Toxic shock syndrome toxin 1 is encoded by a variable genetic element

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Toxic shock syndrome (TSS) is primarily caused by toxic shock syndrome toxin 1 (TSST-1), an exotoxin produced by approximately 20% of Staphylococcus aureus isolates.
• TSST-1 production is a variable genetic trait in Staphylococcus aureus.
• Understanding the genetic basis and mobility of TSST-1 is crucial for comprehending its epidemiology and pathogenesis.

Purpose of the Study:

• To investigate the genetic element responsible for TSST-1 production in Staphylococcus aureus.
• To determine the size, location, and potential mobility of the TSST-1 genetic element.
• To analyze the genetic relatedness of TSST-1-positive Staphylococcus aureus isolates.

Main Methods:

• Southern hybridization experiments were used to detect and characterize the TSST-1 gene and its flanking sequences.
• Preliminary DNA sequencing provided insights into the genetic element's structure.
• Biotyping and DNA hybridization analysis of 75 TSST-1-positive isolates were performed.

Main Results:

• The TSST-1 gene is located on a distinct genetic element approximately 4-7 kilobases in size.
• This genetic element was found in TSST-1-positive isolates but absent in TSST-1-negative isolates.
• Hybridization analysis indicated at least two chromosomal locations for the TSST-1 element, suggesting its mobility.
• A common blotting pattern among most tryptophan-negative TSST-1-positive isolates suggests a clonal origin.

Conclusions:

• The TSST-1 gene resides on a mobile genetic element within Staphylococcus aureus.
• The mobility of this element and the clonal nature of certain TSST-1-producing strains may influence the epidemiology of toxic shock syndrome.
• Further research into the mobile genetic element's characteristics and dissemination is warranted.