Nocardiosis from 1888 to 2017

A Case of Pulmonary Nocardiosis Presenting with Multiple Cavitary Nodules in a Patient with Thrombocytopenia

Nocardiosis is an infrequent opportunistic infection that deserves more attention because of its increasing morbidity and high rate of misdiagnosis. Clinical and radiological manifestations as well as antibiograms of pulmonary nocardiosis are diverse. Herein, we report a patient with idiopathic thrombocytopenia treated with glucocorticoids, which later presented with severe pulmonary infection with widely distributed nodules on chest computed tomography. Fungal infection or tuberculosis was under initial suspicion and microbiological tests of bronchoalveolar lavage fluid eventually yielded an affirmative result of Nocardia cyriacigeorgica. The patient responded in the beginning; however, therapeutic strategies had to be altered several times due to adverse events. The patient eventually ended up with radiographic resolution at the end of six months. We wish to share some experience in dealing with this disease especially recognizing pulmonary nocardiosis in computed tomography imaging.

Disseminated Nocardia paucivorans Infection Resembling Metastatic Disease in a Kidney Transplant Recipient

Recipients of solid-organ transplants (SOT) or hematopoietic stem-cell transplants are prone to various complications, including serious infections. Nocardiosis is an opportunistic bacterial infection that primarily affects the lung. It may also cause skin and soft-tissue infection, cerebral abscess, bloodstream infection, or infection involving other organs. We present a case of an immunocompromised kidney transplant recipient who experienced a prolonged history of unexplained indolent constitutional symptoms without a fever. Initial radiographic findings were suggestive of metastatic disease at multiple sites. However, metagenomic next-generation sequencing of microbial cell-free DNA in blood revealed disseminated Nocardia paucivorans infection, and organisms consistent with Nocardia were identified on histopathology of a lung biopsy. It is crucial for healthcare providers to be aware of unusual opportunistic infections to provide appropriate workups and interventions for immunocompromised SOT recipients.

Estradiol Aggravate Nocardia farcinica Infections in Mice

Males are generally more susceptible to Nocardia infection than females, with a male-to-female ratio of 2 and higher clinical disease. 17β-Estradiol has been implicated in affecting the sex-based gap by inhibiting the growth of N. brasiliensis in experiments, but the underlying mechanisms have not yet been fully clarified. In the present study, however, we report increased severity in N. farcinica IFM 10152-infected female mice compared with male mice with increased mortality, elevated lung bacterial loads and an exaggerated pulmonary inflammatory response, which was mimicked in ovariectomized female mice supplemented with E2. Similarly, the overwhelming increase in bacterial loads was also evident in E2-treated host cells, which were associated with downregulating the phosphorylation level of the MAPK pathway by binding the estrogen receptor. We conclude that although there are more clinical cases of Nocardia infection in males, estrogen promotes the survival of the bacteria, which leads to aggravated inflammation in females. Our data emphasize the need to include and separately analyze both sexes in future studies of Nocardia to understand the sex differences in immune responses and disease pathogenesis.

Transcriptome analysis in the spleen of Northern Snakehead (Channa argus) challenged with Nocardia seriolae

Northern snakehead (Channa argus) is an indigenous fish species and is one of popularly cultured snakeheads in China and other Asian countries. Unfortunately, Nocardia seriolae infections have caused considerable losses in the snakehead aquaculture industry. However, the infectivity and the immune response induced by N. seriolae in snakehead are unclear. In order to better understand the immune response of Northern snakehead in a series of time points after N. seriolae challenge, we conducted the transcriptomic comparison in snakehead spleen at 48, 96, and 144 h after the challenge of N. seriola against their control counterparts. Gene annotation and pathway analysis of differentially expressed genes (DEGs) were carried out to understand the functions of the DEGs. Additionally, protein-protein interaction networks were conducted to obtain the interaction relationships of immune-related DEGs. These results revealed the expression changes of multiple DEGs and signaling pathways involved in immunity during N. seriolae infection, which will facilitate our comprehensive understanding of the mechanisms involved in the immune response to bacterial infection in the northern snakehead.

Comprehensive Analysis of the Nocardia cyriacigeorgica Complex Reveals Five Species-Level Clades with Different Evolutionary and Pathogenicity Characteristics

Nocardia cyriacigeorgica is a common etiological agent of nocardiosis that has increasingly been implicated in serious pulmonary infections, especially in immunocompromised individuals. However, the evolution, diversity, and pathogenesis of N. cyriacigeorgica have remained unclear. Here, we performed a comparative genomic analysis using 91 N. cyriacigeorgica strains, 45 of which were newly sequenced in this study. Phylogenetic and average nucleotide identity (ANI) analyses revealed that N. cyriacigeorgica contained five species-level clades (8.6 to 14.6% interclade genetic divergence), namely, the N. cyriacigeorgica complex (NCC). Further pan-genome analysis revealed extensive differences among the five clades in nine functional categories, such as energy production, lipid metabolism, secondary metabolites, and signal transduction mechanisms. All 2,935 single-copy core genes undergoing purifying selection were highly conserved across NCC. However, clades D and E exhibited reduced selective constraints, compared to clades A to C. Horizontal gene transfer (HGT) and mobile genetic elements contributed to genomic plasticity, and clades A and B had experienced a higher level of HGT events than other clades. A total of 129 virulence factors were ubiquitous across NCC, such as the mce operon, hemolysin, and type VII secretion system (T7SS). However, different distributions of three toxin-coding genes and two new types of mce operons were detected, which might contribute to pathogenicity differences among the members of the NCC. Overall, our study provides comprehensive insights into the evolution, genetic diversity, and pathogenicity of NCC, facilitating the prevention of infections.

IMPORTANCENocardia species are opportunistic bacterial pathogens that can affect all organ systems, primarily the skin, lungs, and brain. N. cyriacigeorgica is the most prevalent species within the genus, exhibits clinical significance, and can cause severe infections when disseminated throughout the body. However, the evolution, diversity, and pathogenicity of N. cyriacigeorgica remain unclear. Here, we have conducted a comparative genomic analysis of 91 N. cyriacigeorgica strains and revealed that N. cyriacigeorgica is not a single species but is composed of five closely related species. In addition, we discovered that these five species differ in many ways, involving selection pressure, horizontal gene transfer, functional capacity, pathogenicity, and antibiotic resistance. Overall, our work provides important clues in dissecting the evolution, genetic diversity, and pathogenicity of NCC, thereby advancing prevention measures against these infections.

Molecular Identification of Nocardia seriolae and Comparative Analysis of Spleen Transcriptomes of Hybrid Snakehead (Channa maculata Female × Channa argus Male) With Nocardiosis Disease

Hybrid snakehead (Channa maculata female × Channa argus male) is a new freshwater aquaculture fish species in southern China. During intensive aquaculture, hybrid snakeheads are often infected by Nocardia seriolae. In this study, hybrid snakehead infected suspiciously by N. seriolae in an artificial breeding pond were examined. Diseased hybrid snakeheads swam slowly without food intake, and the clinical symptoms included skin wound, anal swelling and ascites, and white granulomatous in liver, spleen, and kidney of fish. Through bacterial isolation, 16S rDNA sequencing, fluorescence in situ hybridization (FISH) and artificial infection experiment, the pathogen was identified as N. seriolae. Furthermore, the spleen samples from diseased and healthy male hybrid snakeheads in the same pond were used for RNA-Seq analysis. A total of 3,512 unique transcripts (unigenes) were identified as differentially expressed genes (DEGs), and 1,886 of them were up-regulated in diseased fish. The expression patterns of 20 DEGs were verified by quantitative polymerase chain reaction (qPCR). Several immune-related pathways and many immune-related genes were identified. qPCR results showed that the expression patterns of immune-related genes in the liver and kidney of diseased fish were comparable to that in the spleen. This study provides deep-sequencing data of hybrid snakehead spleen and will help understand the immune response of hybrid snakehead to N. seriolae. It is also helpful for the biomarker screening of fish-borne Nocardia spp. and the breeding of nocardiosis-resistant fish species.

Unusual presentation of Nocardia abscessus infection in an immunocompetent patient

Introduction. Nocardia infections are being increasingly reported in both immunocompetent and immunocompromised patients. We describe a case of Nocardia abscessus infection with an atypical presentation in an immunocompetent patient.

Case Presentation. A previously healthy 47-year-old gentleman presented with hiccups and paroxysmal spasms. Imaging revealed a pulmonary nodule, for which he underwent surgical resection. Pathologic evaluation demonstrated evidence of local inflammation, with growth of Nocardia abscessus on tissue cultures.

Conclusion. Nocardia abscessus may have atypical presentations in immunocompetent patients. Further research is needed to understand the factors leading to Nocardia infections in immunocompetent patients.

Disseminated Nocardia farcinica involves the spinal cord: a case report and review of the literature

Background

Nocardia is a relatively rare opportunistic pathogenic bacteria group, commonly seen in patients with immunocompromised or defective immune system. It can affect multiple organs of the body and cause disseminated infection, among which most occurs in the lung, secondly in the nervous system, soft tissues, rare in the spinal cord and pituitary. No case has been reported involving lung, spinal cord, skin and pituitary gland at the same time.

Case presentation

We report a 55-year-old female with Nocardia infection involving the lung, skin, spinal cord, and pituitary gland. The patient underwent a full set of imaging examinations and showed typical imaging findings. Chest computed tomography (CT) showed multiple nodules with cavities in the lungs. The magnetic resonance imaging (MRI) of the vertebral body showed abnormal signal of the entire spinal cord with cavity formation and ring enhancement. The subcutaneous nodules of the abdomen were punctured under ultrasound. Through the etiological tissue culture of subcutaneous nodules and the second generation sequencing of cerebrospinal fluid, the diagnosis was finally confirmed.

Conclusion

Disseminated Nocardiosis is an uncommon disease. This article will report a rare case of disseminated Nocardiosis simultaneously involving the lung, spinal cord, subcutaneous soft tissue and pituitary gland, especially with neuropathy as the initial symptom. Imaging is helpful for the early diagnosis of the disease and pathological and microbiological examinations are helpful for its confirming.

Membranous Nephropathy Complicated with Disseminated Nocardia farcinica Infection: A Case Report and Literature Review

Disseminated infection caused by Nocardia farcinica with primary nephrotic syndrome is exceedingly rare. A 66-year-old female visited the outpatient department due to fever and fatigue who had been diagnosed as membranous nephropathy and with a long-term prednisone and immunosuppressive therapy. After lung biopsy for many times, culture from space-occupying lesion of the right lung and species identification by mass spectrometry-based methods (MALDI-TOF) revealed Nocardia farcinica. By imaging examination, space-occupying lesions from the lungs, brain, abdominal cavity and kidney were found. After 2 weeks of meropenem intravenous and up to 6 months of trimethoprim-sulfamethoxazole (TMP-SMX) therapy, our patient has remained relapse-free at that time of writing. Disseminated infection caused by Nocardia farcinica is usually subacute with complex clinical manifestations. In addition, it can be easily confused with diseases such as tumor and mycobacterial infection, and lead to fatal consequences. Therefore, we hope that we can remind clinicians considering by discussing common features of disseminated Nocardia farcinica infection.

Whole genome sequencing reveals the genomic diversity, taxonomic classification, and evolutionary relationships of the genus Nocardia

Nocardia is a complex and diverse genus of aerobic actinomycetes that cause complex clinical presentations, which are difficult to diagnose due to being misunderstood. To date, the genetic diversity, evolution, and taxonomic structure of the genus Nocardia are still unclear. In this study, we investigated the pan-genome of 86 Nocardia type strains to clarify their genetic diversity. Our study revealed an open pan-genome for Nocardia containing 265,836 gene families, with about 99.7% of the pan-genome being variable. Horizontal gene transfer appears to have been an important evolutionary driver of genetic diversity shaping the Nocardia genome and may have caused historical taxonomic confusion from other taxa (primarily Rhodococcus, Skermania, Aldersonia, and Mycobacterium). Based on single-copy gene families, we established a high-accuracy phylogenomic approach for Nocardia using 229 genome sequences. Furthermore, we found 28 potentially new species and reclassified 16 strains. Finally, by comparing the topology between a phylogenomic tree and 384 phylogenetic trees (from 384 single-copy genes from the core genome), we identified a novel locus for inferring the phylogeny of this genus. The dapb1 gene, which encodes dipeptidyl aminopeptidase BI, was far superior to commonly used markers for Nocardia and yielded a topology almost identical to that of genome-based phylogeny. In conclusion, the present study provides insights into the genetic diversity, contributes a robust framework for the taxonomic classification, and elucidates the evolutionary relationships of Nocardia. This framework should facilitate the development of rapid tests for the species identification of highly variable species and has given new insight into the behavior of this genus.

Nocardia species can be responsible for opportunistic infections in humans, causing a variety of clinical presentations. They can also cause mycetoma in a normal host through direct inoculation. Although these species are often overlooked and misunderstood by modern medicine, they can cause life-threatening infections. However, most of our knowledge about Nocardia is based upon case reports and a few small studies of limited scope. This study provides an overview of the taxonomic and evolutionary structure of the genus Nocardia through extensive analysis of genome sequences. Our work aids the field by dissecting the genetic diversity of this species and improving the identification scheme for Nocardia species.

A rare case of pulmonary nocardiosis comorbid with Sjogren's syndrome

Background

Nocardia is an opportunistic pathogen, which occurs in patients with autoimmune diseases and immune dysfunction, and can cause bacteremia and other life‐threatening complications. The clinical manifestations of Nocardia pneumonia are similar to tuberculous and other clinical common bacterial pneumonia, but its antibacterial treatments are different and detection methods are unique, which may lead patients to suffer for many years due to clinical misdiagnosis and missed diagnosis.

Methods

Imaging and laboratory examinations were performed for preliminary diagnosis, and next‐generation sequencing was used to identify the exact species type of Nocardia in the bronchoalveolar lavage fluid (BALF) of the patient.

Results

Imaging and laboratory parameters preliminarily implied that the patient was infected with Nocardia with Sjogren's syndrome (SS), and NGS showed that the strain was N. terpenica.

Conclusions

Accurate etiological diagnosis and corresponding antibiotics are key to improve the prognosis of pulmonary nocardiosis in this case. Nocardia pneumonia is rare in clinical practice; it is of great medical significance to improve the understanding of pulmonary nocardiosis.

Case report: pulmonary nocardiosis caused by Nocardia exalbida in an immunocompetent patient

BACKGROUND

Nocardiosis is known as an opportunistic infection in immunocompromised hosts, but it occasionally has been reported in immunocompetent patient. The Nocardia exalbida is first-reported in 2006 from Japan, and a few cases of have been reported in only immunocompromised host, and the characteristic is still unclear. We herein describe the first case of pulmonary nocardiosis caused by N. exalbida in an immunocompetent patient.

CASE PRESENTATION

A77 -year-old Japanese man was admitted to our hospital on November 2, 2018. He was a lifelong non-smoker with no childhood history of respiratory disease. He had a medical history of dyslipidemia. One month before this admission fevers, sputum, mild cough were developed and he was evaluated in a clinic near our hospital. His diagnosis was community acquired pneumonia within his right middle lobe. He was treated with ceftriaxone 1 g/day intravenously for a week, however his symptoms relapsed a few days later. So, the physician retried ceftriaxone for another 3 days, but his symptoms did not improve. He was referred to our hospital. He was treated with sitafloxacin as an outpatient for a week, however his symptoms got worse. The chest CT showed consolidation and atelectasis in his right middle lobe. Low density area was scattered in consolidation, and right pleural effusion was observed. The patient was diagnosed with pulmonary abscess and he was admitted. Administration of piperacillin/tazobactam improved his condition. We switched antibiotics to amoxicillin/clavulanate, and he was discharged. After 2 weeks, he relapsed and was admitted again. After administration of piperacillin/tazobactam for 3 weeks, we perform bronchoscopy and Nocardia species were cultured from samples of the bronchial wash. The isolates were identified as N. exalbida using 16S rRNA gene sequencing. We prescribed Trimethoprim / Sulfamethoxazole (TMP/SMX) for 4 months. Then we switched to minocycline for renal dysfunction caused from TMP-SMX for 1 more month. After 5 months therapy, Consolidation on CT disappeared, and Nocardiosis was cured.

CONCLUSION

we reported the first case of pulmonary nocardiosis caused by N. exalbida in an immunocompetent patient. N. exalbida infection might be associated with a good response to treatment.

A case report of brain abscess caused by Nocardia farcinica

Background

Brain abscess due to the Nocardia genus is rarely reported and it is usually found in immunocompromised patients. Treatment of Nocardia brain abscess is troublesome and requires consideration of the severity of the underlying systemic disease. The difficulties in identifying the bacterium and the frequent delay in initiating adequate therapy often influence the prognosis of patients.

Case presentation

Here, we report a rare case of brain abscess caused by Nocardia farcinica. The patient’s medical history was complicated: he was hospitalized several times, but no pathogens were found. At last, bacteria were found in the culture of brain abscess puncture fluid; the colony was identified as Nocardia farcinica by mass spectrometry. Targeted antibiotic treatment was implemented, brain abscess tended to alleviate, but the patient eventually developed fungal pneumonia and died of acute respiratory distress syndrome (ARDS).

Conclusion

Brain abscess caused by Nocardia farcinica can appear in non-immunocompromised individuals. Early diagnosis, reasonable surgical intervention, and targeted antibiotic treatment are critical for Nocardia brain abscess treatment. In the treatment of Nocardia brain abscess, attention should paid be to the changes in patients’ immunity and infection with other pathogens, especially fungi, avoided.

The Role of 18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT) in Management of Nocardiosis: A Retrospective Study and Review of the Literature

Introduction

18-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is a well-established tool for managing metastatic infections. Nocardiosis, a primarily pulmonary infection, disseminates at high rates. Routine imaging includes chest CT and brain imaging. We examined the use of FDG-PET/CT in nocardiosis and assessed its contribution to diagnosis and management.

Methods

A retrospective study in two tertiary medical centers during 2011–2020. Individuals with nocardiosis for whom FDG-PET/CT was implemented for any reason were included and their medical records were reviewed. A board-certified nuclear medicine physician independently reviewed all scans. Additionally, a systematic review was conducted according to the PRISMA guidelines, to extract data from publications reporting FDG-PET/CT use for the management of nocardiosis.

Results

FDG-PET/CT contributed to the management of all seven patients who met inclusion criteria. It assisted in ruling out an underlying malignancy (29%, 2/7); establishing a wide infection extent (57%, 4/7); and affecting decisions regarding treatment (57%, 4/7), including drug regimen, oral step-down, and duration of therapy. We identified 20 published case reports on this topic. In 80% (16/20), FDG-PET/CT contributed to the management of nocardiosis similar to our study. In addition, in most of the literature cases, FDG-PET/CT guided the diagnostic biopsy.

Conclusion

FDG-PET/CT is valuable in the diagnosis and management of individuals with nocardiosis. The contribution of incorporating FDG-PET/CT to the management of individuals with nocardiosis and its role in monitoring treatment response and shortening treatment duration should be evaluated in prospective studies.

Disseminated nocardiosis involving the central nervous system in the context of newly diagnosed HIV infection: A case report

BACKGROUND

A newly diagnosed HIV patient with tuberculosis-like symptoms was confirmed with disseminated nocardiosis involving the central nervous system (CNS). This case report provides novel insights into the diagnosis and treatment of nocardiosis.

CASE PRESENTATION

A 44-year-old male newly diagnosed HIV patient presented on March 20, 2017, with the major symptoms of fever and headache. Computed tomography (CT) of the chest showed a mass in the lower lobe of the right lung. Brain magnetic resonance imaging (MRI) revealed multiple abnormal signals and ring enhancement. Blood culture suggested the presence of mycobacteria and positive acid-fast staining, and the strain was identified as Nocardia. He was administered an anti-infective therapeutic regimen consisting of cefotaxime sodium and sulbactam sodium (2.25 g, qid, iv), linezolid (0.6 g, bid, iv), moxifloxacin (0.4 g, qd, iv), sulfamethoxazole (1.44 g, qid, per os), and amikacin (0.4 g, qd, iv). After treatment, fever and skin nodules resolved, and reexamination by chest CT and brain MRI suggested improvement compared with the pretreatment situation.

CONCLUSIONS

At present, there are few reports of disseminated Nocardia infection involving the CNS in HIV patients in China. This case report will help to enhance the understanding of disseminated Nocardia infection. In the process of clinical diagnosis and treatment, Nocardia may be initially misdiagnosed as disseminated TB. In the present case, tuberculosis-like symptoms actually corresponded to disseminated nocardiosis involving the CNS.

Isolation and Characterization of Nocardia Species from Pulmonary Nocardiosis in a tertiary hospital in China

The aim of this study was to investigate the clinical features, distribution and antimicrobial susceptibility of Nocardia species isolated from pulmonary nocardiosis cases in tertiary hospital in China. The species were collected from January 1, 2018 to May 31, 2019 and identified using MALDI-TOF MS or PCR. Antimicrobial susceptibility testing was performed using the broth microdilution method. Within the 44 Nocardia species, N. farcinica was the most frequently identified species (n = 36), followed by N. nova (n = 5), N. otitidiscaviarum (n = 1), N. cyriacigeorgica (n = 1), and N. transvalensis (n = 1). The top three predisposing factors of pulmonary nocardiosis were chronic obstructive pulmonary disease (45.5%), hypertension (34.1%), and tuberculosis (31.8%). All 44 Nocardia strains were susceptible to amikacin, trimethoprim / sulfamethoxazole, and linezolid. The resistance rates of Nocardia to amoxicillin-clavulanic acid, ciprofloxacin, clarithromycin, ceftriaxone, tobramycin, and imipenem were 4.5%, 9.1%, 79.5%, 72.7%, 63.6%, and 38.6%, respectively. Two Nocardia strains had decreased sensitivity to trimethoprim / sulfamethoxazole. In conclusion, N. farcinica was the most frequently isolated Nocardia species in the First Hospital of Changsha. All isolated clinical Nocardia strains showed susceptible to amikacin, trimethoprim / sulfamethoxazole, and linezolid, suggesting that these drugs can be primary therapeutic choices for treating Nocardia infections.

Evaluation of pathogenicity and therapeutic effectiveness of antibiotics using silkworm Nocardia infection model

Nocardia is a ubiquitous environmental microbe that causes nocardiosis against immunosuppressed and immunocompromised hosts. The assay system for the quantitative evaluation of virulence of Nocardia sp. or therapeutic effectiveness of antimicrobials for treatment of nocardiosis is not established so far. In this study, we established an infection model of Nocardia sp. using silkworm as an alternative animal model. We found that all tested Nocardia sp. such as Nocardia asiatica, Nocardia elegans, Nocardia exalbida, Nocardia farcinica, and Nocardia nova killed silkworm and their killing ability were different by species. N. farcinica showed higher pathogenicity among tested strain, similar to the mouse model as previously reported. In addition, we found that antimicrobials such as amikacin and minocycline showed therapeutic effectiveness in silkworms infected with N. farcinica, and we could determine effective doses 50 (ED₅₀) values. These results suggest that silkworm is a useful alternative animal to evaluate the pathogenicity of Nocardia pathogen and the therapeutic effects of antimicrobials against Nocardia sp. in a quantitative manner.

Pulmonary alveolar proteinosis complicated with nocardiosis: A case report and review of the literature

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a pulmonary syndrome wherein large volumes of phospholipid and protein-rich surfactants accumulate within the alveoli. PAP forms include primary (auto-immune PAP), secondary, and congenital. Nocardiosis is a form of suppurative disease induced upon infection with bacteria of the Nocardia genus. Clinically, cases of PAP complicated with Nocardia infections are rare, regardless of form. Unfortunately, as such, they are easily overlooked or misdiagnosed. We describe, here, the case of a patient suffering from simultaneous primary PAP and nocardiosis.

CASE SUMMARY

A 45-year-old Chinese man, without history of relevant disease, was admitted to our hospital on August 8, 2018 to address complaints of activity-related respiratory exertion and cough lasting over 6 mo. Lung computed tomography (CT) revealed diffuse bilateral lung infiltration with local consolidation in the middle right lung lobe. Subsequent transbronchial lung biopsy and CT-guided lung biopsy led to a diagnosis of primary PAP (granulocyte-macrophage colony-stimulating factor antibody-positive) complicated with nocardiosis (periodic acid-Schiff-positive). After a 6 mo course of anti-infective treatment (sul-famethoxazole), the lesion was completely absorbed, such that only fibrous foci remained, and the patient exhibited significant symptom improvement. Follow-up also showed improvement in pulmonary function and the CT imaging findings of PAP. No whole-lung lavage has been conducted to date. This case highlights that active anti-nocardia treatment may effectively improve the symptoms and alleviate PAP in patients with PAP and nocardia, possibly reducing the need for whole-lung lavage.

CONCLUSION

When evaluating patients presenting with PAP and pulmonary infections, the potential for nocardiosis should be considered.

Characterization of the Rothia spp. and their role in human clinical infections

The genus Rothia are emerging as opportunistic pathogens associated with various infections in immunocompromised and immunocompetent individuals. This review describes the taxonomy, cell wall structure, pathogenesis, phenotypic and molecular characteristics, clinical diseases, treatment and, as well as, the related genera that may be misidentified by Rothia species.

Pulmonary Nocardiosis in Pemphigus Vulgaris Patients from Tehran, Iran

OBJECTIVE

Nocardiosis is an opportunistic infection in individuals who had organ transplants and in patients with immunosuppressive diseases such as pemphigus Vulgaris (PV), diabetes mellitus, and HIV. Nocardiosis rate has not been assessed in Iranian PV patients, and this was the first study to estimate nocardiosis rate in these patients.

METHODS

In this study, 103 patients with PV were examined. BAL samples were obtained and direct smear was prepared and visualized by microscopy after PAS staining. Samples were cultured on antibiotic-containing blood and chocolate agar media. DNA extraction and PCR were performed on positive cultures, and final identification was done by 16S rRNA gene sequencing. Drug susceptibility testing was done by microbroth dilution method.

RESULTS

Four positive cultures (3.88%) were found in the samples (n = 103). According to sequence analysis, 2 isolates were identified as Nocardia cyriacigeorgica and 2 as Nocardia otitidiscaviarum and Nocardia cerradoensis. Nocardia cerradoensis was isolated from an invasive brain infection. Isolated bacteria were susceptible to majority of the tested antibiotics, except for 2 strains of Nocardia cyriacigeorgica and Nocardia cerradoensis. This was the first isolation of Nocardia cerradoensis of human infection in Asia. Patients with PV are susceptible to nocardiosis, similar to other immunocompromised patients.

CONCLUSION

Pemphigus Vulgaris is a severe autoimmune disease which is treated by a high dosage of corticosteroids. Opportunistic infections are one of the greatest challenges of these patients. One of the neglected agents of opportunistic infection in this disorder is Nocardiosis which can cause a high mortality rate in PV patients.

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.

Pharmacovigilance during treatment of multiple sclerosis: early recognition of CNS complications

An increasing number of highly effective disease-modifying therapies for people with multiple sclerosis (MS) have recently gained marketing approval. While the beneficial effects of these drugs in terms of clinical and imaging outcome measures is welcomed, these therapeutics are associated with substance-specific or group-specific adverse events that include severe and fatal complications. These adverse events comprise both infectious and non-infectious complications that can occur within, or outside of the central nervous system (CNS). Awareness and risk assessment strategies thus require interdisciplinary management, and robust clinical and paraclinical surveillance strategies. In this review, we discuss the current role of MRI in safety monitoring during pharmacovigilance of patients treated with (selective) immune suppressive therapies for MS. MRI, particularly brain MRI, has a pivotal role in the early diagnosis of CNS complications that potentially are severely debilitating and may even be lethal. Early recognition of such CNS complications may improve functional outcome and survival, and thus knowledge on MRI features of treatment-associated complications is of paramount importance to MS clinicians, but also of relevance to general neurologists and radiologists.

Nocardiosis at an Organ Transplant Center in Saudi Arabia: 15 years' experience

Background:

Nocardiosis is a rare infection that affects immunocompromised patients on immunosuppressive medications used for transplantation and cancer therapy. Such therapies are becoming more widely available in the Middle East region. Yet, reports on nocardiosis are scarce.

Materials and Methods:

This was a retrospective analysis of patients who were diagnosed with nocardiosis from 2004 to 2018 at a transplantation and cancer center. Nocardiosis were defined per the European Organization for Research and Treatment of Cancer criteria.

Results:

During the study period, 35 patients with nocardiosis (male: 68.5%) were identified. The most common underlying associated condition was transplantation 11 (31.4%), followed by malignancy 7 (20%), connective tissue disease and sarcoidosis 7 (20%), chronic lung disease 5 (14%), miscellaneous conditions 4 (11%), and one patient with human immunodeficiency virus. Nocardia was disseminated in 8 patients (22.9%) and isolated in 27 (77.1%); the latter included 13 patients (37.1%) with bronchial form, 11 (31.4%) with isolated visceral form, and 3 (8.6%) with cutaneous form. Pulmonary involvement occurred in 90% of the cases with cough, fever, and dyspnea being the most common symptoms. The main strain isolate was Nocardia asteroides, and the cure rate was 90%. Mortality related to nocardiosis occurred in 3 transplant patients (8.6%).

Conclusion:

Wider use of immunosuppressive therapy warrants vigilance to nocardiosis, which can present in a myriad of clinical forms. In our series, mortality was confined to the transplantation group, probably because of the relatively heavy immunosuppression. Nonetheless, prognosis is favorable if the infection is recognized and treated early.

Role of Williamsia and Segniliparus in human infections with the approach taxonomy, cultivation, and identification methods

The genera Williamsia and Segniliparus are of aerobic actinomycetes and at the time of writing, they have 12 and 2 species, respectively. These genera cause various infections in humans. In this review, we surveyed their taxonomy, isolation, identification, as well as their role to cause human infections.

Pulmonary nocardiosis in a patient with pemphigus foliaceus: case report and literature review

BACKGROUND

Nocardiosis is an uncommon opportunistic infection seen in immunocompromised patients or those with a dysfunctional immune system. Nocardia asteroides infection in patients with Pemphigus foliaceus (PF) has never been reported.

CASE PRESENTATION

We report an interesting case of nocardiosis-characterized by pulmonary intra-cavitary infection, in a 54-year-old man with PF and diabetes mellitus. The man finally recovered from the infection.

CONCLUSIONS

This is the first case reporting pulmonary nocardiosis in a patient with PF. We recommend that physicians be aware of nocardiosis in patients with pemphigus as a possible cause of underlying infectious disease to avoid misdiagnoses and mismanagement.

Mce1C and Mce1D facilitate N. farcinica invasion of host cells and suppress immune responses by inhibiting innate signaling pathways

The mammalian cell entry (Mce) family of proteins consists of invasin-like membrane-associated proteins. The roles of Mce1C and Mce1D proteins in host–pathogen interactions have not been investigated. In this study, we demonstrate that Mce1C and Mce1D protein is localized in the cell wall fraction of N. farcinica. Both N. farcinica Mce1C and Mce1D proteins are expressed at the level of protein and mRNA and elicit antibody responses during infection. Mce1C and Mce1D facilitate the internalization of Escherichia coli expressing Mce1C protein or latex beads coated with Mce1D protein by HeLa cells, respectively. We further demonstrate that Mce1C and Mce1D can suppress the secretion of the proinflammatory factors TNF-α and IL-6 in macrophages infected with Mycobacterium smegmatis expressing Mce1C or Mce1D and promote the survival of M. smegmatis expressing Mce1C or Mce1D in macrophages. In addition, Mce1C and Mce1D supress the activation of the NF-κB and MAPK signaling pathways by blocking the phosphorylation of AKT, P65, ERK1/2, JNK, or P38 in macrophages. These findings suggest that Mce1C and Mce1D proteins facilitate N. farcinica invasion of HeLa cells and suppress host innate immune responses by manipulating NF-κB and MAPK signaling pathways, which may provide a target for N. farcinica treatment.

Performance and Application of 16S rRNA Gene Cycle Sequencing for Routine Identification of Bacteria in the Clinical Microbiology Laboratory

This review provides a state-of-the-art description of the performance of Sanger cycle sequencing of the 16S rRNA gene for routine identification of bacteria in the clinical microbiology laboratory. A detailed description of the technology and current methodology is outlined with a major focus on proper data analyses and interpretation of sequences. The remainder of the article is focused on a comprehensive evaluation of the application of this method for identification of bacterial pathogens based on analyses of 16S multialignment sequences. In particular, the existing limitations of similarity within 16S for genus- and species-level differentiation of clinically relevant pathogens and the lack of sequence data currently available in public databases is highlighted. A multiyear experience is described of a large regional clinical microbiology service with direct 16S broad-range PCR followed by cycle sequencing for direct detection of pathogens in appropriate clinical samples. The ability of proteomics (matrix-assisted desorption ionization-time of flight) versus 16S sequencing for bacterial identification and genotyping is compared. Finally, the potential for whole-genome analysis by next-generation sequencing (NGS) to replace 16S sequencing for routine diagnostic use is presented for several applications, including the barriers that must be overcome to fully implement newer genomic methods in clinical microbiology. A future challenge for large clinical, reference, and research laboratories, as well as for industry, will be the translation of vast amounts of accrued NGS microbial data into convenient algorithm testing schemes for various applications (i.e., microbial identification, genotyping, and metagenomics and microbiome analyses) so that clinically relevant information can be reported to physicians in a format that is understood and actionable. These challenges will not be faced by clinical microbiologists alone but by every scientist involved in a domain where natural diversity of genes and gene sequences plays a critical role in disease, health, pathogenicity, epidemiology, and other aspects of life-forms. Overcoming these challenges will require global multidisciplinary efforts across fields that do not normally interact with the clinical arena to make vast amounts of sequencing data clinically interpretable and actionable at the bedside.

Clinical correlates of nocardiosis

Nocardia is an opportunistic pathogen that most frequently affects the lungs. Evidence is limited regarding the risk factors for nocardiosis. The current study assessed clinical correlates of nocardiosis. A retrospective study was conducted based on medical records of consecutive adult patients (N = 60) with nocardiosis hospitalized during 2007–2018 at a tertiary hospital in central Israel. A matched comparison group of 120 patients was randomly selected among hospitalized patients with community-acquired pneumonia. Multivariable conditional logistic regression models were fitted. Immunosuppressive pharmacotherapy was positively associated with nocardiosis (matched odds ratio [OR] 4.40, 95% confidence interval [CI] 2.25–8.62, p < 0.001), particularly corticosteroid therapy (matched OR 4.69, 95% CI 2.45–8.99, p < 0.001). Systemic corticosteroid therapy was strongly associated with pulmonary nocardiosis (matched OR 5.90, 95% CI 2.75–12.66, p < 0.001). The positive association between solid organ transplantation and nocardiosis was attenuated following adjustment for systemic corticosteroids in a multivariable model. The association between corticosteroid therapy and nocardiosis appeared stronger in patients with chronic pulmonary disease (OR 5.74, 95% CI 2.75–12.66, p < 0.001) than in the pooled analysis of all nocardiosis cases. In conclusion, corticosteroid therapy was strongly correlated with nocardiosis, particularly among individuals with chronic pulmonary disease and in pulmonary nocardiosis.

New Nocobactin Derivatives with Antimuscarinic Activity, Terpenibactins A-C, Revealed by Genome Mining of Nocardia terpenica IFM 0406

We report a genomics-guided exploration of the metabolic potential of the brasilicardin producer strain Nocardia terpenica IFM 0406. Bioinformatics analysis of the whole genome sequence revealed the presence of a biosynthetic gene cluster presumably responsible for the generation of formerly unknown nocobactin derivatives. Mass spectrometry-assisted isolation led to the identification of three new siderophores, terpenibactins A (1), B (2) and C (3), which belong to the class of nocobactins. Their structures were elucidated by employing spectroscopic techniques. Compounds 1-3 demonstrated inhibitory activity towards the muscarinic M3 receptor, while exhibiting only a low cytotoxicity.

Efficient differentiation of Nocardia farcinica, Nocardia cyriacigeorgica and Nocardia beijingensis by high-resolution melting analysis using a novel locus

Accurate identification of Nocardia species remains a challenge due to the complexities of taxonomy and insufficient discriminatory power of traditional techniques. We report the development of a molecular technique that utilizes real-time PCR-based high-resolution melting (HRM) analysis for differentiation of the most common Nocardia species. Based on a novel fusA-tuf intergenic region sequence, Nocardia farcinica, Nocardia cyriacigeorgica and Nocardia beijingensis were clearly distinguished from one another by HRM analysis. The limit of detection of the HRM assay for purified Nocardia spp. DNA was at least 10 fg. No false positives were observed for specificity testing of 20 non-target clinical samples. In comparison to established matrix-assisted laser desorption/ionization-time of flight MS, the HRM assay improved the identification of N. beijingensis. Additionally, all the products of PCR were verified by direct sequencing. In conclusion, the developed molecular assay allows simultaneous detection and differentiation of N. farcinica, N. cyriacigeorgica and N. beijingensis with high sensitivity and specificity.

Nocardia nova Infection of Tibia Tenodesis Implant After Anterior Cruciate Ligament Reconstruction in an Immunocompetent Patient

Infection after anterior cruciate ligament reconstruction and Nocardia infection in immunocompetent hosts are rare events in isolation. This case report highlights the rare combination of these events in a 46-year-old healthy man who acquired a Nocardia nova infection of the tibia tunnel site after an anterior cruciate ligament reconstruction with peroneus allograft. He was successfully treated with tibial tenodesis screw removal, two surgical debridements, and 4 weeks of trimethoprim-sulfamethoxazole and meropenem, followed by 6 months of clarithromycin and original graft retention. This report will review the current antibiotic recommendations and surgical management of this challenging situation. Our case is unique in that the infection was isolated to the distal aspect of the tibial tunnel and did not spread into the entire knee joint, highlighting the importance of early debridement and irrigation in the operative suite when graft site infection is suspected.

Nocardia Bloodstream Infection: A Retrospective Clinical Analysis of Seven Cases in a Single Centre

Objective: Nocardiosis is a rare opportunistic infection caused by the Nocardia species. Nocardia bacteremia is a life-threatening presentation of disseminated nocardiosis that presents diagnostic and therapeutic challenges. We performed this retrospective analysis in a Chinese hospital from 2010 to 2019 to describe the characteristics of this rare bloodstream infection.

Methods: We searched the database of the real-time nosocomial infection surveillance system and identified patients whose blood cultures showed Nocardia bacteria growth. The medical records of these patients were extracted and analyzed by two independent researchers. The data included age, gender, complicating disease, duration from blood drawing to reporting, clinical signs and symptoms, blood routine and C-reactive protein results, radiological examinations, sites of involvement, antibiotic treatments, and outcomes.

Results: Seven patients with Nocardia bacteremia were found. There were four male and three female patients, whose ages ranged from 41 to 75 years. Six (85.7%) patients had predisposing conditions and were administrated corticosteroids for various reasons before the identification of Nocardia infection. The most common symptom was fever (100%). Five patients presented with lung or skin involvement; meanwhile, three patients presented with brain involvement. One patient presented with pelvic and peritoneum involvement, respectively. The most common findings of chest CT imaging were consolidation, followed by nodules and cavitations. Trimethoprim/sulfamethoxazole was prescribed to all patients after the diagnosis of Nocardia bacteremia. Six patients recovered, and one patient ultimately died.

Conclusions: Nocardia bacteremia is a rare bloodstream infection that usually occurs in immunocompromised patients. Clinical manifestations of patients are nonspecific. It often causes multiple organ involvement, and early diagnosis and prompt aggressive interventions are important to improve the outcome of this disease.

Nfa34810 Facilitates Nocardia farcinica Invasion of Host Cells and Stimulates Tumor Necrosis Factor Alpha Secretion through Activation of the NF-κB and Mitogen-Activated Protein Kinase Pathways via Toll-Like Receptor 4

The mechanism underlying the pathogenesis of Nocardia is not fully known. The Nfa34810 protein of Nocardia farcinica has been predicted to be a virulence factor. However, relatively little is known regarding the interaction of Nfa34810 with host cells, specifically invasion and innate immune activation. In this study, we aimed to determine the role of recombinant Nfa34810 during infection. We demonstrated that Nfa34810 is an immunodominant protein located in the cell wall.

The mechanism underlying the pathogenesis of Nocardia is not fully known. The Nfa34810 protein of Nocardia farcinica has been predicted to be a virulence factor. However, relatively little is known regarding the interaction of Nfa34810 with host cells, specifically invasion and innate immune activation. In this study, we aimed to determine the role of recombinant Nfa34810 during infection. We demonstrated that Nfa34810 is an immunodominant protein located in the cell wall. Nfa34810 protein was able to facilitate the uptake and internalization of latex beads coated with Nfa34810 protein into HeLa cells. Furthermore, the deletion of the nfa34810 gene in N. farcinica attenuated the ability of the bacteria to infect both HeLa and A549 cells. Moreover, stimulation with Nfa34810 triggered macrophages to produce tumor necrosis factor alpha (TNF-α), and it also activated mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways by inducing the phosphorylation of ERK1/2, p38, JNK, p65, and AKT in macrophages. Specific inhibitors of ERK1/2, JNK, and NF-κB significantly reduced the expression of TNF-α, which demonstrated that Nfa34810-mediated TNF-α production was dependent upon the activation of these kinases. We further found that neutralizing antibodies against Toll-like receptor 4 (TLR4) significantly inhibited TNF-α secretion. Taken together, our results indicated that Nfa34810 is a virulence factor of N. farcinica and plays an important role during infection. Nfa34810-induced production of TNF-α in macrophages also involves ERK, JNK, and NF-κB via the TLR4 pathway.

Safety and Outcomes of Linezolid Use for Nocardiosis

Background

Tropical Australia has a high incidence of nocardiosis, with high rates of intrinsic antimicrobial resistance. Linezolid, the only antimicrobial to which all local Nocardia species are susceptible, has been recommended in empirical combination treatment regimens for moderate-severe Nocardia infections at Royal Darwin Hospital (RDH) since 2014. We report the safety and efficacy of linezolid use for nocardiosis in this setting.

Methods

We identified cases through a retrospective review of all RDH Nocardia isolates from December 2014 to August 2018 and included 5 linezolid-treated cases from a previous cohort. Laboratory, demographic, and clinical data were included in the primary analysis of safety and treatment outcomes.

Results

Between 2014 and 2018, Nocardia was isolated from 35 individuals; 28 (80%) had clinically significant infection and 23 (82%) received treatment. All isolates were linezolid-susceptible. Safety and efficacy were assessed for 20 patients receiving linezolid-containing regimens and 8 receiving nonlinezolid regimens. Median linezolid induction therapy duration was 28 days. Common adverse effects in those receiving linezolid were thrombocytopenia (45%) and anemia (40%). Adverse events prompted discontinuation of trimethoprim-sulfamethoxazole more often than linezolid (40% vs 20%). Linezolid therapeutic drug monitoring was used in 1 patient, with successful dose reduction and outcome. There was no difference in 30-day survival between those treated with linezolid (90%) vs no linezolid (87%). One Nocardia-attributed death occurred during linezolid therapy.

Conclusions

Linezolid is safe and efficacious in empirical treatment for moderate to severe nocardiosis in a monitored hospital setting, with 100% drug susceptibility and no difference in adverse events or outcomes compared with nonlinezolid regimens.

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.

Lymphocutaneous nocardiosis caused by Nocardia brasiliensis in an immunocompetent patient: a case report

Nocardia usually manifests as opportunistic infections in immunocompromised hosts. Here, we report a rare case of an immunocompetent patient with lymphocutaneous nocardiosis. The patient was a 34-year-old man presenting with fever, multiple scattered pustules on both upper limbs and several subcutaneous nodules on the left elbow and forearm. Skin biopsy of the subcutaneous nodule revealed suppurative inflammation of the lymph nodes. Pus cultures were finally identified as Nocardia brasiliensis. The patient fully recovered without relapse after receiving optimized antimicrobial therapy consisting of linezolid combined with sulfonamides. Nocardiosis is a rare opportunistic disease which may be fatal and usually affects immunocompromised hosts, resulting in suppurative and granulomatous inflammation. Nocardia has a long culture cycle, is difficult to diagnose, and is more likely to be neglected in healthy young people. The present case suggests that physicians should be aware that nocardiosis is a differential diagnosis to consider in patients with suppurative infection, especially when anti-infective treatment is ineffective.

Nocardiosis: A Neglected Disease

Nocardiosis is a neglected tropical disease. It has varied geographical presence and a spectrum of clinical presentations. This review aims to focus on the epidemiology of nocardial infections with a systematic approach to their diagnosis and treatment. Nocardiacauses chronic infections and ailments, and may remain cryptic but progressive in its course. Unless suspected, diagnosis can be easily missed resulting in increased morbidity and mortality. Thorough knowledge of local epidemiology, demography, clinical course and presentation, diagnostic modalities, and antibiotic susceptibility patterns of the prevalent Nocardia species is essential to curb spread of this infection. This is a systematic review in which internet search has been done for citation indices (Embase, PubMed, Ovid, and other individual journals) till March 2020 utilizing the following key words "Nocardia," "taxonomy," "prevalence," "clinical features," "diagnosis," "treatment," and "susceptibility." We selected a total of 87 review articles, case series, and case reports all in English language.

Nocardia colonization in contrast to nocardiosis: a comparison of patients' clinical characteristics

Information on Nocardia colonization of the lower respiratory tract is scarce. The current study is aimed at comparing clinical characteristics between individuals with Nocardia colonization and those with nocardiosis. All patients with Nocardia isolation between 2007 and 2018 at a tertiary hospital in Israel were included. Nocardia isolation was based on biochemical tests together with phenotypic susceptibility and resistance patterns until 2011 and on matrix-assisted laser desorption/ionization time-of-flight mass spectrometer from 2012. We defined nocardiosis as a clinically evident infection related to the isolation of the bacteria, which required antibiotic therapy. We defined colonization as Nocardia isolation with no clinical evidence of disease. The medical charts of all included individuals were independently reviewed by an infectious disease specialist to ensure adequate classification. Logistic regression models were fitted to compare clinical characteristics between the groups. Fifteen (20%) of the 75 Nocardia isolations met the criteria for colonization. Of those, 13 (87%) had background illnesses. Having a chronic pulmonary disease was associated with increased likelihood of Nocardia colonization, in contrast to nocardiosis (adjusted odds ratio [OR] 4.06, 95% confidence interval [CI] 1.06-15.48, p = 0.040), while an inverse association was found with corticosteroid therapy (adjusted OR 0.21, 95% CI 0.06-0.74, p = 0.015). Nocardia colonization of the lower respiratory tract accounts for a substantial proportion of all Nocardia isolations. Individuals colonized with Nocardia typically have chronic pulmonary disease and are less frequently treated with corticosteroid than patients with nocardiosis.

Identification of common antigens of three pathogenic Nocardia species and development of DNA vaccine against fish nocardiosis

Fish nocardiosis is a chronic granulomatous bacterial disease and three pathogens have been reported so far, including Nocardia asteroids, N. seriolae and N. salmonicida. However, the absence of antigen markers is a bottleneck for developing effective vaccines against fish nocardiosis. In this study, the antigenicity of whole-cell protein of these three pathogenic Nocardia species were profiled by immunoproteomic analysis and 7 common immunogenic proteins were identified as follows: molecular chaperone DnaK (DnaK), molecular chaperone GroEL (GroEL), 30 S ribosomal protein S1 (RpsA), TerD family protein (TerD), FHA domain-containing protein (FHA), 50 S ribosomal protein L7/L12 (RplL) and PspA/IM30 family protein (PspA). Furthermore, the DNA vaccine encoding FHA gene against fish nocardiosis was developed and its efficacy was investigated in hybrid snakehead. The results suggested that it needed at least 7 d to transport pcDNA-FHA DNA vaccine from injected muscle to head kidney, spleen and liver and stimulate host's immune system for later protection. In addition, non-specific immunity paraments (serum lysozyme (LYZ), peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase (AKP) and superoxide dismutase (SOD) activities), specific antibody (IgM) titers production and immune-related genes (MHCIα, MHCIIα, CD4, CD8α, IL-1β and TNFα) were used to evaluate the immune response induced in pcDNA-FHA vaccinated hybrid snakehead, it proved that all these mentioned immune activities were significantly enhanced after immunization. The results also showed hybrid snakehead vaccinated with pcDNA-FHA had higher survival rate (79.33%) compared with the controls after challenge with N. seriolae, indicating that the pcDNA-FHA DNA vaccine can supply immune protection against N. seriolae infection. Taken together, this study may warrant further development of these common immunogenic proteins as the antigens for vaccine or diagnosis and facilitate the prevention and treatment of fish nocardiosis.

Pyogranulomatous pleuropneumonia caused by Nocardia asiatica in a dog coinfected with canine morbillivirus (canine distemper virus)

Nocardia asiatica causing pyogranulomatous pleuropneumonia is reported for the first time in a dog coinfected with canine morbillivirus (CM), diagnosed based on epidemiological, clinical, haematological, images, microbiological, histopathological, polymerase chain reaction and hsp65 gene sequencing findings. The immunosuppression of CM probably favoured the opportunistic behaviour of N. asiatica. Despite the therapeutic measures, the animal died, mainly due to respiratory distress. The association of methods to improve early diagnosis, therapy procedures and prognosis of canine nocardiosis is discussed, as well as the close relationship between pets and their owners, which may favour the transmission of pathogens such as Nocardia from pets‐to‐humans, which poses an emerging public health issue.

Peritonite piogranulomatosa por Nocardia concava em cão - relato de caso

RESUMO Nocardiose é causada por bactérias do gênero Nocardia do subgrupo Actinomycetos, que são Gram-positivas aeróbicas, filamentosas e podem apresentar ramificações. O diagnóstico baseia-se na presença de lesão inflamatória, com o microrganismo morfologicamente compatível, associada ao isolamento e à identificação microbiológica e molecular. Este trabalho tem por objetivo relatar um caso de nocardiose em canino, que desenvolveu inflamação piogranulomatosa peritoneal seis meses após ovariossalpingo-histerectomia. O animal apresentava hipertermia, distensão abdominal, taquipneia, polidipsia, hiporexia, mucosas hipocoradas e fezes pastosas. Os achados laboratoriais evidenciaram anemia leve e leucocitose por neutrofilia com desvio à esquerda e hipoalbuminemia. Uma massa na região mesogástrica e efusão peritoneal foram evidenciadas por meio da ultrassonografia abdominal. O líquido foi classificado como exsudato piogranulomatoso, e o animal submetido à laparotomia exploratória para lavagem abdominal e remoção da massa. Após procedimentos terapêuticos, ocorreu piora clínica e óbito. Peritonite piogranulomatosa foi a principal alteração anatomopatológica a qual foi associada à Nocardia spp. Molecularmente, a espécie isolada se aproxima da N. concava, por meio da análise filogenética. Essa espécie já foi descrita como causa de infecção em humanos na Ásia, no entanto não há registros na literatura na espécie canina, sendo este o primeiro relato.

Disseminated Nocardiosis: A Case Report

Disseminated nocardiosis is a rare infection associated with underlying immunosuppression, and patients usually have some identifiable risk factor affecting cellular immunity. Due to advances in taxonomy and microbiology identification methods, infections by Nocardia species are more frequent, making the discussion of its approach and choice of antibiotherapy increasingly relevant.

A 77-year-old man presented to the emergency department with marked pain on the right lower limb, weakness, and upper leg edema. He had been diagnosed with organized cryptogenic pneumonia one year before and was chronically immunosuppressed with methylprednisolone 32 mg/day. Blood cultures isolated Nocardia cyriacigeorgica. Computed tomography revealed a gas collection in the region of the right iliacus muscle with involvement of the gluteal and obturator muscles upwardly and on the supragenicular plane inferiorly. Triple therapy with imipenem, amikacin, and cotrimoxazole was started, and the patient was submitted for emergent surgical decompression, fasciotomy, and drainage due to acute compartment syndrome. The patient had a good outcome and was discharged from the hospital after 30 days of intravenous therapy. This case illustrates the severity of Nocardia infection and highlights the need for a meticulous approach in the diagnosis and treatment of these patients.

Antibiotic resistance genes in the Actinobacteria phylum

The Actinobacteria phylum is one of the oldest bacterial phyla that have a significant role in medicine and biotechnology. There are a lot of genera in this phylum that are causing various types of infections in humans, animals, and plants. As well as antimicrobial agents that are used in medicine for infections treatment or prevention of infections, they have been discovered of various genera in this phylum. To date, resistance to antibiotics is rising in different regions of the world and this is a global health threat. The main purpose of this review is the molecular evolution of antibiotic resistance in the Actinobacteria phylum.