Biofilme misto em cateter venoso central com ênfase em Staphylococcus aureus e Candida albicans

Abstract

Biofilms are complex communities of microorganism and use their extracellular products to adhere to biotic or abiotic surfaces. Microbial communities are organized in this structure and maintain an interspecies communication. Inside biofilms microbial cells present different properties from their planktonic state. The aim of this study was to perform a bibliographic review about mixed biofilm in central venous catheter with emphasis on Staphylococcus aureus and Candida albicans. This study was conducted as a literature review, using scientific articles from the Scielo, Pubmed, Science Direct and Microbiology books. The biofilm formation leads to several advantages to microorganisms in the evolutionary context and is the preferential state for most species. It is a complex multistep process involving different bacterial species and steps and is typically classified into three stages: initial attachment (reversible and irreversible), micro-colony maturation and dispersion. Biofilms secrete a matrix of polysaccharides, proteins and fatty acids and water called extracellular polymeric substance that has extreme structural and maintenance importance, being responsible for the capture of nutrients and minerals and their distribution. Biofilms formed over or inside medical devices and on natural environments are often polymicrobial. The presence of co-participation of bacteria and fungi complicates the ability to routinely treat with single antimicrobial regimens. The synergy between microorganisms influences the severity of the infection. S. aureus is one of the main causative agents of biofilm infections in central venous catheters due to the expression of adhesion genes, favoring the survival of the species on environmental surfaces. The ability to form biofilms is one of the main virulence factors of C. albicans. The yeast could be found predominantly colonizing biofilms in catheters, acting as a reservoir of cells that spread and cause systemic diseases. The mixed biofilm of C. albicans and S. aureus develops easily, increasing their pathogenicity. Central venous catheters are essential in the medical routine because they contribute to maintain and monitor critically ill patients needing: antimicrobial administration, parenteral nutrition, use of contrast solution, blood and blood components replacement and for dialysis. Contamination of catheters can lead to chronical infections and high mortality and morbidity rates. Biofilms are intrinsically resistant to conventional therapy, to the host immune system, and to other environmental factors, making biofilm-associated infections a clinical challenge. The interactions between C. albicans and S. aureus increase the metabolic activity, development and complexity of mixed biofilms compared to the results observed in monomicrobial biofilms resulting in increased virulence. The main challenges in the clinical treatment of biofilms are their difficult diagnosis, the lack of adequate biomarkers and the difficulty in eradicating them. An important tool to achieve these goals is to understand the complex interactions between microbial species and the molecular mechanisms in the formation of mixed biofilms.