Routine microbiological analysis

Bacteria were isolated from clinical and environmental samples using standard microbiological procedures as described in the Manual of Clinical Microbiology (editions 8–10, issued by the American Society for Microbiology). In short, blood agar, McConkey and mannitol salt agar plates (all purchased from bioMérieux, Brussels, Belgium) were inoculated and incubated overnight at 37°C. Colonies were identified using the gram-negative (GN) and gram-positive (GP) identification cards for the VITEK 2 microbial ID system (bioMérieux, Brussels, Belgium), according to the manufacturer’s instructions.