In conclusion, the appearance of pseudomulticellular bacteria in the nutgall ethanol extract treated cell and the synergistic effect of the plant extract with b-lactamase-susceptible penicillins indicated that the extract may interfere with staphylococcal enzymes including wall autolysins and b-lactamase. However, further studies are required to directly determine the site and mechanism of action of the plant extract on the staphylococcal autolysins as well as b-lactamase activity even it is known that Quercus infectoria is used to treat infections, gastrointestinal disorders and vaginal infections.