Clinical characteristics of pulmonary nocardiosis in immunocompetent patients

Nocardia in an Immunocompetent Patient Simulating Pulmonary Carcinoma: A Case Report and Literature Review

Nocardiosis is an opportunistic infectious pathology of low incidence that usually affects the lungs, skin, and brain. It has been implicated in causing serious and potentially fatal infections without treatment. It affects immunocompetent and immunocompromised patients. In immunocompetent patients, it is presented with local conditions, and in immunocompromised patients, it is seen in disseminated forms. We present the case of a 61-year-old male immunocompetent patient with a high suspicion of pulmonary carcinoma, in whom pathology showed infection by Nocardia spp.

Pulmonary Infection

Pneumonia is a significant cause of morbidity and mortality in the community and hospital settings. Bacterial, viral, mycobacterial, and fungal pathogens are all potential causative agents of pulmonary infection. Chest radiographs and computed tomography are frequently utilized in the assessment of pneumonia. Learning the imaging patterns of different potential organisms allows the radiologist to formulate an appropriate differential diagnosis. An organism-based approach is used to discuss the imaging findings of different etiologies of pulmonary infection.

Comparative Analysis of CT Findings and Clinical Outcomes in Adult Patients With Disseminated and Localized Pulmonary Nocardiosis

BACKGROUND

Pulmonary nocardiosis is a rare opportunistic infection with occasional systemic dissemination. This study aimed to investigate the computed tomography (CT) findings and prognosis of pulmonary nocardiosis associated with dissemination.

METHODS

We conducted a retrospective analysis of patients diagnosed with pulmonary nocardiosis between March 2001 and September 2023. We reviewed the chest CT findings and categorized them based on the dominant CT findings as consolidation, nodules and/or masses, consolidation with multiple nodules, and nodular bronchiectasis. We compared chest CT findings between localized and disseminated pulmonary nocardiosis and identified significant prognostic factors associated with 12-month mortality using multivariate Cox regression analysis.

RESULTS

Pulmonary nocardiosis was diagnosed in 75 patients, of whom 14 (18.7%) had dissemination, including involvement of the brain in 9 (64.3%) cases, soft tissue in 3 (21.4%) cases and positive blood cultures in 3 (21.4%) cases. Disseminated pulmonary nocardiosis showed a higher frequency of cavitation (64.3% vs. 32.8%, P = 0.029) and pleural effusion (64.3% vs. 29.5%, P = 0.014) compared to localized infection. The 12-month mortality rate was 25.3%. The presence of dissemination was not a significant prognostic factor (hazard ratio [HR], 0.80; confidence interval [CI], 0.23-2.75; P = 0.724). Malignancy (HR, 9.73; CI, 2.32-40.72; P = 0.002), use of steroid medication (HR, 3.72; CI, 1.33-10.38; P = 0.012), and a CT pattern of consolidation with multiple nodules (HR, 4.99; CI, 1.41-17.70; P = 0.013) were associated with higher mortality rates.

CONCLUSION

Pulmonary nocardiosis with dissemination showed more frequent cavitation and pleural effusion compared to cases without dissemination, but dissemination alone did not affect the mortality rate of pulmonary nocardiosis.

Successful treatment with amoxicillin-clavulanic acid: cutaneous nocardiosis caused by Nocardia brasiliensis

AIM

To emphasize the role of non-sulfonamides in the treatment of Nocardia infection and reduce the adverse reactions caused by sulfonamides.

METHODS

We retrospectively analyzed a case of cutaneous nocardiosis in an immunocompetent individual. The colonies obtained by staining the pus in the lesion with antacid and culturing the agar plates were identified by flight mass spectrometry. The pathogenic identification showed Nocardia brasiliensis infection and the patient was treated with amoxicillin-clavulanic acid.

RESULTS

After treatment with amoxicillin and clavulanic acid, the ulcer gradually peeled and crusted, leaving dark pigmentation. The patient has finally recovered.

CONCLUSION

Sulfonamides are the first-line antibacterial agents for years in treatment of nocardiosis but are of great toxicity and side effects. This patient was successfully treated with amoxicillin-clavulanic acid and it provided a reference protocol for patients with sulfonamide-resistant Nocardia or sulfonamides intolerance.

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.

Pulmonary nocardiosis following nodular bronchiectatic Mycobacterium avium complex pulmonary disease in an immunocompetent patient

A woman in her 70s with a history of nodular bronchiectatic Mycobacterium avium complex pulmonary disease (MAC-PD) presented with an exacerbated productive cough and worsening findings on chest imaging. Although repeated sputum culture tests were negative for acid-fast bacilli and only revealed normal respiratory flora, a bronchoscopy identified Nocardia sp. Consequently, she was diagnosed with pulmonary nocardiosis and was successfully treated with levofloxacin. It is known that pulmonary nocardiosis can manifest in immunocompetent individuals with bronchiectasis. For cases of refractory nodular bronchiectatic MAC-PD, it is vital to consider bronchoscopy to identify potential co-infections, such as Nocardia.

Mild Pulmonary Nocardiosis Caused by Nocardia terpenica in an Immunocompetent Patient

A 53-year-old immunocompetent man was admitted to our hospital because of paroxysmal cough with a low fever for more than 5 months. On admission, chest computed tomography showed multiple plaques and nodules, some with small central cavities, in both lungs and cystic and columnar bronchiectasis of the right middle bronchus. Treatment with various antibiotics was ineffective. Metagenomic next-generation sequencing of the bronchoalveolar lavage fluid showed Nocardia terpenica, and this organism was cultured from bronchoalveolar lavage fluid, resulting in a diagnosis of pulmonary nocardiosis. After administration of trimethoprim-sulfamethoxazole for 5 weeks, chest computed tomography showed a significant reduction in the lung lesions that had been detected on admission. Immunosuppressed patients are particularly prone to nocardiosis infection, which is usually severe. N. terpenica has rarely been detected in clinical samples, and its characteristics require further study with the accumulation of more clinical cases.

Disseminated Nocardia Brain Abscess Presenting as Primary Lung Cancer With Brain Metastasis

We present a challenging case of disseminated Nocardia brasiliensis infection manifesting as brain and skin abscesses. Nocardia is an important potential pathogen to consider in patients with a relevant travel history to endemic regions or atypical presentations, such as brain and skin abscesses. About one-third of patients with Nocardia infections are immunocompetent, and their symptoms are nonspecific. This case shows the limitations of imaging studies in diagnosing Nocardia brain abscesses, as the patient's non-magnetic resonance (MR) conditional pacemaker precluded MRI evaluation and led to a diagnostic challenge. Therefore, the patient's initial evaluation was presumed to be primary lung cancer with brain metastasis. High clinical suspicion, imaging studies (especially MRI), and tissue biopsy are needed to diagnose this type of brain abscess in a timely manner to prevent further complications.

Molecular detection of Nocardia: development and application of a real-time PCR assay in sputum and bronchoalveolar lavage fluid samples

The diagnosis of pulmonary nocardiosis remains challenging. Rapid detection of Nocardia is of primary importance for early diagnosis and precise treatment of nocardiosis. In this study, our objective was to develop and validate a new TaqMan real-time PCR (qPCR) assay for rapidly detecting Nocardia spp. in respiratory samples. Based on published sequence data, primers in a conserved region of the 16S rRNA gene and a probe within that region that was specific for Nocardia were designed. The distinction effect of the qPCR assay was assessed between Nocardia and other respiratory-associated bacteria. Furthermore, the specificity and sensitivity of the assay were evaluated in respiratory clinical samples (n = 205), compared to the results of 16S rRNA gene amplicon sequencing and clinical diagnosis. The qPCR assay exhibited high specificity, sensitivity, repeatability, and reproducibility. The limit of detection of standard plasmid DNA was 3 × 10² copies/mL. Additionally, the qPCR assay was applied to the direct detection of 205 clinical respiratory samples. The specificity and sensitivity of the qPCR were all 100% compared to 16S rRNA gene amplicon sequencing, as well as 98.4% and 100% compared to clinical diagnosis respectively. The qPCR yielded results within 3 h of sample processing, compared to several days for culture, significantly reducing turnaround time. The results suggest that the new qPCR assay developed in this study provides reliable and rapid detection of Nocardia spp. in the respiratory tracts and is expected to reduce the time required for diagnosing and treating nocardiosis.

Native Valve Endocarditis Caused by Nocardia asteroides in an Immunocompetent Host: A Case Report and a Review of the Literature

Nocardia species are a rare cause of infective endocarditis (IE). We describe a case of native valve endocarditis caused by Nocardia asteroides in a 38-year-old Hispanic male with no apparent environmental exposures or risk factors for IE. Transesophageal echocardiography revealed severe mitral regurgitation, prompting emergent replacement of the valve. Nocardia asteroides were isolated from the tissue culture of the mitral valve. MRI of the brain also demonstrated innumerable micronodular intra-axial lesions throughout the brain, consistent with disseminated nocardiosis. The patient was treated with intravenous trimethoprim/sulfamethoxazole, meropenem, and amikacin for a six-week course, followed by oral trimethoprim/sulfamethoxazole and minocycline for 12 months. Follow-up after 18 months revealed no evidence of relapse. Although several cases of endocarditis due to Nocardia asteroides have been reported in immunocompromised hosts, to the best of our knowledge we believe the present case is the first to describe native valve endocarditis by Nocardia asteroides in an immunocompetent host with no apparent risk factors for IE.

The Computed Tomography Findings and Follow-up Course of Pulmonary Nocardiosis

OBJECTIVE

Our study aimed to elucidate the computed tomography (CT) features and follow-up course of pulmonary nocardiosis patients to improve the understanding and diagnostic accuracy of this disease.

METHODS

The chest CT findings and clinical data of patients diagnosed with pulmonary nocardiosis by culture or histopathological examination in our hospital between 2010 and 2019 were retrospectively analyzed.

RESULTS

A total of 34 cases of pulmonary nocardiosis were included in our study. Thirteen patients were on long-term immunosuppressant therapy, among whom 6 had disseminated nocardiosis. Among the immunocompetent patients, 16 had chronic lung diseases or a history of trauma. Multiple or solitary nodules represented the most common CT feature (n = 32, 94.12%), followed by ground-glass opacities (n = 26, 76.47%), patchy consolidations (n = 25, 73.53%), cavitations (n = 18, 52.94%), and masses (n = 11, 32.35%). There were 20 cases (61.76%) with mediastinal and hilar lymphadenopathy, 18 (52.94%) with pleural thickening, 15 (44.12%) with bronchiectasis, and 13 (38.24%) with pleural effusion. Significantly higher rates of cavitations were observed among immunosuppressed patients (85% vs 29%, P = 0.005). At follow-up, 28 patients (82.35%) clinically improved with treatment, while 5 (14.71%) had disease progression, and 1 (2.94%) died.

CONCLUSIONS

Chronic structural lung diseases and long-term immunosuppressant use were found as risk factors for pulmonary nocardiosis. While the CT manifestations were highly heterogeneous, clinical suspicion should be raised upon findings of coexisting nodules, patchy consolidations, and cavitations, particularly in the presence of extrapulmonary infections such as those of the brain and subcutaneous tissues. A significant incidence of cavitations may be observed among immunosuppressed patients.

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.

Rapid detection of pulmonary nocardiosis by metagenomic next generation sequencing

We retrospectively analyzed 3 cases of pulmonary nocardiosis. Patients were identified by metagenomic next generation sequencing (mNGS) in the First Affiliated Hospital of Soochow University, from January 2019 to April 2022. All patients had underlying diseases, and were in immunocompromised state, with membranous nephropathy, acute lymphoblastic leukemia (ALL), and systemic lupus erythematosus (SLE), respectively. Symptoms common to all cases included fever, cough and expectoration. Chest computed tomography (CT) presented patchy shadows or nodules, with or without cavitation lesions, or pleural effusion. mNGS detected Nocardia spp. via bronchoalveolar lavage fluid (BALF) or blood samples from patients. All the patients were discharged with recovery after using the trimethoprim-sulfamethoxazole (TMP-SMX) and remained without evidence of disease during regular follow-ups. mNGS may be a tool for rapid and accurate detection and identification of pulmonary nocardiosis, but interpreting the mNGS results should be more cautious because the mNGS assay can also detect colonization.

Nocardia farcinica Pneumonia with Sepsis and a Bronchial Neoplasm in a Healthy Patient: A Case Report

There are few reports on sepsis caused by infection with Nocardia in people with normal immune function, and there is no report on bronchial tumor caused by Nocardia. This paper describes a case of Nocardia farcinica pneumonia with sepsis and a bronchial neoplasm in a healthy patient.

Invasive Nocardiosis Versus Colonization at a Tertiary Care Center: Clinical and Radiological Characteristics

Objective

To describe the clinical and radiographic findings in a large cohort of patients with positive cultures for Nocardia emphasizing the differences between invasive disease and colonization.

Patients and Methods

We conducted a single-center, retrospective cohort study of 133 patients with a positive Nocardia isolate between August 1, 1998, and November 30, 2018, and a computed tomography (CT) of the chest within 30 days before or after the bacteria isolation date.

Results

Patients with colonization were older (71 vs 65 years; P=.004), frequently with chronic obstructive pulmonary disease (56.8% vs 16.9%; P<.001) and coronary artery disease (47.7% vs 27%, P=.021), and had Nocardia isolated exclusively from lung specimens (100% vs 83.1%; P=.003). On CT of the chest, they had frequent airway disease (84.1% vs 51.7%; P<.001). Patients with invasive nocardiosis had significantly (P<.05) more diabetes, chronic kidney disease, solid organ transplant, use of corticosteroids, antirejection drugs, and prophylactic sulfa. They had more fever (25.8% vs 2.3%; P<.001), cutaneous lesions (14.6% vs 0%; P=.005), fatigue (18% vs 0%; P=.001), pulmonary nodules (52.8% vs 27.3%; P=.006), and free-flowing pleural fluid (63.6% vs 29.4%; P=.024). The patterns of nodule distribution were different-diffuse for invasive nocardiosis and peribronchiolar for Nocardia colonization.

Conclusion

The isolation of Nocardia in sputum from a patient with respiratory symptoms does not equal active infection. Only by combining clinical and chest CT findings, one could better differentiate between invasive nocardiosis and Nocardia colonization.

Updated Review on Nocardia Species: 2006-2021

This review serves as an update to the previous Nocardia review by Brown-Elliott et al. published in 2006 (B. A. Brown-Elliott, J. M. Brown, P. S. Conville, and R. J. Wallace. Jr., Clin Microbiol Rev 19:259-282, 2006, https://doi.org/10.1128/CMR.19.2.259-282.2006). Included is a discussion on the taxonomic expansion of the genus, current identification methods, and the impact of new technology (including matrix-assisted laser desorption ionization-time of flight [MALDI-TOF] and whole genome sequencing) on diagnosis and treatment. Clinical manifestations, the epidemiology, and geographic distribution are briefly discussed. An additional section on actinomycotic mycetoma is added to address this often-neglected disease.

Co-infection with Nocardia spp. in a patient with Mycobacterium avium complex pulmonary disease: A case report

Mycobacterium avium complex pulmonary disease (MAC-PD) is sometimes accompanied by co-infection with other pathogenic microorganisms such as Pseudomonas aeruginosa and Haemophilus influenzae. However, co-infection with Nocardia spp. has been rarely reported. We report on a patient diagnosed as having co-infection with Nocardia after treatment for MAC-PD, which was successfully treated using trimethoprim-sulfamethoxazole (TMP-SMX). A 74-year-old woman with MAC-PD was admitted to our hospital to undergo re-examination for pathogenic microorganisms because chest computed tomography (CT) findings did not improve after treatment for MAC-PD. She underwent bronchoscopy and Nocardia spp. was detected from bronchoalveolar lavage fluid culture. Chest CT findings improved after 6 months of treatment using TMP-SMX. Co-infection with other pathogenic microorganisms should be considered when chest CT findings worsen after adequate treatment of MAC-PD. Chest CT findings of Nocardia pulmonary disease in immunocompetent patients can mimic those of MAC-PD and should therefore be differentiated one from the other.

Nocardia in an Immunocompetent Host Masquerading As Lung Cancer: A Case Report

Nocardiosis is generally regarded as an opportunistic infection that can present as a cutaneous, pulmonary, or disseminated disease based on host immunity status. Pulmonary nocardiosis is typically seen in immunocompromised patients; however, it can rarely be present in immunocompetent patients. We present a rare case of an immunocompetent patient who was thought to have a lung malignancy but was found to have pulmonary nocardiosis upon further investigation.

Pneumococcal Pneumonia Co-infection with Mycobacterium avium and Nocardia cyriacigeorgica in an Immunocompetent Patient

A 61-year-old woman was transferred with a complaint of a fever and productive cough. She had tested positive for Mycobacterium avium and Nocardia cyriacigeorgica at least twice, and Streptococcus pneumonia (PISP) was isolated (3+) from her purulent sputum. As radiological findings, a lower lung field-dominant infiltration shadow and nodular shadow with cavity were recognized in the bilateral lung fields. We diagnosed her with pneumococcal pneumonia co-infection with M. avium and N. cyriacigeorgica. She was treated with MEPM for pneumococcal pneumonia, a standard regimen containing clarithromycin for pulmonary M. avium complex (MAC) disease, and sulfamethoxazole/trimethoprim for pulmonary nocardiosis. She improved with appropriate treatment.

Nocardiosis in Japan: a multicentric retrospective cohort study

Background Nocardia species cause a broad spectrum of infections, especially in immunocompromised patients. Given its relative rarity, data on the prognosis and distribution of nocardiosis from a large cohort are scarce. The present study aimed to scrutinize the clinical features and outcomes of nocardiosis in Japan, including one-year mortality and microbiological data. Methods The present, multicentric, retrospective cohort study enrolled patients aged ≥ 18 years with nocardiosis diagnosed between January 2010 and December 2017 and recorded their clinical and microbiological characteristics. Factors associated with one-year mortality were also determined using Cox proportional hazard analysis. Results In total, 317 patients were identified at 89 hospitals. Almost half (155/317, 48.9%) were receiving immunosuppressive agents, and 51 had disseminated nocardiosis (51/317, 16.1%). The one-year, all-cause mortality rate was 29.4% (80/272; lost to follow-up, n = 45). The most frequently isolated species was Nocardia farcinica (79/317, 24.9%) followed by the N. nova complex (61/317, 19.2%). Selected antimicrobial agents were generally effective, with linezolid (100% susceptibility [S]) and amikacin (94% S) having the most activity against Nocardia species. In Cox proportional hazard analysis, factors independently associated with one-year mortality were a Charlson Comorbidity Index score ≥ 5 (adjusted hazard ratio [aHR], 3.61; 95% confidence interval [CI], 1.95-6.71, P < 0.001) and disseminated nocardiosis (aHR, 1.79; 95%CI, 1.01-3.18, P = 0.047). Conclusions The presence of advanced comorbidities and disseminated infection, rather than variations in antimicrobial therapy or Nocardia species, were independently associated with one-year mortality.

Pulmonary Nocardia infection in a child with idiopathic pulmonary hemosiderosis

BACKGROUND

Idiopathic pulmonary hemosiderosis (IPH) encompasses a rare and agnogenic group of diffuse alveolar capillary hemorrhagic diseases. Corticosteroid treatment is the globally preferred therapeutic strategy for IPH; however, it can cause immunodeficiency. Nocardia infection often occurs in immunocompromised patients and primarily involves the pleura and lungs. Herein, we describe a case of pediatric pulmonary Nocardia infection after the corticosteroid treatment of IPH.

CASE PRESENTATION

A 7-year-old girl presented with chief complaints of pale complexion persisting for 1 year and a cough for 20 days. Abundant hemosiderin-laden macrophages were detected in the gastric juice, which supported the diagnosis of IPH. Uninterrupted doses of corticosteroids were administered during the last hospitalization. After nearly 2 months of corticosteroids therapy, the patient began to cough and produce a purulent sputum. Next-generation sequencing of the bronchoalveolar lavage fluid revealed Nocardia abscessus (N. abscessus) DNA. Linezolid was administered with good response, and the patient was discharged after 18 days of hospitalization. Her symptoms and pulmonary lesions had recovered, and the IPH appeared to be well-controlled with low dose of corticosteroids in follow-up.

CONCLUSIONS

Nocardia infection should be considered in the differential diagnoses for IPH patients receiving corticosteroid therapy, especially in patients with poor response to conventional empirical antibiotic therapy. Next-generation sequencing of bronchoalveolar lavage fluid may be used to quickly identify the Nocardia. Sulfonamides or linezolid are effective for pediatric pulmonary Nocardia infection.

Nocardia Infections: Ten Years Experience from a Tertiary Health Care Center in North India (2007-2016)

BACKGROUND

Nocardia species are important cause of infections in humans but are underreported due to missed diagnosis as well as misdiagnosis. Majority of the literature on these infections consists of case reports or series with few articles describing high number of cases.

OBJECTIVE

To study the epidemiology of Nocardia infections in a tertiary care center.

MATERIALS AND METHODS

This retrospective observational study was done in a tertiary care centre of North India over a period of 10 years (2007-2016). The detection of Nocardia spp. from clinical specimens was done by conventional methods viz. direct microscopy (Gram's stain, modified Ziehl -Neelsen stain [1%], KOH examination) and culture.

RESULTS

A total of 25 cases of nocardiosis were diagnosed during the study period. The mean age of the patients was 50.9 years (range 30-72 years) with a male:female ratio of 3:2. The site of disease in these patients included pulmonary (n=18), cutaneous (n=4), perinephric abscess (n=1), ocular (n=1) and bone (n=1). Risk factors associated were underlying lung disease (n=11), smoking (n=7), diabetes (n=5) and steroid therapy (n=4) in pulmonary nocardiosis, iatrogenic (n=1) and leprosy (n=1) in cutaneous nocardiosis, diabetes in perinephric abscess and cataract surgery in ocular nocardiosis. Culture was positive in 12/25 (48%) patients for Nocardia spp. Direct microscopy was positive in 22 patients. We wish to highlight that meticulous observation of KOH wet mount examination helped in clinching the diagnosis of Nocardiosis in 3 cases which were earlier missed by other methods.

CONCLUSION

Good communication with the clinician alongside a meticulous effort in the laboratory is essential for appropriate diagnosis and management of these cases.

Invasive Nocardiosis: Disease Presentation, Diagnosis and Treatment - Old Questions, New Answers?

Nocardia spp. is an environmental filamentous Gram-positive bacterium that may cause infections in humans and, despite recent progress, many challenges remain regarding the management of nocardiosis. This review aims at describing most recently published data regarding the diagnosis, treatment and follow-up of patients with invasive nocardiosis. As nocardiosis mainly affects patients with cell-mediated immunity defects, a comprehensive workup is mandatory in case of invasive nocardiosis occurring in ”apparently healthy patients”. Indeed, invasive nocardiosis might reveal an unknown primary immunodeficiency or the presence of anti-GM-CSF autoantibodies. Even if the diagnosis of nocardiosis mostly relies on direct examination and bacterial culture, a genus-specific PCR may be used for the detection of Nocardia, when directly performed on a clinical sample. Brain imaging should always be performed, even in the absence of neurological symptoms. Cotrimoxazole (trimethoprim/sulfamethoxazole), linezolid, parenteral cephalosporins, carbapenems and amikacin may be used as initial antibiotics to treat nocardiosis. Cotrimoxazole or linezolid can be used as monotherapy in selected patients without brain involvement. Although treatment duration has historically been set to at least 6 months in the absence of central nervous system involvement, shorter durations (<120 days) seem to be associated with a favourable outcome.

Asymptomatic cerebral abscesses after pleuropulmonary Nocardia farcinica infection

We report the case of a 68-year-old man with long-term receipt of steroid therapy who was diagnosed with cerebral abscesses and pulmonary nocardiosis. This patient displayed only respiratory symptoms. Confirmation of Nocardia farcinica species was achieved by specific PCR sequencing of the 16S ribosome RNA in bronchoalveolar lavage cultures. Cerebral magnetic resonance imaging revealed abscesses. Antibiotic therapy with trimethoprim/sulfamethoxazole was prescribed given the results of susceptibility tests and was maintained for 12 months, with no evidence of relapse afterwards.

Nocardia colonization in contrast to nocardiosis: a comparison of patients' clinical characteristics

Information on Nocardia colonization of the lower respiratory tract is scarce. The current study is aimed at comparing clinical characteristics between individuals with Nocardia colonization and those with nocardiosis. All patients with Nocardia isolation between 2007 and 2018 at a tertiary hospital in Israel were included. Nocardia isolation was based on biochemical tests together with phenotypic susceptibility and resistance patterns until 2011 and on matrix-assisted laser desorption/ionization time-of-flight mass spectrometer from 2012. We defined nocardiosis as a clinically evident infection related to the isolation of the bacteria, which required antibiotic therapy. We defined colonization as Nocardia isolation with no clinical evidence of disease. The medical charts of all included individuals were independently reviewed by an infectious disease specialist to ensure adequate classification. Logistic regression models were fitted to compare clinical characteristics between the groups. Fifteen (20%) of the 75 Nocardia isolations met the criteria for colonization. Of those, 13 (87%) had background illnesses. Having a chronic pulmonary disease was associated with increased likelihood of Nocardia colonization, in contrast to nocardiosis (adjusted odds ratio [OR] 4.06, 95% confidence interval [CI] 1.06-15.48, p = 0.040), while an inverse association was found with corticosteroid therapy (adjusted OR 0.21, 95% CI 0.06-0.74, p = 0.015). Nocardia colonization of the lower respiratory tract accounts for a substantial proportion of all Nocardia isolations. Individuals colonized with Nocardia typically have chronic pulmonary disease and are less frequently treated with corticosteroid than patients with nocardiosis.

Species Distribution And Antibiotic Susceptibility Of Nocardia Isolates From Yantai, China

Purpose

This study aimed to investigate the species distributions and drug sensitivities among 19 strains of Nocardia isolated from Yantai, China, from 2017 to 2019.

Patients and methods

Definitive species identification was performed by sequencing a fragment of the 16S rRNA gene (1480 bp) and by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The susceptibilities of the isolates to 15 commonly-used antibiotics were tested using the microbroth dilution method.

Results

Among the 19 Nocardia isolates, five species were confirmed. Seventeen of the 19 Nocardia spp. strains were identified consistently by the two methods, while two isolates of N. cyriacigeorgica were misidentified as N. otitidiscaviarum by MALDI-TOF MS. N. farcinica was the most common species (8/19), followed by N. cyriacigeorgica (6/19), N. otitidiscaviarum (2/19), N. brasiliensis (2/19), and N. nova (1/19). All isolates were susceptible to trimethoprim-sulfamethoxazole and amikacin, followed by linezolid and tigecycline (94.7% susceptibility rates). The sensitivity and minimum inhibitory concentration patterns for ciprofloxacin, moxifloxacin, clarithromycin, and tobramycin were significantly correlated with the species.

Conclusion

These results regarding the distribution and antibiotic resistance features of Nocardia species further our understanding of the diversity of Nocardia species circulating in Yantai, China, and thus support the use of more accurate empirical treatments.

A multicentre analysis of Nocardia pneumonia in Spain: 2010-2016

OBJECTIVE

To analyse all cases of Nocardia pneumonia occurring between 2010 and 2016 in five Spanish hospitals.

METHODS

This was a retrospective observational analysis of clinical and microbiological data collected from 55 cases of Nocardia pneumonia.

RESULTS

There were one to 20 cases per hospital and six to nine cases per year. Chronic obstructive pulmonary disease, bronchiectasis, and asthma were the main predisposing underlying respiratory conditions. Thirty-four patients were receiving systemic and/or inhaled corticosteroids prior to infection, eight had neoplasia, and six had haematological malignancies. Clinical and radiological findings were common to pneumonia of other infectious aetiologies, except for the frequent presence of nodules and cavitation. Overall, the 1-year mortality was high (38.2%), and mortality was directly related to the pulmonary disease in 15 patients (27.3%). The most frequently identified species were N. cyriacigeorgica (n=21), N. abscessus (n=8), and N. farcinica (n=5). All Nocardia isolates were susceptible to linezolid and all but two were susceptible to amikacin and trimethoprim-sulfamethoxazole.

CONCLUSIONS

Nocardia pneumonia-associated mortality remains high, probably because of the debilitated status of patients in whom this pathogen is able to cause pulmonary infection.

Disseminated Nocardiosis: A Case Report

Disseminated nocardiosis is a rare infection associated with underlying immunosuppression, and patients usually have some identifiable risk factor affecting cellular immunity. Due to advances in taxonomy and microbiology identification methods, infections by Nocardia species are more frequent, making the discussion of its approach and choice of antibiotherapy increasingly relevant.

A 77-year-old man presented to the emergency department with marked pain on the right lower limb, weakness, and upper leg edema. He had been diagnosed with organized cryptogenic pneumonia one year before and was chronically immunosuppressed with methylprednisolone 32 mg/day. Blood cultures isolated Nocardia cyriacigeorgica. Computed tomography revealed a gas collection in the region of the right iliacus muscle with involvement of the gluteal and obturator muscles upwardly and on the supragenicular plane inferiorly. Triple therapy with imipenem, amikacin, and cotrimoxazole was started, and the patient was submitted for emergent surgical decompression, fasciotomy, and drainage due to acute compartment syndrome. The patient had a good outcome and was discharged from the hospital after 30 days of intravenous therapy. This case illustrates the severity of Nocardia infection and highlights the need for a meticulous approach in the diagnosis and treatment of these patients.

Pulmonary Reinfection by Nocardia in an Immunocompetent Patient with Bronchiectasis

Pulmonary reinfection by Nocardia has been rarely reported. We describe a case of pulmonary reinfection by Nocardia in an immunocompetent patient. An 82-year-old immunocompetent woman with bronchiectasis presented with exacerbation of cough. She had a history of pulmonary nocardiosis three years earlier. At that time, Nocardia species were cultured from the sputum and identified as N. cyriacigeorgica with 16S ribosomal RNA gene sequencing. In the present episode, cultures of sputum and bronchial washing specimens grew N. beijingensis, which was identified with 16S ribosomal RNA gene sequencing. Pulmonary reinfection by different Nocardia species can occur in immunocompetent patients.

Nocardia infections in the transplanted host

BACKGROUND

Nocardia are uncommon pathogens that disproportionately afflict the immunocompromised host. Epidemiology and outcome data of Nocardia infections in transplant recipients are limited.

METHODS

We performed a retrospective chart review of all patients at Duke University Hospital with a history of solid organ transplant (SOT) or hematopoietic cell transplant (HCT) and at least one positive culture for Nocardia between 1996 and 2013. Our aim was to describe the epidemiology and outcomes of Nocardia infections in the transplanted host.

RESULTS

During the 18-year study period, 51 patients (14 HCT and 37 SOT recipients) had Nocardia infection. Nocardia incidence was stable during the study period in all populations except heart transplants, whose incidence declined. Infection occurred earlier in the HCT group than the SOT group (median time to diagnosis of 153 and 370 days, respectively). In both groups, the most common site involved was the lung. Outcomes were overall poor, especially in the HCT group with a cure rate of 29%. Heart transplant recipients had significantly better overall survival (P < .05) than other patients. Trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis did not provide complete protection from Nocardia infections, nor did it appear to select for resistant Nocardia isolates.

CONCLUSIONS

Infections with Nocardia are typically a late post-transplant complication. The use of TMP-SMX prophylaxis was not associated with TMP-SMX-resistant Nocardia. Overall outcomes remain poor.

Increasing Nocardia Incidence Associated with Bronchiectasis at a Tertiary Care Center

RATIONALE

Nocardia is a genus of pathogens that most commonly afflict immunocompromised hosts but may be an emerging infection among persons with bronchiectasis.

OBJECTIVES

To examine the epidemiology and clinical presentation of adult patients with Nocardia and bronchiectasis relative to other patient groups.

METHODS

We examined a retrospectively assembled cohort of adults at Duke University Hospital in Durham, North Carolina with at least one positive culture from a bodily fluid or tissue specimen for Nocardia between January 1996 and December 2013. Denominator data for key populations (e.g., bronchiectasis, transplant) were obtained using International Classification of Diseases, Ninth Revision codes. In addition, we performed a case-control analysis to examine the relationship between inhaled corticosteroid use and Nocardia lung infection among otherwise immunocompetent patients with bronchiectasis.

MEASUREMENTS AND MAIN RESULTS

We identified 183 patients with one or more cultures positive for Nocardia: 44 from 1996 to 2001, 64 from 2002 to 2007, and 75 from 2008 to 2013. Immune compromise was common (56%), particularly solid organ or hematopoietic cell transplant (30%). Infection usually was confined to the lungs (62%), followed by skin (10%), other sites (6%), brain (2%), and multiple sites (17%). Non-cystic fibrosis bronchiectasis was common among both immunocompetent (38%) and immunocompromised (10%) patients. Nocardia incidence in patients with bronchiectasis increased significantly over time, but there was no significant change in Nocardia incidence in hematopoietic cell or solid organ transplant recipients (our largest immunocompromised population). Among patients with bronchiectasis, Nocardia was positively but nonsignificantly associated with use of inhaled corticosteroids (odds ratio, 1.8; 95% confidence interval, 0.7-4.4).

CONCLUSIONS

The increasing incidence of Nocardia infections at our medical center appears to be driven by increased incidence in patients with bronchiectasis rather than increases in immunocompromised populations. It is unclear whether increased environmental exposures, microbiologic surveillance, or other factors account for the increased incidence of Nocardia in our patients with bronchiectasis.