The phylum Proteobacteria, more precisely the family Enterobacteriacea, has been shown to be a major cause of inflammation in the human microbiome. Their standard level in the human intestine is usually kept below 1% in a healthy person, and their overgrowth above this number leads to intestinal inflammation, which can cause the development of inflammatory bowel diseases - most often Crohn's disease or ulcerative colitis. The minimum inhibitory concentrations (MICs) of a series of eighteen recently synthesized N-(alkoxyphenyl)-2-hydroxynaphthalene-1-carboxamides were determined against two representatives of the Enterobacteriaceae family – Escherichia coli CCM 3954 and Salmonella typhimurium LT 2-18. Although the tested compounds are cyclic analogs of salicylanilides known to have strong antimicrobial properties, the minimum inhibitory concentrations found were in the range between 50 µM and 1000 µM. However, it can be concluded that S. typhimurium was generally more sensitive to the tested antimicrobial agents than E .coli. N-[2-(But-2-yloxy)phenyl]-1-hydroxynaphthalene-2-carboxamide was the most active of the compounds with an MIC of 100 µM against pro E. coli and an MIC of 50 µM against S. typhimurium.