Affiliation:
1. Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, C1121ABG Buenos Aires, Argentina
2. Department of Microbiology, Dartmouth Medical School, Hanover, New Hampshire 03755
Abstract
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.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
20 articles.
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