First report of a brain abscess caused by Nocardia veterana

Brain Abscesses by Nocardia: An Interesting Case

The successful management of disseminated Nocardia infection is not well described in medical literature. Immunocompetent individuals presenting with complicated and widespread Nocardia infection is an uncommon phenomenon. We describe an interesting case of a large Nocardia abscess in the brain in an immunocompetent patient that was aspirated. The patient clinically improved and was discharged home on a prolonged course of intravenous antibiotics and close outpatient follow-up. He successfully finished the antibiotic therapy for one year, and repeat imaging studies suggested the resolution of the abscess. With this case, we also intend to do a brief literature analysis about the management of brain abscess caused by Nocardia species.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Nocardia veterana infections: case report and systematic review

Members of the genus Nocardia are filamentous, Gram-positive, aerobic bacteria and exist ubiquitously in most environments. In 2001, the species Nocardia veterana was first isolated, and it predominantly causes pulmonary infections in immunocompromised hosts. We present the first report of a soft-tissue abscess caused by N. veterana in a 59-year-old woman being treated for chronic cutaneous graft-versus-host disease. After failing to improve with empirical treatment, two incision and drainage procedures were required. She subsequently completed a 1-year course of oral antibiotic therapy consisting of trimethoprim-sulfamethoxazole then azithromycin. No relapse occurred over the next 5 years of follow up. To better characterize N. veterana infections, we performed a systematic literature review and summarized all previously reported cases. Overall, the rising prevalence of immunocompromising conditions warrants increased vigilance for infections caused by atypical or opportunistic pathogens.

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Systematic review of Nocardia veterana infections.

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First report of N. veterana soft tissue abscess.

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N. veterana typically causes pulmonary infections in immunocompromised hosts.

The emergence of rare nocardiosis following allogeneic hematopoietic stem cell transplantation in the era of molecular taxonomy

OBJECTIVE

The purpose of this study was to describe the clinical features of nocardiosis after allogeneic hematopoietic stem cell transplantation (allo-HSCT), focusing on new Nocardia species.

METHODS

We retrospectively reviewed data from patients with nocardiosis after allo-HSCT treated at our hospital and documented cases in the medical literature.

RESULTS

Fifty-seven cases were identified from our institution and the literature review. Although 51 patients (89.5%) responded to initial treatment, 28 (49.1%) patients were switched over to other treatment regimens due to the recurrence of nocardiosis or adverse events of antimicrobials. Nocardiosis-attributed mortality occurred in ten patients (17.5%). Antimicrobial susceptibilities varied among intra- and inter-species except linezolid (LZD). In the present study, five species were newly discovered after 2000, including N. cyriacigeorgica, N. veterana, N. abscessus, N. aobensis, and N. mexicana. All isolates of N. cyriacigeorgica, N. veterana, N. abscessus, and N. aobensis were sensitive to trimethoprim/sulfamethoxazole, amikacin (AMK), imipenem (IPM), and LZD; however, N. mexicana was resistant to AMK and IPM.

CONCLUSION

Newly identified Nocardia species have various antimicrobial susceptibility patterns. Long-term maintenance therapy could be challenging due to the adverse events of antimicrobials, especially in the allo-HSCT setting. Prudent evaluation is crucial for selecting a second-line or further treatment options.

Clinical characteristics and course of primary brain abscess

BACKGROUND

Due to improved diagnostic methods, the incidence of brain abscess is still rising. Therefore, clear and evidence-based therapy for the patients who suffer from brain abscesses is necessary. Brain abscesses are potentially life-threatening conditions that possibly lead to permanent injuries even after sufficient healing has taken place. The aims of this study were to analyze the clinical aspects of patients with brain abscesses and thereby to reveal the relevant aspects for the future treatment of the brain lesions.

METHODS

We retrospectively identified 47 patients (24 male, 23 female) who had received surgery or undergone the frameless stereotactic drainage of brain abscesses in our center from March 2009 to May 2017. We analyzed the clinical characteristics of the patients, as well as comorbidities and outcomes.

RESULTS

The mean age was 58 (range 7 to 86). Focus identification was successful in 28 patients (60%), with the most frequent causes of brain abscesses including the following: sinusitis (25%), dental infections (25%), and mastoiditis (21%). The mean Charlson Comorbidity Index was 1.57. Among the patients, 34% showed immunosuppressive conditions. We performed 1.5 surgeries per patient (53% via craniotomy, 28% biopsies or stereotactic drainage, 19% both procedures), followed by antibiotic treatment for 6.5 weeks (mean). In 30% of patients, no bacteria could be isolated. During the follow-up period (a median of 12 months), 23.4% of the patients died. The mortality rate during the initial hospital stay was 4.3%.

CONCLUSION

One third of the patients with brain abscesses showed immunosuppressive conditions, whereas brain abscesses also often occur in patients with good medical conditions. The isolation of the focus of infection is often possible. Surgical procedures showed very good outcomes. Patients over 60 years showed significantly worse clinical outcomes.

Nocardiosis from 1888 to 2017

The genus Nocardia is an aerobic bacterium, Gram-positive and catalase positive that is in Nocardiaceae family. This bacterium first described by Edmond Nocard in 1888 and is not in human commensal bacteria. To date, nocardiosis incidence is increasing due to increase population growth rate, increase in patients with immune disorder diseases and immunocompromised patients. We surveyed taxonomic position, isolation methods, phenotypic and molecular identification at the genus and species levels, antibiogram, treatment and epidemiology in the world from 1888 to 2017.

Successful Treatment of Disseminated Nocardiosis Caused by Nocardia veterana in a Dog

A 5‐year‐old male castrated Lhasa Apso cross was evaluated for a 1‐month history of inappetence, lethargy, gagging, and progressive right thoracic limb lameness. Synovial fluid analysis revealed nonseptic suppurative inflammation, and a diagnosis of immune‐mediated polyarthritis (IMPA) was made. After 3 months of treatment with prednisone and later cyclosporine, the dog developed multiple firm cutaneous and subcutaneous masses and a focal mass within the jejunum. Cultures of blood, urine, skin lesions, and the jejunal mass identified Nocardia veterana by matrix‐absorption laser desorption ionization‐time‐of‐flight mass spectrometry (MALDI‐TOF MS) and allowed for earlier identification of the organism compared to more traditional secA1 gene sequencing. Immunosuppressive drug treatment was discontinued, and the dog was treated for 3 months by administration of trimethoprim‐sulfamethoxazole (TMS). No recurrence of clinical signs was reported 1 year later. This case report highlights the clinical utility of MALDI‐TOF MS, particularly for the rapid identification of slow‐growing, fastidious organisms.

Diversity and frequency of Nocardia spp. in the soil of Isfahan province, Iran

OBJECTIVE

To isolate and identify Nocardia spp. from soil in different regions of Isfahan province in the center of Iran.

METHODS

This study was conducted in 32 districts (16 cities and 16 villages) in Isfahan province during two years. A total of 800 soil samples from these regions were studied by using kanamycin. The isolated Nocardia species were examined by gram and acid-fast staining and were identified biochemically and morphologically. The frequency and distribution of Nocardia spp. were determined in relation to different factors such as soil pH and temperate climate.

RESULTS

From 153 (19.1%) Nocardia isolates identified, Nocardia asteroids (N. asteroids) complex (45.5%) and Nocardia brasiliensis (N. brasiliensis) (24.7%) were the most frequently isolated species, followed by Nocardia otitidiscaviarum (2.2%), Nocardiopsis dassonvillei, Actinomadura actinomadura (each 1.7%) and Nocardia transvalensis (1.1%) and also unknown spp. (23.0%). In this study, most species (54.4%) of Nocardia, especially N. asteroides complex were isolated from soils with pH: 7.01-8, whereas in pH: 8.01-9 more N. brasiliensis was isolated. The most Nocardia spp. was detected from regions with semi-nomadic and temperate climate (41.1%).

CONCLUSIONS

N. asteroids complex is more prevalent in Isfahan province and soil can be a potential source of nocardiosis infections. It is to be considering that climate and soil pH are involved in the frequency and diversity of aerobic Actinomycetes.

Nocardia veterana: disseminated infection with urinary tract infection

Nocardia spp. are a group of aerobic actinomycetes widely distributed in soil, and associated with severe opportunistic infections, essentially pulmonary infections. We report the first case of disseminated infection associated with urinary tract infection caused by Nocardia veterana. The diagnosis was difficult; despite the presence of pulmonary nodules, the lung biopsies remained negative while only one aerobic blood culture and the urine culture were positive for N. veterana, identified after a 16S rDNA gene sequence analysis. Few cases of clinical importance due to N. veterana have been published since its characterization. The bacteriological diagnosis of nocardiosis can be difficult to establish because of the delayed growth and the specific techniques that are required. This case illustrates the necessity of performing specific investigations in immunocompromised patients who present with infectious disease because the severity of this infection requires early diagnosis and quick initiation of appropriate antibiotic therapy.

Nocardiosis of the central nervous system: experience from a general hospital and review of 84 cases from the literature

Central nervous system (CNS) nocardiosis is a rare disease entity caused by the filamentous bacteria Nocardia species. We present a case series of 5 patients from our hospital and a review of the cases of CNS nocardiosis reported in the literature from January 2000 to December 2011. Our results indicate that CNS nocardiosis can occur in both immunocompromised and immunocompetent individuals and can be the result of prior pulmonary infection or can exist on its own. The most common predisposing factors are corticosteroid use (54% of patients) and organ transplantation (25%). Presentation of the disease is widely variable, and available diagnostic tests are far from perfect, often leading to delayed detection and initiation of treatment. The optimal therapeutic approach is still undetermined and depends on speciation, but lower mortality and relapse rates have been reported with a combination of targeted antimicrobial treatment including trimethoprim/sulfomethoxazole (TMP-SMX) for more than 6 months and neurosurgical intervention.

First case report of Nocardia veterana causing nodular lymphangitis in an immunocompromised host

We report a unique case of ascending cutaneous lymphangitis in a 72-year-old immunocompromised man from which a newly described Nocardia species was isolated by 16S ribosomal gene sequencing. Treatment with trimethoprim-sulfamethoxazole resulted in successful resolution of symptoms. To the best of our knowledge, this is the first case report of N. veterana implicated in causing ascending cutaneous lymphangitis.

Nocardia veterana endogenous endophthalmitis in a cardiac transplant patient

Background

Endogenous endophthalmitis secondary to Nocardia species is extremely rare but often portends a poor visual prognosis often owing to the advanced nature of disease at presentation and delay in diagnosis. Patients who are systemically immunosuppressed are at greatest risk and early suspicion of the role of this organism in patients with acute panuveitis is paramount.

Findings

A 66-year-old cardiac transplant patient on oral prednisone, Myfortic, and tacrolimus developed unilateral panuveitis with a focal white subretinal and retinal lesion. His past medical history was notable for Aspergillus pneumonia and cytomegalovirus retinitis in the contralateral eye 12 months prior. Aqueous humor sampling for eubacterial, eufungal, and viral PCR testing, as well as vitreous cultures for bacteria and fungi were unsuccessful in the identification of a causative organism. Progressive enlargement of the lesion was noted despite intravitreal foscarnet, vancomycin, ceftazidime, and voriconazole. A pars plana vitrectomy and retinal and subretinal biopsy led to the identification of Nocardia veterana, a recently identified Nocardia species. A combination of linezolid, meropenem, azithromycin, ceftriaxone, and intravitreal amikacin resulted in eradication of the infection.

Conclusion

This is the first reported case of N. veterana endogenous endophthalmitis in an immunosuppressed patient. Pars plana vitrectomy with a subretinal biopsy was required to establish a diagnosis, as other testing including aqueous PCR and vitreous cultures were negative. The poor visual outcome in our patient highlights the importance of early consideration of Nocardia in the differential diagnosis of panuveitis with subretinal disease in the context of immunosuppression.