Trimethoprim ReadyMadeTM solution is provided as a sterile-filtered solution of Trimethoprim formulated in DMSO at a concentration of 25 mg/ml. It has been filter-sterilized using a 0.22 μm filter.
Trimethoprim is a synthetic derivative of trimethoxybenzyl-pyrimidine with bacteriostatic and antiprotozoal properties. As a dihydrofolate reductase inhibitor, trimethoprim binds tightly to the bacterial enzyme, blocking the production of tetrahydrofolic acid from dihydrofolic acid, arresting folic acid synthesis.
When Trimethroprim is combined with sulfonamides, like Sulfamethoxazole (S045), the two compounds show bactericidal effects, but are only bacteriostatic when used separately. The activity is attributed to their synergistic effect in inhibiting folic acid metabolism in bacteria.
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|Mechanism of Action||Trimethoprim inhibits bacterial dihydrofolate reductase (DHFR) thus interfering with the conversion of dihydrofolate (DHF) to tetrahydrofolate (THF). THF is a precursor in the thymidine synthesis pathway and a disruption in this pathway inhibits bacterial the synthesis of bacterial DNA.|
|Spectrum||Trimethoprim has a wide antibacterial spectrum and is active against most Gram-positive and Gram-negative aerobic bacteria, including Nocardia, Brucella, Gram-negative bacilli, and some Gram-positive bacteria like Streptococcus.|
Trimethoprim is commonly used in clinical in vitro microbiological antimicrobial susceptibility tests (panels, discs, and MIC strips) against Gram-positive and Gram-negative microbial isolates. Medical microbiologists use AST results to recommend antibiotic treatment options. Representative MIC values include:
Escherichia coli 0.25 µg/mL - 64 µg/mL
For a representative list of Trimethoprim MIC values, click here.
Columbia Blood Agar - Campylobacter Selective Supplement (Skirrow)
Columbia Blood Agar - Campylobacter Selective Supplement (Blaser-Wang)
Campylobacter Agar - Campylobacter Selective Supplement (Preston)
Columbia Blood Agar - Helicobacter pylori Selective Supplement (Dent)
Bolton Broth - Bolton Broth Selective Supplement
Campylobacter Agar Base - Modified Preston Campylobacter Selective Supplement
Bolton Broth - Modified Bolton Broth Selective Supplement
Chromogenic Bacillus cereus Agar - Chromogenic Bacillus cereus Selective Supplement
Trimethoprim: A review of its antibacterial activity, pharmacokinetics and therapeutic use in urinary tract infections. Drugs. 1982 23(6):405-430 PMID: 7049657
Weir DG and Scott J (2000) Mechanism of the antimicrobial drug Trimethoprim revisited. FASEB J 14(15):2519-2524 PMID 11099470