In Vitro Studies of Toxic Shock Toxin-1-secreting Staphylococcus aureus and Implications for Burn Care in Children

The Pediatric Infectious Disease Journal, 05/04/2012

Laabei M et al. – The authors suggest that there is no correlation between the expression of toxic shock syndrome toxin–1 (TSST–1) and lack of exotoxin production. They also suggest that apurulence in an S. aureus–infected burn wound in a child should not be used to rule out toxic shock syndrome.

Methods

  • The lytic and cytolytic activity of a number of clinical and laboratory TSST-1–positive strains of methicillin-susceptible S. aureus (101, 253, 279 and RN4282, respectively) and Pseudomonas aeruginosa PAO1 strain were tested in vitro using an assay designed to assess the relative exotoxin activity of bacteria using phospholipid vesicles and a T cell toxicity assay.
  • In addition, the activity of lytic exotoxins such as delta -toxin and the secretion of nonlytic TSST-1 toxin from S. aureus was measured using the vesicle assay and Western blotting over the 20-hour growth of TSST-1–positive S. aureus culture.

Results

  • Both the vesicle and T cell assays suggest a lytic exotoxin-mediated mechanism of vesicle rupture and T cell death, with high levels of vesicle lysis and T cell toxicity.
  • It is important to note that the clinical TSST-1–positive methicillin-susceptible S. aureus strains exhibited lytic exotoxin production as well as TSST-1 expression as confirmed by Western blot.

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