Comparing amoxicillin and trimethoprim: Overall performance in combating Escherichia coli-causing urinary tract infection

Urinary Tract Infection (UTI) is one of the most prevalent bacterial infections in the world, and 80% of reported UTI cases are derived by gram negative bacteria Escherichia coli. Uropathogenic Escherichia coli is strongly adaptive and resilient against immune response, forming Intracellular Bacterial Communities (IBC) inside uroepithelium cells that constitute the urethra and the bladder. Their rapid absorption of cellular nutrients enables them to advance upward toward the kidney and cause inflammation. Hence, based on the perceived severity of UTI, multiple antibiotics are used to treat UPEC-causing UTI. This article provides a detailed review on the contemporary performance of amoxicillin and trimethoprim, both widely used to treat UPEC-causing UTI for decades. Amoxicillin is a penicillin-derivative that produces bactericidal by inhibiting transpeptidase to disrupt peptidoglycan synthesis, causing rapid-growing bacteria to lyse. It is a well-tolerated drug that can be used on pregnant patients. Resistant UPEC develop beta-lactamase to counter amoxicillin. Trimethoprim, on the other hand, is a dihydropyrimidine antibiotic that impedes the production of tetrahydrofolic acids, producing either bacteriostatic or bactericidal effects. Resistant UPEC transforms the shape of tetrahydrofolic acids-producing enzyme, dihydrofolic reductase, to resist trimethoprim. Although amoxicillin and trimethoprim are competitive inhibitors are effective against a variety of gram-positive and gram-negative species, trimethoprim, in statistical study, is proven to be more effective than amoxicillin in treating gram-negative UTI. Today, the wide-spread resistant strains of UPEC exists for both drugs. Thus, amoxicillin and trimethoprim are implemented mainly through combination therapies, amoxicillin/clavulanate and trimethoprim sulfamethoxazole, respectively. These combinations are more effective than the drugs to be used alone and are able to counter some resistant strains, but UPEC that are resistant to combinations also exists. Regardless, both amoxicillin and trimethoprim are still used as first-line antibiotics, while more powerful antibiotics are reserved for special multi-resistant superbugs.