Saccharopolyspora rectivirgula from Quebec dairy barns: application of simplified criteria for the identification of an agent responsible for farmer's lung disease

Abstract

Saccharopolyspora rectivirgula (Micropolyspora faeni) is one of the major agents responsible for farmer's lung disease, a form of hypersensitivity pneumonitis. It is frequently isolated from the air of contaminated barns. The identification of this actinomycete is difficult because most of its phenotypic characteristics are variable and classical tests are not easy to perform on actinomycetes. Fatty acid analysis is very useful for the identification of these strains, but is not available except in some research or reference laboratories. Morphological (microscopic and macroscopic observations), physiological and biochemical tests (growth properties; macromolecules degraded; citrate utilisation and acid production from carbohydrates; resistance to antibiotics, lysozyme and heat), cell wall and fatty acid analyses and IgG analyses with serum from patients with farmer's lung were performed on 12 environmental isolates presumed to be S. rectivirgula and two control strains of S. rectivirgula. From this, a simple and rapid scheme for the identification of this actinomycete is proposed: optimal growth temperature (55°C); colony appearance based on morphology (filamentous) and colour (beige to orange-brown); microscopic morphology (chains of spores on both aerial and substrate mycelium); growth on NaCl 10%; cell-wall analysis (type IV); and the verification of antibody response with serum from a patient with farmer's lung. This last criterion is important to confirm the immunogenicity of the strains identified as S. rectivirgula. This scheme provides an accurate and efficient way of identifying S. rectivirgula strains and evaluating exposure to this bacterium. The study shows the limited value and the lack of reproducibility of some classical biochemical tests.

Influence of Building Maintenance, Environmental Factors, and Seasons on Airborne Contaminants of Swine Confinement Buildings

“…Thermophilic actinomycetes were counted and the presence of Saccharopolyspora rectivirgula, the bacteria most frequently responsible for farmer's lung disease, was evaluated using common growth characteristics. (10) …”

Bioaerosols concentrations in working areas in biomethanization facilities

“…It is well documented that the thermophilic actinomycete SR is a contaminant found in compost and in the air of composting facilities (Duchaine et al 1999;Schafer et al 2013). It has been recently established that SR is one of the major agents responsible for causing extrinsic allergic alveolitis, or farmer's lung disease (Douwes et al 2003;Duchaine et al 1999). Great concentrations of airborne SR, ranging from 1.2 × 10 2 to 1.5 × 10 7 cells/ m 3 , were found with qPCR in composting facilities (Schafer et al 2013).…”

Characterization of Bioaerosols from Dairy Barns: Reconstructing the Puzzle of Occupational Respiratory Diseases by Using Molecular Approaches

“…As previously described, total IgGs specific for Saccharopolyspora rectivirgula from plasma of dairy barn workers and control subjects were measured by indirect enzyme-linked immunosorbent assay (ELISA) (10). Plasma samples from workers and control subjects were diluted 1/500 before they were added to the antigen (crude extract)-coated plate, prepared as previously described (15). Blank, negative, and positive controls were also added to each plate.…”