Key points
- •
Given the high false-positive rate of urinary tests it is important to test a population with a high pretest probability of infection.
- •
The sensitivity and specificity of a catheterized specimen is significantly better than those of a bagged sample, and has a specificity of 83% to 89% compared with a suprapubic sample; in samples with greater than 100,000 colony-forming units/mL approaches 99%.
- •
Comparing a positive urine dipstick and positive microscopic analysis showed no difference between the two methods when correlating with urine culture.
- •
Pediatric UTIs are treated with 2 goals: to eliminate the infection and prevent severe systemic illness; and to prevent and/or reduce possible long-term complications, such as renal scarring and hypertension.
Introduction
Pediatric urinary tract infection (UTI) is a common cause of presentation to health care providers and is an area of concern for parents and clinicians alike. There is a broad spectrum of presentations ranging from asymptomatic infection to mild lower urinary tract symptoms, to febrile and systemic illness.
The prevalence and incidence of pediatric UTI varies by age, race/ethnicity, sex, and circumcision status ( Table 1 ). Although calculating the true cumulative incidence is challenging given the varied reporting in different clinical settings, it is likely to be at least 2% in boys and 7% in girls in the first 6 years of life, with 2.2% of boys and 2.1% of girls having had a UTI before reaching 2 years of age. Controlling for other clinical parameters, Hispanic and white children are more likely to be diagnosed with a UTI than black children. After the first 12 months, girls are more likely to be diagnosed with a UTI. About half of boys with UTI are diagnosed within the first 12 months of life; however, 80% of girls are diagnosed at a later age. Circumcision has been shown to have a protective effect on UTI, reducing the odds of infection by 87%, with an even greater effect for boys with recurrent infections or posterior urethral valves.
| Organism | Male | Female | ||
|---|---|---|---|---|
| Outpatient (%) | Inpatient (%) | Outpatient (%) | Inpatient (%) | |
| Escherichia coli | 50 (48–52) | 37 (35–39) | 83 (83–84) | 64 (63–66) |
| Enterobacter | 5 (5–6) | 10 (8–11) | 1 (1–1) | 4 (4–5) |
| Enterococcus | 17 (16–18) | 27 (25–29) | 5 (5–5) | 13 (12–14) |
| Klebsiella | 10 (9–11) | 12 (10–13) | 4 (4–5) | 10 (9–11) |
| Pseudomonas aeruginosa | 7 (6–8) | 10 (8–11) | 2 (2–2) | 6 (5–7) |
| Proteus mirabilis | 11 (10–12) | 5 (4–6) | 4 (4–4) | 2 (2–3) |
Pediatric UTI costs the health care system more than $180 million annually, and accounts for more than 1.5 million clinician visits per year. Accurate and timely diagnosis of these infections is important for determining appropriate treatment and preventing long-term complications, such as renal scarring, hypertension, and end-stage renal disease.
Introduction
Pediatric urinary tract infection (UTI) is a common cause of presentation to health care providers and is an area of concern for parents and clinicians alike. There is a broad spectrum of presentations ranging from asymptomatic infection to mild lower urinary tract symptoms, to febrile and systemic illness.
The prevalence and incidence of pediatric UTI varies by age, race/ethnicity, sex, and circumcision status ( Table 1 ). Although calculating the true cumulative incidence is challenging given the varied reporting in different clinical settings, it is likely to be at least 2% in boys and 7% in girls in the first 6 years of life, with 2.2% of boys and 2.1% of girls having had a UTI before reaching 2 years of age. Controlling for other clinical parameters, Hispanic and white children are more likely to be diagnosed with a UTI than black children. After the first 12 months, girls are more likely to be diagnosed with a UTI. About half of boys with UTI are diagnosed within the first 12 months of life; however, 80% of girls are diagnosed at a later age. Circumcision has been shown to have a protective effect on UTI, reducing the odds of infection by 87%, with an even greater effect for boys with recurrent infections or posterior urethral valves.
| Organism | Male | Female | ||
|---|---|---|---|---|
| Outpatient (%) | Inpatient (%) | Outpatient (%) | Inpatient (%) | |
| Escherichia coli | 50 (48–52) | 37 (35–39) | 83 (83–84) | 64 (63–66) |
| Enterobacter | 5 (5–6) | 10 (8–11) | 1 (1–1) | 4 (4–5) |
| Enterococcus | 17 (16–18) | 27 (25–29) | 5 (5–5) | 13 (12–14) |
| Klebsiella | 10 (9–11) | 12 (10–13) | 4 (4–5) | 10 (9–11) |
| Pseudomonas aeruginosa | 7 (6–8) | 10 (8–11) | 2 (2–2) | 6 (5–7) |
| Proteus mirabilis | 11 (10–12) | 5 (4–6) | 4 (4–4) | 2 (2–3) |
Pediatric UTI costs the health care system more than $180 million annually, and accounts for more than 1.5 million clinician visits per year. Accurate and timely diagnosis of these infections is important for determining appropriate treatment and preventing long-term complications, such as renal scarring, hypertension, and end-stage renal disease.
History and physical
Clinicians must have a high index of suspicion for UTI in the pediatric population, especially in infants and children less than 2 years of age. The evaluation must include a thorough history and the importance of the physical examination in pediatric patients cannot be overstated.
Children Less Than 2 Years of Age
This is the most challenging population in which to make the diagnosis of UTI. Presentations are often vague and include irritability, poor feeding, lethargy, jaundice, vomiting, and fever. In evaluating risk factors among children less than 2 years old presenting to emergency rooms with an ill appearance, high fever (greater than 39°C); history of UTI; change in urine characteristics (malodor or hematuria); and distension and tenderness in the suprapubic area, abdomen, or flanks were associated with UTI. History of a previous UTI, temperature greater than 40°C, and suprapubic tenderness are the most useful for diagnosing UTI in febrile infants.
Children Aged 2 to 12 Years
Toddlers and verbal children are more able to describe their symptoms and localize them to the urinary tract; however, given the high prevalence of UTI, the lack of localizing symptoms does not rule out UTI in this population.
History
Descriptions of dysuria, frequency, urgency, and urinary incontinence (in a toilet-trained child) increase the likelihood of UTI diagnosis.
Examination
A thorough examination should include evaluation of external genitalia, with special attention to identifying any external lesions, discharge, or foreign bodies. Palpation of the abdomen, suprapubic region, and costovertebral angles to elicit tenderness is key.
- •
Special considerations for girls include evaluation for labial adhesions, foreign bodies, vulvovaginitis, and signs of sexually transmitted diseases.
- •
Special considerations for boys include evaluation for phimosis, meatal stenosis, and tenderness in the testes to suggest epididymitis and/or orchitis.
Adolescent Children
Although adolescents are better able to provide history and participate in physical examinations, sexual activity is a special consideration for this population that requires additional diagnostic attention. Among surveyed high-school students in 2013, 47% had had sexual intercourse and 34% reported having sexual activity in the last 3 months. Sexually transmitted infections (STIs) are an important consideration for adolescents with urinary symptoms.
Adolescent girls and urinary tract infection
- •
Adolescent girls with urinary symptoms often present with a UTI, STI, or both. Statistics on STI rates vary, with a prospective study finding that 29% of adolescent girls with urinary symptoms had had an STI. Among sexually active girls with urinary symptoms, history of STI, more than 1 partner in the last 3 months, and urinalysis with blood and leukocyte esterase were predictive of STI.
- •
No specific symptoms or history findings have been shown to reliably predict which adolescent girls with urinary symptoms are at increased risk for either UTI or STI.
- •
Current recommendations suggest testing sexually active girls with urinary symptoms for UTI as well as STIs including Neisseria gonorrhoeae , Chlamydia , and Trichomonas , especially in those with sterile pyuria. Patients being evaluated or treated for STI should be offered HIV testing.
Adolescent boys and urinary tract infection
- •
Although the prevalence of UTI in this age group is low, several risk factors have been identified, including sexual activity and lack of circumcision.
- •
In adolescent boys with urinary symptoms it is also important to evaluate for balanitis xerotica obliterans, with nearly 35% incidence reported globally. In pubertal boys, prostatitis can also present with symptoms of voiding dysfunction.
Urine testing
Clinical and demographic factors should be used to determine the probability of an infection and guide the decision-making process to obtain a specimen for analysis. Given the high false-positive rate of urinary tests it is important to test a population with a high pretest probability of infection.
Urine specimen collection in non–toilet-trained children
Bag Specimen
- •
The simplest method of using a taped sterile bag to collect the urine is the least reliable, and has been consistently shown to have the greatest contamination rate.
- •
A positive urine culture from a bag specimen has up to a 75% rate of false-positives, with periurethral organisms being isolated more than 98% of the time. Given its low positive predictive value, this method of collection has the lowest diagnostic utility in the clinical setting.
- •
If a bag specimen is negative, this can be used to rule out UTI without the need for confirmatory culture; however, positive urinalysis tests from bag specimens warrant further investigation with a catheterized specimen or suprapubic aspiration.
Urethral Catheterization
- •
Obtaining a catheterized specimen is a safe, fast, reliable way of collecting urine for analysis in the non–toilet-trained population.
- •
The success of specimen collection depends on the specific anatomy and cooperation of the patient and the technical skill of the medical provider.
- •
Success rates in the literature have been quoted from 23% to 99%.
- •
The possible complications, including trauma and hematuria, have been shown to be minimal.
- •
The sensitivity and specificity of a catheterized specimen are significantly better than those of bagged samples, and have a specificity of 83% to 89% compared with a suprapubic sample, and in samples with greater than 100,000 colony-forming units (CFU)/mL approaches 99%.
Suprapubic Aspiration
- •
Arguably the most invasive method of urine collection, suprapubic aspiration is the most accurate. It is the least likely to be contaminated and any presence of bacteria indicates infection.
- •
Suprapubic aspiration has an advantage for uncircumcised boys with phimosis, or girls with labial adhesions in whom catheterized specimens are more technically challenging to obtain.
- •
Despite its advantages, in the clinic or emergency room setting, suprapubic aspiration may prove more challenging to perform in a timely manner, given the requirement for physician participation and variable success rate per attempt (46%–97%), although this is improved with the use of ultrasonography.
Urine tests
Dipstick Urinalysis
This is the most clinically available, affordable, and accessible urine test, and the most widely used in the outpatient setting. The most clinically useful findings are the presence or absence of leukocyte esterase and nitrite in the urine specimen.
- •
Positive leukocyte esterase is suggestive of inflammation in the urine and the presence of white blood cells (WBC). False-positives include other inflammatory conditions, such as Kawasaki disease; appendicitis; gastroenteritis; and presence of reactive inflammation, in the case of urinary stone disease. False-negatives include urine collected too early in the disease course or in a child with a suppressed immune response. Positive leukocyte esterase is 84% sensitive and 78% specific for diagnosing UTI.
- •
Positive nitrite is suggestive of the presence of gram-negative bacteria. False-negatives include urine collection that has been in the bladder less than 4 hours, which is the approximate conversion time from nitrate to nitrite; and infection with gram-positive bacteria or non–nitrite-producing bacteria (namely enterococci and Pseudomonas ). A positive nitrite test is up to 50% sensitive and 98% specific for diagnosing UTI.
- •
Combined positive nitrite-leukocyte esterase on dipstick analysis is 80% to 90% sensitive and 60% to 98% specific. When both are negative, the negative predictive value approaches 100%.
Microscopic Analysis
This method of analysis is more expensive and requires more equipment and skilled analysis than a urine dipstick. Analysis is performed to evaluate the presence of WBC, red blood cells, and bacteria in the sample.
- •
Pyuria is the presence of greater than 5 WBC per high-power field on a centrifuged sample (10 WBC per high-power field in an uncentrifuged sample).
- •
Bacteriuria is the presence of any bacteria per high-power field.
- •
In a centrifuged sample, the presence of both pyuria and bacteriuria is up to 66% sensitive and 99% specific for diagnosing UTI.
- •
Comparing a positive urine dipstick and positive microscopic analysis showed no difference between the two methods when correlating with urine culture.
Urine Culture
This is the gold standard for diagnosing UTI and should be processed as soon as possible after collection to maximize diagnostic accuracy.
- •
Greater than 50,000 CFU on a catheterized specimen or suprapubic aspiration indicate the presence of a UTI.
- •
Greater than 100,000 CFU on a voided specimen is considered a positive culture.
- •
Diagnosis of UTI in children 2 to 24 months old is made based on the presence of both pyuria and at least 50,000 colonies per milliliter of a single organism obtained via suprapubic aspiration or catheterization.
Serum Tests
Serum markers, including complete blood count, blood cultures, serum creatinine, C-reactive protein, erythrocyte sedimentation rate, and procalcitonin, have been evaluated as measures for UTI severity; however, none has been shown to be clinically useful or to alter management.
Related posts:
Update on Antibiotic Prophylaxis for Genitourinary Procedures in Patients with Artificial Joint Replacement and Artificial Heart Valves
Preprostate Biopsy Rectal Culture and Postbiopsy Sepsis
Treatment of Fungal Urinary Tract Infection
Sexually Transmitted Infections
Urinary Tract Infection and Bacteriuria in Pregnancy
Asymptomatic Bacteriuria in Noncatheterized Adults
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
