Corrigendum: Nocardiosis: A two-center analysis of clinical characteristics

[This corrects the article DOI: 10.3389/fmed.2022.996442.].

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.

Multiple nocardial abscesses secondary to anti‑neutrophil cytoplasmic antibody‑associated vasculitis in an elderly patient: A case report and literature review

A nocardial abscess is a relatively rare opportunistic infection that typically occurs after immunosuppressive treatment and is a clinical challenge. In the present study, the case of a 69-year-old patient with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, and lung and kidney involvement, was reported. The patient received systemic glucocorticoid and cyclophosphamide treatment for 6 months, after which a large encapsulated abscess appeared on magnetic resonance imaging and CT in the subcutaneous tissue of the left hip and lung, respectively, and the pus culture showed Nocardia. Orthopedic abscess incision and ultrasound-guided thoracic puncture drainage were performed, and the lesion was completely absorbed after 1 month of treatment with linezolid and compound sulfamethoxazole. Tests for ANCA were negative, and renal function and urine tests were completely normal after 1 year of follow-up. Furthermore, a literature review performed for the present study retrieved a few reports of successful treatment of multiple nocardial abscesses secondary to ANCA-associated vasculitis in elderly patients in a short period of time. Therefore, the present case report and literature review have been reported to improve awareness of this rare disease, so as to facilitate its early diagnosis and treatment.

Diagnosis of Rare Bone Infection Caused by Nocardia by 16S rRNA Gene Sequencing

Nocardia is an aerobic actinomycete that causes serious opportunistic infections in immunocompromised individuals. Gene sequencing is the gold standard for pathogenic bacteria diagnosis. This study uses 16S rRNA gene sequencing to diagnose three cases of bone infections caused by Nocardia, including one rare case (N. cyriacigeorgica), and the clinial features, etiological characteristics, treatment, and prognosis of the patients.

Nocardia arthritidis scleritis: A case report

Purpose

This report describes a case and management of a 69-year-old female with infectious scleritis found to be caused by Nocardia arthritidis species.

Observations

Our patient presented with severe constant pain in the left eye (OS) following cataract surgery. She had a pertinent past medical history significant for renal transplantation (on oral tacrolimus, mycophenolate, and prednisone). Slit lamp examination OS (1 month after cataract surgery) demonstrated 3+ injection temporally accompanied by scleral thickening and multiloculated abscesses with purulent drainage from small conjunctival erosions. The abscesses were debrided and sent for gram stain and culture. The patient was treated with repeated subconjunctival injections of antibiotics and an antifungal; topical amphotericin, vancomycin, and amikacin; and oral trimethoprim-sulfamethoxazole (double strength). Two separate gram stains with cultures confirmed the diagnosis and species identification. The patient responded well to repeat subconjunctival injections early on in addition to the prescribed regimen, remaining free of disease at the last follow-up (12 months following presentation).

Conclusions and Importance

This unique case demonstrates infectious scleritis caused by an uncommon Nocardia species (N. arthritidis) that was successfully treated with similar strategies used for other reported Nocardia species. As Nocardia scleritis can lead to adverse outcomes if not treated promptly and properly, it should be considered on the differential diagnoses in an immunocompromised patient who presents with acute ocular symptoms after any recent ocular surgery.

The Clinical Characteristic and Management of Patients with Nocardiosis in a Tertiary Hospital in China

Nocardiosis is an uncommon opportunistic bacterial infection which becomes a significant health problem due to its increasing incidence and high mortality rate. However, many nocardiosis patients are underdiagnosed by physicians. To summarize the clinical characteristics and management of nocardiosis would help with better diagnosis and prognosis of nocardiosis. This retrospective study was conducted based on the medical records of nocardiosis patients between January 2015 and December 2021 in a tertiary hospital in China. Overall, 44 nocardiosis patients with 54 specimens were included. The patients consisted of 26 males and 18 females with a mean age of 50.4 ± 13.2 years. Among 44 patients, 26 (59.1%) were previously given immunosuppressive therapy. Connective tissue diseases (CTDs) were the most common underlying disease (16/44). The most frequent infection sites were the lungs (17/44) and skin or soft tissues (8/44). Common symptoms included cough (23/44), expectoration (18/44), fever (15/44), and subcutaneous abscesses (15/44). Forty-five out of 54 specimens (83.3%) required over 48 hours of culture time for nocardiosis detection. Thirty-six patients were cured or improved, 5 patients were discharged from the hospital due to poor prognosis, and 1 patient died. The average diagnosis time of poor prognosis cases was 19.7 days, which was significantly longer than those of improved or cured patients (7.3 days). Immunosuppressed patients comprise a large part of nocardiosis cases, which is worth attention in clinical practice. Early diagnosis, specifically through prolonged cultivation time of specimen, could help achieve better prognosis of nocardiosis patients.

Nodular Cutaneous Lesions in Immune-Compromised Hosts as a Clue for the Diagnosis of Disseminated Nocardiosis: From Bedside to Microbiological Identification

BACKGROUND

Nocardia is a group of ubiquitous bacteria known to cause opportunistic infections in immunocompromised hosts, including those affected by malignancies and solid-organ or hematopoietic stem cell transplants. Pulmonary involvement, occurring in two-thirds of cases, is the most frequent presentation. Diagnosis might be challenging both because of microbiological technical issues, but also because of the variability of organ involvement and mimicry.

METHODS

We describe four cases of disseminated nocardiosis caused by N. farcinica observed between September 2021 and November 2021 in immune-compromised hosts presenting with nodular cutaneous lesions that had raised a high degree of clinical suspect and led to microbiological identification through MALDI-TOF MS.

RESULTS

Cutaneous involvement is typically reported in immunocompetent hosts with primary cutaneous nocardiosis with multiple forms of manifestation; nonetheless, disseminated nocardiosis rarely involves the skin and subcutaneous tissues, and this occurs as a result of metastatic spread. Our cases were disseminated nocardiosis in which the metastatic cutaneous involvement, even if rare, provided a clue for the diagnosis.

CONCLUSIONS

The pathomorphosis of disseminated nocardiosis may have changed in the current years with more rapid spread due to advanced immunosuppression. For this reason, after clinical suspicion, the prompt start of an active targeted therapy based on rapid microbiological identification might potentially open the way to hopeful results, even in the most immune-compromised patients.

Septic arthritis by Nocardia farcinica: Case report and literature review

Nocardiosis is a bacterial infection caused by organisms of the Nocardia genus. The disease typically involves the skin, central nervous system or pulmonary system. Very rarely nocardiosis can cause disease of other organs including bone and joints. Nocardiosis is typically a chronic, somewhat indolent infection, occurring in patients with defective cell mediated immunity. We describe a 78-year-old female with right shoulder septic arthritis resulting from Nocardia farcinica with associated involvement of her skin and lungs as well. She was treated with surgical debridement and combination antibiotic therapy. We also share a literature review of bone and joint infection caused by the N. farcinica species, highlighting its rarity. Understanding uncommon manifestations of nocardiosis allows for early recognition and treatment of the condition and optimal patient care.

Updated Review on Nocardia Species: 2006-2021

This review serves as an update to the previous Nocardia review by Brown-Elliott et al. published in 2006 (B. A. Brown-Elliott, J. M. Brown, P. S. Conville, and R. J. Wallace. Jr., Clin Microbiol Rev 19:259-282, 2006, https://doi.org/10.1128/CMR.19.2.259-282.2006). Included is a discussion on the taxonomic expansion of the genus, current identification methods, and the impact of new technology (including matrix-assisted laser desorption ionization-time of flight [MALDI-TOF] and whole genome sequencing) on diagnosis and treatment. Clinical manifestations, the epidemiology, and geographic distribution are briefly discussed. An additional section on actinomycotic mycetoma is added to address this often-neglected disease.

Erythema Nodosum following Nocardia Infection: A Case Report

Cutaneous nocardiosis is a rare bacterial infection that can result in various dermatologic manifestations such as actinomycetoma, lymphocutaneous infection, superficial skin infection, and secondary infection due to hematogenous dissemination. We report on a Chinese patient with erythema nodosum-like exanthema, possibly secondary to nocardiosis. Our diagnosis for this patient was based on the clinical presentation, histopathological evidence, and microbiological findings. Given the protean manifestation of Nocardia, persistent reports on new presentations of the disease are important for early identification and treatment.

A Complete Genome of Nocardia terpenica NC_YFY_NT001 and Pan-Genomic Analysis Based on Different Sources of Nocardia spp. Isolates Reveal Possibly Host-Related Virulence Factors

OBJECTIVE

We aimed to identify the possible virulence genes associated with Nocardia NC_YFY_NT001 isolated by ourselves and other Nocardia spp.

METHODS

The genome of Nocardia terpenica NC_YFY_NT001 was completed by using PacBio and Illumina platforms. A pan-genomic analysis was applied to selected complete Nocardia genomes.

RESULTS

Nocardia terpenica NC_YFY_NT001 can cause healthy mice death by tail intravenous injection. The genome of NT001 has one circular chromosome 8,850,000 bp and one circular plasmid 70,000 bp with ~68% GC content. The chromosome and plasmid encode 7914 and 80 proteins, respectively. Furthermore, a pan-genomic analysis showed a total of 45,825 gene clusters, then 304 core, 21,045 shell and 24,476 cloud gene clusters were classified using specific parameters. In addition, we found that catalases were more abundant in human isolates. Furthermore, we also found no significant differences in the MCE proteins between different strains from different sources. The pan-genomic analysis also showed that 67 genes could only be found in humoral isolates. ReX3 and DUF853 domain protein were found in all eight human isolates. The composition of unique genes in humoral isolate genomes indicated that the transcriptional regulators may be important when Nocardia invades the host, which allows them to survive in the new ecological system.

CONCLUSION

In this study, we confirmed that NT001 could cause infected animal death, and identified many possible virulence factors for our future studies. This study also provides new insight for our further study on Nocardia virulence mechanisms.

A case report of pulmonary nocardiosis during pembrolizumab: the emerging challenge of the infections on immunotherapy

The increasing occurrence of infectious complications during immune checkpoint inhibitor (ICI) therapy is an emerging challenge for oncologists. ICIs can reverse T-cell exhaustion, and this may lead to hyperinflammatory dysregulated immunity with subsequent potentially fatal infections. Nocardia spp. are opportunistic pathogens belonging to aerobic Actinomycetes. The authors report a case of Nocardia pneumonia in a 62-year-old male with oral squamous cell carcinoma and lung cancer while taking pembrolizumab. The patient did not take corticosteroids or other immunosuppressant medications. Since ICIs are able to stimulate the immune response, the authors hypothesize that immune reconstitution inflammatory syndrome due to pembrolizumab might cause this opportunistic infection.

Epidemiology and in vitro antimicrobial susceptibility of aerobic Actinomycetales in a clinical setting

INTRODUCTION

The incidence of infections caused by aerobic actinomycetes is increasing. Recent changes in taxonomy and the variability in susceptibility patterns among species make necessary a proper identification and antibiotic susceptibility testing.

MATERIAL AND METHODS

Fifty-three strains of aerobic actinomycetes were identified by MALDI-TOF MS using the VITEK MS Mycobacterium/Nocardia kit (bioMérieux, France) in a tertiary hospital in Spain during a six-year period. Antimicrobial susceptibility testing of the isolates was performed using the Sensititre Rapmycoi microdilution panel (Thermo Fisher Scientific, Massachusetts, USA).

RESULTS

Forty strains of Nocardia spp. were identified in the study, being N. farcinica and N. cyriacigeorgica the most prevalent ones. All isolates were susceptible to linezolid and the resistance to amikacin was only observed in one isolate of Gordonia sputi. Resistance to cotrimoxazole was only found in five isolates.

CONCLUSIONS

Routine identification and antimicrobial susceptibility testing of aerobic actinomycetes is advisable for an efficient identification of species and effective treatment.

Identification of a novel drug-resistant community-acquired Nocardia spp. in a patient with bronchiectasis

A previously unknown Nocardia species was isolated from the lung tissue and bronchoalveolar lavage fluid (BALF) of a 58-year-old woman with bronchiectasis and recurrent pneumonia. This Nocardia (GZ2020^T), which grew readily in Columbia blood agar and could induce pneumonia in a mouse model, represents a novel Nocardia species, and its closest known relatives are Nocardia anaemiae NBRC 100462^T, Nocardia pseudovaccinii NBRC 100343^T and Nocardia vinacea NBRC 16497^T. However, unlike all previously known species, GZ2020^T is the first genus of Nocardia spp. that is not susceptible to multiple drugs but does show susceptibility to linezolid and moxifloxacin, and thus, GZ2020^T potentially represents a substantial health threat to patients with bronchiectasis and immunocompromised individuals. Although the original pathogen source and method of spreading remain uncertain, a mode of transmission from the environment to humans could exist. Vigilance with respect to its spread in the population and the transmission of antibiotic resistance genes in the environment should be maintained.

Nocardiosis: A two-center analysis of clinical characteristics

Objective

The objective of the present study was to describe and analyze the clinical characteristics of nocardiosis.

Materials and methods

We described and analyzed the clinical characteristics of nocardiosis cases from two centers over the past 5 years from the following aspects: age and sex, Nocardia species, sites of Nocardia infection, test specimens, detection methods, concurrent pathogens, symptoms, imaging features, co-conditions, drug susceptibility tests, antibiotic therapy/duration, outcomes, and follow-up.

Results

The median age of the 19 cases was 64 years, with an interquartile range (IQR) of 56-68 years. Eight cases (42.1%) were immunocompromised [those who had been on corticosteroid use (62.5%), those who had used immunosuppressants (50.0%), or those who had suffered from chronic nephrosis (37.5%) or diabetes mellitus (DM) (25.0%)]. The plethora of comorbidities of these cases included diabetes (10.5%), chronic kidney disease (CDK) (15.8%), chronic lung disease (36.8%), and rheumatic diseases (10.5%). Cough and expectoration (73.7%) was the most common symptom of nocardiosis. The respiratory tract (89.5%) was the most common site of the clinical disease. Nearly half (9 cases, 47.3%) of these patients had concurrent infections. The most common Nocardia isolation site was the respiratory tract (73.7%). All patients were given antibiotic therapies, out of whom as many as 63.6% of patients were treated with two concurrent antimicrobial agents, 15.8% of patients were treated under monotherapy and 21.1% of patients were treated with three or more concurrent antimicrobial agents.

Conclusions

An uncommon life-threatening infection, nocardiosis, affects those patients with structural lung disease or immunosuppression. Although nocardiosis is capable of progressing into a serious and metastatic disease, early recognition and prompt treatment usually result in successful outcomes benefitting the patient.

Mycobacteriaceae Mineralizes Micropolyethylene in Riverine Ecosystems

Microplastic (MP) contamination is a serious global environmental problem. Plastic contamination has attracted extensive attention during the past decades. While physiochemical weathering may influence the properties of MPs, biodegradation by microorganisms could ultimately mineralize plastics into CO₂. Compared to the well-studied marine ecosystems, the MP biodegradation process in riverine ecosystems, however, is less understood. The current study focuses on the MP biodegradation in one of the world's most plastic contaminated rivers, Pearl River, using micropolyethylene (mPE) as a model substrate. Mineralization of ¹³C-labeled mPE into ¹³CO₂ provided direct evidence of mPE biodegradation by indigenous microorganisms. Several Actinobacteriota genera were identified as putative mPE degraders. Furthermore, two Mycobacteriaceae isolates related to the putative mPE degraders, Mycobacterium sp. mPE3 and Nocardia sp. mPE12, were retrieved, and their ability to mineralize ¹³C-mPE into ¹³CO₂ was confirmed. Pangenomic analysis reveals that the genes related to the proposed mPE biodegradation pathway are shared by members of Mycobacteriaceae. While both Mycobacterium and Nocardia are known for their pathogenicity, these populations on the plastisphere in this study were likely nonpathogenic as they lacked virulence factors. The current study provided direct evidence for MP mineralization by indigenous biodegraders and predicted their biodegradation pathway, which may be harnessed to improve bioremediation of MPs in urban rivers.

Neutralizing GM-CSF autoantibodies in pulmonary alveolar proteinosis, cryptococcal meningitis and severe nocardiosis

Background

Anti GM-CSF autoantibodies (aAb) have been related to acquired pulmonary alveolar proteinosis (PAP) and described in cases of severe infections such as cryptococcosis and nocardiosis in previously healthy subjects. Whether there are different anti-GM-CSF autoantibodies corresponding to these phenotypes is unclear. Therefore, we examined anti-GM-CSF autoantibodies to determine whether amount or neutralizing activity could distinguish between groups.

Methods

Plasma samples gathered in the National Institute of Health from patients with anti GM-CSF aAb and either PAP (n = 15), cryptococcal meningitis (n = 15), severe nocardiosis (n = 5) or overlapping phenotypes (n = 6) were compared. The relative amount of aAb was assessed using a particle-based approach, reported as a mouse monoclonal anti-human GM-CSF as standard curve and expressed in an arbitrary Mouse Monoclonal Antibody Unit (MMAU). The neutralizing activity of the plasma was assessed by inhibition of GM-CSF-induced intracellular phospho-STAT5 (pSTAT5) in monocytes.

Results

Anti-GM-CSF aAb relative amounts were higher in PAP patients compared to those with cryptococcosis (mean 495 ± 464 MMAU vs 197 ± 159 MMAU, p = 0.02); there was no difference with patients with nocardiosis (430 ± 493 MMAU) nor between the two types of infections.

The dilution of plasma resulting in 50% inhibition of GM-CSF-induced pSTAT5 (approximate IC₅₀) did not vary appreciably across groups of patients (1.6 ± 3.1%, 3.9 ± 6% and 1.8 ± 2.2% in PAP patients, cryptococcosis and nocardiosis patients, respectively). Nor was the concentration of GM-CSF necessary to induce 50% of maximal GM-CSF-induced pSTAT5 in the presence of 10 MMAU of anti-GM-CSF aAb (EC₅₀). When studying longitudinal samples from patients with PAP or disseminated nocardiosis, the neutralizing effect of anti-GM-CSF aAb was relatively constant over time despite targeted treatments and variations in aAb levels.

Conclusions

Despite different clinical manifestations, anti-GM-CSF antibodies were similar across PAP, cryptococcosis and nocardiosis. Underlying host genetics and functional analyses may help further differentiate the biology of these conditions.

Case report: Nocardial brain abscess in a persistently SARS-CoV-2 PCR positive patient with systemic lupus erythematosus

Coronavirus disease (COVID-19) in immunocompromised patients represents a major challenge for diagnostics, surveillance, and treatment. Some individuals remain SARS-CoV-2 PCR-positive for a prolonged period. The clinical and epidemiological significance of this phenomenon is not well understood. We report a case of a patient with a history of systemic lupus erythematosus (SLE) who has been persistently SARS-CoV-2 PCR positive for 9 months, with multiple thromboembolic complications, and development of nocardial brain abscess successfully treated with surgery and antibiotics.

Identification and antimicrobial susceptibility of referred Nocardia isolates in Victoria, Australia 2009-2019

Introduction. Nocardia is an opportunistic pathogen that can cause significant morbidity and mortality, particularly in the immunocompromised host. Antimicrobial susceptibility profiles vary across Nocardia spp. and vary within Australia as well as worldwide. Knowledge of local susceptibility patterns is important in informing appropriate empiric antimicrobial therapy.Gap Statement. This is the largest study to date in Australia that correlates antimicrobial susceptibility profiles with molecular identification of Nocardia species. It is the first study that examines isolates from multiple institutions across the state of Victoria, Australia.Aim. To investigate the species distribution and antibiotic susceptibility of Nocardia spp. isolates referred to the Mycobacterial Reference Laboratory (MRL) in Victoria, Australia from 2009 to 2019.Methodology. We conducted a retrospective review of Nocardia spp. isolates which were identified using molecular sequencing. Antimicrobial susceptibility testing was performed using standardized broth microdilution method with Sensititre RAPMYCO1 plates. Species distribution and antibiotic susceptibility profiles were analysed.Results. In total, 414 Nocardia isolates were identified to 27 species levels, the majority originating from the respiratory tract (n=336, 81.2 %). N. nova (n=147, 35.5 %) was the most frequently isolated, followed by N. cyriacigeorgica (n=75, 18.1 %). Species distribution varied by isolate source, with N. farcinica and N. paucivorans found more commonly from sterile sites. Linezolid and amikacin had the highest proportion of susceptible isolates (100 and 99% respectively), while low susceptibility rates were detected for ceftriaxone (59 %) and imipenem (41 %). Susceptibility to trimethoprim sulfamethoxazole varied by species (0-100 %).Conclusion. This is the largest study to date in Australia of Nocardia species distribution and antimicrobial susceptibility patterns. N. farcinica and N. paucivorans were more likely to be isolated from sterile sites, while N. brasiliensis and N. otitidiscvarium were more likely to be isolated from skin and soft tissue. First line therapeutic antimicrobial recommendations by local guidelines were not necessarily reflective of the in vitro susceptibility of Nocardia isolates in this study, with high susceptibility detected for linezolid and amikacin, but poor susceptibility demonstrated for ceftriaxone and imipenem. Profiles for trimethoprim-sulfamethoxazole varied across different Nocardia species, warranting ongoing susceptibility testing for targeted clinical use.

Infective endocarditis by Nocardia species: a systematic review

Nocardiosis, is a potentially life-threatening disease, especially in immunocompromised individuals where it manifests as a disseminated disease. Infective Endocarditis (IE) is a rare disease with significant morbidity and mortality. Importantly, even though there are scarce data of IE by Nocardia spp. in the literature, a review adequately summarizing systematically all available evidence on the topic is lacking. The aim of this study was to systematically review all cases of IE by Nocardia spp. and describe the epidemiology, microbiology, clinical characteristics, treatment and outcomes of this infection. A systematic review of PubMed, Scopus and Cochrane library (through 7 December 2021) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of patients with IE by Nocardia spp. was performed. A total of 25 studies providing data for 26 patients were included. A prosthetic valve was present in 30.8%, while the most common microorganism was N. asteroides. Aortic valve was the most commonly infected intracardiac site, followed by the mitral valve. Diagnosis was most commonly performed with transthoracic echocardiography, while the diagnosis was made at autopsy in 11.5%. Co-trimoxazole, aminoglycosides and carbapenems were the most commonly used antimicrobials. Clinical cure was noted in 73.1%, while mortality was 26.9%. This systematic review thoroughly describes IE by Nocardia and provides information on epidemiology, clinical presentation, treatment and outcomes.

Functional Characterization of a Regiospecific Sugar-O-Methyltransferase from Nocardia

Methyltransferases transfer a methyl group to a diverse group of natural products, thus providing structural diversity, stability, and altered pharmacological properties to the molecules. A limited number of regiospecific sugar-O-methyltransferases are functionally characterized. Thus, discovery of such an enzyme could solve the difficulties of biological production of methoxy derivatives of glycosylated molecules. In the current study, a regiospecific sugar-O-methyltransferase, ThnM1, belonging to the biosynthetic gene cluster (BGC) of 1-(α-L-(2-O-methyl)-6-deoxymannopyranosyloxy)-3,6,8-trimethoxynaphthalene produced by Nocardia sp. strain CS682, was analyzed and functionally characterized. ThnM1 demonstrated promiscuity to diverse chemical structures such as rhamnose-containing anthraquinones and flavonoids with regiospecific methylation at the 2′-hydroxyl group of the sugar moiety. Compared with other compounds, anthraquinone rhamnosides were found to be the preferred substrates for methylation. Thus, the enzyme was further employed for whole-cell biotransformation using engineered Escherichia coli to produce a methoxy-rhamnosyl derivative of quinizarin, an anthraquinone derivative. The structure of the newly generated derivative from Escherichia coli fermentation was elucidated by liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopic analyses and identified as quinizarin-4-O-α-l-2-O-methylrhamnoside (QRM). Further, the biological impact of methylation was studied by comparing the cytotoxicity of QRM with that of quinizarin against the U87MG, SNU-1, and A375SM cancer cell lines.

IMPORTANCE ThnM1 is a putative sugar-O-methyltransferase produced by the Nocardia sp. strain CS682 and is encoded by a gene belonging to the biosynthetic gene cluster (BGC) of 1-(α-l-(2-O-methyl)-6-deoxymannopyranosyloxy)-3,6,8-trimethoxynaphthalene. We demonstrated that ThnM1 is a promiscuous enzyme with regiospecific activity at the 2′-OH of rhamnose. As regiospecific methylation of sugars by chemical synthesis is a challenging step, ThnM1 may fill the gap in the potential diversification of natural products by methylating the rhamnose moiety attached to them.

[Systemic nocardiosis with mediastinal lymph node involvement proven by endoscopic ultrasound]

INTRODUCTION

Systemic nocardiosis is an infectious disease that is rarely associated with mediastinal lymph nodes.

CASE REPORT

We report the case of a 72-year-old male patient treated with a high dose of oral corticosteroids for rheumatoid polyarthritis. This patient presented with rapid overall deterioration associated with mediastinal lymph nodes. Endobronchial ultrasound enabled us to establish a diagnosis of systemic nocardiosis. The patient recovered after having received suitable antibiotic treatment for four months.

CONCLUSION

This work reports on a rare clinical presentation of systemic nocardiosis associated with mediastinal lymphadenopathies and highlights the key role of endobronchial ultrasound in diagnosing mediastinal lymph nodes, especially in differential diagnosis for lung cancer.

Prognosis and factors associated with disseminated nocardiosis: a ten-year retrospective multicenter study

OBJECTIVES

Nocardiosis is a rare opportunistic infection that is frequently associated with dissemination (i.e. involvement of several body sites). Identifying the factors associated with Nocardia spp. dissemination may help improving the management of patients with nocardiosis.

METHODS

This 10-year (2010-2020) retrospective multicenter cohort study included adult patients with Nocardia-confirmed infections. The first objective was to determine the factors associated with disseminated nocardiosis. The secondary endpoints were to determine and compare the management and the 12-month overall mortality in patients with localized and disseminated nocardiosis. Univariate and multivariate logistic regression analyses were used.

RESULTS

Nocardia spp. infection was confirmed in 110 patients, of whom 38 (34.5%) had disseminated nocardiosis. In univariate analysis, the factors associated with dissemination were immunosuppressive conditions: having an auto-immune disease and receiving high-dose corticosteroid (31.5% vs 8.3%, P=0.003 and 52.6% vs 26.3%, P=0.007, respectively). Absolute lymphocyte count <1G/L at diagnosis was the only biomarker associated with dissemination (57.2% vs 26.3%, P=0.007). Nocardia farcinica was not only the most frequent species identified in patient specimens (n=22, 20%) but was also associated with a higher rate of dissemination (36.8% vs 11.1%, P=0.002). Multivariate analysis confirmed the association between auto-immune diseases, lymphopenia, N. farcinica species and the higher rate of dissemination. Even though patients with disseminated nocardiosis were treated longer and more often with an antibiotic combination therapy, their 12-month overall mortality was significantly higher than that of patients with localized nocardiosis (36.8% vs 18%).

CONCLUSIONS

Dissemination of Nocardia spp. is favoured by auto-immune diseases, lymphopenia, and infection with N. farcinica.

Long-term use of tedizolid for pulmonary nocardiosis

Nocardiosis usually occurs in immunocompromised patients and causes infections in various organs, including the lungs, skin, and organs of the central nervous system. Herein, we report the case of a patient with minimal change nephrotic syndrome who had been on immunosuppressive drugs and developed pulmonary nocardiosis due to Nocardia nova complex and Pneumocystis pneumonia. For pulmonary nocardiosis, trimethoprim-sulfamethoxazole, linezolid, and clarithromycin were initiated sequentially, but were subsequently discontinued due to side effects; the treatment was completed with tedizolid. Tedizolid was used safely for 200 out of 286 days of antibiotic treatment, and clinical improvement was observed. Tedizolid is a bacteriostatic oxazolidine antibiotic that inhibits bacterial protein synthesis, the same mechanism as its predecessor, linezolid. Tedizolid is thought to cause less frequent myelosuppression than linezolid, at least for short-term use. In the future, tedizolid may be a promising alternative to linezolid in cases of nocardiosis that usually require long-term treatment.

Case Report: Cerebral Nocardiosis Caused by Nocardia cyriacigeorgica Detected by Metagenomics in an Apparently Immunocompetent Patient

We report a case of meningoencephalitis due to Nocardia cyriacigeorgica diagnosed with metagenomics, while all the standard methods were negative. This diagnosis made adaptation of antimicrobial treatment possible and led to the discovery of a rare, acquired immunodeficiency syndrome.

Epidemiology and Antimicrobial Resistance Profiles of the Nocardia Species in China, 2009 to 2021

The genus Nocardia includes ubiquitous environmental saprophytes and the most frequently isolated aerobic actinomycete human pathogen responsible for localized or disseminated infection. Herein, the species distribution and antimicrobial susceptibility profiles of 441 nonrepetitive Nocardia strains are reported, collected from 21 provinces/cities in China over 13 years (from 2009 to 2021). These isolates were identified to species level by mass spectrometry or targeted DNA sequencing. The susceptibility profiles of Nocardia species for 15 antibiotics were determined by the broth microdilution method. Among these Nocardia isolates, Nocardia farcinica was the most commonly isolated species (39.9%, 176 of 441), followed by Nocardia cyriacigeorgica (28.6%, 126), Nocardia abscessus (6.6%, 29), and Nocardia otitidiscaviarum (5.9%, 26). Furthermore, 361 Nocardia strains (81.9%) were collected from lower respiratory tract (sputum, lung tissue, and bronchoalveolar lavage fluid), 50 (11.3%) were collected from skin and soft tissues, 9 were collected from blood, 9 were collected from eye, 4 were collected from cerebrospinal fluid and brain abscesses, and 2 were collected from pleural effusion. All of the Nocardia strains were susceptible to linezolid, followed by amikacin (99.3%) and trimethoprim-sulfamethoxazole (TMP-SMX) (99.1%). The antibiotic resistance profiles of other antibiotics varied tremendously among different Nocardia species. This demonstrated that accurate species identification and/or antibiotic susceptibility testing should be performed before the usage of these antibiotics. In summary, this is the largest study on the species and antibiotic resistance profiles of the genus Nocardia circulating in China, and our data will contribute to a better understanding of clinical nocardiosis.

IMPORTANCE The genus Nocardia has the potential to cause nocardiosis, which might be underrecognized and underdiagnosed. Herein, the demographical features of 441 nonrepetitive nocardiosis cases and species distribution of their Nocardia strains in China, 2009 to 2021, are summarized. The susceptibility profiles for 15 antibiotics against all of the above Nocardia strains were also determined by the broth microdilution method. To date, this is the largest study on the genus Nocardia contributing to nocardiosis in China. Our study will be helpful for understanding the species diversity of Nocardia isolates distributed in China and for decision-making in the context of nocardiosis diagnosis and treatment.

Nocardia asteroides occipital abscess as a cause of lupus nephritis?

Systemic lupus erythematosus (SLE) is a multisystem disease with a complex etiology, which manifests in a multitude of manners. We present a case of lupus nephritis in a patient who developed complications of immunosuppressive treatment with eventual resolution of her nephritis following cure of her Nocardia brain abscess.

Clinical Characteristics and Treatment Outcome of Central Nervous System Nocardiosis: A Systematic Review of Reported Cases

BACKGROUND

The clinical spectrum of systemic nocardiosis encompasses pulmonary and disseminated disease. Central nervous system (CNS) involvement is an important feature of disseminated disease with significant mortality and high relapse rate, especially in those with suppressed cell-mediated immunity. This systematic review aimed to evaluate the epidemiology, clinical features, diagnosis, therapeutic interventions, and outcome in patients with CNS nocardiosis.

METHODS

A literature search was performed in major databases (PubMed, Google Scholar, and Scopus) by using distinct keywords: "CNS disease," "Nocardia," "meningitis," "brain abscess," "disseminated disease," and "Cotrimoxazole." We included all patients ≥18 years with CNS nocardiosis reported between January 2000 and December 2020.

RESULTS

A total of 129 papers were included in the final analysis. The mean age of patients was 55 ± 16 years, and the majority were male (70.8%). Nocardia farcinica was the commonest species (39.6%), followed by Nocardia nova (5.9%). Thirty-four percent of the patients were found to be immunocompetent. Corticosteroid use was the most common predisposing factor (55.8%). Among neuroimaging findings, brain abscess was most common (86.9%), followed by leptomeningeal enhancement (12.1%). The overall case-fatality rate in CNS disease was 22.8%. On multivariate analysis, patients who underwent surgery (OR 2.4, 95% CI 0.99-4.11, p value 0.046) had better survival than those treated with antimicrobial therapy alone. Immunodeficient state (OR 0.32, 95% CI 0.15-0.90, p value 0.019) was independently associated with poor outcome.

CONCLUSION

CNS nocardiosis carries significant mortality, especially in immunodeficient patients. We advocate the use of surgery combined with antimicrobials to improve clinical outcome.

The developed molecular biological identification tools for mycetoma causative agents: An update

Mycetoma is a chronic granulomatous inflammatory disease that is caused either by bacteria or fungi. Bacterial mycetoma (actinomycetoma) can be caused by various causative agents of the genera Nocardia, Streptomyces and Actinomadura. On the other hand, fungal mycetoma (eumycetoma) is most commonly caused by causative agents belonging to the genera Madurella, Scedosporium and Falciformispora. Early and accurate diagnosis of the causative organisms can guide proper patient management and treatment. To allow rapid and accurate species identification, different molecular techniques were developed over the past decades. These techniques can be protein based (MALDI-TOF MS) as well as DNA based (Sequencing, PCR and isothermal amplification methods). In this review, we provide an overview of the different molecular techniques currently in use and identify knowledge gaps, which need to be addressed before we can implement molecular diagnostics for mycetoma in different clinical settings.

Nocardia acididurans sp. nov., an acid-tolerant actinobacterium isolated from bio-fertilizer of Musa species

A novel acid-tolerant actinobacterium (strain LPG 2^T), which formed fragmented substrate mycelia, was isolated from bio-fertiliser of Musa spp. collected from Lampang Province, Thailand. Its morphological and chemotaxonomic properties, e.g., the presence of mycolic acid and MK-8 (H_4ω-cycl) in the cells, showed that strain LPG 2^T was a member of the genus Nocardia. 16S rRNA gene sequence analysis revealed that this strain was closely related to Nocardia otitidiscaviarum NBRC 14405^T (98.7 %). The low average nucleotide identity-blast and digital DNA-DNA hybridization values (<78.6 and <24.0 %, respectively), and several phenotypic differences between strain LPG 2^T and its related Nocardia type strains, indicated that the strain merits classification as representing a novel species of the genus Nocardia, for which we propose the name Nocardia acididurans sp. nov. The type strain is LPG 2^T (=TBRC 11242^T=NBRC 114293^T).

MLSA phylogeny and antimicrobial susceptibility of clinical Nocardia isolates: a multicenter retrospective study in China

Background

With the increase of detection rate and long treatment period, nocardiosis has become a noticeable problem in China. However, there are limited large-scale studies on the epidemiology and antimicrobial susceptibility profiles of clinical Nocardia spp. in China. The present study aimed to explore the species distribution and drug susceptibility pattern of 82 clinical Nocardia isolates from three tertiary hospitals in China by multilocus sequence analysis (MLSA) and broth microdilution (BMD) method.

Results

Pulmonary nocardiosis (90.2%) was the most common clinical presentation of infection. N. cyriacigeorgica (n = 33; 40.2%) and N. farcinica (n = 20; 24.4%) were the most frequently encountered Nocardia species, followed by N. otitidiscaviarum (n = 7; 8.5%), N. abscessus (n = 5; 6.1%), N. asiatica (n = 4; 4.9%), and N. wallacei (n = 4; 4.9%). Trimethoprim/sulfamethoxazole (SXT) remained high activity against all Nocardia isolates (susceptibility rate: 98.8%). Linezolid and amikacin were also highly active; 100 and 95.1% of all isolates demonstrated susceptibility, respectively. Except for N. otitidiscaviarum, all the Nocardia isolates exhibited high susceptibility rates to imipenem. The resistance rates of all isolates to clarithromycin and ciprofloxacin were 92.7 and 73.2%, respectively, but the resistance rate of N. farcinica to ciprofloxacin was only 25%.

Conclusions

The clinically isolated Nocardia spp. had diverse antimicrobial susceptibility patterns, which were similar to the reports by other groups elsewhere, but some differences were also observed, mainly including imipenem and ciprofloxacin. According to this study, SXT still can be the first choice for empirical therapy due to the low resistance rate. Linezolid can be chosen when a patient is allergic to SXT, and amikacin and imipenem can be the choice in a combination regimen.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02412-x.

The Role of GM-CSF Autoantibodies in Infection and Autoimmune Pulmonary Alveolar Proteinosis: A Concise Review

Autoantibodies to multiple cytokines have been identified and some, including antibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF), have been associated with increased susceptibility to infection. High levels of GM-CSF autoantibodies that neutralize signaling cause autoimmune pulmonary alveolar proteinosis (aPAP), an ultrarare autoimmune disease characterized by accumulation of excess surfactant in the alveoli, leading to pulmonary insufficiency. Defective GM-CSF signaling leads to functional deficits in multiple cell types, including macrophages and neutrophils, with impaired phagocytosis and host immune responses against pulmonary and systemic infections. In this article, we review the role of GM-CSF in aPAP pathogenesis and pulmonary homeostasis along with the increased incidence of infections (particularly opportunistic infections). Therefore, recombinant human GM-CSF products may have potential for treatment of aPAP and possibly other infectious and pulmonary diseases due to its pleotropic immunomodulatory actions.

Evaluation of antimicrobial susceptibility testing of Nocardia spp. isolates by broth microdilution with resazurin and spectrophotometry

BACKGROUND

Nocardia species are ubiquitous in natural environments and can cause nocardiosis. In the present study, the use of Resazurin salt and Spectrophotometry were proposed as alternative methods to reduce subjectivity in the interpretation of susceptibility results to antimicrobials by the broth microdilution method for Nocardia spp.

RESULTS

The susceptibility of Nocardia spp. isolates to Amikacin, Ciprofloxacin, Minocycline and Trimethoprim-Sulfamethoxazole was evaluated by Minimum Inhibitory Concentration (MIC) determinations by the broth microdilution method. To verify cellular growth, the colour-changing dye Resazurin was applied, the Optical Densities were measured on a spectrophotometer, and both were compared to Clinical and Laboratory Standards Institute (CLSI) Gold Standard method (visual MIC determination). Percentages of essential and categorical agreements and interpretative categorical errors were calculated within each method (intra-reading) and between them (inter-reading). The Gold Standard visual reading demonstrated 100% of essential and categorical intra-reading agreements for Amikacin, and there was no error when compared with the alternative methods. For Ciprofloxacin, the comparison between the Gold Standard and the Spectrophotometric reading showed 91.5% of essential agreement. In the categorical intra-reading analysis for Minocycline, there were 88.1 and 91.7% in the Gold Standard and in the Spectrophotometric readings, respectively, and 86.4% of concordance between them. High rates of categorical agreement were also observed on the Trimethoprim-Sulfamethoxazole analyses, with 93.7% for the Gold Standard, 84.9% for the Resazurin readings, and 80.5% between them.

CONCLUSIONS

The alternative methods with Resazurin and Spectrophotometric readings showed high agreement rates with the Gold Standard.

Soil actinobacteria inhibit antagonistic fungi of leafcutter ant colonies

Founder females of the leaf-cutting ant species Atta sexdens experience high mortality during the founding and establishment of their colonies. The foundation site is crucial for the success of a new colony. In this study, we isolated and identified actinobacteria from fungus garden chambers of A. sexdens colony growth in soils from (1) forested areas without leafcutter ant nests and (2) open ground areas close to leafcutter ant nests. The inhibitory effect of these isolates on pathogenic fungi and the mutualistic fungus cultivated by leafcutter ants was evaluated. The 16S rRNA gene sequences were employed to identify nine selected actinobacteria species found in the soil: Streptomyces (6), Nocardia (2), and Kitasatospora (1). One Streptomyces and one Kitasatospora isolate inhibited all the tested fungi. Since there is no evidence of actinobacteria cultivation in the workers' cuticle of the Atta genus, our results corroborate the hypothesis that these workers may establish temporary adaptive symbiosis with soil microorganisms that produce antibiotic substances, living in some parts of their nest, or even inside their bodies. Pathogenic fungi are a risk factor that can be controlled by actinobacteria metabolites from soils, with minimal energy cost to the colony.

Recurrent nocardiosis in solid organ transplant recipients: An evaluation of secondary prophylaxis

BACKGROUND

Immunocompromised individuals are at risk for Nocardia infection, with a recurrence rate of approximately 5%. Solid organ transplant (SOT) recipients often receive secondary prophylaxis due to their requirement of lifelong immunosuppression. However, data supporting this practice is sparse. We sought to evaluate Nocardia recurrence in SOT recipients, specifically evaluating secondary prophylaxis.

METHODS

We conducted a retrospective cohort study of SOT recipients diagnosed with nocardiosis from 2000 through 2020. We included adult SOT recipients who completed their course of Nocardia therapy and had at least 6 months of posttherapy follow-up. The primary outcome was Nocardia recurrence, which included relapse and reinfection.

RESULTS

One hundred two patients met inclusion criteria. Sixty-six (64.7%) were male and mean age was 58.6 ± 11.7 years. Most common SOT types were kidney (46.1%), heart (18.6%), kidney-pancreas (11.8%), and lung (10.8%). Most common sites of infection were lung (85.3%), skin (17.6%), and brain (14.7%). Secondary prophylaxis was utilized in 53 (52.0%) patients. Trimethoprim-sulfamethoxazole (TMP-SMX) single-strength daily was the most common prophylaxis agent and dose. Five patients (4.9%) experienced Nocardia recurrence, three of which were receiving secondary prophylaxis at time of recurrence. Two recurrences were with the same Nocardia species. Factors associated with recurrence were lung transplantation (p = .011), chronic lung disease (p = .032), and treatment ≤120 days (p = .006). Time from treatment completion to recurrence ranged from 107 to 875 days.

CONCLUSIONS

Nocardia recurrence in SOT recipients is an uncommon event. TMP-SMX secondary prophylaxis is incompletely protective and recurrence may be dependent upon other factors. Further study of secondary prophylaxis is warranted.

Insights from the comparative genome analysis of natural rubber degrading Nocardia species

Nocardia are known to be a facultative human pathogen and can cause infection in immune compromised patients. Though the details research on the virulence factors of Nocardia are scanty but numerous genes that code such factors were reported from different species of Nocardia. Despite of the presence of several virulence factors, species of this genus have been shown to have role in remediation of many toxic and hazardous materials from the environment. In this study, genome sequences of rubber degrading Nocardia sp. BSTN01 and N.nova SH22a have been analyzed to locate the potential virulence genes. Also, the genomes of facultative pathogenic Nocardia like, N.africana, N. brasiliensis, N. kruczakiae, N. transvalensis and N. veterana have been analyzed to find the gene encoding latex clearing protein (Lcp), a rubber oxygenase enzyme of Gram-positive action bacteria. The study provides an insight about the potentiality of rubberdegrading Nocardia species to emerge as future human pathogens and also the probability of a serious concern if the studied facultative pathogens of Nocardia like N. africana, N. brasiliensis, N. kruczakiae, N. transvalensis and N. veterana are capable of degrading rubber, a regularly used material in clinics. Moreover, use of such possible pathogenic strains for their known role in bioremediation of rubber waste from the environment might be deleterious.

Diagnosis and Neurosurgical Management of Cerebral Nocardiosis

Primary Nocardia infections are uncommon gram-positive bacterial infections caused by aerobic actinomycetes and are typically regarded as opportunistic infections (only one-third of infected patients are immunocompetent). Risk factors include: glucocorticoid therapy, malignancy, organ transplant recipients, human immunodeficiency virus infections, tumor necrosis factor-α inhibitor therapy, diabetes mellitus, alcoholism, inflammatory bowel disease, chronic obstructive pulmonary disease, chronic granulomatous disease, and tuberculosis. The organism has a predisposition to disseminate to the central nervous system and can relapse or progress despite appropriate therapy. Treatment ranges from oral antibiotic management to multiple intravenous antibiotic therapy, with surgical intervention required for severe cases. The surgical options include aspiration or complete excision of abscess contents and capsule. In the present case, we describe the use of bilateral craniotomy with assisted image guidance and multiple abscess excision in an immunocompetent patient with systemic nocardiosis.

Isolated nocardial brain abscess in an immunocompetent patient with lung adenocarcinoma: A case report

Brain metastases are common in non-small cell lung cancer (NSCLC) and can often be the presenting symptom. However, it is important to consider other etiologies for brain masses even in patients with a malignancy with a propensity to metastasize. We discuss the case of a 60 year-old immunocompetent male who presented with neurologic deficits thought to be secondary to brain metastases in the setting of an incidentally discovered lung cancer. Instead, the mass proved to be a rare isolated Nocardial brain abscess.

Nocardiosis in Immunocompromised Patients on Alternative Pneumocystis Prophylaxis

Prophylactic trimethoprim/sulfamethoxazole (TMP/SMX) prevents Pneumocystis jirovecii pneumonia and nocardiosis in immunocompromised patients but sometimes is avoided because of purported allergies or side effects. Of 25 immunocompromised patients receiving alternative prophylaxis in whom nocardiosis developed, 16 subsequently tolerated TMP/SMX treatment. Clinicians should consider TMP/SMX allergy evaluation and rechallenging to assess patient tolerance.

Sulfamethoxazole-induced sulfamethoxazole urolithiasis: a case report

BACKGROUND

Drug-induced urolithiasis falls into two categories: drug-induced and metabolically-induced. Certain antimicrobials are associated with each; sulfonamides are associated with drug- or metabolite-containing calculi when taken in large doses over a long period of time. Trimethoprim-sulfamethoxazole, a member of the sulfonamide family, is a rare cause of drug-induced calculi. Cases of sulfonamide urolithiasis occurring in patients with known stone disease have rarely been reported.

CASE PRESENTATION

We report a case of a patient with a brief history of recurrent calcium oxalate nephrolithiasis requiring 2 ureteroscopic procedures whose existing 6 mm lower pole renal stone more than quadrupled in size to form a 4 cm renal staghorn after 4 months of high-dose treatment for Nocardia pneumonia with trimethoprim-sulfamethoxazole. After ureteroscopy with laser lithotripsy and basketing of fragments, the stone was found to be predominantly composed of N4-acetyl-sulfamethoxazole, a metabolite of sulfamethoxazole.

CONCLUSION

Stones composed of sulfamethoxazole or its metabolites are rare but have known associated risk factors that should be considered when prescribing this antibiotic. This case report illustrates additional risk factors for consideration, including pre-existing urinary calculi that may serve as a nidus for sulfamethoxazole deposition, and reviews treatment and prevention methods.

False-positive galactomannan antigen testing in pulmonary nocardiosis

Early diagnosis of invasive aspergillosis (IA) is facilitated by detection of galactomannan (GM) in serum and bronchoalveolar lavage fluid (BALF) using an enzyme-linked immunosorbent assay (ELISA). Although accurate, false positive results have been reported with these tests in numerous contexts. We report for the first time the occurrence of false positive GM ELISA due to nocardiosis, initially in a clinical sample of BALF from a patient with pulmonary nocardiosis, and subsequently corroborated by in vitro reactivity of 26% of tested isolates. Since patients at risk for IA are also at risk for nocardiosis, this finding has important clinical implications.

LAY SUMMARY

Early diagnosis of aspergillosis has been facilitated by the routine use of antibody-based detection of galactomannan in various bodily fluids. We report for the first time the occurrence of false positive results of this assay in the context of nocardiosis.

Diagnosing Disseminated Nocardiosis in a Patient With COVID-19 Pneumonia

Signs and symptoms of atypical pneumonia include fever, shortness of breath, cough, and chest pain. During the coronavirus disease 2019 (COVID-19) pandemic, identifying other causes of febrile respiratory illness in patients who tested positive for COVID-19 has been very challenging. Concerns over infecting healthcare personnel and other patients can impede further evaluations like bronchial lavage, lung biopsies, and other invasive tests. A very high index of suspicion, perhaps unreasonably so, is required to perform invasive tests to investigate alternative possible causes of the illness. We present the case of a 63-year-old man who presented to the hospital with dyspnea. Chest X-ray demonstrated a consolidation in the left lower lobe lung field with a possible underlying mass, and the patient tested positive for COVID-19. He received the standard treatment for COVID pneumonia at the time in our institution (remdesivir and dexamethasone), empiric antibiotics for community-acquired pneumonia, and was eventually discharged home with supplemental oxygen. Several days later, the patient returned to the hospital again with worsening dyspnea and was readmitted. Persistent illness and worsening imaging prompted bronchoscopy. The bronchoscopy showed narrowing of the airway in the left upper lobe, and Nocardia asteroides was isolated from bronchial aspirate. The isolation of Nocardia prompted an investigation for central nervous system involvement with an magnetic resonance imaging (MRI) of the head. The MRI demonstrated multiple bilateral ring-enhancing lesions in the brain. To our knowledge, this is the first reported case of disseminated nocardiosis superimposed on COVID-19 pneumonia.

UPLC-PDA coupled HR-TOF ESI/MS2 -based identification of derivatives produced by whole-cell biotransformation of epothilone A using Nocardia sp. CS692 and a cytochrome P450 overexpressing strain

Epothilone A, a microtubule-stabilizing agent used as therapeutics for the treatment of cancers, was biotransformed into three metabolites using Nocardia sp. CS692 and recombinant Nocardia overexpressing a cytochrome P450 from Streptomyces venezuelae (PikC). Among three metabolites produced in the biotransformation reaction mixtures, ESI/MS² analysis predicted two metabolites (M1 and M2) as novel hydroxylated derivatives (M1 is hydroxylated at the C-8 position and M2 is hydroxylated at C-10 position), each with an opened-epoxide ring in their structure. Interestingly, metabolite M3 lacks an epoxide ring and is known as deoxyepothilone A, which is also called epothilone C. Metabolite M1 was produced only in PikC overexpressing strain. The endogenous enzymes of Nocardia sp. catalyzed hydroxylation of epothilone A to produce metabolite M2 and removed epoxide ring to produce metabolite M3. All the metabolites were identified based on UV-vis analysis and rigorous ESI/MS² fragmentation based on epothilone A standard. The newly produced metabolites are anticipated to display novel cytotoxic effects and could be subjects of further pharmacological studies.

Empyema necessitans with osteomyelitis of fifth rib due to Nocardia farcinica: a case report

BACKGROUND

Empyema necessitans is a rare pulmonary condition described as the presence of pus in the pleural cavity with insidious extension into the surrounding soft tissue. The common microbial aetiology of empyema necessitans is tuberculosis. Nocardiosis a cause of empyema necessitans is rarely described in the literature. We herein present a case of an 80-year-old male with empyema necessitans with osteomyelitis of rib caused by Nocardia farcinica.

CASE PRESENTATION

An 80-year-old male presented with complaints of soft swelling on the left lower posterior chest wall associated with dry cough and breathlessness on exertion. Computed Tomography (CT) thorax demonstrated empyema necessitans with features of left fifth rib osteomyelitis. Radiological guided aspiration of the chest wall collection revealed Nocardia species and surgical drainage of abscess was performed. Matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) identified the isolate as Nocardia farcinica. He was treated with three-drug regimen: Trimethoprim-sulfamethoxazole, amikacin and ceftriaxone for 2 weeks. After showing improvement patient was discharged and advised to take oral Trimethoprim-sulfamethoxazole for the next 6 months with periodic follow-up.

CONCLUSIONS

As our case demonstrates, the possibility of invasive Nocardiosis should not be overlooked even in immunocompetent patients. Clinicians should aware of this rare entity while treating patients with empyema necessitans.

Disseminated Nocardia Paucivorans in an immunocompetent patient: A case report and literature review

Nocardia paucivorans can cause disseminated infection in immunocompetent hosts in rare occasions. Nocardia paucivorans is usually susceptible to many antibiotics including Trimethoprim/Sulfamethoxazole. Duration of treatment is usually 6-12 months.