: In the last decade, the increased rate of resistance to antibiotics has been critical barrier to successful treatment of various bacterial diseases. Given the increasing antibiotic resistance in urinary tract infection (UTI), alternative strategies need to be examined. In the current work, four main bacteria were isolated from urinary tract infected patients. The isolates were biochemically characterized as Escherichia coli, Klebsiella pneumonia, Staphylococcus saprophyticus and Enterobacter faecalis. These UTI bacterial isolates differed in their resistance to the 12 used antibiotics with percentages between 56-100% and therefore cannot be used for empiric therapy in many geographic regions.Thyme oil showed some active compounds such as thymol, P-cymene, Carvacrol, Cineol and Linalool with different percentages when examined by GC-ISQ mass spectrometry. Addition of thyme oil and thymol crystals in the form of emulsion and nano-emulsion (2.5%) to the used antibiotics against resistant UTI isolates showed synergistic action as the E.coli isolate that were resistant to β-lactams, aminoglycosides and glycolipids antibiotics get affected and become susceptible to used antibiotics. Moreover, the concentrations of thyme oil or thymol crystal used to reach the MIC and MBC were reduced by 50% when nano-forms of either compounds were applied. While transmission electron microscope (TEM) image of E.coli isolate treated with nanoform of thymol crystals (2.5%) revealed disruption and phenotypic changes of cell wall compared with untreated control, and therefore improve bacterial penetration and increasing the  activity of antibiotics and prove the synergistic action.