The invention relates to heterosubstituted N-thiolated beta-lactams, compositions comprising these compounds, methods for their production, and methods of use as antibiotics to inhibit the growth of bacteria. In one embodiment, the compounds have the structure shown in formula (A) or formula (B) or formula (C): wherein the R groups are as defined in the specification. The antibacterial agents of the invention can be administered to a human or animal to treat or inhibit bacterial infection, such as that of Staphylococcus species, including methicillin-resistant Staphylococcus aureus (MRSA).