Pulmonary Nocardiosis in the Immunocompetent Host: Case Series

Unremitting Asthma as a Presentation of Pulmonary Nocardiosis: A Case Report

Severe, refractory asthma requires a combination of multiple maintenance inhalers and medications including high-dose inhaled corticosteroids and immunomodulators to achieve control of symptoms. The use of inhaled corticosteroids, however, increases the susceptibility of opportunistic bacterial infections, such as Nocardia, resulting in pulmonary nocardiosis. This case describes a 46-year-old patient with a history of severe, refractory asthma who presented with progressively worsening asthma exacerbation symptoms. She was treated with immunomodulators, high-dose inhaled corticosteroids and oral steroids, and several courses of antibiotics. CT imaging revealed bibasilar peri-bronchial thickening and tree-in-bud nodularity in the right lower lobe. Pulmonary cultures collected from bronchoscopy grew Nocardia nova complex. This was a rare case of persistent asthma exacerbation by N. nova complex bronchopulmonary infection. Broad differentials should be considered in patients with severe, refractory asthma who were previously controlled and were found to fail treatment therapies. Immunocompromised patients with chronic lung disease are at higher risk of severe infection with disseminated nocardiosis. These patients have a higher mortality and morbidity risk if early diagnosis of pulmonary nocardiosis does not occur.

Nocardia beijingensis lung mass in an immunocompetent adult

A 47-year-old man was referred for ongoing workup of an enlarging lung mass. Extensive workup of the mass had been unrevealing for several months until cultures grew Nocardia beijingensis He was successfully treated with trimethoprim/sulfamethoxazole and then doxycycline with near-complete resolution of the mass on follow-up. This case presents a rare species of N. beijingensis It highlights the importance of considering nocardiosis in immunocompetent adults and the challenge in initiating targeted treatment due to delayed culture results.

Microbial risk assessment of Nocardia cyriacigeorgica in polluted environments, case of urban rainfall water

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Urban infiltration basins are a reservoir of a high diversity of Nocardia encompassing both pathogenic and not-pathogenic species.

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Relative abundance of pathogenic Nocardia species presents a positive correlation with metal trace elements.

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High infraspecific variability within N. cyriacigeorgica, forming three phylogroups.

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Environmental N. cyriacigeorgica strains may be as virulent as clinical GUH-2 strain.

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hsp65 marker can be used by metabarcoding approach for assessment of environmental Nocardia biodiversity.

Urban Infiltration Basins (UIBs) are used to manage urban runoff transfers and feed aquifers. These UIBs can accumulate urban pollutants and favor the growth of potentially pathogenic biological agents as Nocardia.

Objectives

To assess the spatio-temporal dynamics of pathogenic Nocardia in UIBs and to stablish phylogenetic relationships between clinical and UIB N. cyriacigeorgica strains. To assess pathogenicity associated with environmental N. cyriacigeorgica using an animal model, and to identify genetic elements that may be associated to its virulence.

Methods

A well-characterized UIB in terms of chemical pollutants from Lyon area was used in this study during a whole year. Cultural and Next-Generation-Sequencing methods were used for Nocardia detection and typing. Clinical and environmental isolates phylogenetic relationships and virulences were compared with Multilocus-Sequence-Analysis study together with a murine model.

Results

In autumn, N. cyriacigeorgica and N. nova were the pathogenic most prevalent species in the UIB. The complex N. abscessus/asiatica was also detected together with some other non-pathogenic species. The presence of pathogenic Nocardia was positively correlated to metallic trace elements. Up to 1.0 × 10³ CFU/g sediment of N. cyriacigeorgica and 6 OTUs splited in two different phylogroups were retrieved and were close to clinical strains. The EML446 tested UIB isolate showed significant infectivity in mice with pulmonary damages similar to clinical clone (GUH-2).

Conclusion

Hsp65 marker-based metabarcoding approach allowed detecting N. cyriacigeogica as the most abundant Nocardia pathogenic species in a UIB. Metal trace elements-polluted environments can be reservoirs of pathogenic Nocardia which may have a similar virulence to clinical strains.

Pulmonary Nocardiosis with Aspergillosis in a patient with COPD: A rare co-infection

Pulmonary Nocardiosis and invasive Aspergillosis are well documented in immunocompromised patients. The coexistence of both infections is a diagnostic rarity, especially in patients with underlying structural lung diseases. We describe this rare association in a 46-year-old female with a history of pulmonary tuberculosis and COPD. The diagnosis of pulmonary Nocardiosis is challenging due to non-specific clinical features, inherent ability to mimic malignancy, tuberculosis and difficulty in the cultivation of the organism. The treating physicians should aware of the rare occurrence of such co-infections in order to prevent misdiagnosis and prompt treatment.

Infections causing central airway obstruction: role of bronchoscopy in diagnosis and management

Central airway obstructive infections (CAOI) are challenging medical conditions that may represent an advanced and complicated process of ongoing infections. The epidemiology of CAOI is unknown as well as the pathophysiology and the mechanism of development. This is due to sparse data in the literature that consists mainly of case reports and retrospective case series. CAOI can be caused by fungal, bacterial, parasitic and viral infections. Most patients with CAOI can be diagnosed clinically and with chest imaging, which demonstrate obstruction of the central airways. However, bronchoscopy is commonly used to confirm and obtain a specific diagnosis to guide specific therapy. In recent years, interventional pulmonology (IP) is becoming widely available and offer a minimally invasive approach for the management of central airway diseases such as cancers, benign strictures, and other conditions. Various bronchoscopic modalities are used to treat central airway obstruction (CAO), such as mechanical debulking, endobronchial laser therapy, electrocautery, argon plasma coagulation, cryotherapy, and airway stenting. In patients with CAOI, the role of therapeutic bronchoscopy is not clearly defined, but many isolated reports in the literature described bronchoscopic intervention in combination with medical therapy as the initial management approach. In this paper, we present cases of CAOI that underwent bronchoscopic intervention as part of their management. We described the infectious etiology, locations, bronchoscopic findings and bronchoscopic modalities for airway management.

Pulmonary nocardiosis in Chronic Obstructive Pulmonary Disease: A new clinical challenge

Pulmonary nocardiosis (PN) is a rare but severe disease caused by Nocardia spp. Despite the traditional description as opportunistic infection, case reports and case series of pulmonary nocardiosis have recently been reported in immunocompetent patients too, in particular among people with chronic pulmonary diseases such as advanced Chronic Obstructive Pulmonary Disease (COPD). PN is characterized by non-specific symptoms and radiological findings; bacteriological culture can be difficult. For the reasons above, diagnosis of PN is challenging, sometimes resulting in a misdiagnosis of tuberculosis. We report an interesting case of PN in a 75-year-old male with COPD. He complained a 3-months history of fatigue, evening rise in body temperature, night sweats, unexplained weight loss of 5 kg, worsening dyspnea, cough and mucopurulent sputum. The chest X-ray showed multiple nodules with cavitations bilaterally in the apical and subclavian regions. Nocardia cyriacigeorgica with 100% identity was identified in three sputum samples. Since the patient has never undergone a systemic and/or inhaled steroid therapy, and has no respiratory failure and comorbidities entailing immunodepression, it is conceivable that, in this immunocompetent patient, the COPD could represent an isolated risk factor for PN. Risk factors, clinical presentations, radiographic findings, differential diagnosis and review of the literature of PN cases in COPD, pointing out the similarities and differences, are also described.