The present invention includes novel compounds and pharmaceutically acceptable formulations of said compounds which exhibit antibiotic activity against microorganisms bearing a guanine riboswitch that controls the expression of the guaA gene, including organisms which are resistant to certain antibiotic families, and which are useful as antibacterial agents for treatment or prophylaxis of bacterial infections in animals or in humans, in particular but not limited to infections of the mammary gland, or their use as antiseptics, agents for sterilization or disinfection.