Final answer:
Trimethoprim/sulfamethoxazole is an antibiotic combination that is synergistically effective against bacterial infections by inhibiting two steps in the bacterial folic acid synthesis pathway, leading to a bactericidal effect.
Step-by-step explanation:
Trimethoprim/sulfamethoxazole is an antibiotic medication that inhibits the folic acid synthesis pathway in bacteria. The combination of trimethoprim and sulfamethoxazole showcases antibacterial synergy, meaning that when used together, they are more effective than when used individually. Trimethoprim alone only decreases the production of folic acid in bacteria to a point where it inhibits bacterial growth without killing the bacteria. However, combined with sulfamethoxazole, the reduction in folic acid synthesis is so marked that it becomes lethal to bacteria.
It is therefore used to treat various bacterial infections such as urinary tract infections, ear infections, and bronchitis. Caution is advised when prescribing this combination during early pregnancy due to the importance of folic acid for fetal development. While both compounds can inhibit bacterial growth independently, their combination is essential for the bactericidal effect they are known for.