Extracellular biofilm matrix leads to microbial dysbiosis and reduces biofilm susceptibility to antimicrobials on titanium biomaterial: An in vitro and in situ study
Raphael Cavalcante Costa, João Gabriel Silva Souza, Martinna Bertolini, Belén Retamal‐Valdes, Magda Feres, Valentim Adelino Ricardo Barão
Abstract
OBJECTIVES: To test the role of exopolysaccharide (EPS) polymers matrix to modulate the composition/virulence of biofilms growing on titanium (Ti) surfaces, the effect on antibiotic susceptibility, and whether a dual-targeting therapy approach for disrupted EPS matrix could improve the antimicrobial effect. MATERIALS AND METHODS: A microcosm biofilm model using human saliva as inoculum was used, and the microbial composition was assessed by checkerboard DNA-DNA hybridization. EPS-enriched biofilms virulence was tested using fibroblast monolayer. Povidone-iodine (PI) was used as EPS-targeting agent followed by amoxicillin + metronidazole antibiotic to reduce bacterial biomass using an in situ model. RESULTS: An EPS-enriched environment, obtained by sucrose exposure, promoted bacterial accumulation and led to a dysbiosis on biofilms, favoring the growth of Streptococcus, Fusobacterium, and Campylobacter species and even strict anaerobic species related to peri-implant infections, such as Porphyromonas gingivalis and Tannerella forsythia (~3-fold increase). EPS-enriched biofilm transitioned from a commensal aerobic to a pathogenic anaerobic profile. EPS increased biofilm virulence promoting higher host cell damage and reduced antimicrobial susceptibility, but the use of a dual-targeting approach with PI pre-treatment disrupted EPS matrix scaffold, increasing antibiotic effect on in situ biofilms. CONCLUSION: Altogether, our data provide new insights of how EPS matrix creates an environment that favors putative pathogens growth and shed light to a promising approach that uses matrix disruption as initial step to potentially improve implant-related infections treatment.