Final answer:
Trimethoprim + Sulfamethoxazole (TMP-SMZ) is used to treat urinary tract infections, ear infections, and bronchitis. It inhibits folic acid synthesis and has synergistic antibacterial effects when used in combination with sulfamethoxazole.
Step-by-step explanation:
Trimethoprim, when used in combination with sulfamethoxazole (TMP-SMZ), is used to treat urinary tract infections, ear infections, and bronchitis. It is a synthetic antimicrobial compound that inhibits a step in the folic acid synthesis pathway, similar to sulfonamides. When used together, the combination of trimethoprim and sulfamethoxazole decreases folic acid synthesis to a level that is lethal to the bacterial cell. However, the use of these drugs should be carefully considered during early pregnancy due to the importance of folic acid in fetal development.