Specific antimicrobial synergism of synthetic hydroxy isothiocyanates with aminoglycoside antibiotics.

Hydroxy isothiocyanates, especially 2-(4-hydroxyphenyl)ethyl isothiocyanate (hITC), were examined for antimicrobial synergism with several antibiotics against Escherichia coli and Staphylococcus aureus, using a multiwell plate system. hITC had antibacterial synergism, specifically with aminoglycoside antibiotics. The synergism was observed in synthetic medium (M9 minimal medium) or soybean casein digest broth, but not in nutrient broth. Synergism was seen in the presence of certain sugars such as glucose, fructose, and maltose in the medium.