Stephen L Thornton, MD,
Assistant Professor of Emergency Medicine,
University of Kansas Hospital
Nothing to disclose.
Specialty Editor(s)
David S Howes, MD,
Professor of Medicine and Pediatrics, Section
Chief and Residency Program Director, Emergency Medicine,
University of Chicago/Pritzker School of
Medicine
Nothing to disclose.
Grace M Young, MD,
Associate Professor, Department of
Pediatrics, University of Maryland Medical
Center
Nothing to disclose.
John D Halamka, MD, MS,
Associate Professor of Medicine, Harvard
Medical School, Beth Israel Deaconess Medical Center; Chief
Information Officer, CareGroup Healthcare System and Harvard
Medical School; Attending Physician, Division of Emergency
Medicine, Beth Israel Deaconess Medical
Center
Nothing to disclose.
Mary L Windle, PharmD,
Adjunct Associate Professor, University of
Nebraska Medical Center College of Pharmacy; Pharmacy Editor,
eMedicine
Nothing to disclose.
Chief Editor
Richard G Bachur, MD,
Associate Professor of Pediatrics, Harvard
Medical School; Associate Chief and Fellowship Director,
Attending Physician, Division of Emergency Medicine,
Children's Hospital of Boston
Nothing to disclose.
Background
In the pediatric patient, urinary tract infections (UTIs) are among the most common serious bacterial infections (SBI) encountered.[1] They are a frequent cause of fever and can cause significant morbidity if not properly identified and treated.
Presentation varies based on the age of the patient. Neonates and infants often present with vague, nonspecific symptoms, necessitating a high index of suspicion for UTIs in this age group. Older pediatric patients are more likely to present with more typical and localized complaints.
Treatment should be tailored to treat the most commonly encountered causative organisms, keeping in mind increasing antibiotic resistance among urinary pathogens. If not properly identified or treated, UTIs can progress to pyelonephritis or urosepsis. Long-term complications from UTIs may include renal scarring, hypertension, and even renal failure.
The urinary tract is normally a sterile environment and has several mechanisms that work to maintain urine sterility (urethral sphincter, length of urethra, constant anterograde flow). In most cases, failure of one of these mechanisms leads to or exacerbates infection.
The most common causative organisms are bowel flora, typically gram-negative rods. Escherichia coli is the most commonly isolated organism from pediatric patients with UTIs. However, any organism that gains access to the urinary tract system may cause infection, including fungi (Candida species) and viruses.
Pathogens can infect the urinary tract through direct spread via the fecal-perineal-urethral route or from hematogenous seeding. Hematogenous spread is much more likely in neonates than in older children. Most infections begin in the bladder, and, from there, pathogens can spread up the urinary tract to the kidneys (pyelonephritis) and possibly the bloodstream (bacteremia). Pyelonephritis may lead to renal scarring and long-term complications such as hypertension and chronic renal failure.
Prevalence and incidence of UTIs varies based on age, sex, and gender. Overall, UTIs are estimated to affect 2.4-2.8% of all children every year. As many as 5% of all children younger than 2 years who present to the emergency department with fever have a UTI. An approach using low-risk criteria for febrile infants younger than 3 months who have temperature of more than 38 º C is shown in the image below.
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Application of low-risk criteria and approach for the febrile infant: A reasonable approach for treating febrile infants younger than 3 months who hav....
International
International prevalence and incidence is difficult to accurately assess, especially in developing countries, but is assumed to be similar to that in the United States.
Mortality/Morbidity
Bacteremia or urosepsis may develop from UTI. This risk is highest in neonates and very young infants. Simple cystitis may progress to pyelonephritis. Predicting which patients will develop pyelonephritis is difficult, although evidence suggests that genetics may play a role. Approximately 10-30% of children with UTIs develop renal scarring. Severe and/or recurrent cases of pyelonephritis may lead to kidney damage. This may cause hypertension, renal insufficiency, or renal failure.
Race
Studies indicate that nonblacks have a higher incidence of UTI than blacks.
Sex
Uncircumcised males have a significantly higher incidence of UTIs than circumcised males. Uncircumcised male infants have a higher incidence of UTI than female infants during the first year of life. After the first year of life, females have a much higher incidence of UTIs than males. Incidence is highest in sexually active adolescent females.
Age
Prevalence of UTIs in the first 3 months of life is estimated to be as high as 7.5%. During the first year of life, males have an incidence of UTIs of 2.7% compared with 0.7% for girls. For children older than 1 year, females have a 1-2% incidence of UTIs and males have a 0.1-0.2% incidence of UTIs. In sexually active teenaged females, the incidence of UTIs approaches 10%.
The criterion standard for diagnosing urinary tract infections (UTIs) is the isolation of a pathogen from a urine culture obtained via suprapubic aspiration.[2]
Although suprapubic aspiration is the criterion standard method for obtaining urine, catheterization is the most commonly used technique in infants and younger children. More than 50,000 CFU/mL in a catheterized specimen is defined as a UTI, although some experts recommend 10,000 CFU/mL as the cutoff.
Midstream clean catch urine specimens are also adequate for older children who can provide them. More than 100,000 CFU/mL in a midstream clean catch urine specimen is defined as a UTI.
Bagged urine specimens are of no value for the diagnosis of UTIs due to high rates of false-positives, and their use should be discouraged.
Although urine culture is the criterion standard for diagnosis UTIs, it may take as long as 48 hours for cultures to be positive. Therefore, evaluation of urinalysis is often needed to help make the initial diagnosis of a UTI.
A urine specimen that is found to be positive on dipstick for nitrite, leukocyte esterase, or blood may indicate a UTI.
Dipstick tests have sensitivities approaching 85-90%.
Microscopic examination of spun urine can evaluate for presence of WBCs, RBCs, bacteria, casts, and skin contamination (eg, epithelial cells).
With regards to a suprapubic aspirate, 5 or more WBC/high power field suggests an infection.
Hemacytometer measures cells per volume and has been found to be more sensitive and specific than standard microscopic examination.[3, 4]
With regards to a suprapubic aspirate, 10 or more WBC/μL is consistent with infection.[3, 4]
Gram stain of unspun urine may reveal organisms.
A combination of hemacytometer cell count and Gram stain has been shown in studies to have a sensitivity approaching 95%.
In pediatric patients, urine cultures should be sent to the laboratory even if urinalysis results are inconclusive.
Approximately 10-20% of pediatric patients with UTIs have normal urinalyses results.
Multiple organisms may be present if structural abnormalities are present.
Hematological studies do not tend to help in the diagnosis of UTIs, although they should be obtained in patients that appear ill.
In patients with suspected bacteremia or urosepsis, blood cultures should be obtained.
Renal function can be measured by serum creatinine and BUN levels and may be elevated in severe disease.
Electrolyte abnormalities may be present.
Procalcitonin, a propeptide of calcitonin that has been found to be elevated in response to bacterial endotoxins, has shown promise in helping diagnosis pyelonephritis and early renal damage.[5, 6, 7]
Imaging is recommended by the American Academy of Pediatrics for patients aged 2 months to 2 years old with febrile UTIs.
The recommendation is for a renal ultrasonography and a voiding cysto-urography (VCUG). The purpose is to identify those with vesicoureteral reflux (VUR).
Renal ultrasonography allows for the identification of anatomical abnormalities (ie, duplication) and hydroureter/nephrosis. It does not allow for definitive diagnosis of VUR, although it can suggest it.
VCUG allows for anatomical definition of urethra and bladder and grading of VUR, if present.
Although still the standard of care, many question the use and effectiveness of the current imaging recommendations, especially in light of recent trends to minimize exposure to ionizing radiation.
Neither renal ultrasonography nor VCUG can evaluate for pyelonephritis or renal scarring, which could lead to long-term complications.
Tc 99m dimercaptosuccinic (DMSA) is the criterion standard to detect pyelonephritis and renal scarring.
DMSA involves injecting a radionuclide that binds to renal proximal tubular cells.
Decreased uptake represents abnormal or damaged cells.
Some experts recommend screening with DMSA during the acute UTI with the reasoning that if no kidney involvement is noted during the acute phase no risk of renal scarring and further complication is noted and further imaging is unnecessary.
Transurethral catheterization of the urinary bladder is the most common procedure performed in the evaluation of UTIs. Catheterization may introduce pathogens.
A suprapubic bladder aspiration may also be performed to obtain urine and is the criterion standard despite the potential for gross or microscopic hematuria. Risk of infection is lower than with transurethral catheterization, and complications are low.
Prehospital care is rarely applicable in patients with urinary tract infections (UTI), although patients who are uroseptic and in shock may present via EMS, in which case, standard supportive measures for septic patients should be followed.
Start antibiotics after urinalysis and culture are obtained in patients with urinary tract infections (UTIs). A 10-day course of antibiotics is recommended, even for uncomplicated infection. Typical short course treatments should be reserved for non-toxic-appearing adolescent females with UTIs. Be aware of increasing rates of antibiotic resistance and to choose antibiotic therapy accordingly.
If the urinalysis is positive for nitrites, the bacterium responsible for the infection is exceedingly likely to be sensitive to a third-generation cephalosporin. However, the 8+% resistance of nitrite-positive organisms to first-generation oral cephalosporins limits their use.[8]
Empiric antibiotics should be chosen for coverage of the most common uropathogens, namely E coli and Enterococcus, Proteus, and Klebsiella species. For suspected pyelonephritis, parenteral antibiotics are recommended. Recent evidence indicates that oral antibiotics are adequate therapy for febrile UTIs in young infants and children; short-term (fever) and long-term (renal scarring) outcomes are comparable to that with parenteral therapy. For uncomplicated cystitis, oral antibiotic therapy is generally adequate. The possibility of antibiotic resistance must be considered when choosing empiric therapy, especially ampicillin. Knowledge of the local antibiotic resistance helps in guiding antibiotic choice.
Clinical Context:
Provides bactericidal activity against susceptible organisms. Administered parenterally and used in combination with gentamicin or cefotaxime.
Clinical Context:
Aminoglycoside antibiotic for gram-negative coverage. Provides synergistic activity with ampicillin against gram-positive bacteria including enterococcal species. Inhibits protein synthesis by irreversibly binding to bacterial 30S and 50S ribosomes. Dosing regimens are numerous; adjust dose based on CrCl and changes in volume of distribution. May be administered IV/IM.
Clinical Context:
Third-generation cephalosporin with gram-negative spectrum. Lower efficacy against gram-positive organisms. Used as initial parenteral therapy for pediatric patients with acute complicated pyelonephritis. May be used for neonates or jaundiced patients. Requires dosing at q6-8h intervals.
Clinical Context:
Interferes with synthesis of cell wall mucopeptides during active multiplication, resulting in bactericidal activity against susceptible bacteria. Activity against gram-positive and some gram-negative bacteria.
Clinical Context:
Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid. Antibacterial activity of TMP-SMZ includes common urinary tract pathogens, except Pseudomonas aeruginosa.
Clinical Context:
First-generation cephalosporin that inhibits bacterial replication by inhibiting bacterial cell wall synthesis. Bactericidal and effective against rapidly growing organisms forming cell walls.
Resistance occurs by alteration of penicillin-binding proteins. Effective for treatment of infections caused by streptococcal or staphylococci, including penicillinase-producing staphylococci. Used PO when outpatient management is indicated.
Clinical Context:
Third-generation PO cephalosporin with broad activity against gram-negative bacteria. By binding to one or more of the penicillin-binding proteins, arrests bacterial cell wall synthesis and inhibits bacterial growth. Has shown poor activity against staphylococcal and enterococcal species. Cefixime compared favorably to a quinolone in one study.
Clinical Context:
Fluoroquinolone that inhibits bacterial DNA synthesis and, consequently, growth, by inhibiting DNA gyrase and topoisomerases, which are required for replication, transcription, and translation of genetic material. Quinolones have broad activity against gram-positive and gram-negative aerobic organisms. Has no activity against anaerobes. Continue treatment for at least 2 d (7-14 d typical) after signs and symptoms have disappeared.
The American Academy of Pediatrics recommends all infants and young children (2 months to 2 years of age) with first UTI have a urinary tract ultrasonography and voiding cysto-urography (VCUG). These tests should be acquired promptly if patients fail to show expected clinical response within 2 days of treatment.
All patients should have close follow-up to evaluate response to antibiotics.
Repeat urinalysis and/or urine cultures are not needed if the patient’s condition responds to therapy as expected.
Most non-toxic-appearing patients with uncomplicated cystitis will do well on oral antibiotics.
Any patient with suspected pyelonephritis should be started on parenteral antibiotics and then transitioned to oral antibiotics once afebrile for more than 24 hours.
Neonates should be kept on parenteral antibiotics for 3-4 days before being transitioned to oral antibiotics.
Prevention of UTI is focused on the identification and correction of structural abnormalities.
Prophylactic antibiotics are controversial though widely practiced for patients with vesicoureteral reflux (VUR) and recurrent infections. Prophylactic antibiotics are associated with increased risk of resistant infection.[9]
The on-going Randomized Intervention for Children With Vesicoureteral Reflux (RIVUR) study is designed to determine the value of antimicrobial prophylaxis with regard to the recurrence of urinary tract infection and the incidence of renal scarring.[10]
Dehydration is the most common complication of UTI in the pediatric population. Intravenous fluid replacement is necessary in more severe cases. Treat febrile UTI as pyelonephritis, and consider parenteral antibiotics and admission for these patients.
Untreated UTI may progress to renal involvement with systemic infection (eg, urosepsis).
Long-term complications include renal parenchyma scarring, hypertension, decreased renal function, and, in severe cases, renal failure.
Weisz D, Seabrook JA, Lim RK. The Presence of Urinary Nitrites Is a Significant Predictor of Pediatric Urinary Tract Infection Susceptibility to First- and Third-Generation Cephalosporins. J Emerg Med. Jul 2010;39(1):6-12.
Application of low-risk criteria and approach for the febrile infant: A reasonable approach for treating febrile infants younger than 3 months who have a temperature of greater than 38°C.
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