Trimethoprim

Definition

Trimethoprim is an antibacterial medication that works primarily by inhibiting bacterial dihydrofolate reductase, which is crucial for the synthesis of folate and subsequently for nucleic acid production. This drug is often used in combination with sulfamethoxazole, enhancing its effectiveness against various bacterial infections, particularly urinary tract infections and certain respiratory infections.

5 Must Know Facts For Your Next Test

1. Trimethoprim is primarily effective against gram-positive and some gram-negative bacteria, making it a valuable tool in treating infections like urinary tract infections.
2. The combination of trimethoprim and sulfamethoxazole (commonly known as TMP-SMX) enhances antibacterial activity by targeting different points in the folate synthesis pathway.
3. Trimethoprim can be administered orally or intravenously, depending on the severity of the infection.
4. Common side effects of trimethoprim include nausea, vomiting, and rash, while more serious adverse effects may involve blood dyscrasias and renal toxicity.
5. Resistance to trimethoprim can develop through mutations in the target enzyme or increased production of dihydrofolate reductase by bacteria, highlighting the need for careful use of this antibiotic.

Review Questions

• How does trimethoprim work at a molecular level to inhibit bacterial growth?
  • Trimethoprim works by specifically inhibiting the enzyme dihydrofolate reductase in bacteria. This enzyme is essential for converting dihydrofolate to tetrahydrofolate, which is crucial for synthesizing nucleic acids. By blocking this pathway, trimethoprim effectively starves bacteria of folate, hindering their ability to reproduce and grow.
• Discuss the benefits and potential risks associated with the use of trimethoprim in combination therapy with sulfamethoxazole.
  • Combining trimethoprim with sulfamethoxazole creates a synergistic effect that enhances antibacterial efficacy against a broader range of pathogens. This combination therapy can lead to improved outcomes in treating infections. However, there are potential risks, such as increased likelihood of adverse reactions and the development of resistance if not used appropriately. Close monitoring and appropriate prescribing practices are essential to mitigate these risks.
• Evaluate the implications of antibiotic resistance on the effectiveness of trimethoprim and strategies to combat this issue.
  • Antibiotic resistance significantly impacts the effectiveness of trimethoprim as resistant strains can render the drug ineffective against certain infections. To combat this issue, strategies include promoting responsible prescribing practices to avoid unnecessary use of antibiotics, encouraging adherence to prescribed regimens among patients, and conducting ongoing research to develop new antibacterial agents. Additionally, regular surveillance for resistance patterns helps inform treatment decisions and preserve the efficacy of existing antibiotics like trimethoprim.

Related terms

Sulfamethoxazole: An antibiotic that inhibits bacterial folate synthesis and is often combined with trimethoprim to create a synergistic effect against a broad range of bacteria.

Dihydrofolate Reductase: An enzyme targeted by trimethoprim, essential for converting dihydrofolate to tetrahydrofolate, which is necessary for DNA and RNA synthesis in bacteria.

Antibiotic Resistance: A phenomenon where bacteria evolve and develop mechanisms to resist the effects of antibiotics, making infections harder to treat.