Pulmonary Nocardiosis With Endobronchial Involvement Caused by Nocardiaaraoensis

We report a rare case of pulmonary nocardiosis with endobronchial involvement caused by Nocardia araoensis. A 79-year-old man with a history of asthma and a previous right upper lobectomy for lung cancer and organizing pneumonia presented with cough and dyspnea. He presented with right bronchial stenosis associated with various mucosal lesions, including ulcerative and exophytic lesions. N araoensis was detected in sputum samples collected via bronchoscopy. The mucosal lesions improved after a 2-week course of meropenem. After a further 6 months of oral sulfamethoxazole-trimethoprim treatment, the mucosal lesions completely disappeared. Based on bronchoscopic and pathophysiologic findings, the patient was diagnosed with pulmonary nocardiosis with endobronchial involvement. Nocardiosis should be considered in the differential diagnosis of endobronchial mucosal lesions.

Clinical screening of Nocardia in sputum smears based on neural networks

Objective

Nocardia is clinically rare but highly pathogenic in clinical practice. Due to the lack of Nocardia screening methods, Nocardia is often missed in diagnosis, leading to worsening the condition. Therefore, this paper proposes a Nocardia screening method based on neural networks, aiming at quick Nocardia detection in sputum specimens with low costs and thereby reducing the missed diagnosis rate.

Methods

Firstly, sputum specimens were collected from patients who were infected with Nocardia, and a part of the specimens were mixed with new sputum specimens from patients without Nocardia infection to enhance the data diversity. Secondly, the specimens were converted into smears with Gram staining. Images were captured under a microscope and subsequently annotated by experts, creating two datasets. Thirdly, each dataset was divided into three subsets: the training set, the validation set and the test set. The training and validation sets were used for training networks, while the test set was used for evaluating the effeteness of the trained networks. Finally, a neural network model was trained on this dataset, with an image of Gram-stained sputum smear as input, this model determines the presence and locations of Nocardia instances within the image.

Results

After training, the detection network was evaluated on two datasets, resulting in classification accuracies of 97.3% and 98.3%, respectively. This network can identify Nocardia instances in about 24 milliseconds per image on a personal computer. The detection metrics of mAP50 on both datasets were 0.780 and 0.841, respectively.

Conclusion

The Nocardia screening method can accurately and efficiently determine whether Nocardia exists in the images of Gram-stained sputum smears. Additionally, it can precisely locate the Nocardia instances, assisting doctors in confirming the presence of Nocardia.

Nocardiosis in glomerular disease patients with immunosuppressive therapy

Background

Glomerular disease patients have a high risk of infection, which contributes to the progression of disease per se and mortality, especially in those with long-term use of glucocorticoids and (or) immunosuppressive agents. Cases of sporadic nocardiosis have been reported in glomerular disease patients, and this observation was conducted to comprehensively understand the manifestations of and treatments for nocardiosis, which is commonly misdiagnosed as pneumonia or tuberculosis or even as lung cancer or metastatic tumors in glomerular disease patients.

Methods

We reviewed the demographic characteristics, laboratory abnormalities, radiological features, and treatments of 7 patients with nocardiosis and glomerular disease receiving steroids and immunosuppression therapy at the nephrology department of the Second Xiangya Hospital between 2012 and 2019.

Results

It was found that all 7 patients had been receiving methylprednisolone for renal disease at a median dose of 20 mg per day and a median duration of 4 months before developing nocardiosis. There were 4 males and 3 females, and the median age was 52.14 years. All 7 patients had hypoalbuminemia at the time of admission. In addition, various cystic abscesses in the subcutaneous tissue, with or without lung and brain involvement, were observed in these patients. Encouragingly, body temperatures returned to normal, and subcutaneous abscesses diminished or disappeared with compound sulfamethoxazole treatment alone or in combination with linezolid, imipenem and mezlocillin/sulbactam.

Conclusions

It was shown that multisite abscesses, including subcutaneous, pulmonary and cerebral abscesses, were the common manifestations of nocardiosis in glomerular disease patients. Sulfonamide was the first-line antibiotic therapy for nocardiosis, and combinations of other antibiotics were also needed in some serious cases.

Nocardia araoensis Causing Brain Abscess

Nocardial brain abscess is a rare central nervous system infection with high morbidity and mortality. Most of the human infections, i.e., about 90%, are due to Nocardia asteroides group comprising N. asteroides complex, Nocardia farcinica, and Nocardia nova. Other species rarely cause human infections. Here, we report a case of left parieto-occipital abscess caused by a rare species, Nocardia araoensis, its diagnosis, treatment options, and review of literature. A 73-year-old male, known case of diabetes mellitus, on prolonged oral corticosteroid for autoimmune hemolytic anemia presented with a 1-month history of memory deficit and gait imbalance. On examination, he had a right inferior quadrantanopia and hemiparesis. Magnetic resonance imaging showed a multiloculated ring-enhancing lesion in the left parieto-occipital region. Navigation-assisted biopsy was done. The organism isolated was N. araoensis. He was treated successfully with prolonged course of antibiotics which resulted in complete clinical and radiological resolution. N. araoensis is a rare cause of brain abscess and needs to be suspected in immunocompromised individuals. Early diagnosis and prolonged treatment can result in complete clinical and radiological resolution.

Sporotrichoid Skin Infection Caused by Nocardia brasiliensis in a Kidney Transplant Patient

Prompt and accurate diagnosis of Nocardia skin infections is important in immunocompromised hosts, especially transplant patients. The sporotrichoid form, which is otherwise known as the lymphocutaneous form of Nocardia skin involvement, can mimic other conditions, including those caused by fungi, mycobacteria, spirochetes, parasites and other bacteria. Delayed or inaccurate diagnosis and treatment of Nocardia skin infections in transplant patients could lead to dissemination of disease and other poor outcomes. Nocardia brasiliensis is a rare cause of lymphocutaneous nocardiosis in solid organ transplant patients with only two other cases reported to our knowledge. This case describes a middle-aged man, who presented 16 years post kidney transplant. He developed a sporotrichoid lesion on his upper extremity one week after gardening. Ultrasound showed a 35-cm abscess tract on his forearm, which was subsequently drained. Nocardia brasiliensis was isolated from pus culture and he was treated successfully with amoxicillin/clavulanate for 6 months. A review of the relevant literature is included.

Cutaneous nocardiosis by a new pathogenic species: Nocardia grenadensis

Nocardiosis is a rare, predominantly opportunistic, suppurative disease caused by bacteria of the order Actinomycetales. There are currently more than 100 species of Nocardia described, less than half are pathogenic to humans. Cutaneous nocardiosis can be caused by direct inoculation from a contaminated material or by secondary dissemination. The authors present a 70-year-old man with an autoimmune haemolytic anaemia treated with prednisolone and azathioprine. The patient presented multiple erythematous tender nodules with linear distribution and proximal progression along the left upper limb with 2 months of evolution. The skin biopsy revealed non-specific inflammation with areas of abscess. Culture was positive for bacteria of the genus Nocardia, and molecular techniques revealed Nocardia grenadensis The patient was treated with minocycline with good response, but the disease recurred. N. grenadensis was first identified in 2012 in a bioprospecting process. The authors now describe the first case of cutaneous nocardiosis caused by N. grenadensis.

Meningitis and Ventriculitis due to Nocardia araoensis Infection

A 73-year-old man was admitted to our hospital with disturbance of consciousness, fever and headache. Cerebrospinal fluid (CSF) analysis revealed pleocytosis with neutrophil predominance, increased protein and low glucose. CSF and blood cultures yielded negative results. Antibiotics and antituberculous drugs were started for meningitis. An antimycotic was also added. The patient died from transtentorial hernia 99 days after admission. Autopsy revealed meningitis, ventriculitis and brain abscess, and Nocardia araoensis was detected in pus from the left lateral ventricle. This appears to represent the first report of N. araoensis meningitis complicated by ventriculitis and brain abscess.

First case of cerebral abscess due to a novel Nocardia species in an immunocompromised patient

We report the first case of cerebral abscess due to a novel species of Nocardia in a heart transplant patient and describe the antimicrobial susceptibility of this isolate. As our patient was intolerant to trimethoprim-sulfamethoxazole, we also discuss alternative therapeutic options in brain abscess due to Nocardia sp.