Urinary tract infections (UTI) are the most commonly reported bacterial infection in the United State. E coli causes 90% of them, some of which are hospital acquired. Hospital acquired UTI are difficult to treat. Other UTI are caused by Pseudomonas aeruginosa, Serratia, and Enterobacter.

A family of antibiotics called sulfonamides, that stops the growth of bacteria, is used to treat UTI. These include trimethoprim-sulfamethoxazole (TMP-SMX) and cephalasporins. Aztreonam and fluoroquinolones are used as urinary tract antiseptics. Phenazopyridine (Pyridium) is used to treat pain from a UTI.

Patients who are prescribed sulfonamides should avoid coffee, tea, and juices. These are high in citric acid. They also should abstain from cola, alcohol, chocolate, and spices which irritate the bladder.

Avoid using sulfonamides if the patient is allergic to one member of the sulfonamide family of medication. Sulfonamides should not be administered to neonates.

Sulfonamides may adversely affect the level of some medications causing a toxic effect. Avoid using sulfonamides with anticoagulants such as coumarin or indanedione derivatives and anticonvulsants (hydantoin) as well as oral anti-diabetic agents and methotrexate.

Patients need at least 3000 mL of fluid each day in order to flush the urinary tract and follow good hygiene to reduce the likelihood of acquiring the infection again. The patient should be instructed to drink at least three quarts of water


Pregnancy Category: C





Protein-Binding: 20-30%

Half-Life: 8-12 hours


2-4 mg first dose

7-10 days

Drink 250 mL H2O

2-4 g subsequent

with each dose

Sulfisoxazole (Gantrisin):

Protein-Binding: 60-70% (TMP-SMX)

Half-Life: 7-12 hours


2-3 g/d in 2-3

7-10 days

divided doses


Protein-Binding: 50-65% (TMP-SMX)

Half-Life: 8-12 hours

Most widely used antibacterial agent in the world


160/800 mg


Sulfamethoxazole (co trimoxazole) (TMP)

Protein-Binding: 99%

Half-Life: 5.5 hours


160 mg TMP BID


20 mg/kg


daily and take sulfonamides on an empty stomach. Patients should avoid the use of antacids while taking sulfonamides because antacids decrease the absorption of sulfonamides.

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