Morphological changes of some pathogenic microbial strains induced by novel thiadiazole derivatives

In the quest for potent antimicrobial agents, some new 1,3,4-thiadiazole derivatives (2-11) were synthesized from the starting compound (1) 5-amino-1,3,4-thiadiazole-2(3H)-thione, with an aim to evaluate their antimicrobial effect on different pathogenic organisms isolated from microbial-infected cancer patients who had not yet received their radiation dose, compared to reference antibiotics. The titled compounds 5, 6, 10, and 11 were found to possess comparable or more potent activity than the reference compounds amikacin and sulperazone. Compound 5 was the most distinctive derivative identified in the present study because of its remarkable antibacterial activity exhibited against the Gram +ve strains, it has been scanned under electron microscope to determine the morphological changes that has taken place in the bacterial cells of Bacillus cereus and non-irradiated and irradiated Staphylococcus aureus. MIC of compound 5 and/or gamma irradiation affected the morphology of the tested strains causing; membrane damage, deformity on the surface of some cells, disappearance of the septum, elongation of some cells, and shortening of others. It may be hoped that the present study will encourage efforts toward the development of novel antibacterial agents that could be better in terms of efficacy and safety.