Abstract: A limited class of compounds is disclosed for use in low dosage to inhibit the growth of or to kill fungi, Gram-positive, and especially Gram-negative bacteria. These compounds are members of a family in which the trichloromethylthio group is appended to a nitrogen atom forming part of a ring structure. While a number of the compounds of this general family have some effect against other microorganisms, such as Staphylococcus Aureus, Aspergillus Niger, Streptoverticillium Reticuli, only a few of the compounds in this general family have been found to have an effect against Gram-negative bacteria as well. This unique property makes the present compounds especially useful as bacteriostatic and bactericidal agents to be incorporated in resinous materials, such as polymeric resinous materials, whether contained in bulk, film, or liquid solution or dispersion.