Bacillary angiomatosis and other Bartonella species infections

Development and validation of a droplet digital PCR assay for the detection and quantification of Bartonella species within human clinical samples

This report describes the development, optimization, and validation of a ddPCR assay for the detection of Bartonella spp. DNA within several sample matrices, including clinical blood samples from patients with or without documented Bartonella spp. bacteremia. The Bartonella spp. ddPCR assay was developed based upon previously published TaqMan-based qPCR assays that can amplify DNA of over 25 Bartonella spp. Host DNA (housekeeping gene) amplification serves as a reference target to facilitate quantification. The efficiency, sensitivity, and specificity of the Bartonella spp. ddPCR assay was assessed by direct comparison with the current qPCR methods used by the Intracellular Pathogens Research Laboratory (North Carolina State University, North Carolina, USA), and Galaxy Diagnostics (Research Triangle Park, North Carolina, USA). Bartonella spp. ddPCR assay parameters were successfully optimized to detect Bartonella concentrations equivalent to 0.5 bacterial genome copies per microliter of blood (0.001 pg/ul of bacterial DNA). The number of droplets detected (resolution) for each concentration was consistent across each of four assessed time points. The Bartonella spp. ddPCR assay detected 16 species/strains including B. henselae; B. quintana; B. vinsonii subsp. berkhoffii (genotypes I, II, III and IV); B. vinsonii subsp. vinsonii; B. melophagi; B. volans; B. monaki; B. alsatica; B. bovis; B. elizabethae; B. clarridgeiae; and B. koehlerae. Bartonella DNA was detected in only one previously negative patient sample (119/120 negative; 99% specificity). The ddPCR sensitivity (53/112) was significantly better than qPCR (6/112) when testing patient blood and enrichment blood culture samples. The development of commercial ddPCR systems with integrated technologies has significantly streamlined the DNA detection process, making it more efficient and standardized for clinical diagnostic testing. The assay described in this work is the first step toward the development of a multiplex ddPCR assay (i.e., using the QX One from Bio-Rad) for the simultaneous detection and absolute quantification of multiple vector-borne pathogens (such as Babesia, Bartonella and Borrelia) within clinical samples.

Differential expression of active mitogen-activated protein kinase in cutaneous endothelial neoplasms: implications for biologic behavior and response to therapy

BACKGROUND

Tumors of endothelium range from benign hemangiomas of infancy to highly malignant angiosarcomas of the elderly. Hemangiomas are the most common tumors in infants and may affect up to 10% of all children. The biologic behavior of these lesions ranges from self-resolving, in the case of hemangiomas and pyogenic granulomas, to lethal metastatic neoplasms in the case of angiosarcoma. Although the clinical outcomes of these diseases are easily distinguished, the biologic basis for these differences is not well understood. Activation of mitogen-activated protein kinase (MAPK) is an important signal transduction mechanism that may predict response of a tumor to chemotherapy.

OBJECTIVE

Our purpose was to examine expression of phosphorylated (activated) MAPK in hemangiomas of infancy, pyogenic granulomas, hemangioendotheliomas, and angiosarcomas to determine whether phosphorylated MAPK was expressed in endothelial tumors. In addition, we examined endothelial tumors of infectious origin, Kaposi's sarcoma, and verruga peruana.

METHODS

Skin sections from benign and malignant endothelial tumors, including hemangioma of infancy, angiosarcoma, and infectious endothelial lesions (Kaposi's sarcoma, verruga peruana) were stained with an antibody specific for phosphorylated MAPK.

RESULTS

We demonstrated strong expression of phosphorylated MAPK in benign endothelial tumors, including capillary hemangioma of infancy and pyogenic granuloma, and greatly decreased expression in angiosarcoma. In addition, infectious endothelial tumors stained strongly with this antibody, similar to benign tumors. The presence of immunoreactive phosphorylated MAPK appears to be inversely correlated with degree of malignancy.

CONCLUSION

We demonstrate that the use of antibodies specific for signal transduction pathways is feasible in paraffin-fixed tissue. Thus the activity of a given signal transduction pathway can be ascertained in a biopsy specimen. Immunohistochemistry for phosphorylated MAPK may help the pathologist distinguish benign from malignant endothelial processes and thus guide therapy.

The immune compromised host in the twenty-first century: management of mucocutaneous infections

Infectious diseases encountered in dermatology have changed tremendously during the past few decades with the emergence of the immunocompromised host. This change is a result of the human immunodeficiency virus epidemic, use of immunomodulating drugs, bone marrow transplantation, increasing prevalence of diabetes mellitus, and an aging population. New pathogens have been discovered and new disorders have occurred. In the compromised host, infection can be more aggressive and widespread locally, be caused by opportunistic pathogens, and be disseminated hematogenously from or to the skin. The prevalence of nonmelanoma skin cancer has increased, and squamous cell carcinomas can be more aggressive with more rapid local growth as well as frequency of metastasis.