Is Bactrim (Trimethoprim/Sulfamethoxazole) effective for treating Enterobacter cloacae urinary tract infections (UTIs)?

From the Guidelines

Trimethoprim-sulfamethoxazole (Bactrim) should not be used as the first-line treatment for Enterobacter cloacae urinary tract infections (UTIs) due to increasing resistance rates, and alternative antibiotics such as fluoroquinolones, carbapenems, or cephalosporins may be necessary. For uncomplicated UTIs, the typical adult dosage of Bactrim is one double-strength tablet (160 mg trimethoprim/800 mg sulfamethoxazole) every 12 hours for 3-5 days, but this may not be effective against Enterobacter cloacae 1. Before starting treatment, antibiotic susceptibility testing is essential as E. cloacae frequently carries resistance mechanisms against multiple antibiotics, including Bactrim 1. Patients should complete the full course of antibiotics even if symptoms improve, drink plenty of water, and contact their healthcare provider if symptoms worsen or don't improve within 48-72 hours. E. cloacae is an opportunistic pathogen that can produce beta-lactamases, making it naturally resistant to some antibiotics, which is why targeted therapy based on susceptibility testing is crucial for effective treatment 1.

Some key points to consider when treating Enterobacter cloacae UTIs include:

• The importance of antibiotic susceptibility testing to guide treatment decisions 1
• The potential need for alternative antibiotics such as fluoroquinolones, carbapenems, or cephalosporins 1
• The importance of completing the full course of antibiotics and monitoring for symptoms 1
• The potential for E. cloacae to produce beta-lactamases, making it resistant to some antibiotics 1

In terms of specific treatment recommendations, the guidelines suggest that oral trimethoprim-sulfamethoxazole (160/800 mg [1 double-strength tablet] twice-daily for 14 days) may be an appropriate choice for therapy if the uropathogen is known to be susceptible 1. However, if the susceptibility is not known, an initial intravenous dose of a long-acting parenteral antimicrobial, such as 1 g of ceftriaxone, may be recommended 1. Ultimately, the choice of antibiotic and treatment duration will depend on the individual patient's needs and the results of antibiotic susceptibility testing.

From the FDA Drug Label

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

• The drug label indicates that trimethoprim/sulfamethoxazole is used to treat urinary tract infections caused by Enterobacter species.
• The recommended dosage for adults is 4 teaspoonfuls (20 mL) of sulfamethoprim/sulfamethoxazole oral suspension every 12 hours for 10 to 14 days 2.
• The recommended dose for children with urinary tract infections is 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days 2.

From the Research

Enterobacter cloacae and UTI Treatment with Bactrim

• Enterobacter cloacae is a type of bacteria that can cause urinary tract infections (UTIs) 3
• Bactrim, also known as trimethoprim-sulfamethoxazole, is an antibiotic that is sometimes used to treat UTIs 4, 5, 6
• However, the use of Bactrim to treat Enterobacter cloacae UTIs is limited due to high rates of resistance 4, 3
• Alternative treatment options for Enterobacter cloacae UTIs include nitrofurantoin, fosfomycin, and pivmecillinam 4, 7
• ESBL-producing Enterobacter cloacae isolates have been shown to be resistant to many antibiotics, including ampicillin, amoxicillin-clavulanate, and cephalosporins 7, 3
• Carbapenems, such as meropenem and imipenem, may be effective against ESBL-producing Enterobacter cloacae isolates, but the potential for future resistance should be considered 3

Antimicrobial Resistance and Treatment Options

• The emergence of multidrug-resistant Enterobacter cloacae is a significant problem in healthcare settings 3
• The use of antimicrobial susceptibility testing, such as the Kirby Bauer method, can help guide treatment decisions 3
• The development of new antimicrobial agents and the rediscovery of forgotten antibiotics, such as pivmecillinam and fosfomycin, may be helpful in treating UTIs caused by multidrug-resistant Enterobacter cloacae 7
• The use of MALDI-TOF MS, a proteomic analytical technique, can help identify and differentiate Enterobacter cloacae isolates 3

Clinical Implications

• The treatment of Enterobacter cloacae UTIs requires careful consideration of antimicrobial resistance patterns and the use of effective treatment options 4, 7, 3
• The use of Bactrim to treat Enterobacter cloacae UTIs should be avoided due to high rates of resistance 4, 3
• Alternative treatment options, such as nitrofurantoin, fosfomycin, and pivmecillinam, should be considered 4, 7