Key Points
- To determine how magnesium concentrations influence bacterial growth and toxic-shock-syndrome toxin-1 (TSST-1) production across various culture media.
- Conducted in vitro collaborative experiments using brain-heart infusion and beef-heart media modified with ethylenediamine-tetraacetic acid (EDTA) or varying magnesium (Mg++) levels.
- Assessed TSST-1 expression across different bacterial inoculum sizes, wash conditions (Mg++-deficient medium), and sampling times through bacterial growth phases.
- EDTA addition to media enhanced TSST-1 production by chelating magnesium, an effect completely reversed by adding excess Mg++.
- Small bacterial inocula washed in Mg++-deficient media failed to multiply or produce toxin in the absence of Mg++, whereas large inocula transferred enough residual Mg++ to permit growth.
- Maximal TSST-1 expression occurred during late logarithmic phase across all conditions, with Mg++ availability directly controlling the timing of this growth stage.
Structured PICO
PPopulationBacterial cultures producing toxic-shock-syndrome toxin-1 (TSST-1) in various culture media (brain-heart infusion and beef-heart medium)
IInterventionManipulation of Mg++ concentration (addition of EDTA or excess Mg++)
CComparatorDifferent concentrations of Mg++ or untreated medium
OOutcomeProduction of toxic-shock-syndrome toxin-1 (TSST-1)surrogate
Magnesium concentration controls the timing of the late logarithmic growth phase and influences the production of toxic-shock-syndrome toxin-1 in bacterial cultures.