Treatment of Bacterial Infections

Recommended Dosage and Duration

The Infectious Diseases Society of America recommends a dosage of trimethoprim-sulfamethoxazole of 1-2 double-strength tablets (160mg/800mg) twice daily for 7-14 days, with duration determined by infection severity and clinical response 1, 2
For uncomplicated infections, the recommended duration of treatment is 7-10 days, with clinical cure rates of 90% and bacterial cure rates of 91% reported for susceptible organisms with trimethoprim-sulfamethoxazole treatment 2

Trimethoprim-sulfamethoxazole is contraindicated in pregnant women, nursing mothers, infants <2 months of age, and patients with known hypersensitivity to trimethoprim or sulfonamides, with a strength of evidence based on case reports and observational studies 3, 2
The American College of Obstetricians and Gynecologists and other medical societies imply that trimethoprim-sulfamethoxazole is not recommended for pregnant women in the third trimester, with a strength of evidence based on expert opinion and clinical studies 2
The Centers for Disease Control and Prevention (CDC) recommends various antimicrobial prophylaxis regimens for different patient populations, including pediatric and adult patients, with a strength of evidence based on expert opinion and clinical studies 3, 4

For children ≥2 months, the CDC recommends a dosage of 5 mg/kg (trimethoprim component) every 12 hours, with a strength of evidence based on clinical studies 3
For adults and adolescents, the CDC recommends one double-strength tablet daily for PCP prophylaxis, with a strength of evidence based on expert opinion 5

The American Urological Association recommends urodynamic studies prophylaxis for high-risk patients (those with neurogenic lower urinary tract dysfunction, immunosuppression, or abnormalities of the urinary tract), with a strength of evidence based on expert opinion and clinical studies 4
Elderly patients may require dose adjustment as they tend to have higher peak concentrations and reduced clearance of trimethoprim, although the strength of evidence for this recommendation is low 6

Common adverse effects include gastrointestinal disturbances, hypersensitivity reactions, and rarely Stevens-Johnson syndrome, blood dyscrasias, and hepatic necrosis, with a strength of evidence based on case reports and observational studies 3
Complete blood counts with differential and platelet count should be performed at initiation of TMP-SMX prophylaxis and at monthly intervals to assess hematologic toxicity, as recommended by the MMWR Recommendations and Reports guideline society 7

Dose adjustments are necessary in patients with impaired renal function, but not in those with normal renal function and impaired hepatic function, with a strength of evidence based on clinical studies 3
Always consider local antimicrobial resistance patterns when prescribing trimethoprim-sulfamethoxazole, particularly for empiric therapy of skin and soft tissue infections where MRSA prevalence may vary by region, with a strength of evidence based on expert opinion 6
For severe infections requiring IV therapy, dosing is typically based on the trimethoprim component at 8-12 mg/kg/day divided in either 4 doses (IV) or 2 doses (oral), as recommended by the Clinical Infectious Diseases guideline society 6