Is cefdinir (Cefdinir) effective against E. Faecalis in a pediatric urinary tract infection (UTI) in a 4-year-old female?

Cefdinir Coverage for E. Faecalis in Pediatric UTI

No, cefdinir will NOT provide adequate coverage for E. faecalis in a 4-year-old female with a UTI, and an alternative antibiotic should be selected.

Why Cefdinir Fails Against Enterococcus

Cefdinir is an extended-spectrum cephalosporin that demonstrates excellent activity against common uropathogens like E. coli, Klebsiella, and Proteus species, with 95.6% susceptibility rates in pediatric UTI isolates 1. However, cephalosporins as a drug class have inherently poor activity against enterococcal species, including E. faecalis, due to the organism's intrinsic resistance mechanisms.

• Enterococcus species possess low-affinity penicillin-binding proteins that render cephalosporins ineffective 1
• When cefdinir was tested against opportunistic or nosocomial pathogens (which would include enterococci), susceptibility dropped dramatically to only 64.7% 1

Recommended Alternative Antibiotics

For confirmed E. faecalis UTI in this 4-year-old, amoxicillin or amoxicillin-clavulanate would be the appropriate oral first-line choice 2, 3.

Specific Treatment Options:

• Amoxicillin-clavulanate: Listed as a first-line option for pediatric UTI and provides excellent enterococcal coverage 2
• Ampicillin: If parenteral therapy is needed (toxic appearance, unable to retain oral intake), intravenous ampicillin combined with gentamicin is recommended 3
• Treatment duration should be 7-14 days 4, 2

Clinical Decision Algorithm

1. If culture results show E. faecalis and child is currently on cefdinir: Switch to amoxicillin-clavulanate immediately based on sensitivity results 2

2. If child appears toxic or cannot tolerate oral medications: Admit for IV ampicillin plus gentamicin 3

3. If child is clinically stable on oral therapy: Continue amoxicillin-clavulanate for full 7-14 day course 4, 2

4. Monitor for clinical improvement: Expect improvement within 24-48 hours; if no improvement, this constitutes an "atypical" UTI requiring further evaluation including renal ultrasound 2

Important Caveats

• Cephalexin, while recommended as first-line for typical pediatric UTI, also lacks reliable enterococcal coverage and should not be used for confirmed E. faecalis 2, 5
• Trimethoprim-sulfamethoxazole has variable enterococcal activity and faces increasing resistance rates (19-63% for E. coli), making it a less reliable choice 2
• The fact that E. faecalis was isolated (rather than the typical E. coli which causes 80-90% of pediatric UTIs) may suggest an atypical presentation or underlying urinary tract abnormality that warrants renal and bladder ultrasound 4, 3

Follow-Up Considerations

• Obtain renal and bladder ultrasound after this first febrile UTI to detect anatomic abnormalities, as recommended for all children with first UTI 2
• Non-E. coli organisms are considered an indication for imaging evaluation 2
• Ensure urine culture is obtained at onset of any future febrile illnesses 4