Effect of salicylic acid on biofilm formation by Staphylococcus aureus strains.

DOTTO C; GRUNERT T; CATTELAN N; LOMBARTE SERRAT A; SULIGOY LOZANO CM; YANTORNO O; SORDELLI DO; BUZZOLA FR

CORDOBA

Conferencia; Conferencia bianual de la Society for General Microbiology (SAMiGe-Argentina).; 2015

Society for General Microbiology (SAMiGe-Argentina).

Staphylococcus aureus is the causative agent of a broad spectrumof infections due to its ability to attach to damaged epithelia and inanimatesurfaces, and to adopt a biofilm lifestyle. Biofilm is involved in thedevelopment of device-related infections and chronic infections of diverse tissues.During the biofilm development, the polysaccharide intercellular adhesin (PIA)encoded by the icaADBC operon contributes to thebacterial agglomeration. The extracellular DNA (eDNA) from autolytic cells andseveral proteins are also involved in sticking the bacterial cells together.Unlike methicillin-resistant S. aureus, available evidence indicatesthat biofilm formation by methicillin-susceptible S. aureus isolates depends upon the PIA production.The environmental conditions and metabolic status of the bacteria affect thebiofilm formation. Salicylic acid (SAL), the main aspirin metabolite produced in vivo, interferes with expression of several S. aureus virulence factors (such as capsularpolysaccharide, Eap) and global regulators (such as mgrA, saeRS). The aim of the present study was toinvestigate the effect of SAL on biofilm formation by S. aureus and determine the nature of the biofilm?smatrices after the treatment with SAL.Twenty-four hours biofilms formed by S. aureus in polystyrene microtiter plates, with orwithout SAL, were stained with crystal violet for spectrophotometricquantification. Detachment of preformed biofilms was determined after treatingthe biofilms with Dispersin B, proteinase K or DNAse I. Biofilms grown with orwithout SAL for 24 hours were processed and analysed by Fourier transform infraredspectroscopy (FTIR) in the spectral ranges of 1,200 to 800 cm-1(polysaccharides region) and 1,800 to 1,200 cm-1 (amide and ?mixed? region).Here, we demonstrated that SAL enhances biofilm production in all strains understudy. The principal component analyses in the polysaccharide external andamide regions from the FTIR data determined that SAL caused polysaccharide andproteins perturbations in S. aureusbiofilms.Dispersal of established biofilm by enzymatic treatments shown that theextracellular matrices of the SAL treated-biofilms are mainly of proteinaceousand polysaccharide nature. The contribution of the eDNA would be not relevant.Taken together the results suggest that SAL promotes the biofilm formation by S. aureus which would contribute to the persistence ofinfection.