Final answer:
The enhanced antimicrobial effect produced when antimicrobial drugs work together is known as synergism. This can be seen with the combined use of trimethoprim and sulfamethoxazole, contrasting with antagonism, which decreases drug effectiveness.
Step-by-step explanation:
The process where some antimicrobial drugs work together to produce an enhanced antimicrobial effect is called synergism. This interaction can be more beneficial than the efficacy of either drug alone.
A classic example of this is the use of trimethoprim and sulfamethoxazole (Bactrim) together, which shifts their properties from bacteriostatic to bactericidal. In contrast, antagonism is when drug interactions produce detrimental effects, such as decreased effectiveness of antimicrobial drugs due to increased pH in the stomach from antacid use.