The effect of wound dressings on growth and exotoxin production by staphylococcus aureus
Toxic shock syndrome is a rare complication of Staphylococcus aureus infection
associated with small burn wounds of under 5 % total body surface area; it is
predominantly observed in young children. Environmental factors that occur within a burn
wound have been suggested to increase the risk of TSS developing, and wound dressings
have been implicated to contribute to this risk.
This study examined the effects of 11 wound dressings on the production of TSST-1 by
two strains of S. aureus (strains T1 and T4). Initially, the effects of the wound dressings
on growth and exotoxin production were assessed using a liquid culture medium, as this
was used in other studies. The results indicated that growth was not markedly affected
using this system, however there were a number of problems associated with the
evaluation. TSST-l production was altered (increased or decreased) depending upon the
dressing type, the gaseous environment or the strain of S. aureus used. Other exotoxins did
not appear to be greatly affected by any of the dressings.
When a semi-solid system was developed to minimise disintegration of the dressings
and simulate a more appropriate wound model in terms of support and environment,
similar results were observed as to those found in a liquid culture system. A l-layered
semi-solid agarose system incubated in 6 % (v/v) carbon dioxide supported optimum
TSST-1 production by both test strains in the presence and absence of most wound
dressings. Actisorb Plus™ and crepe increased TSST-l production. Levels of TSST-l
increased over time and Actisorb Plus™ continued to stimulate increased toxin production.
Gamgee, and Biobrane ™previously implicated. in TSS, increased TSST-1 production
t.. . I
between 48-72 hours.
Serine, thiol and metalloproteases were produced by both strains of S. aureus and
proportions of each were altered by the presence of dressings.
This study showed that some wound dressings may potentially increase the risk of a
patient developing TSS, but further studies need to be done in vivo.