Urinary tract infection (pediatrics): Clinical sciences

Urinary tract infection, or UTI for short, is a common bacterial infection in children that can involve any part of the urinary tract. In children, UTIs are usually caused by gastrointestinal flora, such as Escherichia coli, that ascend into the bladder or kidneys, causing cystitis, pyelonephritis, or even urosepsis. If not treated promptly, UTIs can result in long-term complications, such as renal scarring, hypertension, and chronic renal disease. The management of UTIs depends on the patient’s age; more specifically, whether they are less or more than 2 months old.

If a child presents with a chief concern suggesting a UTI, you should first perform an ABCDE assessment to determine whether the child is stable or unstable. If your patient is unstable, stabilize the airway, breathing, and circulation. Next, obtain IV access, administer IV fluids, and start broad-spectrum antibiotics. Finally, begin continuous vital sign monitoring, including blood pressure, heart rate, respiratory rate, and oxygen saturation. If needed, don’t forget to provide supplemental oxygen.

Okay, now let’s go back to the ABCDE assessment and take a look at stable patients. In this case, start by obtaining a focused history and physical exam. Next, assess the patient's age, which will guide the treatment!

First, let’s take a look at term infants of 2 months of age and younger. These patients typically present with vague systemic symptoms, like fever, fussiness, and lethargy. Additionally, caretakers may report poor oral intake or vomiting, and they may describe the baby’s urine as foul-smelling. Next, the physical exam typically reveals an ill-appearing, uncomfortable infant with a body temperature of 38 degrees Celsius or higher. The physical exam could also reveal tachycardia and suprapubic tenderness.

Based on these findings, you should suspect a UTI, so your next step is to order labs, which include CBC, CRP, procalcitonin, and urinalysis, as well as urine and blood cultures. Your work-up for this age group may also include a cerebrospinal fluid analysis and culture as part of a sepsis evaluation.

Now here’s a clinical pearl to keep in mind! You can collect a urine sample from an infant by bag collection, bladder catheterization, or suprapubic bladder aspiration. Because urine collected by a bag specimen is often contaminated with skin flora, it should only be sent for a urinalysis and not for culture. For this reason, bladder catheterization is the most common method used in this age group to collect a urine sample for culture. On the other hand, suprapubic needle aspiration is a painful procedure that’s not commonly used due to a relatively low success rate!

Next, admit your patient to the hospital and start empiric antibiotics, which include ampicillin, and either gentamicin or cefotaxime for coverage of gram-negative bacteria. Additionally, don’t forget to provide adequate hydration with IV fluids and administer antipyretics, such as acetaminophen, for fever.

Now let’s take a look at lab results! CBC will typically reveal elevated white blood cell count, and inflammatory markers will be elevated. Additionally, urinalysis often shows the presence of white blood cells and positive leukocyte esterase, indicating an inflammatory response that is suggestive but not diagnostic of a UTI. A urine culture with bacterial growth of over 50,000 colony-forming units per milliliter from a catheterized urine specimen confirms UTI; but for neonates and children with immune deficiency, growth of as few as 10,000 colony-forming units per milliliter suggests infection. Finally, positive bacterial growth from the blood culture is concerning for urosepsis.

At this point you can be sure that your patient has a UTI, so tailor antibiotics based on culture results. Continue supportive care with adequate hydration and antipyretics as needed. Finally, once the UTI resolves, all infants under 2 months of age with UTI should have a renal and bladder ultrasound. If the ultrasound reveals a urinary tract abnormality, such as a ureterocele or posterior urethral valves, order a voiding cystourethrogram, or VCUG for short, to assess for vesicoureteral reflux, bladder or urethral dysfunction, and structural abnormalities.