Can Bactrim (trimethoprim/sulfamethoxazole) be used as an alternative to Macrobid (nitrofurantoin) for a patient with a urinary tract infection (UTI) who is not responding to Macrobid?

From the Guidelines

Bactrim (trimethoprim/sulfamethoxazole) can be used as an alternative to Macrobid (nitrofurantoin) for a patient with a urinary tract infection (UTI) who is not responding to Macrobid, provided that local resistance rates of uropathogens do not exceed 20% or if the infecting strain is known to be susceptible 1. When considering switching to Bactrim, it's crucial to confirm treatment failure through persistent symptoms and possibly a urine culture to identify the specific bacteria and its antibiotic susceptibilities.

• The typical adult dosage for uncomplicated UTIs is one double-strength tablet (160 mg trimethoprim/800 mg sulfamethoxazole) twice daily for 3 days, as recommended by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases 1.
• Bactrim works by inhibiting bacterial synthesis of folic acid and is effective against many common UTI pathogens, including E. coli.
• However, Bactrim should be used with caution in patients with kidney or liver impairment, G6PD deficiency, or sulfa allergies.
• 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 of starting the new medication.
• It's also important to note that the fluoroquinolones, such as ofloxacin, ciprofloxacin, and levofloxacin, are highly efficacious in 3-day regimens but have a propensity for collateral damage and should be reserved for important uses other than acute cystitis 1.

From the FDA Drug Label

To reduce the development of drug-resistant bacteria and maintain the effectiveness of sulfamethoxazole and trimethoprim oral suspension and other antibacterial drugs, sulfamethoxazole and trimethoprim oral suspension 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. 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

Bactrim (trimethoprim/sulfamethoxazole) can be used as an alternative to Macrobid (nitrofurantoin) for a patient with a urinary tract infection (UTI), but only if the UTI is due to susceptible strains of the listed organisms.

• The decision to use Bactrim should be based on culture and susceptibility information, if available.
• Local epidemiology and susceptibility patterns may contribute to empiric selection of therapy in the absence of such data 2.

From the Research

Bactrim as an Alternative to Macrobid for UTI

• Bactrim (trimethoprim/sulfamethoxazole) can be considered as an alternative to Macrobid (nitrofurantoin) for treating urinary tract infections (UTIs) in patients who are not responding to Macrobid 3, 4.
• However, the effectiveness of Bactrim may be limited due to increasing resistance rates among uropathogens, with studies showing resistance rates of up to 46.6% against trimethoprim/sulfamethoxazole 4.
• Nitrofurantoin, on the other hand, has been shown to be effective against UTIs, with susceptibility rates of 85.5% in one study 4.
• The choice of antibiotic should be based on individual patient factors, such as the presence of underlying medical conditions, allergy history, and local resistance patterns 5, 6.

Considerations for Antibiotic Selection

• When selecting an antibiotic, it is essential to consider the patient's clinical data, local sensitivity data, and the potential for resistance 5, 3.
• Fluoroquinolones, although effective, should be reserved for more invasive infections due to increasing resistance rates 3.
• Fosfomycin, nitrofurantoin, and cefuroxime may be considered as first-line therapies for uncomplicated cystitis, with trimethoprim/sulfamethoxazole being an alternative option 3, 4.

Patient-Specific Factors

• Patient-specific factors, such as age, gender, and underlying medical conditions, can influence the choice of antibiotic 6.
• For example, patients with diabetes may require different treatment approaches, and those with a history of antibiotic use may be at higher risk for resistance 6.
• A thorough evaluation of the patient's medical history and current condition is necessary to determine the most effective treatment approach 5, 3.