A new class of anti-microbial agents and methods for preventing or reducing the risk of sexually transmitted infections and/or diseases is provided. Preferably, these anti-microbial agents are also contraceptive and, thus, also prevent or reduce the risk of unplanned pregnancies. The anti-microbial agents comprise a delivery vector having anti-microbial activity (and preferably contraceptive activity) coupled with a nitric oxide donor moiety.