Candida and Staphylococcus species can cause hospital-acquired infections due to their ability to inhabit and form biofilms on the host or on abiotic surfaces in polymicrobial interactions. Despite health establishments prioritizing the application of disinfection programs to minimize the risk of contamination, the literature shows little efficiency of disinfectants in these environments, a fact related to the presence of biofilms, which are less susceptible to biocides, antibiotics and physical stress. In addition, interactions between microorganisms can generate changes in the composition of the biofilm matrix, induce the appearance of persistent cells (persister cells) and alter the community's response to antimicrobials, resulting in increased morbidity and mortality of infected patients. In this context, this study proposes to evaluate the effect of disinfectants - chlorhexidine and orthophthalaldehyde on the matrix components of biofilms of C. parapsilosis sensu stricto and S. aureus in monospecies or in combination. Environmental and clinical strains of C. parapsilosis stricto sensu, biofilm formers, and the strain S. aureus ATCC 25923 will be used. Commercial preparations of disinfectants will be diluted to use concentrations in distilled water and sterilized by filtration. Biofilms will be formed in 96-well microplates. Matrix components will be quantified by specific methodologies before and after exposure of biofilms to disinfectants. Knowledge of the matrix components of single- or dual-species C. parapsilosis and S. aureus biofilms can enhance knowledge of microbial tolerance to environmental stresses, which has been largely underestimated.
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