Glycerol monolaurate (GML) is a naturally occurring
surfactant that has potential use as an additive to tampons and
wound dressings to reduce the incidence of certain
bacterial toxin-mediated illnesses. In vitro studies were undertaken to evaluate the effect of GML on the growth of and toxin production by potentially pathogenic bacteria. GML inhibited the growth of clinical isolates of group A, B, F, and G streptococci at concentrations of 10 to 20 micrograms/ml.
Exotoxin production, including that of pyrogenic
exotoxins and
hemolysins, was reduced by concentrations of GML that were below those inhibitory for growth as well as growth inhibitory. The growth of Staphylococcus aureus strains from patients with
toxic shock syndrome and scalded skin syndrome was inhibited or delayed in the presence of 100 to 300 micrograms of GML per ml. Growth inhibition by GML could be overcome by the production of
lipase. S. aureus elaboration of
hemolysin,
toxic shock syndrome toxin 1, and exfoliative toxin A was inhibited at GML concentrations below those necessary to inhibit growth. Results similar to those for S. aureus were obtained in tests of S. hominis. Escherichia coli growth and Salmonella minnesota growth were unaffected by GML, but an S. minnesota Re mutant was susceptible to growth-inhibitory activity.
Endotoxin release into the medium from E. coli cells was also unaffected by GML, but the release or activity of E. coli
hemolysin was increased by GML. Streptococcal pyrogenic
endotoxin A production by an E. coli clone was not affectd by GML. These studies indicate that GML is effective in blocking or delaying the production of
exotoxins by pathogenic gram-positive bacteria.