Salicylic acid diminishes Staphylococcus aureus capsular polysaccharide type 5

ALVAREZ LP, BARBAGELATA MS, GORDIOLA M, CHEUNG AL, SORDELLI DO, BUZZOLA FR.

INFECTION AND IMMUNITY

AMER SOC MICROBIOLOGY

Año: 2010 vol. 78 p. 1339 - 1344

0019-9567

Capsular polysaccharides (CP) of serotypes 5 (CP5) and 8 (CP8) are majorStaphylococcus aureus virulence factors. Previous studies have shown thatsalicylic acid (SAL), the main aspirin metabolite, affects the expression ofcertain bacterial virulence factors. In the present study, we found that S.aureus strain Reynolds (CP5) cultured with SAL was internalized by MAC-T cells inlarger numbers than strain Reynolds organisms not exposed to SAL. Furthermore,the internalization of the isogenic nonencapsulated Reynolds strain into MAC-Tcells was not significantly affected by preexposure to SAL. Pretreatment of S.aureus strain Newman with SAL also enhanced internalization into MAC-T cellscompared with that of untreated control strains. Using strain Newman organisms,we evaluated the activity of the major cap5 promoter, which was significantlydecreased upon preexposure to SAL. Diminished transcription of mgrA andupregulation of the saeRS transcript, both global regulators of CP expression,were found in S. aureus cultured in the presence of SAL, as ascertained byreal-time PCR analysis. In addition, CP5 production by S. aureus Newman was also decreased by treatment with SAL. Collectively, our data demonstrate that exposureof encapsulated S. aureus strains to low concentrations of SAL reduced CPproduction, thus unmasking surface adhesins and leading to an increased capacity of staphylococci to invade epithelial cells. The high capacity of internalizationof the encapsulated S. aureus strains induced by SAL pretreatment may contribute to the persistence of bacteria in certain hosts.