Sulfamethoxazole inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA). Trimethoprim blocks the production of tetrahydrofolic acid from dihydrofolic acid by binding to and reversibly inhibiting the required enzyme, dihydrofolate reductase. Thus, sulfamethoxazole and trimethoprim blocks two consecutive steps in the biosynthesis of nucleic acids and proteins essential to many bacteria.
In vitro studies have shown that bacterial resistance develops more slowly with both sulfamethoxazole and trimethoprim in combination than with either sulfamethoxazole or trimethoprim alone.
To reduce the development of drug-resistant bacteria and maintain the effectiveness of sulfamethoxazole and trimethoprim tablets and other antibacterial drugs, sulfamethoxazole and trimethoprim should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to empiric selection of therapy.
Urinary Tract Infections
For the treatment of urinary tract infections due to susceptible strains of the following organisms: Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis and Proteus vulgaris. It is recommended that initial episodes of uncomplicated urinary tract infections be treated with a single effective antibacterial agent rather than the combination.
Acute Otitis Media
For the treatment of acute otitis media in pediatric patients due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae when in the judgment of the physician sulfamethoxazole and trimethoprim offers some advantage over the use of other antimicrobial agents. To date, there are limited data on the safety of repeated use of sulfamethoxazole and trimethoprim in pediatric patients under two years of age. Sulfamethoxazole and trimethoprim is not indicated for prophylactic or prolonged administration in otitis media at any age.
Acute Exacerbations of Chronic Bronchitis in Adults
For the treatment of acute exacerbations of chronic bronchitis due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae when in the judgment of the physician sulfamethoxazole and trimethoprim offers some advantage over the use of a single antimicrobial agent.
For the treatment of enteritis caused by susceptible strains of Shigella flexneri and Shigella sonnei when antibacterial therapy is indicated.
Pneumocystis Carinii Pneumonia
For the treatment of documented Pneumocystis carinii pneumonia and for prophylaxis against Pneumocystis carinii pneumonia in individuals who are immunosuppressed and considered to be at an increased risk of developing Pneumocystis carinii pneumonia.
Traveler's Diarrhea in Adults
For the treatment of traveler's diarrhea due to susceptible strains of enterotoxigenic E. coli.
Published Studies Related to Sulfamethoxazole and Trimethoprim (Sulfamethoxazole / Trimethoprim)
Clindamycin versus trimethoprim-sulfamethoxazole for uncomplicated skin
community-acquired methicillin-resistant Staphylococcus aureus (MRSA) is unclear... CONCLUSIONS: We found no significant difference between clindamycin and TMP-SMX,
Itraconazole vs. trimethoprim-sulfamethoxazole: A comparative cohort study of 200
patients with paracoccidioidomycosis. 
Paracoccidioidomycosis (PCM) is a systemic mycosis endemic to Latin America. Brazil accounts for approximately 80% of cases, where it represents a major
public health issue due to its disabling impact and the number of premature
deaths it causes... Although the results of this study show that
itraconazole was the best treatment option for PCM patients, a double-blind,
randomized, controlled trial is necessary to confirm this conclusion.
Short- and long-term cure rates of short-duration trimethoprim-sulfamethoxazole
treatment in female dogs with uncomplicated bacterial cystitis. 
BACKGROUND: Long-duration beta-lactam antibiotics are used for empirical
treatment in female dogs with uncomplicated bacterial cystitis. However, women
with bacterial cystitis are treated with short-duration potentiated sulfonamides
because longer courses of beta-lactams result in lower cure and higher recurrence
Randomized controlled trial of trimethoprim-sulfamethoxazole for uncomplicated skin abscesses in patients at risk for community-associated methicillin-resistant Staphylococcus aureus infection. [2010.09]
STUDY OBJECTIVE: Community-associated methicillin-resistant Staphylococcus aureus is now the leading cause of uncomplicated skin abscesses in the United States, and the role of antibiotics is controversial. We evaluate whether trimethoprim-sulfamethoxazole reduces the rate of treatment failures during the 7 days after incision and drainage and whether it reduces new lesion formation within 30 days... CONCLUSION: After the incision and drainage of uncomplicated abscesses in adults, treatment with trimethoprim-sulfamethoxazole does not reduce treatment failure but may decrease the formation of subsequent lesions. Copyright (c) 2010 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.
Standard versus newer antibacterial agents in the treatment of severe acute exacerbation of chronic obstructive pulmonary disease: a randomized trial of trimethoprim-sulfamethoxazole versus ciprofloxacin. [2010.07.15]
BACKGROUND. Although the use of antibiotics in the treatment of acute exacerbation of chronic obstructive pulmonary disease (COPD) is largely accepted, controversy remains regarding whether the choice of antibiotic has any impact on outcome.
Clinical Trials Related to Sulfamethoxazole and Trimethoprim (Sulfamethoxazole / Trimethoprim)
Sulfamethoxazole Drug Interaction Study With MMX� Mesalazine/Mesalamine [Completed]
This is a drug interaction study evaluating the pharmacokinetic profiles of Sulfamethoxazole
administered alone & in combination with MMX Mesalazine/mesalamine.
Influence of Trimethoprim-Sulfamethoxazole for the Recurrence of Ocular Toxoplasmosis [Recruiting]
The protozoan Toxoplasma gondii is an obligate intracellular parasite, a common cause of
intraocular inflammation in the world. The treatment of toxoplasmosis is the sulfonamide
group of drugs, which acts on tachyzoites forms, no acting on bradyzoites, that grown from
latent focus located on boards and are responsible for recurrence. The investigators study
aims to determine the effect of prophylactic therapy with Trimethoprim-sulfamethoxazole on
the recurrences of toxoplasma retinochoroiditis gondii. This is a randomized, double-masked,
in patients with eye condition of acute Toxoplasma gondii retinochoroiditis. The study
population consist of patients treated at Ophthalmology department, University of Campinas.
They present symptoms compatible with a diagnosis of Recurrent ocular toxoplasmosis.
Volunteers will be recruited with a previous diagnosis of chorioretinitis presumed
Toxoplasma gondii, which show active lesions compatible with recurrence.
After the acute phase of treatment of all patients [1 tablet Trimethoprim-sulfamethoxazole
(800/160mg) 12/12h during 45 days], the same Stratified by gender) will be randomized in a
1: 1 ratio between the group 1 (prophylactic treatment with trimethoprim-sulfamethoxazole
tablet every other day) or group 2 (consisting of a placebo pill containing no active
ingredient of similar appearance to trimethoprim-sulfamethoxazole, 1 time a day to day
alternate). The definition of a patient with a recurrent episode of chorioretinitis
Toxoplasmosis is the presence of old scars of chorioretinitis, associated with satellite
active lesions chorioretinitis with positive IgG and IgM negative for toxoplasmosis. The
patients will be tested for visual acuity, examination biomicroscopy, tonometry, fundus
photography and indirect ophthalmoscopy. In each study, patients will be randomized in
blocks of four (two in group I and two Group II) with stratification by gender. The primary
outcome is incidence of episodes of recurrent chorioretinitis by toxoplasmosis in the follow
up of 12 months. It was planned a minimum sample of 140 patients (70 in group I and 70 in
group II). Assuming an incidence of 6% recurrence in group A, this sample will have a 80%
power to detect a difference of 18% between groups. The results of this analysis will be
considered significant if p <0. 05.
Vancomycin Or Trimethoprim/Sulfamethoxazole for Methicillin-resistant Staphylococcus Aureus (MRSA) Osteomyelitis (VOTSMO) [Active, not recruiting]
Study of Trimethoprim/Sulfamethoxazole as PCP Prophylaxis in CTD Patients [Recruiting]
Evaluation the efficacy and safety profile of trimethoprim/sulfamethoxazole as Pneumocystis
carinii pneumonia (PCP) prophylaxis in Patients With Connective Tissue Diseases (CTD)
treated with high-dose glucocorticoids and immunosuppressive agents.
Open-labeled, randomized, prospective single-center clinical trial. Observation period of 12
Effect of Weight and/or Obesity on Sulfamethoxazole and Trimethoprim Concentrations [Completed]
This study will find how weight affects the dosing of a drug called sulfamethoxazole and
trimethoprim. Currently, the amount of sulfamethoxazole and trimethoprim a patient receives
is the same regardless of the patient's weight.
All sulfamethoxazole and trimethoprim (Trade name is Bactrim or Septra) medication that you
will receive in this study will be referred to as study medication within this informed
consent form. This drug is a combination of two antibiotics, sulfamethoxazole and
trimethoprim, which belongs to a class of medication known as "sulfones" and is approved by
the US Food and Drug Administration (FDA) for the treatment of a wide variety of bacterial
infections such as ear infections, urinary tract infections, bronchitis, traveler's
diarrhea, and Pneumocystis carinii pneumonia. Sulfamethoxazole and trimethoprim is given
Reports of Suspected Sulfamethoxazole and Trimethoprim (Sulfamethoxazole / Trimethoprim) Side Effects
Renal Failure Acute (41),
Stevens-Johnson Syndrome (21),
Pruritus (15), more >>
Page last updated: 2015-08-10