From the Guidelines
Trimethoprim-sulfamethoxazole (Bactrim) is an appropriate treatment for a Klebsiella aerogenes urinary tract infection (UTI) that shows sensitivity to this antibiotic, with a recommended dosage of 160/800 mg twice-daily for 14 days 1.
Treatment Considerations
- The standard dosage for uncomplicated UTIs in adults is typically one double-strength tablet (160 mg trimethoprim/800 mg sulfamethoxazole) every 12 hours for 3-5 days, or one single-strength tablet (80 mg trimethoprim/400 mg sulfamethoxazole) every 12 hours for 3-5 days.
- For complicated UTIs, treatment may be extended to 7-14 days.
- Patients should take the full course of antibiotics even if symptoms improve before completion.
- Adequate hydration is important during treatment to help flush bacteria from the urinary tract.
Mechanism of Action and Efficacy
- Bactrim works by inhibiting bacterial synthesis of tetrahydrofolic acid and dihydrofolic acid, which are essential for bacterial DNA synthesis and cell division.
- This dual mechanism makes it effective against many gram-negative bacteria including Klebsiella species.
Potential Side Effects and Contraindications
- Patients should be monitored for potential side effects including rash, gastrointestinal disturbances, and rare but serious adverse reactions like Stevens-Johnson syndrome.
- Those with sulfa allergies, G6PD deficiency, or severe renal impairment may require alternative antibiotics.
Clinical Evidence
- Studies have shown that trimethoprim-sulfamethoxazole is highly effective in treating acute uncomplicated cystitis, with early clinical and microbiological cure rates in the 90% - 100% range 1.
- The Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases recommend trimethoprim-sulfamethoxazole as a first-line treatment for acute uncomplicated cystitis, provided the local resistance rate does not exceed 20% 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Klebsiella Aerogenes UTI Sensitivity to Bactrim
- Klebsiella spp. are known to be susceptible to trimethoprim-sulfamethoxazole (also known as bactrim) 2, 3, 4
- A study from 2025 found that trimethoprim-sulfamethoxazole can be a cost-effective long-term solution for patients with multidrug-resistant K. pneumoniae UTIs 3
- Another study from 2017 reported that trimethoprim-sulfamethoxazole therapy was effective in treating patients with carbapenemase-producing Klebsiella pneumoniae infections 4
- However, a study from 2013 found that the sensitivity of Klebsiella isolates to cotrimoxazole (a combination of trimethoprim and sulfamethoxazole) was only 43.1% 5
- It is essential to note that antibiotic resistance patterns can vary by region and over time, and susceptibility testing is crucial to determine the effective treatment for a specific infection 2, 6
Treatment Implications
- The treatment of Klebsiella UTIs should be guided by susceptibility testing to ensure the use of effective antibiotics 2, 6
- Combination therapy with a carbapenem and synergy using polymyxin may be considered for treating multidrug-resistant Gram-negative bacilli (GNBs) 6
- Trimethoprim-sulfamethoxazole may be a viable option for treating Klebsiella UTIs, especially in cases where other antibiotics are not effective 3, 4