Quantifying biofilm matrix components: effects of chlorhexidine and orthophthalaldehyde on <i>Candida parapsilosis</i> and <i>Staphylococcus aureus</i>

<i>Candida</i> and <i>Staphylococcus</i> species are responsible for hospital-acquired infections, forming resilient biofilms. This study evaluated the impact of biocides on the biofilm matrix components of <i>Candida parapsilosis</i> and <i>Staphylococcus aureus</i> 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 <i>C. parapsilosis</i> and 17.25 ± 1.86 µg/mL for <i>S. aureus</i>) after CLX and OPA exposure, especially in isolates 935 M, 936 C, and <i>S. aureus</i> biofilms (<i>p</i> < 0.01). Carbohydrates significantly decreased (<i>p</i> < 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.