Bacteriostatic antibacterial agents function by disrupting or inhibiting which cellular process?

• A. Cell wall synthesis
• B. Cell metabolism
• C. Protein synthesis
• D. Nucleic acid replication

Answer: (B)

Bacteriostatic drugs slow bacterial growth by interfering with essential metabolic processes the bacteria need to multiply, rather than directly killing them. A classic mechanism is blocking folate metabolism, which is required for nucleotide synthesis and DNA replication. Sulfonamides and trimethoprim inhibit enzymes in this pathway, so bacteria can’t make thymidine and can’t divide, while the host remains relatively unaffected because humans obtain folate from the diet and don’t rely on bacterial synthesis. With growth halted, the immune system clears the infection.

Cells that build and maintain the cell wall, or that suffer damage to DNA or proteins, tend to be killed outright, which is why inhibitors of cell wall synthesis and nucleic acid replication are usually bactericidal. Protein synthesis inhibitors can be either bacteriostatic or bactericidal depending on the drug and organism, so they aren’t the definitive mechanism for bacteriostatic action.