Isolation and purification of bacteriocin from Escherichia coli and study its synergistic effect with antibiotics and nanoparticles on pathogenic bacteria

Antibiotic resistance is becoming remarkably prominent and urgent in clinical practice with the increasing and wide application of antibacterial drugs. Bacteriocins, peptidic toxins produced by bacteria, offer promising potential as substitutes or conjugates to current therapeutic compounds. These peptides exhibit significant potency against certain bacteria (including multidrug-resistant species). The study aimed to isolate and purify bacteriocin from Escherichia coli isolated from different sources (clinical and sewage) and study its synergistic effect with antibiotics and nanoparticles against Staphylococcus aureus and Pseudomonas aeruginosa as Indicator isolates that have multiple resistance towards antibiotics. Thirty isolates of Escherichia coli were diagnosed, 11 of them were producing crude bacteriocin in terms of the Indicator isolates, partial purification of bacteriocin was carried out and its synergistic effect was measured with each of the antibiotics Vancomycin, Ceftazidime, Zinc Oxide Nanoparticles (ZnO) and Titanium Oxide Nanoparticles (TiO₂). after measurement of The minimum inhibitory concentrations (MIC) for each of them, as the results showed that the MIC values of antibiotics and nanoparticles decreased when mixed with bacteriocin, and the FICI (Fractional Inhibitory Concentration Index) value of (Vancomycin + bacteriocin) and (Ceftazidime + bacteriocin) was between (0.25-0.5) and (0.126-0.5), respectively, and the FICI value of (ZnO + bacteriocin) and (TiO₂ + bacteriocin) for Staph. aureus was between (0.062-0.126),While for (ZnO + bacteriocin) and (TiO₂ + bacteriocin) of P.aeruginosa was between (0.062-0.126), and these values fall within the range of synergistic interactions. The results of this study show that bacteriocin is a potential alternative agent against common pathogens, and could be included in the development of new therapies to inhibit the growth of pathogenic bacteria.