Biofilm formation by Staphylococcus aureus isolated from food poisoning outbreaks and effect of Butia odorata Barb. Rodr. Extract on planktonic and biofilm cells

The aims of this study were to verify the ability of S. aureus isolates from food poisoning outbreaks to form biofilm, and evaluate the susceptibility of these isolates to Butia odorata extract (BOE) and its effect on S. aureus biofilm. All 13 S. aureus isolates formed biofilm on polystyrene; and 84.6% (11/13) carried icaA and icaB genes, 69.2% (9/13) the icaD gene, and 61.5% (8/13) the icaC gene. All S. aureus isolates were susceptible to BOE, with minimum inhibitory concentration (MIC) values ranging from 2.8 to 11.4 mg.mL-1. Confocal laser scanning microscopy (CLSM) analysis showed that BOE damaged the cell membrane of S. aureus. The addition of 2 X MIC (60 min contact) decreased the number of biofilm cells by 99.99%, and using 4 X MIC (30 and 60 min contact) the reduction was 99.9%. All S. aureus isolates were biofilm formers, which causes concern because these isolates were involved in outbreaks. On the other hand, the isolates were susceptible to BOE, as the extract damaged the cell membrane of S. aureus. Besides that, BOE reduced the number of S. aureus biofilm cells, having the potential to be used as a sanitizer. •Staphylococcus aureus isolates were biofilm formers.•Staphylococcus aureus isolates were susceptible to B. odorata extract.•Butia odorata extract damaged the cell membrane of S. aureus.•Butia odorata extract reduced the number of S. aureus biofilm cells.