EFFECT OF SALICYLIC ACID ON BIOFILM FORMATION BY Staphylococcus aureus STRAINS

DOTTO C; GRUNERT T; CATTELAN N; LOMBARTE A; SULIGOY C; YANTORNO O; SORDELLI D; BUZZOLA F

Córdoba

Congreso; XI Congreso Argentino de Microbiología General.; 2015

Staphylococcusaureus is the causative agent of a broadspectrum of infections due to its ability to attach to damaged epithelia andinanimate surfaces, and to adopt a biofilm lifestyle. Biofilm is involved inthe development of device-related infections and chronic infections of diversetissues. During the biofilm development, the polysaccharideintercellular adhesin (PIA) encoded by the icaADBCoperon contributes to the bacterial agglomeration. The extracellular DNA (eDNA)from autolytic cells and several proteins are also involved in sticking thebacterial cells together. Unlike methicillin-resistantS. aureus, available evidence indicates that biofilm formation bymethicillin-susceptible S. aureusisolates depends upon the PIA production. Theenvironmental conditions and metabolic status of the bacteria affect thebiofilm formation. Salicylic acid (SAL), the main aspirin metabolite produced in vivo, interferes with expression ofseveral S. aureus virulence factors(such as capsular polysaccharide, Eap) and global regulators (such as mgrA, saeRS). The aim of the present study was to investigate the effectof SAL on biofilm formation by S. aureus and determine the nature of thebiofilm?s matrices after the treatment with SAL. Twenty-four hours biofilmsformed by S. aureus in polystyrene microtiter plates, with orwithout SAL, were stained with crystal violet forspectrophotometric quantification. Detachment of preformedbiofilms was determined after treating the biofilms with DispersinB, proteinase K or DNAse I. Biofilms grown with or without SAL for 24 hours wereprocessed and analysed by Fourier transform infrared spectroscopy (FTIR) in thespectral ranges of 1,200 to 800 cm-1 (polysaccharidesregion) and 1,800 to 1,200 cm-1 (amideand ?mixed? region). Here, we demonstrated thatSAL enhances biofilm production in all strains under study. The principalcomponent analyses in the polysaccharide external and amide regions from the FTIRdata determined that SAL caused polysaccharide and proteins perturbations in S. aureus biofilms. Dispersal ofstablished biofilm by enzymatic treatments shown that the extracellularmatrices of the SAL treated-biofilms are mainly of proteinaceous andpolysaccharide nature. The contribution of the eDNA would be not relevant. Taken together theresults suggest that SAL promotes the biofilm formation by S. aureus which would contribute to the persistence of infection.