mites tested, were PCR positive, suggesting that fleas, or lice, or both, might be vectors of bartonellae between squirrels. Six distinct strains of Bartonella sp. were detected, 2 in fleas and 4 in lice.

Bartonella and Coxiella antibodies in 334 prospectively studied episodes of infective endocarditis in Sweden

Bartonella spp. have been identified as aetiological agents in culture-negative infective endocarditis (IE). Coxiella burnetii may cause chronic Q-fever with endocarditis, 334 blood samples collected from 329 patients (334 episodes) with IE diagnosed between 1984 and 1996 in Göteborg, Sweden, were investigated for antibodies to Bartonella spp. and C. burnetii. 71 of the episodes (21%) were blood culture negative. A microimmunofluorescence assay revealed immunoglobulin G (IgG) antibodies to Bartonella in 13 of the culture verified episodes and in 2 of the culture-negative episodes. Three of the patients had IgG antibodies to > or = 200 in the blood culture-verified group, but none had a titre > or = 800, the cut-off level for Bartonella endocarditis. One patient had elevated antibodies to C. burnetii, diagnosing chronic Q-fever endocarditis. In conclusion, serologically verified Bartonella endocarditis is not prevalent in western Sweden and Q-fever endocarditis is rare.

Bartonella quintana lipopolysaccharide effects on leukocytes, CXC chemokines and apoptosis: a study on the human whole blood and a rat model

Bartonella quintana, an emerging gram-negative pathogen, may cause trench fever, endocarditis, cerebral abscess and bacillary angiomatosis usually with the absence of septic shock in humans. B. quintana lipopolysaccharide (LPS), a deep rough endotoxin with strong reactivity in the limulus amebocyte lysate (LAL)-assay, was studied in human whole blood and in a rat model. A significant (P<0.05) increase of interleukin-8 (IL-8) concentration, comparable to the level induced by enterobacterial LPS, was stimulated in the human whole blood by B. quintana LPS. Isolated human neutrophils delayed their apoptotic behavior in the presence of B. quintana LPS. In the rat, B. quintana LPS induced a significant (P<0.001) increase in white blood cell count, both 30 and 60 min after intravenous injection. Such leukocytosis was inhibited by pretreatment with prazosin, an alpha-adrenergic antagonist. B. quintana LPS did not significantly change heart rate (HR), hematocrit (HCT) and platelet count in the above reported in vivo model, and regarding mean blood pressure (MAP) only a very early (5 min after LPS) and mild (yet significant) hypotension was observed. In contrast, a long-lasting decrease of MAP was found in Salmonella minnesota R595 LPS-treated animals. Blood TNFalpha levels did not change significantly from the baseline in rats injected with either saline or with B. quintana LPS, on the contrary S. minnesota R595 LPS-injected animals showed substantial increase of TNFalpha levels up to 2924 pg/ml at 60 min after LPS injection. B. quintana LPS as well as Salmonella LPS-injected rats exhibited an increase of the blood levels of GRO/CINC-1, particularly at 240 min after LPS administration. Apical part of rat gut villi showed several TUNEL-positive cells in tissue sections from B. quintana LPS-treated animals. Taken together, our data demonstrates that B. quintana LPS is able to selectively stimulate some inflammatory mediators. B. quintana LPS-induced leukocytosis appears mediated by an alpha-adrenergic receptor. The delayed apoptotic process of leukocytes and the chemokine increase may explain the apoptotic cells found in the rat gut and the inflammatory reactions in some human Bartonella diseases. This peculiar inflammatory pattern induced by B. quintana LPS, may partially account for the lack of severe septic shock, observed in human B. quintana infections.

Occurrence of Bartonella henselae and Bartonella quintana in a healthy Greek population

The purpose of this study was to determine the prevalence of IgM and IgG antibodies against Bartonella henselae and B. quintana in a healthy Greek population using a commercially available immunofluorescent test (Focus test). Five hundred healthy individuals were divided by sex into four age groups and three groups according to contact with cats. IgM antibodies were not detected in any of the subjects examined, while 99 (19.8%) and 75 (15%) were IgG seropositive to B. henselae and to B. quintana, respectively. No statistical difference in the seropositivity was observed among these groups. The IgG antibody titers ranged from 1/64 to 1/256 for B. henselae and from 1/64 to 1/512 for B. quintana. A high percentage (12.4%) of cross-reactivity between the two species was observed. Our data show that the prevalence of both Bartonella species in Greece is high. However, low IgG antibody levels are not sufficient evidence of active infection.

Diagnostic methods. Current best practices and guidelines for identification of difficult-to-culture pathogens in infective endocarditis

IE is a serious, life-threatening disease. Because treatment must often be adapted to the pathogen involved, rapid identification of the etiologic agent is critical to successful management of each patient. When difficult-to-culture pathogens are involved, routine microbiologic tests, including blood culture, may remain negative. Because such cases may account for up to 31% of all IE cases, alternative diagnostic approaches are necessary. Among the etiologic agents of culture-negative endocarditis, C burnetii and Bartonella spp play a major role; each is responsible for up to 3% of episodes of IE. The authors therefore recommend the systematic use of specific serologies in all cases of clinically suspected endocarditis. The cross-reactivity between C burnetii, Bartonella spp, and Chlamydia spp is of diagnostic importance because all are potential etiologic agents of endocarditis. However, given that the levels of specific antibodies observed in Bartonella endocarditis are extremely high, low-level cross-reactions with other antigens should not lead to misdiagnosis, provided serology for all suspected agents is performed. When serologic test results are negative for both Bartonella spp and C burnetii, special staining by the Gram, Giemsa, Gimenez, PAS, Warthin-Starry, and Grocott methods may guide the use of new diagnostic tools such as PCR and tissue culture for isolation and identification of the causative agent. Such novel approaches may lead to more comprehensive patient evaluations and the discovery of new etiologic agents of IE.

Chlamydia pneumoniae, but not Bartonella quintana, is associated with coronary heart disease: results of a French case-control study

Serologic cross-reactivity has been demonstrated between Bartonella quintana and Chlamydia pneumoniae. Therefore, the association between antibodies to C. pneumoniae and coronary heart disease (CHD) as described in the literature may be due to antibodies cross-reacting with B. quintana. To investigate this hypothesis, we evaluated, in a case-control study, the prevalence of C. pneumoniae and B. quintana antibodies among 296 cases with angiographically significant artery lesions and 170 controls without angiographically demonstrable coronary artery disease. The prevalence of C. pneumoniae antibodies was higher among cases than among controls: 69% versus 49% (P < 0.001; OR 1.39; 95% CI (1.55; 3.52)). Multiple logistic regression demonstrated that C. pneumoniae seropositivity is an independent risk factor for CHD (adjusted OR 2.31; 95% CI (1.49; 3.60)). No statistically significant association was demonstrated between B. quintana seropositivity and CHD. Antibodies to both C. pneumoniae and B. quintana were found in nine subjects (seven cases and two controls), suggesting co-infection rather than cross-reactivity.

Infection and re-infection of domestic cats with various Bartonella species or types: B. henselae type I is protective against heterologous challenge with B. henselae type II

Four Bartonella species have been isolated from domestic cats, of which two serotypes/genotypes of Bartonella henselae and possibly B. clarridgeiae are human pathogens, causing cat scratch disease (CSD).Our objectives were to evaluate infection and potential cross-protection during re-infection in domestic cats with various Bartonella species or types.Thirty-six cats were primarily inoculated with B. henselae type I (n=16), B. henselae type II (n=10), B. clarridgeiae (n=6) or B. koehlerae (n=4). They were challenged with B. henselae type I (n=15), B. henselae type II (n=13) or B. clarridgeiae (n=8). All 36 cats became bacteremic (1.25x10(2)-1.44x10(6)CFU/ml) and bacteremia lasted from 37 to 582 days. Duration of bacteremia for cats inoculated with B. henselae type I was shorter than for cats inoculated with either B. henselae type II (P=0.025) or B. clarridgeiae (P=0.011). After challenge, 26 cats became bacteremic. Among the nine cats primarily inoculated with B. henselae type I and challenged with B. henselae type II, six cats stayed abacteremic. The three bacteremic cats had a transient low-level bacteremia. No bacteremia was observed in three cats primarily inoculated with B. henselae type I and challenged with another strain of B. henselae type I. Bacteremia levels in the 26 cats were significantly lower than for primary inoculation (P=0.022) and its duration was shorter (P=0.012). Among the eight cats challenged with B. clarridgeiae, duration of bacteremia in the four cats primarily inoculated with B. henselae type I was shorter than in the four cats primarily inoculated with B. henselae type II (P=0.01). Bartonella clarridgeiae inoculated cats were more likely to have relapses for both primary and secondary infections. This is the first demonstration of cross-protection, evidenced by absence of bacteremia, in cats primarily infected with B. henselae type I and challenged with B. henselae type II, whereas no cross-protection was previously shown for cats primarily infected with B. henselae type II and challenged with B. henselae type I. Such results are of major importance for future feline Bartonella vaccine development.

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.

Western immunoblotting for Bartonella endocarditis

To differentiate infectious endocarditis (IE) from other Bartonella infections and to identify infecting Bartonella bacteria at the species level on a serological basis, we used Western immunoblotting to test sera from 51 patients with Bartonella IE (of which 27 had previously benefited from species identification by molecular techniques), 11 patients with chronic Bartonella quintana bacteremia, and 10 patients with cat scratch disease. Patients with IE were Western blot positive in 49 of 51 cases, and significant cross-reactivity with three heterologous Bartonella antigens was found in 45 of 49 cases. Sera from bacteremic patients did not react with more than one heterologous antigen, and sera from patients with cat scratch disease gave negative results. Sera reacted only with B. henselae in four cases of IE, including one with a positive PCR result for valve tissue. Western blot and cross-adsorption performed on serum samples from patients with IE (the identity of the causative species having been determined by PCR) were demonstrated to identify efficiently the causative species in all cases. When applied to patients diagnosed on the basis of serological tests only, this technique allowed identification of the causative species in 20 of 22 cases. The results were in accordance with epidemiological features. Six reactive bands of B. quintana (of molecular sizes from 10 to 83 kDa) demonstrated significant association with sera from patients with B. quintana endocarditis. Overall, Western blotting and cross-adsorption made it possible to identify the causative species in 49 of 51 (96%) IE cases.

High rate of Bartonella henselae infection in HIV-positive outpatients in Johannesburg, South Africa

The emerging opportunistic pathogen Bartonella henselae has a wide range of clinical presentation, which includes, particularly, bacillary angiomatosis. This non-random pilot survey of outpatients attending HIV clinics in Johannesburg, South Africa, sampled 188 patients, in whom there was a 10% prevalence of Bartonella bacteraemia, as determined by nested polymerase chain reaction.

An uncommon presentation of Bartonella-associated neuroretinitis

BACKGROUND

This article documents a case of neuroretinitis initially presenting with ocular pain, 20/20 visual acuities, optic disc edema, and macular serous detachment without macular star formation in the absence of a history of exposure to pets or cats or symptoms suggestive of Bartonella infection. This initial clinical presentation appeared unilateral, but later became bilateral.

CASE REPORT

Physical and neuroophthalmologic consultation, neuroimaging studies, blood chemistry, and serologic analysis were requested. Positive serologic (IGG) titers to Bartonella henselae and Bartonella quintana were detected. Treatment was instituted initially with oral tetracycline (250 mg) qid and subsequently with doxycycline (100 mg) bid and prednisone (20 mg) qd.

CONCLUSION

Bartonella infection may cause optic disc edema and serous detachment without macular star formation. This presentation may occur without the generally characteristic signs and symptoms of Bartonella-associated neuroretinitis. A bilateral involvement may follow an initial unilateral presentation during the affliction period of this disorder.

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.

Lack of correlation between Bartonella DNA detection within fleas, serological results, and results of blood culture in a Bartonella-infected stray cat population

OBJECTIVE

To correlate the presence of different Bartonella species in the blood of a stray cat population trapped on a French military base with specific antibodies and species detected in cat fleas.

METHODS

The prevalence of Bartonella bacteremia was investigated in 61 cats by plating frozen whole blood on blood agar plates. Identification of isolates and detection of Bartonella DNA from cat flea batches from ten cats was achieved by PCR amplification and sequencing. Antibody detection was performed by microimmunofluorescence.

RESULTS

We obtained 38 isolates of Bartonella from blood. Sixteen were identified as B. clarridgeiae, 15 as B. henselae genotype/serotype Houston 1 (type I), and seven as B. henselae genotype/serotype Marseille (type II). B. henselae was detected in five fleas, and B. clarridgeiae in one flea. Sixty-one per cent of the cats had detectable antibodies against at least one species or serotype. Sixteen cats had antibodies against only one antigen. For each species, the distribution of bacteremia among the cats could not be correlated with either the distribution of infected fleas or the distribution of specific antibodies.

CONCLUSIONS

The lack of correlation between Bartonella DNA detection within fleas, serological results, and results of blood culture is probably due to a lack of natural heterologous protection between species or serotypes. Cats suffer bacteremia with three Bartonella species and should therefore be considered the reservoirs of at least three human pathogens.

Diagnostic methods current best practices and guidelines for identification of difficult-to-culture pathogens in infective endocarditis

Culture-negative endocarditis currently represents a diagnostic challenge for physicians. Traditional methods such as histology, serology, and culture have been improved and new molecular techniques have been developed to improve the detection of difficult-to-culture agents. Serologic tests for the two most frequent etiologic agents, Coxiella burnetii and Bartonella spp, should be performed first because they can usually be identified easily in this way. The sensitivity of culture for intracellular bacteria has been improved by inoculation of samples in shell vials and by the use of novel tissue cell lines. Recently, universal and species-specific primers have been designated to amplify bacterial DNA directly from resected valves, allowing positive identification.

Genotypic characteristics of two serotypes of Bartonella henselae

The study of 16S rRNA gene sequences of all isolates of Bartonella henselae obtained in our laboratory and others from human patients or cats has revealed two genotypes according to the sequence of the 16S rRNA gene. Two isolates of these genotypes have previously been related to two different serotypes, and lack of cross-protection of the two serotypes has been demonstrated in cats. We investigated the grouping of eight strains of B. henselae on the basis of 16S ribosomal DNA, 35-kDa protein, Pap 31 protein, and internal transcribed spacer (ITS) gene sequencing; sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles; and monoclonal antibody reactivity studies. Houston-1, 90-615, and SA2 strains showed the same patterns in SDS-PAGE, but they differed from the patterns of B. henselae isolates URBHLLY8, URBHLIE9, Cat6, Fizz, and CAL-1. Nine monoclonal antibodies derived from BALB/c mice immunized with B. henselae Houston-1 strain reacted only with strains Houston-1, 90-615, and SA2, and not with any other Bartonella strains. The two serogroups corresponded with two genotypes based on differences in the sequences of the genes encoding 16S rRNA, 35-kDa protein, and Pap 31 protein. Sequences of ITS genes were highly divergent among strains, as each had a unique sequence and the subdivision was not supported by DNA-DNA relatedness study. Study of 22 additional strains of B. henselae isolated from French bacteremic cats demonstrated that they all belong to one or the other of the proposed serotype or genotype.

Bartonella-associated endothelial proliferation depends on inhibition of apoptosis

Bartonella is a Gram-negative pathogen that is unique among bacteria in being able to induce angioproliferative lesions. Cultured human endothelial cells have provided an in vitro system in which to study the basis of angioproliferation. Previous studies have attributed the organism's ability to induce angioproliferative lesions to direct mitotic stimulation of endothelial cells by these bacteria. Here we show that Bartonella inhibits apoptosis of endothelial cells in vitro, and that its ability to stimulate proliferation of endothelial cells depends to a large extent on its antiapoptotic activity. Bartonella suppresses both early and late events in apoptosis, namely caspase activation and DNA fragmentation, respectively. Its ability to inhibit death of endothelial cells after serum starvation can be recapitulated by media conditioned by bacteria, indicating that direct cell contact is not necessary. Among tested strains, the activity is produced only by Bartonella species that are significant human pathogens and are associated with angioproliferative lesions. We suggest that endothelial cells normally respond to infection by undergoing apoptosis and that Bartonella evolved the antiapoptotic activity to enhance survival of the host cells and therefore itself. We propose that Bartonella's antiapoptotic mechanism accounts at least in part for its ability to induce vascular proliferation in vivo.

Unsuspected extralymphocutaneous dissemination in febrile cat scratch disease

Cat scratch disease (CSD) commonly manifests as regional self-limited lymphadenitis. However, dissemination of the infection to distant multiple sites may occur even in immunocompetent patients. We report a series of 11 children with fever and extralymphocutaneous manifestations of CSD, in order to highlight potential multiorgan involvement in patients with febrile CSD. To be eligible for enrollment, patients had to present with involvement of sites other than regional lymph nodes. The diagnosis was based on suggestive clinical criteria, histological findings and positive serology. The utilization of ultrasound imaging revealed hepatic lesions in 3 children and splenic lesions in 8 children, whereas osteolytic lesions were observed in 4 children by bone scan. Hepatic or splenic involvement was not suggested by clinical signs or biochemical investigation in 2/3 and 6/8 children, respectively. Bone involvement was supported either by relative symptoms or signs. Our findings indicate that, in the presence of fever, extralymphocutaneous manifestations have to be anticipated in patients with clinically suspected CSD. The systematic use of imaging modalities in patients with serologically documented Bartonella henselae infection could contribute to a better understanding of the clinical spectrum of CSD.

Immunopathology of Bartonella vinsonii (berkhoffii) in experimentally infected dogs

Following natural infection with Bartonella, dogs and humans develop comparable disease manifestations including endocarditis, peliosis hepatis, and granulomatous disease. As the immunologic response to infection in these hosts has not been clearly established, data presented here was derived from the experimental infection of six specific pathogen free (SPF) beagles with a known pathogenic strain of Bartonella. Six dogs were inoculated intravenously with 10(9)cfu of B. vinsonii ssp. berkhoffii and six control dogs were injected intravenously with an equivalent volume of sterile saline. Despite production of substantial levels of specific antibody, blood culture and molecular analyses indicated that Bartonella established chronic infection in these dogs. Flow cytometric analysis of monocytes indicated impaired bacterial phagocytosis during chronic Bartonella infection. There was also a sustained decrease in the percentage of CD8+ lymphocytes in the peripheral blood. Moreover, modulation of adhesion molecule expression (downregulation of L-selectin, VLA-4, and LFA-1) on CD8+ lymphocytes suggested quantitative and qualitative impairment of this cell subset in Bartonella-infected dogs. When compared with control dogs, flow cytometric analysis of lymph node (LN) cells from B. vinsonii infected dogs revealed an expanded population of CD4+ T cells with an apparent naïve phenotype (CD45RA+/CD62L+/CD49D(dim)). However, fewer B cells from infected dogs expressed cell-surface MHC II, implicating impaired antigen presentation to helper T cells within LN. Taken together, results from this study indicate that B. vinsonii establishes chronic infection in dogs which may result in immune suppression characterized by defects in monocytic phagocytosis, an impaired subset of CD8+ T lymphocytes, and impaired antigen presentation within LN.

Interaction of Bartonella henselae with the murine macrophage cell line J774: infection and proinflammatory response

Bartonella henselae is the causative agent of cat scratch disease (CSD), a self-limiting condition characterized by a subacute regional lymphadenopathy that may develop into disseminated bartonellosis in immunocompromised subjects. Mice experimentally infected with B. henselae display typical liver and spleen granulomas rich in T cells and macrophages. So far there are no data on the interaction between bartonellae and macrophages. In order to clarify this topic, we investigated the interaction of B. henselae with J774, a mouse macrophage cell line. Analysis of bacterial uptake by functional assays and transmission electron microscopy indicates that bartonellae can enter and survive inside J774. Entry occurred within 30 min postinfection and reached a plateau at 160 min. Infection of J774 was followed by a dose-dependent release of the proinflammatory cytokines tumor necrosis factor alpha, interleukin 1beta (IL-1beta), and IL-6. Bartonellae persisted intracellularly without loss of viability for at least 8 h, and their number slightly decreased 24 h postinfection. Gamma interferon (IFN-gamma) treatment of J774 significantly decreased the number of recoverable bacteria at 8 and 24 h. This enhancement of macrophage bactericidal activity was associated with nitric oxide (NO) release and was prevented by the addition of the competitive inhibitor of NO synthesis N(G)-monomethyl L-arginine. These findings suggest that IFN-gamma-mediated activation of macrophages may be important for the clearing of B. henselae infection and that anti-B. henselae microbicidal activity of IFN-gamma-activated macrophages is mediated to a large extent by NO production.

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.

Immunofluorescent detection of intraerythrocytic Bartonella henselae in naturally infected cats

To determine the presence of Bartonella henselae bacteremia in six cats, we compared isolation using blood culture with direct immunofluorescence on blood smears. Three cats that were positive by blood culture were also positive by direct immunofluorescence, and laser confocal microscopy confirmed the intraerythrocytic location of B. henselae.

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

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

Cat-scratch disease: considerations for dentistry

BACKGROUND

Cat-scratch disease, or CSD, results from inoculation of the gram-negative bacillus Bartonella henselae via a cat's scratch. A regional lymphadenitis, which usually is cervical, develops and may progress to suppuration. It is necessary to differentiate CSD from other lymphadenopathies.

CASE DESCRIPTION

A patient who had close contact with a cat subsequently developed a localized, suppurative cervical lymphadenitis. As B. henselae was identified in 1992, the authors were able to confirm the existence of CSD serologically. Surgical drainage resulted in a successful resolution of the disease process.

CLINICAL IMPLICATIONS

As patients with CSD may be seen in the dental office, an awareness of its symptomatology can prevent unnecessary dental intervention and facilitate early treatment.

Production of Bartonella genus-specific monoclonal antibodies

Monoclonal antibodies (MAbs) which react with heat-resistant proteins with molecular masses of 32 to 33 kDa of 14 different Bartonella species were produced. These antibodies did not react with antigens of 26 diverse bacterial strains by microimmunofluorescence assay except MAb B3D4, which reacted with Chlamydia psittaci and Chlamydia trachomatis at low titers. The identification of a common Bartonella antigenic protein will make it possible to later produce a diagnostic antigen by cloning and expressing it in Escherichia coli. Moreover, these MAbs allow all Bartonella species to be identified to the genus level.

Detection and culture of Bartonella quintana, Serratia marcescens, and Acinetobacter spp. from decontaminated human body lice

As part of a survey for trench fever among homeless people in Marseilles, France, we attempted isolation of Bartonella quintana from body lice. A decontamination protocol of immersion in 70% ethanol with 0.2% iodine was devised and was tested with a laboratory colony of body lice. Lice which had been experimentally contaminated with either Escherichia coli, Staphylococcus epidermidis, or Acinetobacter spp. were successfully decontaminated, and this process did not prevent the culture of B. quintana from these lice. One hundred sixty-one lice obtained from homeless patients were studied by the protocol. B. quintana was isolated on axenic medium from 15 of 161 body lice and was detected in 41 of 161 lice by PCR. Acinetobacter spp. and Serratia marcescens were also isolated from body lice. The sensitivities of PCR and culture of B. quintana were 98 and 36%, respectively. These procedures may be useful for epidemiologic studies of trench fever and for the recovery of strains for characterization and comparison.

Passive antibody to Bartonella henselae protects against clinical disease following homologous challenge but does not prevent bacteremia in cats

We challenged cats transfused with anti-Bartonella serum and kittens born to antibody-positive queens with Bartonella henselae to determine the contribution of antibodies to the control of B. henselae in cats. In both experiments, antibody-positive cats were protected from clinical disease but passive antibody to the homologous strain of B. henselae did not prevent bacteremia.

Endocarditis due to rare and fastidious bacteria

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

A flea-associated Rickettsia pathogenic for humans

A rickettsia named the ELB agent, or "Rickettsia felis," was identified by molecular biology techniques in American fleas in 1990 and later in four patients from Texas and Mexico. We attempted to isolate this rickettsia from infected fleas at various temperatures and conditions. A representative isolate of the ELB agent, the Marseille strain, was characterized and used to develop a microimmunofluorescence test that detected reactive antibodies in human sera. The ELB agent was isolated from 19 of 20 groups of polymerase chain reaction-proven infected fleas. The microimmunofluorescence results provided serologic evidence of infection by the ELB agent in four patients with fever and rash in France (2) and Brazil (2), supporting the pathogenic role of this rickettsia. Our successful isolation of this rickettsia makes it available for use in serologic tests to determine its clinical spectrum, prevalence, and distribution.

Bartonella henselae associated uveitis and HLA-B27

AIM

To investigate the frequency of HLA-B27 in patients with presumed Bartonella henselae associated uveitis and to describe the clinical characteristics of HLA-B27 positive patients with uveitis and presumed ocular bartonellosis (POB).

METHODS

The diagnosis of POB was considered in 19 patients with unexplained uveitis (except for the HLA-B27 association) and high positive IgG (titre >/=1:900) and/or IgM (titre >/=1:250) antibodies against B henselae. In addition to B henselae serology and HLA-B27 typing, all patients underwent an extensive standard diagnostic screening procedure for uveitis and in all cases the results were within the normal limits. The control group consisted of 25 consecutive patients with panuveitis and negative B henselae serology.

RESULTS

HLA-B27 was positive in six of the 19 patients (32%) with POB in contrast to the 4% frequency of HLA-B27 in the control group (p=0.03) and 8% prevalence of HLA-B27 in the Dutch population (p=0.003). At the time of positive Bartonella serological testing five of six HLA-B27 positive patients with POB had severe posterior segment involvement with papillitis, macular oedema, and vitreitis. The duration of intraocular inflammatory activity was more than 6 months in five HLA-B27 positive patients. Although four of the six HLA-B27 positive patients had previous recurrent attacks of acute anterior uveitis, the clinical presentation at the time of positive Bartonella serology differed, as illustrated by the involvement of the posterior segment and chronic course of the ocular disease.

CONCLUSIONS

The frequency of HLA-B27 in patients with uveitis and serological characteristics of acute infection with B henselae is higher than in the general Dutch population. The findings of this study also suggest a relation between infection with Bartonella species and HLA-B27.