Acute Cystitis in Children
A 5-year-old girl has 2 days of burning on passing urine, frequency, and mild suprapubic discomfort. Her temperature is 37.0 °C and she is tolerating oral intake. There is no flank pain, costovertebral angle tenderness, or vomiting, and she has had no previous urinary infections. Urinalysis shows leukocyte esterase and nitrites positive with more than 50 white cells per high-power field. What is the most appropriate initial antibiotic?
- A.Oral nitrofurantoinCorrect
- B.Intravenous ceftriaxone
- C.Oral amoxicillin
- D.Intravenous gentamicin
Explanation
This girl has uncomplicated lower urinary tract infection (cystitis): dysuria, frequency, and suprapubic pain WITHOUT fever, flank pain, or systemic toxicity, so she should be treated with an oral agent that achieves high urinary concentrations. Acceptable first-line choices are a first or second generation cephalosporin such as cephalexin, nitrofurantoin, trimethoprim-sulfamethoxazole, or amoxicillin-clavulanate, given for 3 to 5 days in cystitis compared with 7 to 14 days for pyelonephritis. Nitrofurantoin is an excellent choice for cystitis because it concentrates in the urine with minimal tissue and serum levels and retains high activity against Escherichia coli with little effect on gut flora, but for exactly that reason it must NOT be used when upper tract infection is suspected, since it does not reach adequate renal parenchymal levels. Plain amoxicillin is a poor empiric choice because resistance among community Escherichia coli isolates commonly exceeds 50 percent, so it should only be used once susceptibility is documented. Parenteral therapy with ceftriaxone or an aminoglycoside is reserved for infants under 2 to 3 months, children who are toxic, septic, or vomiting, those unable to tolerate oral intake, and cases of pyelonephritis with clinical instability, and it exposes an otherwise well outpatient to unnecessary cannulation. Culture with susceptibility should always be sent before starting therapy so that treatment can be narrowed, and imaging with renal ultrasound is indicated in febrile or recurrent urinary tract infection rather than in a single episode of cystitis.
Why each option
- A.
- Correct. Nitrofurantoin achieves high urinary concentrations, retains activity against Escherichia coli, and is a recommended oral agent for cystitis.
- B.
- Intravenous ceftriaxone is reserved for toxic children, young infants, or those unable to tolerate oral therapy, none of which apply here.
- C.
- Community Escherichia coli resistance to plain amoxicillin frequently exceeds 50 percent, making it unsuitable for empiric therapy.
- D.
- Intravenous gentamicin adds nephrotoxicity and ototoxicity risk and is unnecessary in an afebrile, well child with lower tract infection.
Reference: AAP Clinical Practice Guideline, Urinary Tract Infection in Febrile Infants and Young Children, reaffirmed 2024; Nelson Textbook of Pediatrics, 22nd ed., 2024
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