Nocardiosis: a review

Structure-guided discovery of novel dUTPase inhibitors with anti-Nocardia activity by computational design

The zoonosis caused by Nocardia is increasing seriously. But commonly used antibiotic drugs often lead to resistance. N. seriolae dUTPase (NsdUTPase) plays a key role in the proliferation of Nocardia, and was regarded as a potent drug target. However, there was little report about the NsdUTPase inhibitors. In this study, we discovered a series of novel NsdUTPase inhibitors to fight against Nocardia. The first crystal structure of NsdUTPase was released, and a structure-based computational design was performed. Compounds 4b and 12b exhibited promising activities towards NsdUTPase (IC50 = 0.99 μM and 0.7 μM). In addition, they showed satisfied anti-Nocardia activity (MIC value ranges from 0.5 to 2 mg/L) and low cytotoxicity, which were better than approved drugs oxytetracycline and florfenicol. Molecular modelling study indicated that hydrophobic interaction might be the main contribution for ligand binding. Our results suggested that NsdUTPase inhibitors might be a useful way to repress Nocardia.

Infection route influence the consequences of Nocardia farcinica infection in BALB/c mice

BACKGROUND

Nocardia, a rare but potentially fatal pathogen, can induce systemic infections with diverse manifestations. This study aimed to investigate the tissue and organ damage caused by Nocardia farcinica (N. farcinica) in mice via different infection routes, evaluate the resulting host immune responses, and assess its invasiveness in brain tissue.

METHODS

BALB/c mice were infected with N. farcinica through intranasal, intraperitoneal, and intravenous routes (doses: 1 × 10^8, 1 × 10^7, 1 × 10^7 CFU in 50 µl PBS). Over a 7-day period, body temperature, weight, and mortality were monitored, and samples were collected for histopathological analysis and bacterial load assessment. Serum was isolated for cytokine detection via ELISA. For RNA-seq analysis, mice were infected with 1 × 107 CFU through three infection routes, after which brain tissue was harvested.

RESULTS

Intraperitoneal and intravenous N. farcinica infections caused significant clinical symptoms, mortality, and neural disruption in mice, resulting in severe systemic infection. Conversely, intranasal infection primarily affected the lungs without causing significant damage to other organs. Intraperitoneal and intravenous infections significantly increased serum cytokines, particularly TNF-α and IFN-γ. RNA-seq analysis of brains from intravenously infected mice revealed significant differential gene expression, whereas the intranasal and intraperitoneal routes showed limited differences (only three genes). The enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in the intravenous group were primarily related to immune processes.

CONCLUSION

The study demonstrated that intravenous N. farcinica infection induces significant clinical symptoms, triggers an inflammatory response, damages multiple organs, and leads to systemic infections.

Multiple brain abscesses caused by Nocardia farcinica infection after hand injury: A case report and literature review

RATIONALE

Nocardia infection is commonly regarded as an opportunistic pulmonary pathogen affecting debilitated or immunocompromised individuals. Brain abscesses caused by Nocardia farcinica are rare and pose a diagnostic challenge. Traditional diagnostic techniques for identifying Nocardia species, such as blood culture, microscopy, and pathology, have shown inadequate performance. In the reported case, we applied metagenomic next-generation sequencing (mNGS) to diagnose a case of brain abscess due to N. farcinica.

PATIENT CONCERNS

A 66-year-old female developed a brain abscess after sustaining a hand injury. The patient exhibited a gradual change in personality and experienced tremors in her right upper limb for a duration of 1 month.

DIAGNOSES

The pathogen responsible for the multiple brain abscesses was identified in the cerebrospinal fluid as N. farcinica through mNGS.

INTERVENTIONS

Antibiotic treatment included trimethoprim-sulfamethoxazole, linezolid, amikacin, meropenem, and moxifloxacin.

OUTCOMES

The patient's symptoms and signs improved significantly after administration of antibiotics to which the pathogen is known to be sensitive. After 5 months of follow-up, magnetic resonance imaging of the head showed that the abscess was basically cured. The patient lived a normal life with no adverse drug reactions.

LESSONS

Nocardia brain infection is characterized by an insidious onset and lacks distinctive clinical and imaging features. mNGS was advantageous for the timely identification and management of Nocardia-associated brain abscess in the present case and obviated the need for invasive brain surgery. Expeditious and precise diagnosis coupled with prompt antibiotic therapy can significantly reduce the mortality rate associated with this condition.

Enhanced effectiveness in preventing Nocardia seriolae infection utilizing heterologous prime-boost approach in orange-spotted grouper Epinephelus coioides

Persistent nocardiosis has prompted exploration of the effectiveness of heterologous approaches to prevent severe infections. We have previously reported the efficacy of a nucleic acid vaccine in protecting groupers from highly virulent Nocardia seriolae infections. Ongoing research has involved the supplementation of recombinant cholesterol oxidase (rCho) proteins through immunization with a DNA vaccine to enhance the protective capacity of orange-spotted groupers. Recombinant rCho protein exhibited a maturity and biological structure comparable to that expressed in N. seriolae, as confirmed by Western blot immunodetection assays. The immune responses observed in vaccinated groupers were significantly higher than those observed in single-type homologous vaccinations, DNA or recombinant proteins alone (pcD:Cho and rCho/rCho), especially cell-mediated immune and mucosal immune responses. Moreover, the reduction in N. seriolae occurrence in internal organs, such as the head, kidney, and spleen, was consistent with the vaccine's efficacy, which increased from approximately 71.4 % to an undetermined higher percentage through heterologous vaccination strategies of 85.7 %. This study underscores the potential of Cho as a novel vaccine candidate and a heterologous approach for combating chronic infections such as nocardiosis.

Successful Treatment of Disseminated Nocardiosis by Rapid Identification of the Organism via Genetic Analysis in a Leukemia Patient Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Nocardia infections have been reported to occur in immunocompromised patients. Early diagnosis and therapeutic intervention are especially important for disseminated nocardiosis because of its high mortality rate. A case of disseminated nocardiosis after allogeneic hematopoietic stem cell transplantation, which was promptly treated after identification of the organism by genetic analysis, is presented. A 43-year-old man was diagnosed with T-cell prolymphocytic leukemia and underwent allogeneic hematopoietic stem cell transplantation. Subsequently, during long-term prednisolone administration for chronic graft-versus-host disease, he developed mass lesions throughout his body at 1033 days after transplantation. Pus culture and genetic testing of the parotid mass showed Nocardia farcinica, which improved with treatment with sulfamethoxazole, trimethoprim, and imipenem cilastatin, and there has been no recurrence. When multiple mass lesions occur after hematopoietic stem cell transplantation, and the diagnosis is difficult, disseminated nocardiosis should be included in the differential diagnosis, and appropriate laboratory testing and treatment should be performed.

["And zebras do exist after all"! : Pulmonary nocardiosis: case series and overview]

Nocardiosis is a rare disease that occurs primarily in patients with predisposing factors (immunosuppression/chronic lung disease). It is caused by aerobic, Gram-positive bacteria that are ubiquitous in soil. Cutaneous and pulmonary manifestations are most common, but disseminated forms also occur. In terms of treatment, long-term antibiotic therapy is usually necessary. The prognosis for the cutaneous or pulmonary form is generally good.

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

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

How an Antimicrobial Stewardship Team Treated a Nocardia farcinica-Associated Brain Abscess: A Case Report

Nocardia species, which are ubiquitous in the environment, form lesions primarily in immunocompromised patients via oral or cutaneous infection. Some of these Nocardia species, such as N. farcinica, also infect the central nervous system via hematogenous dissemination, which rarely results in brain abscesses. Notably, N. farcinica is resistant to numerous antimicrobial drugs used in empirical therapy, necessitating the intervention of an infectious disease specialist. To date, no case of antimicrobial stewardship teams (ASTs) playing a central role in community hospitals without an infectious disease specialist has been reported. Here, we describe a case of N. farcinica-associated brain abscess in a small-to-medium-sized hospital with no infectious disease department or specialist, in which the AST assisted in the identification of the causative organism and in selecting appropriate therapeutic agents, ultimately leading to a cure. The patient was an 88-year-old man with a high fever. He had been taking prednisolone (10-15 mg/day) for approximately 1 year for pemphigoid. Considering the possibility of fever owing to bacteremia of cutaneous origin, ampicillin/sulbactam antimicrobial therapy at 6 g/day was initiated. A subsequent close examination led to the diagnosis of a brain abscess. Emergency abscess drainage was performed by a neurosurgeon, and postoperative antimicrobial combination therapy comprising ceftriaxone (4 g/day), vancomycin (2 g/day), and metronidazole (1,500 mg/day) was commenced. The AST suspected Nocardia infection earlier, but further testing was difficult to perform at this facility. Therefore, by requesting assistance from Nagoya University Hospital, we performed early bacterial identification by mass spectrometry and appropriate antimicrobial susceptibility testing by a custom panel on day 11. The patient was non-responsive to all the previously used antibiotics at the time of admission. On day 13 after admission, the patient was successfully treated with trimethoprim-sulfamethoxazole (TMP-SMX) and imipenem/cilastatin sodium, and the patient was cured. The AST can be as effective as an infectious disease specialist when a strong working relationship is established between the team and clinicians. Further, the activities of the AST can improve patient survival via active medical support in collaboration with attending physicians.

Disseminated Nocardia nova in a child with relapsed acute lymphoblastic leukemia: a case report

BACKGROUND

Nocardiosis is a rare infection that typically results from inhalation of or inoculation with Nocardia organisms. It may cause invasive disease in immunocompromised patients. This case describes nocardiosis with bacteremia and pulmonary involvement in a child with a hematologic malignancy.

CASE PRESENTATION

A boy with testicular relapsed acute lymphoblastic leukemia with marrow involvement presented with sudden onset of fever, body aches, headaches, chills, and moderate respiratory distress during continuation 2 chemotherapy. Radiographic imaging demonstrated consolidation and ground glass opacities in bilateral lower lungs. Central line blood cultures grew Nocardia nova complex, prompting removal of the central line and initiation of triple therapy with imipenem-cilastatin, linezolid, and trimethoprim-sulfamethoxazole with rapid improvement of symptoms. Antibiotic susceptibilities showed a multidrug-susceptible isolate. The patient is anticipated to remain on trimethoprim-sulfamethoxazole for at least 12 months.

CONCLUSIONS

In an immunocompromised child, blood cultures, chest imaging, and head imaging can aid in the diagnosis of disseminated nocardiosis. Long-term antibiotic therapy is necessary, guided by the organism and simplified with the results of antimicrobial susceptibility testing.

Nocardia brasiliensis Pyomyositis in an Immunocompetent Patient Following Gardening Activity

Nocardia pyomyositis in immunocompetent patients is a rare occurrence. The diagnosis may be missed or delayed with the risk of progressive infection and suboptimal or inappropriate treatment. We present the case of a 48-year-old immunocompetent firefighter diagnosed with pyomyositis caused by Nocardia brasiliensis acquired by direct skin inoculation from gardening activity. The patient developed a painful swelling on his right forearm that rapidly progressed proximally and deeper into the underlying muscle layer. Ultrasound imaging of his right forearm showed a 7-mm subcutaneous fluid collection with surrounding edema. Microbiologic analysis of the draining pus was confirmed to be N brasiliensis by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry. After incision and drainage deep to the muscle layer to evacuate the abscess and a few ineffective antibiotic options, the patient was treated with intravenous ceftriaxone and oral linezolid for 6 weeks. He was then de-escalated to oral moxifloxacin for an additional 4 months to complete a total antibiotic treatment duration of 6 months. The wound healed satisfactorily and was completely closed by the fourth month of antibiotic therapy. Six months after discontinuation of antibiotics, the patient continued to do well with complete resolution of the infection. In this article, we discussed the risk factors for Nocardia in immunocompetent settings, the occupational risks for Nocardia in our index patient, and the challenges encountered with diagnosis and treatment. Nocardia should be included in the differential diagnosis of cutaneous infections, particularly if there is no improvement of "cellulitis" with traditional antimicrobial regimens and the infection extends into the deeper muscle tissues.

Microplastic polymer properties as deterministic factors driving terrestrial plastisphere microbiome assembly and succession in the field

Environmental microplastic (MP) is ubiquitous in aquatic and terrestrial ecosystems providing artificial habitats for microbes. Mechanisms of MP colonization, MP polymer impacts, and effects on soil microbiomes are largely unknown in terrestrial systems. Therefore, we experimentally tested the hypothesis that MP polymer type is an important deterministic factor affecting MP community assembly by incubating common MP polymer types in situ in landfill soil for 14 months. 16S rRNA gene amplicon sequencing indicated that MP polymers have specific impacts on plastisphere microbiomes, which are subsets of the soil microbiome. Chloroflexota, Gammaproteobacteria, certain Nitrososphaerota, and Nanoarchaeota explained differences among MP polymers and time points. Plastisphere microbial community composition derived from different MP diverged over time and was enriched in potential pathogens. PICRUSt predictions of pathway abundances and quantitative PCR of functional marker genes indicated that MP polymers exerted an ambivalent effect on genetic potentials of biogeochemical cycles. Overall, the data indicate that (i) polymer type as deterministic factor rather than stochastic factors drives plastisphere community assembly, (ii) MP impacts greenhouse gas metabolism, xenobiotic degradation and pathogen distribution, and (iii) MP serves as an ideal model system for studying fundamental questions in microbial ecology such as community assembly mechanisms in terrestrial environments.

Clinical characteristics, outcomes, and factors associated with mortality in Nocardia pneumonia: 18 years' real-world data from a tertiary care hospital in Karachi, Pakistan

BACKGROUND

Pulmonary nocardiosis is a rare pulmonary infection with high morbidity and mortality. Limited real-world data on pulmonary nocardiosis patients are available from developing countries like Pakistan.

METHODS

This retrospective observational study was conducted at the Aga Khan University Hospital, Karachi, Pakistan, from August 2003 to June 2020. Demographics, immune status, underlying diseases, laboratory data, treatment, and outcomes of all nocardiosis patients were recorded in predesigned proforma.

RESULTS

Sixty-six patients with smear/culture-proven pulmonary nocardiosis were identified. Most patients (83.3%) were treated with trimethoprim-sulfamethoxazole alone or in combination with other medicines. The overall mortality rate in our study was 33.3% (n = 22/66). Factors significantly associated with mortality were respiratory failure (p < 0.001), raised procalcitonin levels (p = 0.01), concomitant fungal infections (p = 0.01), concomitant TB (p = 0.03), and patients on combination therapy (p < 0.001). Respiratory failure (odds ratio [OR] 46.94 [95% confidence intervals [CI]: 5.01-439.03] p < 0.001), concomitant fungal infection (OR 17.09 [95% CI: 1.47-197.88] p- = 0.02) and patients on combination therapy (OR 6.90 [95% CI: 1.23-38.61] p = 0.02) were also identified as independent risk factors for mortality on multivariate analysis.

CONCLUSIONS

This study provides essential information on the clinical characteristics and risk factors, outcomes, and factors associated with mortality for pulmonary nocardial infections.

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.

A fatal case of disseminated nocardiosis due to Nocardia otitidiscaviarum resistant to trimethoprim-sulfamethoxazole: case report and literature review

Background

Disseminated nocardiosis still causes significant morbidity and mortality and is often caused by Nocardia asteroides, N. basiliensis, and N. farcinica and are often treated with trimethoprim–sulfamethoxazole (TMP–SMX). Nocardia otitidiscaviarum (N. otitidiscaviarum) rarely causes disseminated disease and resistance to TMP–SMX is even more rare.

Case presentation

A 37-year-old woman with metastatic breast cancer and right ear deafness with recent occupational gardening and manipulating soil, presented to the hospital with first time seizure and multiple skin nodules. Magnetic resonance imaging (MRI) showed ring enhancing lesions, biopsy of the skin and brain lesions grew N. otitidiscaviarum. She was empirically treated with TMP–SMX and Imipenem–Cilastatin, however, almost three weeks into therapy, susceptibility results revealed it to be resistant to both antimicrobials, she was subsequently changed to Amikacin, Linezolid, Moxifloxacin, and Doxycycline but ultimately died.

Conclusions

This case report highlights the importance of suspecting a rare Nocardia species in patients at risk with proper occupational exposure, moreover, TMP–SMX resistance should be suspected with lack of clinical response, this may have important implications on clinical practice when facing similar infections.

Brain Abscess Caused by Nocardia farcinica and Diagnosed by Metagenomic Next-Generation Sequencing: A Case Report

Background

Brain abscesses caused by Nocardia farcinica are rare and difficult to diagnose. Conventional methods for diagnosing Nocardia species include blood culture, microscopy, and tissue slice, but the performance is not satisfied. We report a case of brain abscess due to N. farcinica diagnosed by metagenomic next-generation sequencing (mNGS).

Case Presentation

We report a case of a 58-year-old man with brain abscess caused by N. farcinica. The patient had a history of pemphigus and required long-term methylprednisolone administration. No pathogen was detected in blood culture, cerebrospinal fluid (CSF) culture, and fast-acid staining. mNGS identified N. farcinica in the CSF. The symptoms and signs of the patient were significantly improved after changing the antibiotics accordingly to sensitive antibiotics.

Conclusion

Metagenomic next-generation sequencing (mNGS) is helpful for early diagnosis and subsequent treatment of Nocardia-associated meningitis and encephalitis, avoiding brain surgery. Early and accurate diagnosis and prompt antibiotic treatment reduced its mortality.

Disseminated Nocardiosis in a Breast Cancer Patient Caused by Nocardia otitidiscaviarum: A Case Report of Tertiary Centre in Saudi Arabia

Nocardiosis is a rare opportunistic disease that primarily affects patients with deficient immune systems. Nocardia otitidiscaviarum is one of the rare species of Nocardia and it represents less than 3% of all Nocardia cases. Clinical presentation can be varied according to the affected organ. This study describes a case of a breast cancer patient who is immunocompromised due to the chemotherapy. This patient presented with a feature of febrile neutropenia. Investigations of this case led to the diagnosis of Nocardia otitidiscaviarum. Treatment of this underlying infection required to hold the chemotherapy for good time and to adapt patient-specific cancer treatment according to the balance between both need of cancer control and infection treatment according to the susceptibility test as in our case.

Nocardiosis in Free-Ranging Cetaceans from the Central-Eastern Atlantic Ocean and Contiguous Mediterranean Sea

We report the pathologic features of nocardiosis in five free-ranging delphinids from the Canary Islands and Andalusia, namely four striped dolphins (Stenella coerulealba) and one bottlenose dolphin (Tursiops truncatus). All animals had a multiorgan (disseminated) pattern of infection involving suppurative to pyogranulomatous and thromboembolic lesions in two or more organs. Most affected organs were (by decreasing order) lung, pulmonary lymph nodes, liver, kidney, adrenal glands, and central nervous system. Typical intralesional and intravascular branched and filamentous bacteria were highlighted by Grocott's methenamine silver and Gram stains. Bacterial analysis including 16S rRNA gene sequencing identified Nocardia farcinica in two striped dolphins and Nocardia otitidiscaviarum in one striped dolphin and the bottlenose dolphin. All dolphins tested (n = 4) for cetacean morbillivirus were negative; one dolphin had concurrent cutaneous herpesvirosis. These results provide the first record of N. otitidiscaviarum in cetaceans, the first account of N. farcinica in free-ranging dolphins, and confirmation of nocardiosis in central eastern Atlantic Ocean. These results expand the known geographic range of nocardiosis in cetaceans.

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.

Primary Nocardia brain abscesses and role of intraventricular antibiotic therapy

Intracranial infections caused by Nocardia Farcinica are challenging to treat and potentially lethal because of the organism's tendency to resist antibiotics and high relapse rates. Such infections usually occur in immunocompromised patients who have predisposing factors. Nocardia brain abscesses carry a higher morbidity and mortality rate than other bacterial brain abscesses, with reported mortality rates of 55% (even up to 90% in cases of late diagnosis) in immunocompromised patients. An aggressive therapeutic approach is required and an early identification of the microorganism is paramount. Given the high microbial resistance, it is usually an infection with a low cure rate. We present the case of a patient with primary brain abscesses due to Nocardia Farcinica, successfully treated with intrathecal Amikacin administration through ventricular drain, in addition to surgical evacuation and intravenous antibiotic therapy. In this case, clinical and radiological improvement were observed once the intrathecal treatment was started. To our best knowledge, no cases of intraventricular use of Amikacin have been previously reported to treat this type of infection and we believe that it may be useful in properly selected patients.

A Case Report of Mycetoma and Cranial Osteomyelitis by Nocardia nova

Mycetoma is a chronic, localized, slowly progressive, granulomatous infection of the skin that may progress to subcutaneous tissue, muscle and bone. It is an infrequent manifestation of Nocardia infection that predominantly occurs on the lower extremities.

A previously healthy, 17-year-old boy presented to us with a 3-month history of scalp abscesses. On physical examination he had numerous, large left parietal and occipital inflammatory nodules on the scalp covered by alopecic skin and several sinuses discharging a purulent and serosanguinous material. He underwent a CT-scan and an MRI of the skull that revealed signs of cranial osteomyelitis and epidural empyema. Polymerase chain reaction assay of the purulent exudate was performed and identified Nocardia nova. The patient was discharged from the hospital after 8 weeks of antibiotherapy with meropenem and TMP-SMX with clinical, laboratorial and imaging improvement. He completed 12 months of outpatient oral therapy with TMP-SMX, after which cranial CT-scan showed a significant reduction of soft tissue thickening and bone reconstitution, with no relapses after stopping the treatment.

The best antibiotic regimen and length of treatment are not established for the management of nocardiosis. This is an unusual and severe presentation of infection by Nocardia nova with extent to the bone and epidural space, with full recovery under standard antibiotic therapy. This case shows that a good outcome may be achieved with prolonged antimicrobial treatment in an immunocompetent patient.

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.

Primary cutaneous nocardiosis caused by Nocardia nova with possible Apremilast contribution

Primary cutaneous nocardiosis accounts for 5-8 % of all nocardiosis cases and represents a diagnostic dilemma among immunocompetent and immunocompromised hosts. Herein, we present a case of a 30-year-old male with history of psoriasis with recent addition of Apremilast. Patient received intralesional triamcinolone injections for psoriatic plaques on the hands and abdomen prior to traveling to warm climate vacation. While on vacation, patient developed hand swelling and painful, red nodules on the dorsal hands and abdomen, sites where he received intralesional injections. Patient was empirically given doxycycline, but continued to develop new nodules. An abdominal lesion was biopsied for H&E and tissue culture. Tissue culture revealed beaded gram-positive rods identified as Nocardia nova by MALDI-TOF. Patient was switched to trimethoprim-sulfamethoxazole with significant improvement. This case represents an atypical primary cutaneous nocardiosis with Nocardia nova most likely in the setting of intralesional steroid injections and possible contribution of Apremilast.

Nocardiosis-an uncommon infection in patients with myasthenia gravis: report of three cases and review of literature

Nocardiosis is a rare infection in patients with myasthenia gravis (MG). We identified three cases of MG admitted with nocardiosis in our unit. We performed systematic literature search of previous publications and identified 18 patients. This paper presents three patients and reviews the clinical characteristics of 21 patients. The first case was a 69-year-old woman with thymomatous MG who presented with pustules and left lower limb pain. Evaluation showed osteomyelitis of the pubic ramus and ileopsoas abscess. The second case was a 54-year-old man who presented in myasthenic crisis due to pulmonary nocardiosis. The third case was a 48-year-old man with thymomatous MG who presented with lung abscess. All of them recovered completely after treatment with co-trimoxazole. Analysis of the 21 patients identified four risk factors for nocardiosis in MG: elderly men; thymoma; immunosuppressant medication, mainly steroid therapy; and pre-existing lung disease. Lungs was the most common site of infection. Suppurative disease was common manifestation regardless of organ involved. Clinical course is not unfavourable.

Pulmonary Nocardiosis in Suspected Tuberculosis Patients: A Systematic Review and Meta-Analysis of Cross-Sectional Studies

Background

nocardiosis is an opportunistic infectious disease in immunocompromised patients. The most common form of nocardiosis infection in humans is pulmonary nocrdiosis caused by inhaling Nocardia species from the environment. Thus, this study aimed to evaluate the pulmonary nocardiosis in patients with suspected tuberculosis using systematic review and meta-analysis.

Methods

We conducted a systematic search for cross-sectional studies focused on the pulmonary nocardiosis among patients with pulmonary tuberculosis based on the Preferred Reporting Items for Systematic reviews and Meta-analysis (PRISMA) published from January 2001 to October 2019. The search was conducted in MEDLINE/PubMed, Web of Science, Scopus, Cochrane Library, Google Scholar, Science Direct databases, and Iranian databases. Medical subject headings (MeSH) and text words were searched: “pulmonary nocardiosis”, “nocardiosis”, OR “nocardial infection”, “pulmonary nocardial infections/agents”, AND “pulmonary tuberculosis”, OR “pulmonary TB”, AND “Iran”. Two of the reviewers enrolled independently articles published in English and Persian languages according to the inclusion and the exclusion criteria. Comprehensive Meta-Analysis software (Version 3.3.070) was used for meta-analysis.

Results

Only 4 studies met the eligibility criteria. The pulmonary nocardiosis prevalence varied from 1.7% to 6.7%. The combined prevalence of nocardiosis among patients with suspected pulmonary tuberculosis in Iran was 4.8% (95% CI: 3–7.3, Q=5.8, Z=12.7). No heterogeneity was observed between studies because I² was 48.3. N. cyriacigeorgica and N. asteroides were reported as the prevalent isolates, respectively.

Conclusions

This review showed in patients suspected TB when they were negative in all diagnosis laboratory tests, nocardiosis cases which be considered.

Pulmonary nocardiosis: A Single Center Study

Objectives

Nocardiosis is a rare infection caused by Nocardia spp., a gram-positive bacteria non-commensal of the human flora. Nocardiosis usually presents with lung infection but may disseminate to other organs, most frequently the brain. The major risk factor is immunosuppression, but lung diseases also increase the risk of infection. Treatment with antibiotics is usually prolonged. In this study, we made a retrospective analysis of pulmonary nocardiosis cases and a review of the available literature.

Methods

We made a retrospective analysis of all pulmonary nocardiosis cases from 13 years (January 2005 to December 2017) in our institution, selecting patients from pulmonology and infectious diseases consultation.

Results

We found four patients diagnosed with pulmonary nocardiosis, three males (patients 1, 2 and 3) and one female (patient 4). Median age was 71 ± 15 years old. Different specimens were identified (N. cyriacigeorgica, Nocardia spp., N. nova, and N. wallacei/transvalensis). Bronchofibroscopy with bronchoalveolar lavage culture was the most frequent diagnostic procedure (patients 1 and 4). Only patient 2 presented an unfavorable response to treatment and died from septic shock.

Conclusions

Pulmonary nocardiosis has a good prognosis if diagnosed early and treated adequately. It should always be considered in the differential diagnosis of pulmonary infections concomitant with brain or other soft tissue lesion, especially in immunocompromised patients.

[Sporotrichoid nocardiosis by Nocardia brasiliensis]

Nocardia brasiliensis is a gram-positive, branched, aerobic, acid-resistant, rod-shaped bacillus that inhabits in soil, rotten organic matter and waters. Cutaneous nocardiosis in immunocompetent individuals can manifest in three different forms: actinomycetoma, superficial skin infection or lymphocutaneous infection. A case of an 85-year-old woman with an ulcerated lesion on the back of her left hand with erythematous papules in the lymphatic tract infected by N. brasiliensis is described. The microorganism was presumptively identified by conventional and inexpensive methods for a medium complexity laboratory at the species level. The morphological characteristics of colonies, the mold smell, a positive Kinyoun stain and the presence of aerial mycelium were the key tests to identify the genus. Species level identification was confirmed by mass spectrometry (MALDI-TOF MS). The trimethoprim-sulfamethoxazole treatment was effective as this agent was active in the susceptibility testing.

Disseminated infection with Nocardia otitidiscaviarum in a patient under steroid therapy

Corticosteroid recipients with lung infections should be suspected of having nocardiosis; however, nocardiosis can easily mimic malignancy, tuberculosis, or fungal infection. Though cultural identification is possible, it might be missed due to its slow growth pattern.. Therefore, if filamentous bacteria are seen during staining, plate incubation time should be extended.

Nocardia farcinica as a cause of chronic meningitis - case report

Background

Nocardiosis is an uncommon disease caused by aerobic gram-positive bacteria Nocardia spp. Although it is usually an opportunistic infection affecting immunocompromised patients, even one third of cases occur in immunocompetent persons. The aim of the study was to describe the course of chronic meningitis due to Nocardia infection.

Case presentation

A 52-year-old patient, chalk miner, suffered from a chronic meningitis caused by an extremely rare pathogen. The patient’s history was complicated and diagnostic process covered multiple examinations and consultations. Initially Kocuria rosea was cultured, yet after molecular examination the result was verified to Nocardia farcinica. Targeted antibiotic treatment was implemented, which resulted in gradual improvement of patients condition. A full recovery was achieved after one year antibiotic therapy.

Conclusions

Nocardia farcinica is an uncommon but possible cause of chronic meningitis.

In the case of a chronic meningitis of unknown origin multiple cerebrospinal fluid cultures should be performed as the identification of pathogen may be crucial for patient’s recovery.

In case of unusual culture, such as Kocuria spp. PCR should be performed.

Species Diversity, Molecular Characterization, and Antimicrobial Susceptibility of Opportunistic Actinomycetes Isolated from Immunocompromised and Healthy Patients of Markazi Province of Iran

Background

Actinomycetes widely exist in nature and these species cause infections in immunocompromised and healthy patients, although they are frequently found as members of the normal microbiota of humans and animals. These subsequent infections are often misdiagnosed as malignancy and tuberculosis. Due to this issue, the present study aimed to determine the presence and diversity of actinomycetes species causing infections in Iranian patients.

Materials and Methods

A total of 79 clinical samples collected from five hospitals in Markazi province were analyzed for the existence of actinomycetes using standard protocols for isolation and characterization of the isolates. The conventional tests were used for preliminary identification, the PCR amplification of hsp65 gene, the specific region of the 16S rRNA, and sequence analyses of 16S rRNA were applied for the genus and species identification. MICs of the antimicrobial agent were determined by the broth microdilution method and interpreted according to the NCCLS guidelines.

Results

A total of 17 (21.51%) actinomycetes isolates were recovered from clinical samples. In other analyzed samples, eight (10.12%) gram-positive, 12 (15.18) gram-negative bacteria, and six (7.6) fungi isolates were recovered. The most prevalent actinomycetes species were M. fortuitum (17.64%), N. Mexicana and S. heliomycini (11.76% each), and 10 species, ie, N. farcinica, M. lehmannii, M. flavescens, Arthrobacter crystalopoetis, N. neocaledoniensis, M. phocaicum, M. abscessus, M. arupense, M. setense, and N. cyriacigeorgica made up the single isolates. Results of DST illustrated that all of the isolates were susceptible to Amikacin, Levofloxacin, Ofloxacin, and Ciprofloxacin, whereas all of them were resistant to Rifampicin and Doxycycline.

Conclusion

In conclusion, increasing isolation of actinomycetes found in various clinical cases merits special attention by health authorities in developing countries. In health centers, action should be taken to increase awareness of appropriate diagnostic criteria and management guidelines for actinomycetes diseases. Furthermore, an increase in the number as well as the quality of national and regional reference laboratories may facilitate more accurate diagnosis of actinomycetes diseases.

Disseminated nocardiosis in an immunocompetent patient

Nocardiosis is a rare opportunistic bacterial infection. We describe an 8-year-old immunocompetent patient who presented with constitutional symptoms suggestive of probable tuberculosis (TB) in whom we confirmed a diagnosis of nocardiosis. Nocardia is a Gram-positive bacterium that is ubiquitous in soil and decaying vegetable matter. N. asteroides is the most common species. Despite the traditional description of nocardiosis as an opportunistic infection, case reports and case series of pulmonary nocardiosis have recently been reported in immunocompetent patients. Three clinical presentations of nocardiosis have been described; acute, subacute and chronic suppurative infections with episodes of exacerbations and remissions. We describe the presentation, diagnosis, management and prognosis of a rare case of disseminated nocardiosis managed initially as disseminated TB with no improvement.

Primary Cutaneous Nocardiosis: A Rare Presentation of Nocardiosis

Nocardia is an uncommon gram-positive, weakly acid-fast bacterium that causes systemic or localized suppurative disease in humans and animals. Nocardiosis is typically regarded as an opportunistic infection, but approximately one-third of the patients are immunocompetent. The most common presentation is pulmonary disease (39%) followed by systemic involvement, defined as involvement of more than two sites; cutaneous presentation constitutes only 8% of the cases. Nocardia is widely distributed geographically; however, in the US, it is mostly found in warm and dry areas of South West and South East. We present a perfect case of cutaneous nocardiosis of a 70-year-old male, who presented with a traumatic splinter injury, leading to pustules formation on the right index finger, along with erythema and induration of the right arm. The patient was empirically diagnosed and treated for cellulitis, with amoxicillin and clavulanic acid, resulting in deterioration of the wound. The patient underwent incision and drainage and wound culture grew nocardia. The index of suspicion should be kept in mind while treating infectious blisters which have failed outpatient cellulitis treatment, immunocompromised hosts, and in nocardia prevalent regions.

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.

Beijinchromes A-D, Novel Aromatic Compounds Isolated from Nocardia beijingensis NBRC 16342

Nocardia is a potent bacterial producer of bioactive compounds. From a culture of Nocardia beijingensis NBRC 16342, we isolated four aromatic compounds, named beijinchromes A-D (1-4). We purified them by silica gel chromatography and reverse phase HPLC, and identified their structures by NMR and high resolution (HR)-MS analyses. 1, 2, and 4 are novel 1,2,3,8-tetrasubstituted naphthalenes, and 3 is a novel 3,8-disubstituted ortho-naphthoquinone. 1 and 2 exert antioxidant activities, and 3 exhibits antibiotic activity. Remarkably, the putative biosynthetic gene clusters for 1-4 are widely distributed in 37 Nocardia species, implying their potential to produce this family of compounds and important biological functions of beijinchromes.

Occupational hazard in an immunosuppressed patient

A 60-year-old male liver transplant recipient presented to his local hospital with left-sided partial seizures following a few days of generalised headache. He had undergone transplantation for primary sclerosing cholangitis 4 years earlier and maintained on tacrolimus monotherapy immunosuppression. He had no other comorbidities of note and worked as an arable farmer. At last follow-up, he had been well with preserved graft function and afternoon trough tacrolimus levels of 2-4 ng/mL. Over the preceding 4 weeks, he had been investigated locally for weight loss and a productive cough, where CT of the chest showed calcified mediastinal and hilar lymphadenopathy. Bronchoscopy samples were negative for acid-fast bacilli and he had been empirically treated for assumed community acquired pneumonia. Initial seizure management was with intravenous diazepam and phenytoin. On transfer to our centre, he was noted to be dysarthric with persisting 4/5 left upper limb weakness and nystagmus to all extremes of gaze. Blood tests were significant for mild anaemia (haemoglobin 90 g/L) and elevated C reactive protein (134 mg/L). The peripheral white cell count was 6.6×10⁹/L. Biochemical liver graft function was normal and the 8am trough tacrolimus level was low at 2 ng/mL. CT head revealed bilateral ring enhancing cerebral lesions with surrounding vasogenic oedema but no mass effect. On MRI these exhibited restricted diffusion and marked perilesional oedema, suggestive of infection. Cerebrospinal fluid (CSF) analysis was as follows: white cell count <1/mm³, protein 0.57 g/L (normal range <45 g/L) and glucose 3 mmol/L (paired plasma glucose 4.8 mmol/L). Testing for virological causes via PCR, toxoplasma serology and blood and CSF cultures, including for tuberculosis, were all negative. Whole body positron emission tomography-CT demonstrated uptake in numerous peritoneal and intramuscular lesions as well as right-sided cervical lymphadenopathy, which was sampled with fine needle aspiration. Microscopy revealed a filamentous, beading and branching Gram-positive bacillus that was partially acid-fast, subsequently speciated as Nocardia farcinica.

Nocardial clival osteomyelitis secondary to sphenoid sinusitis: an atypical skull base infection

Clival osteomyelitis is a life-threatening complication of untreated malignant otitis externa or paranasal sinus infection. Although various pathogens have been implicated, to our knowledge, primary nocardial clival osteomyelitis has never been reported. We describe a 74-year-old woman who presented with headaches, abducens and hypoglossal nerve palsies, facial numbness, photophobia, and neck stiffness. Imaging revealed a heterogeneous mass within the sphenoid sinus with clival extension. The lesion was extirpated via a binostril endoscopic endonasal transsphenoidal approach. Histopathological and microbiological examination revealed a nocardial source. Clival osteomyelitis associated with sphenoid sinusitis should be included in the differential diagnosis of progressive skull base lesions in the setting of an underlying infection. Early recognition and intervention with antibiotics and surgical debridement is essential in the management of this rare entity.