SORDELLI Daniel Oscar
congresos y reuniones científicas
Salicylic acid induces augmentation of polysaccharide intercellular adhesin in Staphylococcus aureus biofilms.
DOTTO C; GRUNERT T; LOMBARTE SERRAT A; SULIGOY LOZANO CM; SORDELLI DO; BUZZOLA FR
Simposio; International Symposium on Staphylococcus and Staphylococcal Infections (ISSSI); 2016
ISSSI and Korean Society for Chemotherapy
Background: a strategy used by Staphylococcus aureus to respond to unfavorable conditions is to adopt a biofilm lifestyle. During biofilm development, the polysaccharide intercellular adhesin (PIA) contributes to bacterial agglomeration. Unlike methicillin-resistant S. aureus (MRSA), available evidence indicates that biofilm formation by methicillin-sensitive S. aureus (MSSA) isolates depends upon the PIA production. Previously, we have demonstrated that salicylic acid (SAL) interferes with the expression of capsular polysaccharide (CP) of planktonic S. aureus. The aim of this study was to investigate the effect of SAL on CP and PIA production during biofilm formation.Methods: S. aureus isolates related to USA300 and USA100 clones were selected to conduct the study. The intracellular iron content in biofilms was assessed by the ferrozine assay. Twenty-four hour biofilms formed by S. aureus in microtiter plates, with or without addition of SAL and iron, were stained with crystal violet for spectrophotometric quantification. CP and PIA produced in biofilms were determined by ELISA. Results: we demonstrated that 2 mM of SAL diminished by 25% the free iron intracellular load in bacteria forming biofilm. Both the MRSA and the MSSA strains showed increased biofilm production by exposure to SAL whereas the iron addition provoked a significant reduction of the biomass. SAL caused more aggregation of the cells exhibiting high production of extracellular substances as seen by scanning electron microscopy. The principal component analyses of Fourier Transform Infrared Spectroscopy (FTIR) data determined that iron limitation by SAL induced polysaccharide disturbances in S. aureus biofilms that were partially reverted by iron addition. S. aureus did not produce capsule when bacteria are forming biofilms under any of the conditions investigated. Dispersin treatment provoked a significant detachment of biofilms grown in the presence of SAL. The level of PIA in the biofilms increased with SAL exposure and significantly diminished with iron addition. Conclusions: the results suggest that iron limitation caused by SAL induced a PIA-dependent increment of biofilm production by S. aureus regardless of the methicillin susceptibility status or the clonal genomic characteristics of the strain. The increase in S. aureus biofilm production induced by SAL may contribute to infection persistence.