Should cefdinir (Omnicef) be discontinued for an asymptomatic 13‑year‑old with nitrite‑positive urinalysis and a urine culture growing Staphylococcus epidermidis?

Discontinue Cefdinir Immediately

You should stop the cefdinir now—this is asymptomatic bacteriuria (ASB) in an adolescent, which should not be treated, and Staphylococcus epidermidis is almost certainly a contaminant. 1

Why Treatment Should Be Stopped

This is Asymptomatic Bacteriuria

The 2019 IDSA guideline on asymptomatic bacteriuria provides a strong recommendation against treating ASB in children and adolescents 1. The guideline explicitly states there is:

• No benefit to treating ASB in healthy children
• High-quality evidence of harm from unnecessary antibiotic treatment
• No evidence that treatment prevents renal scarring or renal insufficiency

Multiple randomized controlled trials in school-aged girls with ASB showed no differences in:

• Subsequent symptomatic UTI rates
• Renal scarring
• Kidney growth
• Resolution of vesicoureteral reflux (VUR)

In fact, one observational study found that treating ASB with penicillin actually triggered acute pyelonephritis in 6 of the treated girls 1.

Staphylococcus epidermidis is a Contaminant

S. epidermidis in urine cultures from previously healthy children is almost always a contaminant 2. The organism only causes true UTI in children with:

• Underlying urinary tract abnormalities
• Indwelling catheters
• Recent urologic procedures

In your asymptomatic 13-year-old on a well exam, this is contamination from skin flora during collection.

The Harms of Continuing Treatment

Continuing antibiotics exposes this patient to:

• Gastrointestinal side effects: Cefdinir causes diarrhea in 8% of pediatric patients, with rates up to 17% in younger children 3
• Rash: Occurs in 3% of pediatric patients 3
• C. difficile infection risk 3
• Selection pressure for resistant organisms: Recent evidence shows cefdinir treatment failure is associated with emergence of cephalosporin-resistant pathogens 4
• Disruption of normal microbiome

Practical Action Steps

1. Call the family today and explain:

   • The culture shows a skin contaminant, not a true infection
   • The patient has no symptoms, so no infection to treat
   • Stop the cefdinir immediately
   • No further antibiotics or follow-up cultures needed

2. Reassure them that:

   • Nitrite-positive urinalysis without symptoms does not require treatment
   • This is a common scenario in pediatric practice
   • There is no risk to kidney health from not treating

3. Document your stewardship intervention—discontinuing antibiotics for contaminant cultures is a quality improvement measure 5

Common Pitfalls to Avoid

• Don't "complete the course": There is no benefit and only harm from continuing antibiotics for ASB
• Don't order repeat cultures: This will only lead to more false-positive results and unnecessary treatment
• Don't pursue imaging: Healthy adolescents with contaminant cultures don't need renal ultrasounds or voiding cystourethrograms
• Don't use cefdinir for actual UTIs: When you do treat symptomatic UTI, cephalexin is superior to cefdinir, which has poor urinary penetration and higher treatment failure rates 6, 4

The 2024 WikiGuidelines consensus reinforces that unnecessary treatment of ASB "risks side effects without benefit, represents low value care, and poses a threat to antimicrobial sustainability" 7.