Growth media effect of Candida species and Staphylococcus aureus co-aggregation.

Objectives: This study aimed to elucidate the aggregation ability of six different species of Candida spp. with S. aureus in four different growth media.
Methods: Candida auris (ATCC MYA-5002), Candida albicans (ATCC MYA-4901), Candida lusitaniae (ATCC 64215), Candida dubliniensis (ATCC MYA-2975), Candida parapsilosis (ATCC 22019), and Candida glabrata (ATCC 90030) and S. aureus (ATCC 25923) were cultured in RPMI-1640, yeast extract peptone dextrose (YEPD), Sabouraud dextrose (SD) and Brain Heart Infusion-Yeast Extract (BHIYE) broth. Meanwhile, S. aureus was grown in Brain Heart Infusion (BHI) broth. Then, Candida spp. and S. aureus were standardised in co-aggregation buffer to 10⁶ cells mL^-1 and 10⁷ cells mL^-1, respectively. Auto-aggregation was determined by measuring the absorbance difference at 620 nm (ΔAbs) between 0 h and 1 h at room temperature of a similar kingdom in a different vial. In contrast, co-aggregation was determined by combining two kingdoms in the same vial.
Results: C. glabrata had the highest auto-aggregation in RPMI-1640 (2.54±0.09%), SDB (4.47±0.13%), and BHIYE (10.81±0.45%), respectively, when compared to other Candida spp. In addition, all Candida spp. exhibited decreased co-aggregation in RPMI-1640 when co-cultured with S. aureus. Finally, only C. auris and C. parapsilosis exhibited increased co-aggregation scores in BHIYE (0.22±0.00%) and SDB (1.04±0.02%), respectively, compared to auto-aggregation.
Conclusions: In conclusion, Candida spp. interact antagonistically with S. aureus except for C. auris and C. parapsilosis grown in BHIYE and SDB, respectively.