Serology to Bartonella (Rochalimaea) henselae may replace traditional diagnostic criteria for cat-scratch disease

Serological and Molecular Detection of Bartonella henselae in Cats and Humans From Egypt: Current Status and Zoonotic Implications

Bartonellosis is a vector-borne zoonotic disease caused by the intracellular bacterium of genus Bartonella. The disease has a worldwide distribution and cats represent the major reservoir of this disease. Despite its global distribution, very limited previous studies have investigated the occurrence of bartonellosis in cats and their owners in Egypt. In an endeavor to explore this topic, we investigated the occurrence of Bartonella henselae (B. henselae) infection in 225 samples (blood, saliva, and claw) obtained from 75 healthy cats in Upper Egypt. These samples were routinely obtained during veterinary clinic visits. This study also involved an examination of 100 humans, including cat owners and people with a history of contact with cats. Attempted isolation and identification of B. henselae in cats were also performed. Furthermore, PCR was performed for molecular identification of B. henselae in blood samples from cats. Meanwhile, an immunofluorescent assay was performed to study the seroprevalence of B. henselae infection in humans. In this study, B. henselae could not be isolated from any of the examined blood, saliva, or claw samples from cats. Interestingly, B. henselae was identified molecularly in 8% (6/75) of blood samples from cats. The seroprevalence of B. henselae in humans was 46% and its occurrence was higher in females (46.6%) than in males (41.7%) (P = 0.748). B. henselae infection was higher among cat owners [51.4% (19/37)] than among people with a history of contact with cats [42.9% (27/63)] (P = 0.410). Infection was higher in rural regions [79.5% (31/39)] than in urban regions [24.6% (15/61)] (P < 0.001). Collectively, this data provide interesting baseline information about the occurrence of B. henselae in cats and humans in Upper Egypt, which reflects the potential zoonotic transmission of this bacterium. Future study is mandatory to explore the occurrence of B. henselae in major reservoirs in Egypt.

Pediatric Bartonella henselae Infection: The Role of Serologic Diagnosis and a Proposed Clinical Approach for Suspected Acute Disease in the Immunocompetent Child

BACKGROUND

Bartonella henselae serology is commonly used to diagnose cat-scratch disease (CSD). Titers above a threshold for positivity suggest either a recent or remote infection. Recent infection can be confirmed by a 4-fold rise in the convalescent titer in some cases. Many atypical presentations attributed to CSD utilize a low threshold for positivity without supportive evidence from convalescent sera or supplemental testing, raising a concern for the overdiagnosis of CSD.

METHODS

We conducted a retrospective chart review of immunocompetent pediatric patients at the Hospital for Sick Children, Toronto, spanning an 11-year period. A total of 154 cases were included with serologic titers ≥1:128. These were divided into 3 groups: group 1 = 1:128, group 2 = 1:256, and group 3 ≥ 1:512. Cases within groups were evaluated with respect to cat contact, clinical presentation, further testing, and final diagnosis.

RESULTS

One-third of patients with a titer of 1:128 had an alternative diagnosis. Most cases with a titer of 1:128 or 1:256 did not have convalescent serologic testing performed. Within these 2 groups, only 1 case had a 4-fold rise in the convalescent titer. A trend of decreasing number of cases with alternative diagnoses (P = 0.03) and increasing number of cases presenting with regional lymphadenopathy (P = 0.07) was associated with higher titers in group 3 compared with group 1.

CONCLUSION

Concerns about the serologic diagnosis of CSD include the use of low titers for positivity, incomplete diagnostic evaluation, and the lack of convalescent serologic testing. We propose a clinical guide to assist in managing suspected cases of CSD.

Combining cytomorphology and serology for the diagnosis of cat scratch disease

Cat scratch disease (CSD) is a self limited zoonotic disease that presents most commonly as a regional lymphadenopathy. We are reporting a case of a 25-year-old male patient who presented with fever and large right inguinal lymphadenopathy. The diagnosis of cat scratch disease was confirmed based on the characteristic cytopathological features on aspirate smears from the lymph node and the serological titers for Bartonella henselae. This case report emphasizes the importance of combining Bartonella serology, and cytopathology in the diagnostic work-up of febrile lymphadenopathy and suspected CSD since the culture of this organism is arduous.

Serological evidence for the association of Bartonella henselae infection with arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an important cause of sudden death in young adults. On the basis of histopathological findings its pathogenesis may involve both a genetic origin and an inflammatory process. Bartonella henselae may cause endomyocarditis and was detected in myocardium from a young male who succumbed to sudden cardiac death.

HYPOTHESIS

We hypothesized that chronic infection with Bartonella henselae could contribute to the pathogenesis of ARVC.

METHODS

We investigated sera from 49 patients with ARVC for IgG antibodies to Bartonella henselae. In this study, 58 Swiss blood donors tested by the same method served as controls.

RESULTS

Six patients with ARVC (12%) had positive (>1:256) IgG titres in the immunofluorescence test with Bartonella henselae. In contrast, only 1 elevated titre was found in 58 controls (p < or = 0.05). Interestingly, all patients with increased titres had no familial occurrence of ARVC.

CONCLUSIONS

Further studies in larger patient cohorts seem justified to investigate a possible causal link between chronic Bartonella henselae and ARVC, in particular its sporadic (nonfamilial) form.

Disseminated cat scratch disease with vertebral osteomyelitis and epidural abscess

A 5-year-old boy with cat scratch disease presented with fever of unknown origin and osteomyelitis of the thoracic spine and epidural abscess. He did not have localizing signs or symptoms. Computed tomography of the abdomen, which was initially negative, showed hepatosplenic disease. Cat scratch disease has variable systemic presentations and should be included in the differential diagnosis of fever of unknown origin if an epidemiologic risk factor is present.

Systemic Cat Scratch Disease

Systemic cat scratch disease (CSD) is often associated with prolonged fever and microabscesses in the liver and/or spleen. We report a case of systemic CSD with hepatic, splenic and renal involvement in an aboriginal child in Taiwan. A previously healthy 9-year-old girl had an intermittent fever for about 17 days, and complained of abdominal pain, headache and weight loss. Abdominal computed tomography showed multiple tiny hypodense nodular lesions in the spleen and both kidneys. Laparotomy revealed multiple soft, whitish-tan lesions on the surface of the liver and spleen. Histopathologic examination of a biopsy specimen of the spleen showed necrotizing granulomatous inflammation with central necrosis surrounded by epithelioid cells and occasional Langhans' giant cells, strongly suggestive of Bartonella henselae infection. History revealed close contact with a cat. B. henselae DNA was detected by polymerase chain reaction in the tissue specimen, and the single antibody titer against B. henselae was greater than 1:2048. These results confirmed the diagnosis of visceral CSD caused by B. henselae. The patient's symptoms resolved after treatment with rifampin and tetracycline. This case illustrates the need for inclusion of systemic CSD in patients with fever of unknown origin and abdominal pain.

The Expanded Spectrum of Bartonellosis in Children

Bartonella spp cause various clinical syndromes immunocompetent and immunocompromised hosts. Domestic cats are the natural reservoir, and vectors of B henselae. B henselae infection usually occurs early in childhood, is generally asymptomatic, and in most cases revolves spontaneously. It may, however, produce a wide spectrum of clinical symptoms, the most frequent feature being cat-scratch disease. Disseminated atypical B. henselae infection may follow cat-scratch disease alter a symptom-free period or may present de novo mimicking a wide range of clinical disorders. A careful clinical history researching an intimate contact with a kitten associated with a specific serology and an abdominal ultrasound for typical hepatosplenic involvement may follow a rapid and accurate diagnosis.

High prevalence of antibodies to Bartonella henselae among Italian children without evidence of cat scratch disease

Few data are available on the seroprevalence of antibodies to Bartonella henselae among children. We retrospectively evaluated the presence of immunoglobulin G and M class antibodies to B. henselae in 508 children living in central Italy who were apparently free of any features suggesting B. henselae infection. We found that B. henselae infection is common among children in central Italy, occurs early in life, is in most cases asymptomatic, and resolves spontaneously.

Cat scratch disease simulating a malignant process of the chest wall with coexistent osteomyelitis

A 6-y-old girl developed fever, soft-tissue mass in the right chest wall, osteomyelitis of the 10th rib and hepatic granuloma. Cat scratch disease was diagnosed by histological examination of the mass and serological tests. The patient was treated successfully with antibiotics and recovered completely, as shown by a 10 month follow-up.

Six cases of Lactobacillus bacteraemia: identification of organisms and antibiotic susceptibility and therapy

Six cases of bacteraemia in hospitalized patients, 5 with a depressed immune status, were caused by lactobacilli. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell proteins and API 50 CH carbohydrate patterns assigned the causative agents to the species Lactobacillus rhamnosus, Lactobacillus curvatus, Lactobacillus delbrueckii subsp. lactis and Lactobacillus paracasei subsp. paracasei.

Serological investigation of Bartonella henselae infections in clinically cat-scratch disease-suspected patients, patients with cardiovascular diseases, and healthy veterinary students in Japan

Seroprevalence of Bartonella henselae was investigated in Japan in 48 individuals clinically suspected of having cat-scratch disease (CSD), 159 patients with cardiovascular diseases, and 129 healthy veterinary students. Of 48 CSD-suspected patients examined, 19 (39.6%) were positive for B. henselae-IgG and 4 (8.3%) for B. henselae-IgM. Of 159 patients with cardiovascular diseases, 5 (3.1%) were positive for B. henselae-IgG. In healthy veterinary students, 14 of 129 (10.9%) were positive for B. henselae-IgG and 1 (0.8%) for B. henselae-IgM. The positive rates of B. henselae-IgG and -IgM in CSD-suspected patients were significantly higher than in other sources. Most CSD-suspected and healthy individuals who were positive for B. henselae antibody had had some contacts with cats. In CSD-suspected patients, the B. henselae positive rate in females was significantly higher than in males, and high seropositive rates to B. henselae were found in younger age groups.

Laboratory diagnosis of Bartonella infections

Bartonella species are pathogens of emerging and reemerging significance, causing a wide array of clinical syndromes. In North America and Europe, they are increasingly recognized as a cause of culture negative endocarditis, neuroretinitis, and disease among homeless, HIV-infected, and other immunosuppressed individuals. In South America, bartonellosis continues to plague those in endemic regions and poses a significant threat to travelers in these areas. As the clinician is increasingly faced with these illnesses, which may be difficult to diagnose, laboratory techniques to confirm or refute the diagnosis are becoming increasingly important. Culture methods have improved over the past decade demonstrating increased sensitivity, but still require prolonged periods before isolation of the organism. Specimen handling, media selection, and growth conditions all may affect results and must be optimized in order to provide the highest likelihood of recovering the organism. Pure culture of the bacteria not only provides morphologic information, but also provides material for further diagnostic testing. Work with liquid media, which may provide a more rapid means of cultivation has shown some promise and should continue to be pursued. Improved blood culture techniques were a primary factor in the discovery of Bartonella endocarditis and continued improvements will likely demonstrate further clinical insights. Serologic testing for B henselae infections has become the cornerstone of clinical diagnosis, replacing the skin test that was poorly standardized and posed a potential risk to the patient. Immunofluorescence assays have been well characterized and validated in clinical trials, however they are not universally available. Vero cell cocultivated antigens appear to provide higher sensitivity and specificity when compared with agar-derived antigens. IFA assays are inherently difficult to perform, requiring significant expertise to provide reproducible results. On the contrary, enzyme immunoassays offer ease of use and a high level of reproducibility, however ideal antigens for use in the diagnosis of Bartonella infections have not been clearly identified. Continued work to define antigenic targets of the human response to infection and incorporation of these into a widely available EIA will provide a cost-effective tool for the clinician and epidemiologist alike. Due to the close phylogenetic relationship of B henselae and B quintana, differentiation between these species by serologic means may prove difficult. Molecular techniques including PCR offer high sensitivity and specificity, rapid availability of information, and the ability to differentiate Bartonella organisms at the highest level. Results of studies to date are promising and as methods are refined it will be important to conduct clinical studies to define the role of these assays. In disseminated Bartonella infections such as bacillary angiomatosis, peliosis, endocarditis, and urban trench fever, PCR currently offers the ability to establish the diagnosis when other tests may be unrevealing. For CSD, this technique should be used as a confirmatory technique when the diagnosis is unclear by other means. PCR analysis of blood specimens offers a minimally invasive approach to diagnosis, but clinical data are scarce and further studies are needed. As DNA microarrays move into the clinical arena, specific hybridization probes may allow improved identification and differentiation of Bartonellae at the molecular level.

Comparison of in-house and commercial slides for detection by immunofluorescence of immunoglobulins G and M against Bartonella henselae and Bartonella quintana

We compared the sensitivities and specificities of indirect fluorescent antibody tests developed in our laboratory and commercially available from Focus Technologies (FT; formerly MRL Diagnostic) for detection of serum antibodies to Bartonella spp. Serum samples tested were from patients with culture- or PCR-confirmed Bartonella quintana or B. henselae infections causing cat scratch disease (CSD), chronic bacteremia, or endocarditis. At a cutoff titer of 64, the FT test had higher sensitivity than our in-house test in detecting anti-B. henselae immunoglobulin G (IgG) antibodies in CSD patients (91.2 versus 52.9%; P < 0.001). The specificity in serum samples from 85 control patients was, however, lower with the FT test (87%) than with the in-house test (98.8%) (P = 0.002). A cutoff titer of 128 improves the specificity for the FT test but lowers the sensitivity to 85%. For patients infected with B. henselae, our in-house test, but not the FT test, enabled endocarditis to be detected more reliably. With the in-house test, titers of IgG against B. henselae of >/=1,024 were found only in endocarditis patients and not in CSD patients. With the FT test, 19.1% of CSD patients had titers of IgG against B. henselae of >/=1,024 (P < 0.001). Our in-house technique also improved detection of anti-B. quintana antibodies in homeless patients with endocarditis. IgG titers of >/=1,024 were present in 75% of serum samples, but only in 16.7% of serum samples with the FT test (P = 0.004). Since each test has advantages over the other, the serological diagnosis of Bartonella infections would benefit if both tests were used concurrently.

Positive polymerase chain reaction and histology with borderline serology in Parinaud's oculoglandular syndrome

PURPOSE

To report a case of Parinaud's oculoglandular syndrome (POS) in which, despite a borderline serology, polymerase chain reaction (PCR) testing for a conjunctival biopsy was positive for Bartonella henselae, a source of cat-scratch disease. A Steiner silver stain demonstrated the organism.

METHODS

Case Report.

RESULTS

A 65-year-old man was seen for a foreign body in his left eye (OS) associated with chemosis and a preauricular node.

CONCLUSION

B. henselae is a known cause of POS. This gram-negative pleomorphic rod has been more frequently discovered in connection with this syndrome due to improved diagnostic testing such as indirect immunofluorescence antibody and PCR testing. Frequently, serology is positive if the organism is present. This report describes a patient with clinical findings of POS who, despite borderline serology, had pleomorphic rods on Steiner silver stain and positive PCR testing compatible with Bartonella henselae.

Enzyme immunoassay for the diagnosis of cat-scratch disease defined by polymerase chain reaction

Whole-cell immunofluorescent antibody (IFA) tests for detection of anti-Bartonella henselae immunoglobulin (Ig) G are commonly used to diagnose cat-scratch disease (CSD). The need to cultivate B. henselae in Vero cells for antigen preparation and the absence of routinely applied IFA assays for IgM constitute the major disadvantages of this form of test. We describe the results of an enzyme immunoassay (EIA) for IgM and IgG that used N-lauroyl-sarcosine-insoluble outer membrane antigens from agar-grown B. henselae performed in 84 patients with definite CSD (regional lymphadenitis, cat contact, and > or =1 confirmatory test: polymerase chain reaction, skin test, or B. henselae culture). Although this method has been used as a diagnostic tool in several case reports, it has not previously been evaluated in a large study of definitively proven CSD cases. Results of this study indicate that the EIA described herein can play an important role in the serodiagnosis of CSD, although improvement of the sensitivity, particularly that of the IgM, would be desirable.

Pseudoinfectious mononucleosis: a presentation of Bartonella henselae infection

Six children presented during one year with clinical features of infectious mononucleosis, but with laboratory findings of leucocytosis with neutrophilia, increased erythrocyte sedimentation rate, and hypergammaglobulinaemia. Serology for Epstein-Barr virus, cytomegalovirus, adenovirus, and Toxoplasma gondii was negative, while anti-Bartonella henselae IgM with high IgG titre (>/=1/1024) was present in all. All children had contact with kittens. No specific treatment was administered and all recovered.

Cat scratch disease in 2 siblings presenting as acute gastroenteritis

The cases of 2 siblings with cat scratch disease are described who presented with symptoms suggestive of acute febrile gastroenteritis. The first patient, a 7.5-y-old girl, developed mesenteric lymphadenitis, hepatosplenic granulomas and osteolytic bone lesions only late in the course of her protracted illness. Her 3-y-old brother had a shorter, self-limited illness without complications. Cat scratch disease is often unrecognized and the full spectrum of its clinical manifestations remains to be investigated.

Portal vein and bone involvement in disseminated cat-scratch disease: report of 2 cases

Cat-scratch disease (CSD) is a common cause of regional lymphadenopathy. We describe 2 children with an unusual presentation of disseminated CSD, the first one presenting with persistent fever, multilocular abscesses in liver and spleen as well as osteolytic lesions in the lumbar spine and the second one with portal vein thrombosis and severe ascites.

Molecular analysis of riboflavin synthesis genes in Bartonella henselae and use of the ribC gene for differentiation of Bartonella species by PCR

The biosynthesis pathway for riboflavin (vitamin B(2)), the precursor of the essential cofactors flavin mononucleotide and flavin adenine dinucleotide, is present in bacteria and plants but is absent in vertebrates. Due to their conservation in bacterial species and their absence in humans, the riboflavin synthesis genes should be well suited either for detection of bacterial DNA in human specimens or for the differentiation of pathogenic bacteria by molecular techniques. A DNA fragment carrying the genes ribD, ribC, and ribE, which encode homologues of riboflavin deaminase (RibD) and subunits of riboflavin synthetase (RibC and RibE), respectively, was isolated from a plasmid-based DNA library of the human pathogen Bartonella henselae by complementation of a ribC mutation in Escherichia coli. Sequence analysis of the ribC gene region in strains of B. henselae, which were previously shown to be genetically different, revealed that the ribC gene is highly conserved at the species level. PCR amplification with primers derived from the ribC locus of B. henselae was used to isolate the corresponding DNA regions in B. bacilliformis, B. clarridgeiae, and B. quintana. Sequence analysis indicated that the riboflavin synthesis genes are conserved and show the same operon-like genetic organization in all four Bartonella species. Primer oligonucleotides designed on the basis of localized differences within the ribC DNA region were successfully used to develop species-specific PCR assays for the differentiation of B. henselae, B. clarridgeiae, B. quintana, and B. bacilliformis. The results obtained indicate that the riboflavin synthesis genes are excellent targets for PCR-directed differentiation of these emerging pathogens. The PCR assays developed should increase our diagnostic potential to differentiate Bartonella species, especially B. henselae and the newly recognized species B. clarridgeiae.

Systemic Bartonella henselae infection with hepatosplenic involvement

BACKGROUND

Systemic manifestations of Bartonella henselae infection are rare in the immunocompetent host. The infection generally has initial symptoms of prolonged fever and multiple granulomatous lesions in liver and spleen.

METHODS

Retrospective analysis of the records of all patients with hypoechogenic lesions in the liver and/or spleen diagnosed from 1990 through 1996 in three pediatric clinics in northern Italy.

RESULTS

Among the 13 patients reviewed, 9 had evidence of B. henselae infection and hepatosplenic involvement: five had prolonged and unexplained fever lasting from 3 to 16 weeks, and four had typical cat-scratch disease and peripheral lymphadenitis. All patients had increased sedimentation rate and normal aminotransferase serum activity. Five children had a liver biopsy, by laparotomy in three and by needle in two. In all, the predominant liver lesion was a necrotizing granuloma. All patients were treated with broad-spectrum antibiotics. Fever lasted from 3 to 16 weeks, and hepatic and splenic lesions resolved in all with residual splenic calcification in one.

CONCLUSIONS

Systemic B. henselae infection represents an important cause of inflammatory hypoechogenic hepatosplenic lesions in children. Serology provides rapid diagnosis, avoiding multiple and invasive investigations. Hepatosplenic involvement can be found even in children with typical cat-scratch disease without apparent systemic manifestations. The frequency of liver and/or splenic involvement in cat-scratch disease is probably underestimated.

Prevalence of antibodies to Bartonella henselae in patients with suspected cat scratch disease (CSD) in Italy

Cat scratch disease (CSD) is a relatively new diagnosed illness with clinical signs of self-limiting regional lymphadenopathy accompanied by symptoms of fever and malaise, to encephalopathy and neuropathy, occurring after a cat scratch or flea bite. Bartonella henselae is now accepted as the etiologic agent of CSD. From January 1994 to September 1998, 412 patients were evaluated for suspect CSD in Italy. Sera were tested for antibodies to B. henselae by a commercially available indirect immunofluorescent assay (IFA), based on B. henselae-infected Vero-cells as the antigen substrate. Of the 412 patients, 26 (6.3%) were considered positive having titers of immunoglobulin G (IgG) to B. henselae of 64 or higher. In these patients CSD was indeed confirmed by either histopathologic examination of lymph nodes biopsy or fourfold raise in antibody titers. Nevertheless, sera were tested by IFA for Afipia felis and one showed a double reactivity to B. henselae and A. felis. Finally, three sera, negative to B. henselae serology, were positive to A. felis. Three hundred and eighty-six patients received alternative diagnoses. One hundred and twenty-five serum samples from control subjects were negative by IFA for either B. henselae or A. felis. Moreover, a cross-reactivity with sera from patients affected by other diseases was not observed. Our study shows that the ascertained cases of CSD are etiologically determined by B. henselae, IFA assay is confirmed as a useful tool in the laboratory diagnosis and, over a 5 years period of study, the incidence of CSD in Italy has been low.

Detection of Bartonella henselae DNA by two different PCR assays and determination of the genotypes of strains involved in histologically defined cat scratch disease

Cat scratch disease (CSD) is a common cause of subacute regional lymphadenopathy, not only in children but also in adults. Serological and molecular studies demonstrated that Bartonella henselae is the etiologic agent in most cases of CSD. Amplification of B. henselae DNA in affected tissue and detection of antibodies to B. henselae are the two mainstays in the laboratory diagnosis of CSD. We designed a retrospective study and investigated formalin-fixed, paraffin-embedded lymph nodes from 60 patients (25 female, 35 male) with histologically suspected CSD by PCR amplification. The sensitivities of two different PCR assays were compared. The first primer pair amplified a 296-bp fragment of the 16S rRNA gene in 36 of the 60 samples, corresponding to a sensitivity of 60%. The second primer pair amplified a 414-bp fragment of the htrA gene in 26 of the 60 lymph nodes, corresponding to a sensitivity of 43.3%. Bartonella DNA could be detected in a total of 39 (65%) of the 60 lymph nodes investigated. However, histopathologic findings are typical but not specific for CSD and cannot be considered as a "gold standard" for diagnosis of CSD. The sensitivity of the PCR assays increased from 65 to 87% if two criteria (histology and serology) were used in combination for diagnosis of CSD. Two genotypes (I and II) of B. henselae are described as being involved in CSD. Genotype I was found in 23 (59%) and genotype II was found in 9 (23%) of the 39 PCR-positive lymph nodes. Seven (18%) lymph nodes were negative in both type-specific PCR assays. Thirty (50%) of our 60 patients were younger than 20 years old (15 were younger than 10 years), 20 (33%) were between 21 and 40 years old, and 10 (17%) patients were between 41 and 84 years old. Our data suggest that detection of Bartonella DNA in patients' samples might confirm the histologically suspected diagnosis of CSD.

Two different genotypes of Bartonella henselae in children with cat-scratch disease and their pet cats

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.

Cat scratch disease: the rare role of Afipia felis

Since its isolation in 1988, Afipia felis has been associated with cat scratch disease (CSD) in only one report and its role in CSD has been questioned. We have cultured A. felis from a lymph node of a patient with CSD. 16S rRNA gene sequencing, DNA relatedness studies, fatty acid analysis, and PCR of the A. felis ferredoxin gene showed that the isolate is identical to the previously reported A. felis isolate. To determine the role of A. felis in CSD, PCR of the 16S rRNA gene followed by hybridizations with specific probes were performed with lymph node specimens from CSD patients. All 32 specimens tested positive for Bartonella henselae and negative for A. felis. We conclude that A. felis is a rare cause of CSD. Diagnostic tests not conducive to the identification of A. felis might cause the diagnosis of CSD due to A. felis to be missed.

Seroprevalence of antibodies to Bartonella henselae in patients with cat scratch disease and in healthy controls: evaluation and comparison of two commercial serological tests

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.

Evaluation of commercial slides for detection of immunoglobulin G against Bartonella henselae by indirect immunofluorescence

Four commercial slides were compared with in-house slides for the detection of immunoglobulin G (IgG) against Bartonella henselae in 58 healthy persons from a rural region by an indirect immunofluorescence assay. MRL-BA slides (MRL Diagnostics, USA) and Virion slides (Virion, Switzerland) with agar-derived Bartonella henselae showed IgG titers of > or = 1:256 in 44.8% and 51.7%, respectively, whereas Bion slides (Bios, Germany), MRL-Vero slides (MRL Diagnostics), and in-house slides with cell-associated Bartonella henselae showed such titers in 3.4%, 5.1% and 3.4%, respectively. The MRL-Vero slides (Bartonella IgG substrate slides, MRL Diagnostics) were further evaluated with 26 patients with cat scratch disease, 20 patients with lymphadenopathy not due to cat scratch disease, 100 blood donors from an urban area, and 120 blood donors from a mixed urban/rural area. In our mixed urban/rural population the IgG titer of 1:256 had a sensitivity of 84.6% and a specificity of 93.4% for the serodiagnosis of cat scratch disease. Seroprevalence was higher in blood donors from the mixed area (50.8%) than from the urban area (37%). MRL-Vero slides were considered useful for the serodiagnosis of cat scratch disease by indirect immunofluorescence and have replaced our in-house system. However, patients with low IgG titers should be retested three to four weeks after initial sampling to demonstrate a possible rise of IgG titers in paired sera.

Pitfalls and fallacies of cat scratch disease serology: evaluation of Bartonella henselae-based indirect fluorescence assay and enzyme-linked immunoassay

The diagnostic value of the detection of immunoglobulin G (IgG) and IgM by Bartonella henselae-based indirect fluorescence assay (IFA) and enzyme-linked immunoassay (EIA) for the diagnosis of cat scratch disease (CSD) was evaluated. The IFA was performed either with B. henselae that was cocultivated for a few hours with Vero cells or with noncocultivated B. henselae as the antigen. Additionally, the performance of a Bartonella PCR hybridization assay based on the 16S rRNA gene was determined and compared with those of the serologic assays. The study group consisted of 45 patients suspected of suffering from CSD by fulfilling one or more of the classical criteria. The specificities of the immunoassays were set at > or = 95% by analysis of sera from 60 healthy blood donors. It is shown that the sensitivities of the IgG assays are very low (40.9% for the IFA with noncocultivated B. henselae as antigen) and that those of the IgM assays are higher (71.4% for the EIA) for patients who fulfilled two or more criteria for CSD. The IgM EIA showed the highest sensitivity: 71.4% in patients with two or more criteria for CSD and 80.6% for patients with a positive Bartonella PCR result. The results indicate that the specificities of both IFA and EIA IgG serologies and the sensitivity of the IFA IgM serology need to be improved. The PCR hybridization assay showed a sensitivity of 86.4% for patients who fulfilled two or more criteria for CSD and 100% for seven patients who fulfilled three or more criteria. The kinetics of IgG and IgM antibody production were studied in 18 patients with CSD on the basis of a positive B. henselae IFA IgM serology. The results indicate that there is no standard course of anti-B. henselae IgG and IgM production in patients with CSD, because some patients produced high levels of both IgG and IgM, others produced only high levels of IgM, and a few patients produced only low levels of antibodies.

The expanding spectrum of Bartonella infections: II. Cat-scratch disease

Recent advancements and developments in molecular biotechnology have allowed more precise reclassification of many microorganisms. With the use of these new taxonomy tools, several organisms previously thought to belong to other genera have been recently described as bartonellae. Of the 11 organisms now described as Bartonella spp., only four have been shown to be pathogenic for humans. Table 1 lists the four Bartonella human pathogens along with the their known epidemiology and the scope and range of disease associated with each. All are now considered to be bacteria and can be grown on blood-enriched agar although primary isolation in some may best be achieved in cell tissue culture. B. bacilliformis infection is limited to certain geographic regions in South America where the only human reservoir and the sandfly vector(s) that spreads the disease reside together. Specific antibiotic treatment is dramatically effective in treating the highly fatal, acute intraerythrocytic hemolytic form of the disease, but their effectiveness in treating the vascular proliferative forms (verruga peruana) or the chronic asymptomatic, bacteremic, carrier state of the disease has not been effective. This disease should remain confined to its present endemic geographic areas in South American unless asymptomatic bacteremic persons from these areas migrate to areas where sandflies and humans exist that are capable of establishing this infection in new endemic areas. B. quintana and B. henselae cause a wide range of clinical diseases in humans, the type and extent of which varies significantly with the immune status of the host. In immunocompetent hosts the pathologic response is granulomatous, suppurative, extracellular and intracellular, generally self-limited and usually unresponsive to antibiotic treatment, even to those drugs to which the organism is shown to be sensitive in vitro. In contrast, in immunocompromised hosts the pathologic response is vasculoproliferative, organisms may be seen intracellularly but they are often seen in abundance in extracellular clumps and infection is usually progressive and fatal unless treated. In these patients clinical response to treatment with drugs that are effective in vitro against these organisms has usually been dramatic. Of these agents those that penetrate cells and are found in high concentrations intracellularly, such as erythromycin, clarithromycin, azithromycin, rifampin, doxycycline and gentamicin, appear to be most effective. These agents not only appear to provide the most dramatic treatment response in patients with BA, BP and PRFB and other manifestations of B. henselae (and B. quintana as well) in immunocompromised persons, they appear to be the most promising agents for treatment of persons with both typical and atypical CSD. Further studies will be necessary to more clearly elucidated the mechanisms responsible for the diverse clinical presentations of infection with these organisms in human hosts relative to their immune status. In addition clarification of the epidemiology of B. elizabethae infections in humans may be helpful in understanding the nature of infection with Bartonella organisms.

Cat scratch disease: The story continues

OBJECTIVE

To present a perspective on the current state of knowledge of cat scratch disease (CSD), including the evidence for Bartonella henselae as the etiological agent, epidemiological and clinical characteristics of the disease, available diagnostic tests and current therapeutic options.

DATA SOURCES

MEDLINE search of the literature published from 1966 to 1995 using 'cat scratch disease', 'Bartonella henselae', 'Rochalimaea henselae' as key words and bibliographies of selected papers.

DATA EXTRACTION

Selected studies reporting data on etiology, epidemiology, clinical characteristics, diagnosis and therapy of CSD were evaluated.

DATA SYNTHESIS AND CONCLUSIONS

Evidence accumulated to date supports B henselae as the etiological agent of CSD. The most significant risk factors for CSD are being licked on the face, scratched or bitten by a kitten and owning a kitten with fleas. Available serological tests can confirm classic CSD and identify B henselae as the cause of more atypical presentations, such as fever of unknown origin, granulomatous hepatitis, encephalitis and osteomyelitis. Symptomatic management is appropriate for isolated lymphadenopathy caused by CSD in healthy individuals; however, antibiotic therapy may be indicated for patients with more severe manifestations of the disease and immunocompromised hosts. Further study of CSD, in particular the epidemiology and therapy, is warranted. A better understanding of the pathogenesis of B henselae infection will have important implications in both immunocompetent and immunocompromised individuals.

Treatment of nontuberculous mycobacterial lymphadenitis with clarithromycin plus rifabutin

Treatment with clarithromycin plus rifabutin in children with nontuberculous mycobacterial lymphadenitis was associated with resolution of chronic sinus formation and discharge after incomplete excision in five of five cases, and involution of the enlarged lymph nodes in two of three cases treated without surgery.