A Case of Nocardia farcinica Pneumonia and Mediastinitis in an Immunocompetent Patient

Case report: Pathology, antimicrobial resistance, and molecular characterization of bovine abortion cases caused by Nocardia farcinica in Korean native cattle

Introduction

Nocardia farcinica is an opportunistic bacterium that causes bovine mastitis and pulmonary, cutaneous, and central nervous system infections in humans. Bovine abortion caused by N. farcinica has been sporadically reported. The purpose of this study was to analyze the pathological findings of bovine abortions caused by N. farcinica in the Republic of Korea and determine the antimicrobial resistance and genotypical characteristics of N. farcinica isolates.

Case presentation

Three cases of bovine abortions were submitted to the Animal and Plant Quarantine Agency for differential diagnosis. Grossly, one fetus showed severe lung consolidation following palpation of the entire lobes. Histologically, necrotizing granulomatous interstitial pneumonia was observed in all fetuses; a fetus with a gross lesion demonstrated necrotizing lymphadenitis in the mesenteric lymph nodes and necrotizing dermatitis in the ear. N. farcinica isolates were isolated from the abomasal contents and lungs of all fetuses. Finally, two cases were diagnosed as abortions due to N. farcinica, and one was diagnosed as an N. farcinica abortion coinfected with bovine viral diarrhea virus. According to the multilocus sequence analysis, all isolates were identified as N. farcinica and were determined to be genetically related to isolates from humans. Two N. farcinica isolates were resistant to trimethoprim-sulfamethoxazole, which is recommended as the first treatment for human nocardial infections.

Conclusion

This is the first pathological report of bovine abortion caused by N. farcinica in the Republic of Korea. Further studies are needed to phenotypically and genotypically characterize N. farcinica isolates with various sources and continuously monitor antimicrobial resistance patterns.

Nocardia farcinica infection presenting as a solitary bronchial neoplasm in an immunocompetent adult: a case report

Nocardia species are gram-positive, acid-fast, saprophytic, aerobic bacilli, predominantly resulting in opportunistic infections in immunocompromised individuals. Here, we reported a case of Nocardia infection in a 27-year-old woman with normal immunocompetence, who presented as a solitary neoplasm in the left principal bronchus with a chief complaint of postural dyspnea. By electrotomy via bronchoscopy, the neoplasm was successfully removed, and it was further identified as Nocardia farcinica by metagenomic next-generation sequencing.

Clinical Characteristics of Nocardiosis: a Multicenter Retrospective Study in Korea

BACKGROUND

Nocardiosis is a rare, but potentially life-threatening condition. It is difficult to diagnose, and bacterial culture identification can be time consuming. We investigated the characteristics of nocardiosis and the suitability of the treatment approach in Korea.

MATERIALS AND METHODS

This retrospective study was conducted at 5 medical institutions between 2011 and 2021. We reviewed the medical records of patients with microbiologically confirmed nocardiosis. Appropriate antibiotic selection was defined as follows: (1) selecting antibiotics according to the species, (2) if the species of Nocardia was unknown, trimethoprim-sulfamethoxazole-based therapy or linezolid-based therapy was administered, and (3) selection of antibiotics using the antibiotic susceptibility test. The appropriate treatment periods for antibiotics were defined as treatment maintained from 3 to 12 months, depending on involvement of the organs. Descriptive analysis and Fisher exact test were used. Statistical significance was set at P-values of <0.05.

RESULTS

Thirty patients were enrolled. Of these patients, 18 (60.0%) were male. The median age was 70.5 years. Among the diagnosed patients, 12 (40.0%) had an immunocompromised status. Eight (30.0%) patients received optimal treatment for the appropriate treatment period. Appropriate dosing duration was observed in 3 of the 12 (25.0%) immunocompromised patients. There was no significant difference between the presence or absence of immunosuppression and the adequacy of treatment for nocardiosis (P = 1.000). Skin and soft tissue (14 patients) were most frequently involved in this study. Nocardia species (spp.) were isolated from culture at a median of 6.0 days. There were 7 cases with N. farcinica (23.3%).

CONCLUSION

We found that 60.0% of the patients with nocardiosis did not have an immunocompromised status. Further, 26.7% of the total patients received adequate treatment for nocardiosis. The reasons for suboptimal management of nocardiosis in Korea are presumed to be diagnostic difficulties, lack of awareness about nocardiosis, and difficulties in selecting antibiotics for Nocardia spp. among clinicians. The lack of antibiotic susceptibility tests for Nocardia spp. could be the source of these problems. Nocardiosis should be suspected in cases of recurrent infections with skin and soft tissue, musculoskeletal, or respiratory system involvement with or without an immunocompromised status. Clinical microbiological support is required for the diagnosis and selection of antibiotics in Korea. High clinical index of suspicion and clinical microbiological support are required for the accurate diagnosis of nocardiosis in Korea.

Large mediastinal mass diagnosed as Nocardia infection by endobronchial ultrasound-guided transbronchial needle aspiration in a ceramic worker: A case report

Background

Nocardia is a ubiquitous soil saprophyte transmitted through airborne or direct cutaneous inoculation routes. Although Nocardia is more common in immunocompromised patients, Nocardia may also arise in apparently immunocompetent patients.

Case presentation

We report a rare case of Nocardia infection presenting as a large mediastinal mass in an immunocompetent ceramic worker. A 54-year-old man with no previous history of immune dysfunction, a ceramic worker by profession, was referred and admitted to our hospital because of a persistent fever for 19 days. Chest CT showed a large middle mediastinal mass. However, conventional anti-infective treatment was ineffective. Under the guidance of the Virtual bronchoscopic navigation (VBN) system, he underwent Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). The purulent exudate obtained by EBUS-TBNA was further identified as Nocardia by weak acid-fast and metagenomic next-generation sequencing (mNGS). He was subsequently treated with intravenous imipenem/amikacin, switched to intravenous imipenem and oral trimethoprim/sulfamethoxazole, and the clinical symptoms were significantly improved.

Conclusions

Even in immunocompetent patients, Nocardiosis cannot be excluded. For the public, especially soil contact workers, precautions should be taken to avoid Nocardia infection from occupational exposure. This rare case may provide a diagnosis and treatment reference for clinicians.

Disseminated nocardiosis caused by Nocardia farcinica in a patient with colon cancer: A case report and literature review

RATIONALE

Nocardiosis is an uncommon and potentially life-threatening infection that usually affects immunocompromised hosts. No clinical guidelines have been established for managing this rare disease, and the optimal treatment modality remains unclear. Nocardia farcinica, a relatively infrequent pathogen of nocardiosis, causes a clinically aggressive infection. In addition to our patient data, our search of the literature for patients who presented with empyema caused by N. farcinica will provide fundamental information for optimal treatment modalities.

PATIENT CONCERNS

A 64-year-old man was diagnosed with empyema, 4 days following surgery for sigmoid colon cancer. Brain lesions were evaluated only after N. farcinica was isolated and identified as the causative pathogen through repeated culture tests.

DIAGNOSES

N. farcinica was isolated from the pleural effusion and confirmed as the pathogen through 16S rRNA sequencing.

INTERVENTIONS

The patient was successfully treated with tube thoracotomy, neurosurgical evacuation, and a combination of trimethoprim/sulfamethoxazole plus imipenem. Long-term antibiotic therapy was required to prevent recurrence.

OUTCOMES

Pyothorax showed a good clinical response to antimicrobial therapy and drainage of pleural effusion, whereas brain abscess did not respond to medical therapy and required surgery. The patient eventually recovered and continued chemotherapy as treatment for sigmoid colon cancer.

LESSONS

Although extremely rare, this report demonstrates the importance of considering Nocardia infection as the differential diagnosis in immunocompromised patients who present with empyema. In particular, because of the N. farcinica infection's tendency to spread and the resistance of the organism to antibiotics, aggressive evaluation of metastatic lesions and standardized support from microbiological laboratories are important. Surgery may be required in some patients with brain abscesses to improve the chance of survival.

Nocardia farcinica Brain Abscess in an Immunocompetent Host With Pulmonary Alveolar Proteinosis: A Case Report and Review of the Literature

A 55-year-old immunocompetent male presented with new-onset seizures and acute respiratory failure requiring intubation and a stay in the medical intensive care unit. Magnetic Resonance Imaging (MRI) of the brain revealed ring-enhancing lesions, and Computed Tomography (CT) chest showed ground-glass opacity. The patient underwent craniotomy and bronchoscopy, followed by culture of the purulent aspirate from lesions in the brain and bronchoalveolar lavage (BAL). After extensive infectious workup, the patient was diagnosed with a Nocardia farcinica brain abscess plus underlying pulmonary alveolar proteinosis (PAP). Based on a recommendation from an infectious disease expert, the patient was treated with trimethoprim-sulfamethoxazole (TMP/SMX).

This case highlights the importance of understanding that, though rare, infections such as nocardiosis can present in immunocompetent patients and cause severe morbidity.

Isolated Nocardiosis, an Unrecognized Primary Immunodeficiency?

Nocardiosis is an infectious disease caused by the gram-positive bacterium Nocardia spp. Although it is commonly accepted that exposure to Nocardia is almost universal, only a small fraction of exposed individuals develop the disease, while the vast majority remain healthy. Nocardiosis has been described as an "opportunistic" disease of immunocompromised patients, suggesting that exposure to the pathogen is necessary, but a host predisposition is also required. Interestingly, increasing numbers of nocardiosis cases in individuals without any detected risk factors, i.e., without overt immunodeficiency, are being reported. Furthermore, a growing body of evidence have shown that selective susceptibility to a specific pathogen can be caused by a primary immunodeficiency (PID). This raises the question of whether an undiagnosed PID may cause nocardiosis affecting otherwise healthy individuals. This review summarizes the specific clinical and microbiological characteristics of patients with isolated nocardiosis published during the past 30 years. Furthermore, it gives an overview of the known human immune mechanisms to fend off Nocardia spp. obtained from the study of PIDs and patients under immunomodulatory therapies.

Cloning, Expression, Invasion, and Immunological Reactivity of a Mammalian Cell Entry Protein Encoded by the mce1 Operon of Nocardia farcinica

Bacterial mammalian cell entry (Mce) proteins have been implicated in pathogen invasion of mammalian host cells. The aim of this study was to examine the invasion-conferring ability of mce1E operon-encoded proteins, in vivo expression of Mce1E in cells from infected mice and rabbits, and Mce1E immunogenicity. Nocardia farcinica mce1E was cloned into pet30a(+) vectors, expressed in Escherichia coli, and purified. Invasion assays, transmission electron microscopy (TEM), immunoblots, and enzyme-linked immunosorbent assay (ELISA) detection of cytokines were conducted. TEM confirmed the invasion of HeLa cells by Mce1E-coated beads. The antigenicity of E. coli-expressed recombinant Mce1E was confirmed in immunoblots with sera from N. farcinica-infected mouse and rabbit sera. Co-incubation of Mce1E with splenocytes of N. farcinica-infected mice demonstrated upregulation of interferon (IFN-γ), but not interleukin (IL)-4 or IL-10, in the cultural supernatant. These findings demonstrate that Mce1E may facilitate N. farcinica interactions with and invasion of mammalian cells. Notably, Mce1E are expressed and elicited antibody responses in mice and rabbits during infection. Besides, it may play a role in cell-mediated immune reactions and cause host inflammation responses to N. farcinica infection.

Severe pneumonia due to Nocardia otitidiscaviarum identified by mass spectroscopy in a cotton farmer: A case report and literature review

RATIONALE

Nocardia species are aerobic saprophytic bacilli. Among Nocardia species, Nocardia otitidiscaviarum (N otitidiscaviarum) is rarely reported in pulmonary infection.

PATIENT CONCERNS

We reported a case of N otitidiscaviarum pneumonia in a cotton farmer.

DIAGNOSES

N otitidiscaviarum pneumonia was identified by mass spectroscopy.

INTERVENTIONS

Combined treatments (amikacin, imipenem and trimethoprim-sulfamethoxazole) were administered after identification of N otitidiscaviarum.

OUTCOMES

The patient eventually died from severe respiratory insufficiency in the hospital.

LESSONS

Early precise diagnosis and prompt combined therapy are of vital importance in severe Nocardia pulmonary infection.