Based on the obtained results, it can be concluded that the length of the alkyl substituent and the associated amphiphilicity of the quinine-based cation is the main factor affecting the level of antibacterial activity. Hence, it can be stated that obtained compounds most likely exhibit antimicrobial activity according to the same mechanism as other amphiphilic QASs this is also indicated by the higher susceptibility of Gram-positive bacteria to the tested compounds compared to other groups of microorganisms. MIC and MBC/MFC values were in the vast majority of cases independent of the chemical structure of the anion. Only in the case of E. faecalis 2Asp and 2Ala were characterized by significantly reduced activity compared to 2Br, but such differences were not observed between 3Asp or 3Ala, and 3Br.