Quantifying biofilm matrix components: effects of chlorhexidine and orthophthalaldehyde on Candida parapsilosis and...

Candida and Staphylococcus species are responsible for hospital-acquired infections, forming resilient biofilms. This study evaluated the impact of biocides on the biofilm matrix components of Candida parapsilosis and Staphylococcus aureus in monospecies and mixed biofilms. Proteins, carbohydrates, and extracellular DNA (eDNA) were quantified using the Bradford reagent, phenol-sulfuric acid, and silica column extraction with spectrophotometric readings at 260 and 280 nm. Biofilms were treated with 0.5% chlorhexidine (CLX) and 0.55% ortho-phthalaldehyde (OPA) for 3 and 10 min, respectively. Results showed a significant protein increase (8.6 ± 4.94 µg/mL for C. parapsilosis and 17.25 ± 1.86 µg/mL for S. aureus) after CLX and OPA exposure, especially in isolates 935 M, 936 C, and S. aureus biofilms (p < 0.01). Carbohydrates significantly decreased (p < 0.0001), with CLX generally more effective than OPA. eDNA levels increased across all samples. These findings suggest that CLX and OPA alter biofilm matrix composition, facilitating antimicrobial efficacy.