Cerebral nocardiosis

Disseminated Nocardia farcinica Infection in a Renal Transplant Patient: A Case Report

Nocardia farcinica, an aerobic, Gram-positive bacterium belonging to the genus Nocardia, is a challenging opportunistic pathogen, particularly impacting immunocompromised individuals. The prevalence of human disease has witnessed a notable rise over the past two decades, correlating with an expanding population of immunocompromised individuals and advancements in the detection and identification of Nocardia spp. within clinical laboratories. This case is of a 59-year-old male with compromised immunity due to immunosuppressive medication use following a renal transplant who had an array of presentations before confirming a diagnosis of disseminated nocardiosis. The challenges faced in our case provide valuable insights into the complexities associated with diagnosing and managing Nocardia infections in immunocompromised populations, informing future clinical practice and research endeavors.

Cerebral Abscess Due to Nocardia beijingensis Associated With HIV: Case Report and Mini Review

Brain abscesses are severe focal infections of the central nervous system. We report the case of a 37-year-old patient with a recent diagnosis of HIV, who presented with weakness in the left arm that progressed to left hemiplegia, ipsilateral paresthesia, holo cranial headache, fever accompanied by chills, and left tonic-clonic movements. A craniectomy and lesion resection were performed along with antimicrobial treatment. Subsequently, the patient persisted with left hemiplegia, which significantly improved after the procedure and gradually through physical physiotherapy. During the investigation, we complete medical history, physical examination, Image tests, laboratory tests, and cultures. After the finalization of the approach, the final diagnosis was a brain abscess due to Nocardia beijingensis associated with HIV. The patient was managed with anticonvulsants: levetiracetam, antimicrobials: ceftriaxone, trimethoprim/sulfamethoxazole, metronidazole, and vancomycin, Craniotomy plus resection of two brain abscesses, Steroidal anti-inflammatory: dexamethasone and antiretroviral therapy. With this, the patient was discharged successfully from the hospital.

Brain Abscess Caused by Nocardia farcinica in a Young Immunocompetent Patient

Cerebral nocardiosis is a rare opportunistic infectious disease that occurs mainly in immunocompromised hosts; however, immunocompetent patients may be affected too. It often results in the formation of intraparenchymal brain abscess, which represents only 2% of all cerebral abscesses. The overall mortality rate exceeds 20% in immunocompetent patients and 55% in immunocompromised patients. Bacteriological diagnosis is often confirmed only after the surgical excision of the abscess. Thus, the initiation of effective therapy is frequently delayed. Our goal is to highlight a diagnostic approach to cerebral nocardiosis in an immunocompetent patient with the purpose of accelerating the initiation of the appropriate therapy. We report a rare case of brain abscess caused by Nocardia farcinica in a 39-year-old male, a resident of New York City, USA, with a past medical history of intravenous (IV) drug use, who was admitted for altered mental status. The patient was cachectic and ill-appearing. Initial laboratory tests showed neutrophilic leukocytosis. Computed tomography (CT) of the head revealed a large ill-defined multilobulated mass of size 6 × 5 × 4.5 cm in the right cerebral hemisphere, which was confirmed with magnetic resonance imaging (MRI). The hospital course was complicated by the deterioration of mental status requiring endotracheal intubation. The patient underwent a right-sided hemicraniectomy; a wound culture identified Nocardia farcinica. The patient was started on intravenous (IV) Bactrim, which caused an allergic reaction. Thus, he was switched to IV imipenem-cilastatin. After E-test was performed, the patient was switched to oral linezolid. The initiation of targeted antibiotic therapy was crucial for the management of this patient and resulted in a good clinical outcome. In conclusion, cerebral nocardiosis, being an unusual and a potentially fatal infection, should be considered in the differential diagnosis of brain abscess even in immunocompetent hosts. Prompt bacteriological diagnosis helps to initiate a specific antimicrobial therapy. Long-term antimicrobial therapy and long-term follow-up are necessary to prevent relapse.

Design of a multi-epitope vaccine against six Nocardia species based on reverse vaccinology combined with immunoinformatics

Background

Nocardia genus, a complex group of species classified to be aerobic actinomycete, can lead to severe concurrent infection as well as disseminated infection, typically in immunocompromised patients. With the expansion of the susceptible population, the incidence of Nocardia has been gradually growing, accompanied by increased resistance of the pathogen to existing therapeutics. However, there is no effective vaccine against this pathogen yet. In this study, a multi-epitope vaccine was designed against the Nocardia infection using reverse vaccinology combined with immunoinformatics approaches.

Methods

First, the proteomes of 6 Nocardia subspecies Nocardia subspecies (Nocardia farcinica, Nocardia cyriacigeorgica, Nocardia abscessus, Nocardia otitidiscaviarum, Nocardia brasiliensis and Nocardia nova) were download NCBI (National Center for Biotechnology Information) database on May 1st, 2022 for the target proteins selection. The essential, virulent-associated or resistant-associated, surface-exposed, antigenic, non-toxic, and non-homologous with the human proteome proteins were selected for epitope identification. The shortlisted T-cell and B-cell epitopes were fused with appropriate adjuvants and linkers to construct vaccines. The physicochemical properties of the designed vaccine were predicted using multiple online servers. The Molecular docking and molecular dynamics (MD) simulation were performed to understand the binding pattern and binding stability between the vaccine candidate and Toll-like receptors (TLRs). The immunogenicity of the designed vaccines was evaluated via immune simulation.

Results

3 proteins that are essential, virulent-associated or resistant-associated, surface-exposed, antigenic, non-toxic, and non-homologous with the human proteome were selected from 218 complete proteome sequences of the 6 Nocardia subspecies epitope identification. After screening, only 4 cytotoxic T lymphocyte (CTL) epitopes, 6 helper T lymphocyte (HTL) epitopes, and 8 B cell epitopes that were antigenic, non-allergenic, and non-toxic were included in the final vaccine construct. The results of molecular docking and MD simulation showed that the vaccine candidate has a strong affinity for TLR2 and TLR4 of the host and the vaccine-TLR complexes were dynamically stable in the natural environment. The results of the immune simulation indicated that the designed vaccine had the potential to induce strong protective immune responses in the host. The codon optimization and cloned analysis showed that the vaccine was available for mass production.

Conclusion

The designed vaccine has the potential to stimulate long-lasting immunity in the host, but further studies are required to validate its safety and efficacy.

Nocardia Brain Abscess in a Patient With Sarcoidosis

Nocardia species are aerobic, gram-positive, filamentous bacteria. Infection occurs either through inhalation leading to pulmonary symptoms or inoculation presenting with skin findings. Hematogenous dissemination, although uncommon, is possible and can lead to central nervous system involvement. Nocardia brain abscess is a rare manifestation that comprises 2% of all brain abscess etiologies, mostly occurring in immunocompromised patients. Establishing a diagnosis is often difficult, especially due to its rare occurrence and the fact that it can mimic other etiologies on brain imaging including necrotic tumors. High mortality rates have been reported due to delays in establishing a diagnosis and a lack of precise treatment guidelines.

Brain metastasis or nocardiosis? A case report of central nervous system Nocardiosis with a review of the literature

Nocardiosis is an infection caused by the gram-positive bacterium Nocardia, which typically manifests as an isolated pulmonary or systemic disease. Of note, Nocardia has a predilection for the central nervous system (CNS) involvement, which is more commonly seen in systemic nocardiosis rather than as an isolated CNS infection. According to the Centers for Disease Control and Prevention, the estimated incidence of nocardiosis is only 500 to1000 cases in the USA every year, with cases mostly found in immunocompromised people, although infection in the immunocompetent may also occur. Here, we present a case of an immunocompromised patient who presented with neurologic symptoms and intracranial lesions initially concerning metastatic disease. Upon further investigation, the patient was found to have CNS nocardiosis with bacteremia. This is an extremely rare presentation given the lack of concurrent pulmonary and cutaneous involvement. The insidious onset and rarity of nocardiosis can result in a delayed or missed diagnosis. Early recognition is crucial as this is a potentially life-threatening illness. After obtaining adequate culture specimens, empiric treatment must be started expeditiously, keeping in mind the diversity of the Nocardia species and their antimicrobial resistance patterns.