Immunohistochemical Study of Lymph Nodes in Patients with Cat Scratch Disease

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Combined Application of Immunohistochemistry and Warthin-Starry Silver Stain on the Pathologic Diagnosis of Cat Scratch Disease

PURPOSE

Cat scratch disease (CSD) is an infectious disorder caused primarily by the bacterium Bartonella henselae (B. henselae). Immunohistochemistry (IHC) and Warthin-Starry silver stain (WS) are considered to be indispensable to diagnose CSD in combination with morphologic characteristics. In this study, we retrieved and reviewed 46 cases of paraffin-embedded lymphadenitis with histologic and/or clinical suspicion of CSD between 2014 and 2018, and detected B. henselae by IHC and WS, respectively, and evaluated the application significance of IHC and WS for the detection of B. henselae and validated their values in the pathologic diagnosis of CSD.

MATERIALS AND METHODS

B. henselae was detected by IHC and WS; validation of 2 methods for detecting B. henselae was evaluated by sensitivity, specificity, false-positive rate, false-negative rate, precision, negative predictive value, and agreement rate.

RESULTS

Microscopically, suppurative granulomas and/or multiple stellate microabscesses were observed in the accessory cortex of lymph nodes, especially near the subcapsule. Our results showed that 80.4% (37/46) of cases were positive for B. henselae by IHC, manifesting mainly punctuate, granular, or linear to outline the shape of bacteria. However, the positive rate of B. henselae by the WS method was 52.2% (24/46). There was a significant difference between IHC and WS (P=0.023). Moreover, a positive percentage of B. henselae was 97.8% (45/46), which was detected by the combined application of IHC and WS. The combination of IHC and WS exhibited high sensitivity (97.8%) and good agreement rate (86.5%).

CONCLUSION

The combined application of the IHC and WS method may have important clinical advantages, which is with the highest sensitivity and agreement rate for pathologic diagnosis of CSD.

Bartonellosis in Chronic Kidney Disease: An Unrecognized and Unsuspected Diagnosis

Systemic cat scratch disease or bartonellosis is a clinical entity caused by Bartonella henselae, which manifests with necrotizing granulomas in visceral organs. The cat flea, Ctenocephalides felis, is the vector responsible for horizontal transmission of the disease from cat to cat, and its bite can also infect humans. In immunocompromised patients including chronic kidney disease and renal transplant recipients, it can cause persistent and disseminated cat scratch disease. The aim of this paper is to perform a systematic review of the studies that have addressed the diagnostic methods of cat scratch disease in chronic kidney disease and renal transplant recipients. This review was searched via electronic PubMed and Google scholar databases. Few qualitative full-text original articles in chronic kidney disease and kidney transplant were extracted. At this paper, 19 articles identified including six articles in chronic kidney disease and 13 articles in renal transplant recipients. Of these six identified case reports in chronic kidney disease, serology via immunofluorescence antibody test was led to diagnosis of cat scratch disease in five patients and a one patient showed nonreactive serologic test. Polymerase chain reaction usage to detect deoxyribonucleic acid in tissue biopsy and bone marrow biopsy was led to diagnosis. Cat scratch disease diagnosis in 13 renal transplant recipients was attained more by combining serology and polymerase chain reaction to detect deoxyribonucleic acid in tissue specimens. These selected studies demonstrate that serology and polymerase chain reaction via deoxyribonucleic acid extraction of tissue specimens yield the best outcome in diagnostic field of bartonellosis.

Bartonella henselae bacteremia in a mother and son potentially associated with tick exposure

BACKGROUND

Bartonella henselae is a zoonotic, alpha Proteobacterium, historically associated with cat scratch disease (CSD), but more recently associated with persistent bacteremia, fever of unknown origin, arthritic and neurological disorders, and bacillary angiomatosis, and peliosis hepatis in immunocompromised patients. A family from the Netherlands contacted our laboratory requesting to be included in a research study (NCSU-IRB#1960), designed to characterize Bartonella spp. bacteremia in people with extensive arthropod or animal exposure. All four family members had been exposed to tick bites in Zeeland, southwestern Netherlands. The mother and son were exhibiting symptoms including fatigue, headaches, memory loss, disorientation, peripheral neuropathic pain, striae (son only), and loss of coordination, whereas the father and daughter were healthy.

METHODS

Each family member was tested for serological evidence of Bartonella exposure using B. vinsonii subsp. berkhoffii genotypes I-III, B. henselae and B. koehlerae indirect fluorescent antibody assays and for bacteremia using the BAPGM enrichment blood culture platform.

RESULTS

The mother was seroreactive to multiple Bartonella spp. antigens and bacteremia was confirmed by PCR amplification of B. henselae DNA from blood, and from a BAPGM blood agar plate subculture isolate. The son was not seroreactive to any Bartonella sp. antigen, but B. henselae DNA was amplified from several blood and serum samples, from BAPGM enrichment blood culture, and from a cutaneous striae biopsy. The father and daughter were seronegative to all Bartonella spp. antigens, and negative for Bartonella DNA amplification.

CONCLUSIONS

Historically, persistent B. henselae bacteremia was not thought to occur in immunocompetent humans. To our knowledge, this study provides preliminary evidence supporting the possibility of persistent B. henselae bacteremia in immunocompetent persons from Europe. Cat or flea contact was considered an unlikely source of transmission and the mother, a physician, reported that clinical symptoms developed following tick exposure. To our knowledge, this is the first time that a B. henselae organism has been visualized in and amplified from a striae lesion. As the tick bites occurred three years prior to documentation of B. henselae bacteremia, the mode of transmission could not be determined.

Bartonella species and their ectoparasites: selective host adaptation or strain selection between the vector and the mammalian host?

A wide range of blood-sucking arthropods have either been confirmed or are suspected as important vectors in Bartonella transmission to mammals, including humans. Overall, it appears that the diversity of Bartonella species DNA identified in ectoparasites is much broader than the species detected in their mammalian hosts, suggesting a mechanism of adaptation of Bartonella species to their host-vector ecosystem. However, these mechanisms leading to the fitness between the vectors and their hosts still need to be investigated.

Bartonella henselae in skin biopsy specimens of patients with cat-scratch disease

During the past 2 years, we identified live Bartonella henselae in the primary inoculation sites of 3 patients after a cat scratch. Although our data are preliminary, we report that a cutaneous swab of the skin lesion from a patient in the early stage of cat-scratch disease can be useful for diagnosis of the infection.

Does a feline leukemia virus infection pave the way for Bartonella henselae infection in cats?

Domestic cats serve as the reservoir hosts of Bartonella henselae and may develop mild clinical symptoms or none after experimental infection. In humans, B. henselae infection can result in self-limiting cat scratch disease. However, immunocompromised patients may suffer from more-severe courses of infection or may even develop the potentially lethal disease bacillary angiomatosis. It was reasoned that cats with immunocompromising viral infections may react similarly to B. henselae infection. The aim of our study was to investigate the influence of the most important viruses known to cause immunosuppression in cats-Feline leukemia virus (FeLV), Feline immunodeficiency virus (FIV), and Feline panleukopenia virus (FPV)-on natural B. henselae infection in cats. Accordingly, 142 cats from animal shelters were necropsied and tested for B. henselae and concurrent infections with FeLV, FIV, or FPV by PCR and immunohistochemistry. A significant association was found between B. henselae and FeLV infections (P = 0.00028), but not between B. henselae and FIV (P = 1.0) or FPV (P = 0.756) infection, age (P = 0.392), or gender (P = 0.126). The results suggest that susceptibility to B. henselae infection is higher in cats with concurrent FeLV infections, regardless of whether the infection is latent or progressive. Histopathology and immunohistochemistry for B. henselae failed to identify lesions that could be attributed specifically to B. henselae infection. We conclude that the course of natural B. henselae infection in cats does not seem to be influenced by immunosuppressive viral infections in general but that latent FeLV infection may predispose cats to B. henselae infection or persistence.

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

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