One aspect of the invention provides a method of inhibiting an efflux pump in a bacteria, the method comprising contacting the bacteria with 3,4-dibromopyrrole-2,5-dione, thereby inhibiting the efflux pump. Another aspect provides a method of inhibiting proliferation of a bacteria, the method comprising contacting the bacteria with 3,4-dibromopyrrole-2,5-dione and an antibiotic, thereby inhibiting the proliferation of the bacteria. Another aspect of the invention provides a method of increasing the efficacy of an antibiotic, the method comprising contacting a bacteria with 3,4-dibromopyrrole-2,5-dione and an antibiotic, thereby increasing the efficacy of the antibiotic. Another aspect provides a method of inhibiting development of antibiotic resistance in a bacteria, the method comprising contacting the bacteria with 3,4-dibromopyrrole-2,5-dione and an antibiotic, thereby inhibiting development of resistance to the antibiotic. Another aspect of the invention provides a pharmaceutical composition for treating a bacterial infection comprising an effective amount of 3,4-dibromopyrrole-2,5-dione in a pharmaceutically acceptable excipient.