Nocardia cyriacigeorgica and Aspergillus Co-infection in a Patient with Giant-cell Arteritis

Disseminated Nocardiosis with Pulmonary Fungus and Secondary Epilepsy: A Case Report

Disseminated nocardiosis is a rare, life-threatening disease that usually found in immunocompromised patients, and Nocardia farcinica is one of the most common causative pathogens. The difficulty in identifying the bacterium and the delay in initiating appropriate therapy often influence the prognosis of patients with disseminated nocardiosis. Here, we present a rare case of disseminated nocardiosis in a 61-year-old female with pulmonary fungus and secondary epilepsy. She received targeted antibiotic therapy and showed a great recovery in clinical symptoms and radiological signs. Disseminated nocardiosis can be easily overlooked due to the absence of characteristic symptoms and limitations of clinical examinations. Given the variability in antibiotic susceptibility patterns, the management of disseminated nocardiosis must be individualized. Therefore, early diagnosis and targeted antibiotic treatment are critical for the prognosis of disseminated nocardiosis.

Diffuse primary cutaneous infection by Alternaria alternata in a liver transplant recipient with pulmonary nocardiosis: Importance of prompt identification for clinical resolution

Fungal infections are rare in the general population but are an emerging cause of disease in immunosuppressed patients, especially solid organ transplant recipients. Here, we report the case of a female Caucasian liver transplant patient who developed pulmonary nocardiosis two months after an episode of liver rejection. At the time of lung nocardiosis, she was being treated with tacrolimus and corticosteroids and suffered from diffuse papular skin lesions. She was initially suspected of having a cutaneous nocardial infection but culture examination revealed the presence of a dematiaceous fungus; Alternaria alternata. The prompt identification of the fungus and administration of oral Voriconazole resolved the skin infection with complete remission.

The Heparin-Binding Hemagglutinin of Nocardia cyriacigeorgica GUH-2 Stimulates Inflammatory Cytokine Secretion Through Activation of Nuclear Factor κB and Mitogen-Activated Protein Kinase Pathways via TLR4

Heparin-binding hemagglutinin (HBHA) from mycobacteria is involved in the dissemination of infection and the activation of the host immune response. However, the interaction of Nocardia cyriacigeorgica HBHA with the host cells remains unknown. In the present study, we describe N. cyriacigeorgica HBHA interactions with epithelial cells and organ colonization. We then investigate the mechanisms by which HBHA induces the production of inflammatory cytokines in macrophages. Immunofluorescent microscopy showed that HBHA adhered to A549 cells and HeLa cells and that the C-terminal fragment, which contains a Pro-Ala-Lys–rich domain, was responsible for adhesion. The deletion of the hbha gene in N. cyriacigeorgica mutant strains impaired adhesion to A549 cells and HeLa cells. In addition, the HBHA protein activated the mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways and promoted the production of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-10 in macrophages. HBHA-mediated TNF-α production was dependent on the activation of the c-Jun N-terminal kinase (JNK) signal pathways, and the IL-6 and IL-10 production was dependent on the activation of extracellular regulated kinase (ERK) 1/2, MAPK p38 (p38), JNK, and nuclear NF-κB signaling pathways. Additionally, the HBHA-mediated activation of innate immunity was dependent on Toll-like receptor 4 (TLR4). Taken together, these results indicate that N. cyriacigeorgica HBHA not only adheres to epithelial cells and may be involved in organ colonization, but also plays a critical role in the modulation of innate immunity through the MAPK and NF-κB signaling pathways via TLR4.