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

https://doi.org/10.1016/j.csbj.2020.12.017Get rights and content
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Highlights

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

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

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

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

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

Abstract

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.

Keywords

Nocardia
Opportunistic pathogen
Environment
Murine model of transient immunoparalysis
Urban pollution
Hsp65 metabarcoding

Cited by (0)

1

These authors contributed equally to this work.

2

These authors contributed equally to this work.