The condensation reaction of isatin derivatives containing a phenolic fragment with 1-(2-hydrazinyl-2-oxoethyl)-4-aza-1-azoniabicyclo[2.2.2]octane bromide yielded a series of isatin-3-acylhydrazones containing the monocationized DABCO fragment. New compounds have antimicrobial activity against phytopathogenic bacteria and fungi, as well as a number of anthropopathogenic bacteria and fungi. Salts based on 5-alkylisatins exhibit a bactericidal effect against Staphylococcus aureus at a concentration of 15.6 μg/mL.