Effect of magnesium on production of toxic-shock-syndrome toxin-1 by Staphylococcus aureus.

Abstract

Toxic shock syndrome (TSS), first described in 1978 [1], is an acute illness characterized by fever, hypotension or dizziness, rash, desquamation of the skin upon recovery, and a variable multiorgan component [2, 3]. The illness occurs most frequently in young adult women during menstruation and is considered to be caused by Staphylococcus aureus [2, 3]. Strains of S. aureus isolated from menstrual cases consistently express TSS toxin-1 (TSST-1), a toxin that has the capacity to induce many TSS-like symptoms in experimental animals [4-6]. Thus, TSST-1 represents a likely causative toxin. In 1980, studies showed that menstrual TSS is associated with tampon use [2, 3]. In a later study, it was reported that the risk of developing TSS was a function of tampon absorbency rather than tampon brand [7]. Thus, the risk of developing TSS increased with the tampon absorbency [7]. Since these reports, there have been many attempts to explain the association of certain tampons, particularly those of higher absorbency, with TSS. Schlievert and Blomster [8] noted that laboratory conditions necessary for production of TSST-1 were consistent with those present in the vagina, except that air (oxygen) was required for toxin expression, and the vagina is generally regarded as anaerobic [9]. In a subsequent study [9], it was shown that tampons significantly increase the oxygen content of the vagina. These observations, together with a report that tampon components do not support bacterial growth or stimulate TSST-1 production [10], led to the hypothesis that tampons may be associated with TSS as a consequence of introducing air into the vagina. Recently, Mills et al. [11] provided an alternative explanation for the association of TSS with tampon use. These investigators reported that magnesium levels control toxin production. At very low concentrations of magnesium both cell growth and toxin expression were inhibited, at levels of 2-5 pg of magnesium/ml good cell growth and maximal toxin production were achieved, and at concentrations >15 mg of magnesium/ml good cell growth was obtained but expression of TSST-1 was inhibited. It was thus inferred that the association of tampon use with TSS may result from the higher-absorbency tampons binding