title: Salicylic acid diminishes Staphylococcus aureus capsular polysaccharide type 5 expression.
abstract: Capsular polysaccharides (CP) of serotypes 5 (CP5) and 8 (CP8) are major Staphylococcus aureus virulence factors. Previous studies have shown that salicylic acid (SAL), the main aspirin metabolite, affects the expression of certain bacterial virulence factors. In the present study, we found that S. aureus strain Reynolds (CP5) cultured with SAL was internalized by MAC-T cells in larger numbers than strain Reynolds organisms not exposed to SAL. Furthermore, the internalization of the isogenic nonencapsulated Reynolds strain into MAC-T cells was not significantly affected by preexposure to SAL. Pretreatment of S. aureus strain Newman with SAL also enhanced internalization into MAC-T cells compared with that of untreated control strains. Using strain Newman organisms, we evaluated the activity of the major cap5 promoter, which was significantly decreased upon preexposure to SAL. Diminished transcription of mgrA and upregulation of the saeRS transcript, both global regulators of CP expression, were found in S. aureus cultured in the presence of SAL, as ascertained by real-time PCR analysis. In addition, CP5 production by S. aureus Newman was also decreased by treatment with SAL. Collectively, our data demonstrate that exposure of encapsulated S. aureus strains to low concentrations of SAL reduced CP production, thus unmasking surface adhesins and leading to an increased capacity of staphylococci to invade epithelial cells. The high capacity of internalization of the encapsulated S. aureus strains induced by SAL pretreatment may contribute to the persistence of bacteria in certain hosts.
authors.affiliation: Departamento de Microbiología, Parasitología e Inmunología, Universidad de Buenos Aires, Paraguay C1121ABG Buenos Aires, Argentina.
authors.forename: Lucía P
authors.initials: LP
authors.lastname: Alvarez
authors.forename: María S
authors.initials: MS
authors.lastname: Barbagelata
authors.forename: Mariana
authors.initials: M
authors.lastname: Gordiola
authors.forename: Ambrose L
authors.initials: AL
authors.lastname: Cheung
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Sordelli
authors.forename: Fernanda R
authors.initials: FR
authors.lastname: Buzzola
mesh_terms: D016667:Bacterial Capsules / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000382:microbiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006801:Humans; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020156:Salicylic Acid / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*; D037521:Virulence Factors / Q000037:antagonists & inhibitors*
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D037521:Virulence Factors; C054106:capsular polysaccharide, type 5, Staphylococcus aureus; D020156:Salicylic Acid