Is cefdinir (Cefdinir) effective against Gram-negative bacteria in urinary tract infections (UTIs)?

From the Guidelines

Cefdinir is an appropriate choice for the treatment of gram-negative bacteria urinary tract infections (UTIs) when other recommended agents cannot be used, as stated in the 2011 guidelines by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases 1.

Key Points to Consider

• Cefdinir is a third-generation cephalosporin antibiotic that works by inhibiting bacterial cell wall synthesis.
• For UTIs, the typical adult dosage is 300 mg twice daily or 600 mg once daily for 10 days, though treatment duration may vary based on infection severity.
• Cefdinir is particularly effective against common UTI-causing gram-negative bacteria like Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis.
• However, it may not be effective against certain resistant strains or Pseudomonas aeruginosa.
• The European Association of Urology guidelines on urological infections, updated in 2024, recommend the use of third-generation cephalosporins as empirical treatment for complicated UTI with systemic symptoms 1.

Important Considerations

• Patients should take the full course of antibiotics even if symptoms improve.
• Drink plenty of water during treatment.
• Be aware of possible side effects including diarrhea, nausea, and headache.
• If you have a penicillin allergy, inform your healthcare provider as there's potential for cross-reactivity.
• Cefdinir should be taken with food to enhance absorption, and antacids containing aluminum or magnesium should be avoided within 2 hours of taking cefdinir as they can reduce its effectiveness.

Recommendation

Based on the most recent and highest quality study, cefdinir is a viable option for the treatment of gram-negative bacteria UTIs, especially when other recommended agents cannot be used, as supported by the 2011 guidelines by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases 1.

From the FDA Drug Label

Cefdinir has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in INDICATIONS AND USAGE Gram-Negative Bacteria Haemophilus influenzae Haemophilus parainfluenzae Moraxella catarrhalis The following in vitro data are available, but their clinical significance is unknown Cefdinir exhibits in vitro minimum inhibitory concentrations (MICs) of 1 mcg/mL or less against (≥ 90%) strains of the following microorganisms; however, the safety and effectiveness of cefdinir in treating clinical infections due to these microorganisms have not been established in adequate and well-controlled clinical trials Gram-Negative Bacteria Citrobacter koseri Escherichia coli Klebsiella pneumoniae Proteus mirabilis

Cefdinir's effectiveness against Gram-negative bacteria in UTI is not explicitly established. While cefdinir exhibits in vitro activity against certain Gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, the clinical significance of this activity is unknown and the safety and effectiveness of cefdinir in treating UTIs caused by these microorganisms have not been established in adequate and well-controlled clinical trials 2.

From the Research

Effectiveness of Cefdinir on Gram-Negative Bacteria in UTIs

• Cefdinir is a third-generation cephalosporin antibiotic with a broad spectrum of activity against many pathogens, including some gram-negative bacteria 3, 4, 5.
• However, its effectiveness against gram-negative bacteria in urinary tract infections (UTIs) is not well-established, and it is not typically recommended as a first-line treatment for UTIs caused by gram-negative bacteria 6.
• One study compared the efficacy of cefdinir and cefaclor in the treatment of uncomplicated UTIs and found that cefdinir was effective, but the most frequently isolated pathogens were Escherichia coli, Proteus mirabilis, Staphylococcus saprophyticus, and Klebsiella pneumoniae, which are not all gram-negative bacteria 3.
• Another study found that cefdinir had comparable efficacy to cephalexin for the treatment of lower UTIs, but the study did not specifically examine the effectiveness of cefdinir against gram-negative bacteria 7.

Spectrum of Activity

• Cefdinir has a broad spectrum of activity against many gram-negative and gram-positive aerobic organisms, including Haemophilus influenzae, Moraxella catarrhalis, and some strains of Escherichia coli 4, 5.
• However, its activity against other gram-negative bacteria, such as Pseudomonas aeruginosa, is limited 4, 5.
• Cefdinir is stable to hydrolysis by many beta-lactamases, which can make it effective against some bacteria that are resistant to other antibiotics 4, 5.

Clinical Use

• Cefdinir is approved for the treatment of various infections, including community-acquired pneumonia, acute bacterial exacerbations of chronic bronchitis, and uncomplicated skin and skin-structure infections 4, 5.
• However, its use in the treatment of UTIs is not well-established, and other antibiotics, such as nitrofurantoin, fosfomycin, and pivmecillinam, are generally recommended as first-line treatments for UTIs caused by gram-negative bacteria 6.