Antibacterial Evaluation of New Thiazole, Imidazolidine and Tetrahydropyrimidine Derivatives against Pathogenic Gram-Negative Bacteria

Spread of antibiotic-resistant strains of nosocomial gram-negative bacteria is a serious threat to patients, hospital personnel and general health. Researchers consider identifying and using of novel antibacterial compounds as one of the most effective solutions to this threat. Thiazole, imidazolidine and tetrahydropyrimidine derivatives are of the most recognized new antibacterial compounds and in this study, their antibacterial effect against three gram-negative nosocomial bacteria, Proteus mirabilis, Shigella dysenteriae and Acinetobacter baumannii, was evaluated. For the aim of assessing antibacterial effect, the disk diffusion method and the dilution procedure in 96-well plate were used to determine the diameter of growth inhibition zone and the minimum inhibitory concentration (MIC), respectively. None of imidazolidines, tetrahydropyrimidines and thiazoles had any inhibitory effect against tested bacteria; only, the inhibitory effect of thiazole 4 was proven on Proteus mirabilis and Shigella dysenteriae with halo diameters of 16.4 and 19.3 mm as well as MICs of 125 and 62.5 µg/ml, respectively. Of course, this compound itself had no inhibitory effect on Acinetobacter baumannii. In this study, the inhibitory effect of one of the novel thiazole derivatives was shown on two bacteria, Proteus mirabilis and Shigella dysenteriae. This compound can be used as bacterial inhibitor if additional in-vitro and in-vivo tests are carried out and its therapeutic effects and toxicity are investigated.