Table 1 Phenotypic virulence traits tested and respective media

Biofilm

Red Congo Agar [BHI Infusion Broth (VWR, Leuven, Belgium), Bacteriologic Agar (VWR, Leuven, Belgium), sucrose and Red Congo Stain (Sigma-Aldrich, St. Louis, USA), in a concentration of 0.0008%]

72 h at 25 °C

Black halo around the colonies

[32]

Hemolysins

Columbia Agar + 5% Sheep Blood (bioMérieux, Marcy-l’Etoile, France)

72 h at 25 °C

Clear halo (β- hemolysis) or green or brown discoloration (α- hemolysis) around the colonies

[30, 33]

Lipase

Spirit Blue Agar (Difco, Detroit, USA), supplemented with 0.25% Tween® 80 and 25% commercial olive oil

24 h at 25 °C

Blue color halo around the colonies

[30, 34]

Lecithinase

Egg Yolk Agar [Tryptic Soy Agar (VWR, Leuven, Belgium), supplemented with 10% egg yolk emulsion (VWR, Leuven, Belgium]

72 h at 25 °C

Clear halo around the colonies

[35]

DNAse

DNAse agar (VWR, Leuven, Belgium) supplemented with toluidine blue

72 h at 25 °C

Pink halo around the colonies

[31]

Protease

Skim Milk Agar [Skim Milk powder (Oxoid, Hampishire, UK) and Bacteriological Agar (VWR, Leuven, Belgium)]

72 h at 25 °C

Clear halo around the colonies

[36]

Gelatinase

Nutrient Gelatin Agar

72 h at 25 °C

Gelatin liquefaction

[30, 37]