Antibiotic Coverage of Septran DS (Trimethoprim/Sulfamethoxazole)
Trimethoprim-sulfamethoxazole (TMP-SMX) DS provides effective coverage against many gram-positive and gram-negative bacteria, making it a valuable option for treating skin and soft tissue infections, urinary tract infections, respiratory infections, and certain systemic infections. 1, 2
Antimicrobial Spectrum
Gram-Positive Coverage:
- Effective against Staphylococcus aureus, including many community-acquired methicillin-resistant S. aureus (CA-MRSA) strains 3
- Active against β-hemolytic streptococci, though not considered first-line therapy 3
- Covers Streptococcus pneumoniae, though resistance patterns vary 2
Gram-Negative Coverage:
- Excellent activity against many Enterobacteriaceae including Escherichia coli, Klebsiella species, and Proteus mirabilis 2, 4
- Effective against Haemophilus influenzae 5
- Covers Moraxella catarrhalis 5
Other Organisms:
- First-line treatment for Pneumocystis jirovecii pneumonia 6, 2
- Effective against Nocardia species 2, 4
- Active against many strains of Shigella and Salmonella 6, 7
Clinical Applications
Skin and Soft Tissue Infections:
- Recommended for outpatient treatment of purulent skin infections, particularly those caused by CA-MRSA 3
- Standard dosing: 1-2 DS tablets (160mg TMP/800mg SMX) twice daily 6
- Duration typically 7-14 days based on clinical response 3
Urinary Tract Infections:
- Effective for both uncomplicated and complicated UTIs 6, 7
- Standard dosing: 1 DS tablet twice daily for 10-14 days 6
- Achieves high concentrations in urine, making it particularly effective 7
Respiratory Infections:
- Used for acute exacerbations of chronic bronchitis 6
- Standard dosing: 1 DS tablet twice daily for 14 days 6
- Effective against common respiratory pathogens 5
Other Indications:
- Treatment of shigellosis: 1 DS tablet twice daily for 5 days 6
- Traveler's diarrhea: 1 DS tablet twice daily for 5 days 6
- Pneumocystis pneumonia: 15-20 mg/kg TMP and 75-100 mg/kg SMX per day in divided doses every 6 hours for 14-21 days 6
Important Considerations
Resistance Patterns:
- Increasing resistance among MRSA strains has been reported in some regions 3
- When treating skin infections where both streptococci and MRSA coverage is needed, TMP-SMX may need to be combined with a β-lactam (e.g., amoxicillin) 3
Dosage Adjustment:
- Requires dose adjustment in renal impairment 6, 2
- For creatinine clearance 15-30 mL/min: reduce dose by 50% 6
- Not recommended when creatinine clearance is below 15 mL/min 6
Contraindications:
- Contraindicated in children less than 2 months of age 6
- Not recommended during third trimester of pregnancy 3
- Use caution in patients with G6PD deficiency or folate deficiency 4
Clinical Pearls
- TMP-SMX achieves good tissue penetration, making it effective for various soft tissue infections 1, 2
- For empiric coverage of both β-hemolytic streptococci and CA-MRSA in skin infections, TMP-SMX may be combined with a β-lactam antibiotic 3
- The DS (double strength) formulation contains 160 mg trimethoprim and 800 mg sulfamethoxazole 6
- Monitoring for adverse effects including rash, gastrointestinal symptoms, and rare but serious reactions like Stevens-Johnson syndrome is recommended 7, 4