Antibiotic-resistant E. coli from food and water sources is a public health concern because it may contribute to the dissemination of resistance outside the clinical settings. This study investigated the antibacterial and antibiotic-potentiating activities of methanolic extracts of garlic (Allium sativum) and turmeric (Curcuma longa) on a resistant isolate of E. coli. Food and water samples were collected, cultured and screened for E. coli. The isolate was characterized by standard microbiological methods, and its resistance profile was determined by the disc diffusion method. Soxhlet extraction with methanol was used to prepare garlic and turmeric extracts. Antibacterial activity was determined by disc diffusion method with streptomycin and gentamicin alone and in combination with plant extracts. Also, a 96 well plate inhibition assay was performed, and bacterial growth was followed at OD600 for 13 hours. Streptomycin and gentamicin alone gave very weak inhibition zones of about 0–1 mm. Combination treatments, however, increased antibacterial activity. Maximum zone of inhibition was observed in turmeric extract with streptomycin (20 mm) followed by garlic extract with streptomycin (18 mm). The combination of gentamicin with turmeric and garlic gave inhibition zones of 14 mm and 12 mm respectively. In the 96-well assay, the lowest final absorbance was observed for the streptomycin–turmeric combination, indicating stronger growth inhibition. Overall, the results suggest that extracts of garlic and turmeric may enhance antibiotic activity against resistant E. coli. Further studies are necessary to confirm the mechanism of this potentiating effect.