[Cerebral and pulmonary nocardiosis to Nocardia abscessus in an immunocompetent Algerian patient]

The first reported pulmonary nocardiosis caused by Nocardia gipuzkoensis resisted to trimethoprim/sulfamethoxazol (TMP-SMZ) in an immunocompetent patient

OBJECTIVES

Nocardia gipuzkoensis was first described as a novel and distinct species in 2020 by Imen Nouioui and pulmonary nocardiosis associated with N. gipuzkoensis was once reported in two bronchiectasis patients. Noteworthy, both reported N. gipuzkoensis cases showed sensitivity to trimethoprim/sulfamethoxazol (TMP-SMZ), which are usually recommended for empirical therapy.

METHODS

We reported the third case of N. gipuzkoensis infection in a 16-year-old girl with chief complaints of cough and persistent chest and back pain. No underlying immuno-suppressive conditions and glucocorticoid use was revealed. Patchy lesions next to the spine and located in the posterior basal segment of the lower lobes of the left lung were seen in thorax computed tomography (CT), but no pathogenic bacteria were detected according to routine laboratory testings.

RESULTS

Metagenomic next-generation sequencing (mNGS) combined with whole-genome sequencing (WGS) was used to classified our isolate from bronchoalveolar lavage fluid (BALF) as N. gipuzkoensis. It is worth mentioning that drug susceptibility testing of our isolate showed resistance to TMP-SMZ, which was never reported before. The patient improved remarkably both clinically and radiographically according to the treatment with imipenem-cilastatin infusion alone.

CONCLUSION

mNGS and WGS showed excellent performance in identifying the Nocardia genus to the species level and improving the detection rate of N. gipuzkoensis ignored by traditional culture. Different from previously reported cases, the N. gipuzkoensis infection case showed resistance to TMP-SMZ, which is an unprecedented finding and a crucial addition to our understanding of the antibacterial spectrum of N. gipuzkoensis. The successful treatment with imipenem-cilastatin infusion alone in this case is a testament to the importance of precise identification and tailored antibiotic therapy.

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.

Brainstem abscess treated conservatively

Background:

Brainstem abscess is a rare condition with a variety of treatment approaches. In this paper, we report an unusual case of a brainstem abscess with a positive outcome in an immunocompetent patient who was treated with antibiotic therapy.

Case Description:

A 22-year-old female presented with bilateral tetraparesis that was worse on the left hemibody, appendicular tremor, and left upper eyelid ptosis. Brain magnetic resonance imaging showed an abscess in the pons and midbrain due to possible nocardiosis. She was treated with dexamethasone, phenytoin, vancomycin, and meropenem for 8 weeks and trimethoprim-sulfamethoxazole for 6 weeks. The brain injury decreased, and the patient’s neurological status significantly improved.

Conclusion:

Brainstem abscess may be treated conservatively, leading to improvement of the clinical condition and decreased lesion size on imaging.