An unusual case of nocardiosis presented as a mediastinal mass in an immunocompetent patient

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.

Coinfection of Streptococcus suis and Nocardia asiatica in the human central nervous system: A case report

BACKGROUND

Streptococcus suis (S. suis) is an anthropozoonotic pathogen that shows clinical manifestations of meningitis, septicemia, and arthritis in infected humans. Nocardia is another type of anthropozoonotic bacteria, with clinical manifestations of skin, lung, and brain abscesses in infected humans. Few intracranial infections caused by S. suis or Nocardia have been reported. To the best of our knowledge, no study has reported a patient with simultaneous intracranial infection by S. suis and Nocardia.

CASE SUMMARY

A 66-year-old male presented at Liaocheng People’s Hospital (Liaocheng, Shandong Province, China) reporting dizziness with nausea and vomiting. Metagenomic next-generation sequencing (mNGS) was performed on cerebrospinal fluid for examination, and the patient was diagnosed with suppurative meningitis caused by S. suis infection. He received anti-infection treatment with penicillin sodium and ceftriaxone. The patient’s condition initially improved but then deteriorated. Further mNGS of cerebrospinal fluid revealed both S. suis and Nocardia. Imaging examination revealed a brain abscess. Furthermore, a mixed infection of S. suis and Nocardia was detected in the patient’s central nervous system. The patient was treated with antibiotics and sulfamethoxazole. He was discharged after his condition improved.

CONCLUSION

This case shows that the disease can be recurrent in patients with intracranial infection of a rare pathogen. The possibility of mixed infection should also be considered, especially in patients treated with immunosuppressive agents. mNGS of cerebrospinal fluid is a supplement to conventional microbial pathogen identification methods. Patients with unknown pathogen diagnosis, early extensive use of antibiotics and infection with rare pathogens can be diagnosed by the combination of conventional methods and mNGS of cerebrospinal fluid.

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.

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.