The invention provides a method for combating contamination of a site with a microorganism, said method comprising contacting the site and/or the microorganism with an antimicrobial aqueous composition comprising a decylglucoside at a concentration of about 2mM to about 40mM and at least one C1 to C8 carboxylic acid, or a water-soluble salt thereof, at a concentration of about 1µM to about 100mM. The invention further provides such compositions, concentrated forms thereof, dry solid forms thereof and methods and kits for preparing such compositions
