A thousand words just to protect your child’s kidneys!
This issue interprets the latest European guidelines for the diagnosis and management of urinary tract infections in children in 2015, which are still controversial.
1. What is a urinary tract infection (UTI)?
It is an inflammatory disease caused by direct bacterial invasion of the urinary tract
2. Why should we pay attention to urinary tract infection (UTI)?
UTI is the most common bacterial infectious disease in children
UTI is the most common bacterial infection in children, with a high prevalence within 1 year of age and recurrence in up to 30% of children after initial infection. 30% of children with urinary tract abnormalities have UTI as the first manifestation, 85% of children with UTI have abnormal static kidney scans, and 10-40% of them have renal scarring, which may lead to developmental delay, recurrent pyelonephritis, and impaired renal function. This can lead to developmental delay, recurrent pyelonephritis, and impaired renal function.
Early detection and early intervention can prevent kidney damage.
3. Classification of urinary tract infections
According to the site of infection: upper urinary tract infection (pyelonephritis) and lower urinary tract infection (cystitis)
According to the number of episodes: initial UTI, recurrent UTI
According to confounding factors: simple type, complex type (with abnormal urinary tract structure and function)
According to the symptoms: asymptomatic bacteriuria (no leukocyturia and symptoms), symptomatic UTI
4.Manifestations of lower urinary tract infection
Painful urination, frequent urination, urgent urination
Foul-smelling urine
Urinary incontinence
Hematuria
Pain in the suprapubic area
5.Manifestations of upper urinary tract infection
Fever (temperature >38 ℃), back pain
Young children may show poor appetite, lagging growth, drowsiness, irritability, vomiting or diarrhea, etc.
6.Key points of UTI history collection
Number of episodes
Whether fever is present
Whether there are structural deformities of the urinary system
History of previous surgery
Drinking habits
Defecation habits
family history
constipation or not
Any lower urinary tract symptoms
History of adolescent sexual contact
7. Key points of urinary tract infection symptom collection: same as 4 and 5
8.The main points of physical examination of urinary tract infection
Body temperature
Exclude other causes of fever
Signs of constipation
Whether the kidney can be felt and pain in the kidney
Whether the bladder can be palpated
presence of spina bifida or sacrococcygeal dysplasia
presence of genital abnormalities: prepuce, labial adhesions, post-circumcision urethral stricture, abnormal confluence of the genitourinary system, cloacal malformation, vulvovaginitis, epididymitis, etc.
9.About urine collection
Complete urine sample collection before antibiotic application
Urine sample collection includes four methods, namely plastic bag collection method, clean mid-stage urine collection, urine collection by suprapubic cystocentesis and urine collection by catheter
Plastic bag collection has a high false positive rate and is more reliable when the urine culture results are negative
Clean mid-section urine cultures have better reliability
Bladder catheterization also has a high rate of contamination, and risk factors for being contaminated are: age of the child <6 months, difficulty with catheter insertion, and uncircumcised boys. Therefore, the guideline recommends that for children under 6 months of age and uncircumcised boys, the use of a new sterile catheter for each catheter insertion attempt may reduce the rate of contamination
Trans-pubic suprapubic cystocentesis is the most sensitive method of obtaining uncontaminated urine
10. Regarding urinalysis
Mainly includes urine test paper examination and urine sediment microscopy
Positive urine paper test for leukocyte esterase and positive nitrite test are highly sensitive for the diagnosis of urinary tract infection
Negative urine leukocyte esterase and nitrite tests can exclude UTI
Microscopic examination of urine sediment is used to detect pus and bacteriuria, and bacteriuria alone has a higher diagnostic sensitivity compared with pus alone, and if both are positive, it has a higher diagnostic accuracy for UTI
11.About urine culture
For children with normal urine test strips, microscopic examination and automated urinalysis, urine culture is not necessary if there are other causes of fever or signs of inflammation
If urine test strips and or routine urine tests are abnormal, a urine culture must be performed
Urine culture results are affected by the method of urine collection, diuretic application, storage time between urine collection and testing, and storage temperature
The diagnosis of UTI can be confirmed if the urine culture count is ≥10 CFU/ml taken by suprapubic cystocentesis, ≥1000-50,000 CFU/ml taken by catheterization, and ≥104 CFU/ml (when symptomatic) or ≥105 CFU/ml (when asymptomatic) in clean midstream urine
Positive culture of multiple bacteria suggests contamination
12.About hematological examination
For children with severe UTI with fever, serum electrolytes and blood cell counts should be monitored
In severe cases, blood culture and urinary ultrasound should be checked
Serum calcitoninogen (>0.5 ng/ml) is a reliable predictor of upper urinary tract infection
13. About urinary ultrasonography
For children with UTI and urinary sepsis with fever, early urological ultrasound is recommended if there are no previous normal ultrasound findings, or if there is no improvement in 24 hours of treatment, or if UTI is associated with pain or hematuria
The rate of ultrasound abnormalities in children with febrile UTI ranges from 15% to 37%, with 1-2% of children requiring immediate management.
Vesicoureteral reflux (VUR) is present in 27% of those with abnormal ultrasound
Ultrasound also has a high rate of missed diagnoses, with 24-33% of dilated VURs being missed with ultrasound alone
Bladder filling and emptying phases should be examined in toilet-trained children to exclude voiding abnormalities
Rectal filling should also be noted; if rectal filling is >30 mm, constipation must be considered
14. Treatment
Antibiotic therapy should be started early in children with UTI manifestations with fever
No antibiotic therapy unless asymptomatic bacteriuria is a clinical problem or the child is scheduled for surgery
For UTI with fever, the route of administration should be based on the child’s age, severity of illness, refusal of food and water and medication, vomiting or diarrhea, compliance, and complexity
Intravenous administration is recommended for newborns and infants under 2 months of age with a high incidence of urinary sepsis and severe pyelonephritis, and potentially life-threatening hyponatremia and hyperkalemia.
Intravenous broad-spectrum antibiotics are recommended for patients with complicated UTIs not caused by Escherichia coli infection
Oral antibiotics for at least 3-4 days for children with cystitis over 3 months of age
For UTI with fever, intravenous antibiotics are recommended until the child’s fever subsides, followed by oral antibiotics for 7 to 14 days
If outpatient treatment is chosen for children with late infancy, they must be monitored closely
Temporary urinary drainage may be required for patients with obstructive nephropathy
15. Regarding the prophylactic use of antibiotics
There is controversy
The guideline recommends prophylactic medication for children at high risk of
Female infants with grade III and IV reflux
Those with a high susceptibility to UTI
Those at risk for acquired kidney damage
16. Regarding the basis for the guideline’s prophylactic criteria
In 2011, a randomized controlled study in Sweden included 203 children aged 1 to 2 years with grade III and IV reflux, divided into antibiotic prophylaxis, endoscopic treatment, and monitoring groups. The results showed no new renal scarring in girls in the antibiotic prophylaxis group, 8/43 girls in the surveillance group, and 5/42 in the endoscopic treatment group were found to have new renal scarring after 2 years of age
In 2013, Park et al. compared the characteristics of children with VUR with recurrent UTI in infancy (44 cases, mean age 3.2 m) and children without recurrent UTI (47 cases, mean age 4.8 m) and found that early onset of UTI, high VUR, bilateral VUR and first non-E. coli infection significantly increased the risk of recurrent UTI in the first year of life
In 2014, the New England Journal of Medicine reported the results of a randomized intervention study in children with VUR that included 607 children and found that methotrexate/sulfamethoxazole prophylaxis reduced the risk of UTI recurrence by 50%. In particular, children with UTI with fever, cystorectal dysfunction, or dilated VUR benefited from prophylactic treatment
17. Types of prophylactic antibiotics of choice
Furantoin
Methotrexate
Methotrexate sulfamethoxazole
Cefaclor
Cefixime
Cephalosporins should be carefully considered in areas with a high prevalence of ESBL-producing bacterial infections
Cranberry juice may be effective in the prevention of UTI
Prophylaxis requires good parental and child compliance
For boys with prepuce, early treatment should be considered
18. Monitoring of urinary tract infections
If treatment is effective, urine becomes sterile after 24 hours and leukocyturia disappears in 3 to 4 days
90% of patients’ body temperature returns to normal 24~48 hours after treatment
For patients with persistent non-recovery of temperature, antibiotic resistance or the presence of congenital urinary tract malformation or acute urinary tract obstruction needs to be considered and ultrasonography should be performed
For UTI with fever, blood electrolytes and blood cell count should be checked
Evidence that elevated serum calcitoninogen can be used as a reliable early predictor of renal parenchymal inflammation in febrile UTIs stems primarily from a study by Kotoula A. The study included 57 children with initial UTI and found that elevated serum calcitoninogen had a good predictive value for upper urinary tract infection, with serum calcitoninogen >0.85 ng/ml having the best predictive value, and that the degree of elevated calcitoninogen levels correlated closely with the degree of renal parenchymal damage in upper urinary tract infections; therefore, Kotoula et al. suggested that children with significantly elevated serum calcitoninogen should undergo early DMSA or VCUG
19. Which children are at high risk for renal damage?
Diagnosis of urinary tract disease before birth
Defective DMSA scan after UTI
Abnormal urological ultrasound (e.g., dilated upper urinary tract, thickened bladder wall, residual urine after bladder emptying)
Various urogenital developmental abnormalities
History of previous UTI
Bladder emptying dysfunction
enlarged bladder
poor urinary flow
constipation
abdominal masses
Spinal abnormalities
Family history of VUR
Poor family compliance
Further imaging is recommended for children presenting with unexplained recurrent fever, growth retardation, or hypertension. If the parents refuse to perform further testing (excretory cystourethrography or DMSA scan), there is at least a 30% chance of VUR and renal scarring.
20. Regarding renal static DMSA imaging and excretory cystourethrography (MCU)
The guideline clearly recommends renal static DMSA scan as a first-line diagnostic tool, based mainly on
Ultrasound has a 33% missed diagnosis rate in children at high risk for renal damage
Abnormal renal static scans in acute UTI indicate the presence of pyelonephritis or parenchymal damage, and these changes correlate well with the presence of an expansile VUR and the risk of recurrent UTI and future renal scarring
The vast majority of children with abnormal renal static scans have dilated vesicoureteral reflux
For early exclusion of vesicoureteral reflux to avoid recurrence of urinary tract infection, the guideline recommends that renal static scans should be performed within 1-2 months of the onset of UTI
Voiding cystourethrography remains the gold standard for the diagnosis of vesicoureteral reflux
Excretory cystourethrography or renal static scan is recommended after control of the infection at the onset of the first UTI with fever
Both bottom-up approach (excretory cystourethrography followed by renal static scan if positive) and top-down approach (renal static scan followed by excretory cystourethrography if positive) can be used for these two tests
21.About cystorectal dysfunction and urinary tract infection
Cystorectal dysfunction refers to abnormal defecation and urination for unknown reasons, which is not uncommon clinically, but has not received much attention
Cystorectal dysfunction is a risk factor that should be investigated at the onset of every child with UTI
Further diagnosis and effective treatment is recommended if signs of cystorectal dysfunction are present in the interval between infections
Effective treatment of constipation may reduce the recurrence of UTI