Urinary tract infection in small children: the evolution of renal damage over time.

BACKGROUND: Our objective was to analyze the evolution of kidney damage over time in small children with urinary tract infection (UTI) and factors associated with progression of renal damage. METHODS: From a cohort of 1003 children <2 years of age with first-time UTI, a retrospective analysis of 103 children was done. Children were selected because of renal damage at index 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy at least 3 months after UTI, and a late DMSA scan was performed after at least 2 years. Damage was classified as progression when there was a decline in differential renal function (DRF) by ≥4%, as regression when there was complete or partial resolution of uptake defects. RESULTS: Of 103 children, 20 showed progression, 20 regression, and 63 remained unchanged. There were no differences between groups regarding gender or age. In the progression group, 16/20 (80%) children had vesicoureteral reflux (VUR) grade III-V and 13 (65%) had recurrent UTI. In multivariable regression analysis, both VUR grade III-V and recurrent UTI were associated with progression. In the regression group, 16/20 (80%) had no VUR or grade I-II, and two (10%) had recurrent UTI. CONCLUSIONS: Most small children with febrile UTI do not develop renal damage and if they do the majority remain unchanged or regress over time. However, up to one-fifth of children with renal damage diagnosed after UTI are at risk of renal deterioration. These children are characterized by the presence of VUR grades III-V and recurrent febrile UTI and may benefit from follow-up.

Urinary tract infection in infants: the significance of low bacterial count.

BACKGROUND: In national guidelines for urinary tract infection (UTI) in children, different cut-off levels for defining bacteriuria are used. In this study, the relationship between bacterial count in infant UTI and inflammatory parameters, frequency of vesicoureteral reflux (VUR), kidney damage, and recurrent UTI was analyzed. METHODS: We conducted a population-based retrospective study of 430 infants age <1 year with symptomatic UTI diagnosed by suprapubic aspiration. Clinical and laboratory parameters, findings on voiding cystourethrography and (99m)technetium dimercapto-succinic acid scintigraphy, and frequency of recurrence were related to bacterial count at the index UTI. RESULTS: Eighty-three (19%) infants had bacterial counts <100,000 colony-forming units (CFU)/ml and 347 (81%) had ≥100,000 CFU/ml. There was similar frequency of VUR (19% in both groups), kidney damage (17 and 23%, p = 0.33) and recurrent UTI (6 and 12%, p = 0.17) in the low and high bacterial group. Non-E. coli species were more prevalent (19 versus 6%, p = 0.0006) and mean C-reactive protein was lower (50 vs. 79 mg/l, p <0.0001) in the low bacteria group. CONCLUSIONS: UTI with low bacterial count is common and of importance since it may be associated with VUR and renal damage. Non-E. coli species and low inflammatory response were more prevalent in UTI with low bacterial count.

Urinary tract infection in small outpatient children: the influence of age and gender on resistance to oral antimicrobials.

UNLABELLED: Urinary tract infection (UTI) is a common bacterial disease in small children in which treatment with antimicrobials is used. The worldwide increase of bacterial resistance to these drugs is threatening the efficacy of such treatment and may increase the risk for long-term damage. The aim of this retrospective study was to analyse the development of resistance to oral antimicrobials over a 10-year period in an unselected outpatient population of small children with first-time UTI. The patient material included 494 boys and 512 girls below 2 years of age with community acquired symptomatic UTI. Escherichia coli bacteria were isolated in 96 % of girls and 89 % of boys (p < 0.0001). The overall resistance of E. coli was 14 % to trimethoprim and below 1 % to cefadroxil and nitrofurantoin. Over the 10-year period, the trimethoprim resistance of E. coli increased from 5 to 17 % but remained unchanged to cefadroxil and nitrofurantoin. E. coli resistance to trimethoprim was related to age: 11 % below and 19 % above 9 months (p < 0.01). The increase in resistance over time and with age was found only in girls. CONCLUSION: The increasing resistance of E. coli to trimethoprim makes this drug less suitable for empiric treatment of UTI. Young children with UTI seem predisposed to early development of resistance. Therefore, surveillance of resistance to antimicrobials with special regard to age and gender is recommended.

The Swedish reflux trial in children: III. Urinary tract infection pattern.

PURPOSE: We evaluated the difference in the febrile urinary tract infection rate in small children with dilating vesicoureteral reflux randomly allocated to 3 management alternatives, including antibiotic prophylaxis, endoscopic treatment or surveillance only as the control. MATERIALS AND METHODS: At 23 centers a total of 203 children were included in the study, including 128 girls and 75 boys 1 to younger than 2 years. Vesicoureteral reflux grade III in 126 cases and IV in 77 was detected after a febrile urinary tract infection (194) after prenatal screening (9). Voiding cystourethrography and dimercapto-succinic acid scintigraphy were done before randomization and after 2 years. The febrile urinary tract infection rate was analyzed by the intent to treat principle. RESULTS: We noted a total of 67 febrile recurrences in 42 girls and a total of 8 in 7 boys (p = 0.0001). There was a difference in the recurrence rate among treatment groups in girls with febrile infection in 8 of 43 (19%) on prophylaxis, 10 of 43 (23%) with endoscopic therapy and 24 of 42 (57%) on surveillance (p = 0.0002). In girls the recurrence rate was associated with persistent reflux after 2 years (p = 0.0095). However, reflux severity (grade III or IV) at study entry did not predict recurrence. CONCLUSIONS: In this randomized, controlled trial there was a high rate of recurrent febrile urinary tract infection in girls older than 1 year with dilating vesicoureteral reflux at study entry but not in boys. Antibiotic prophylaxis and endoscopic treatment decreased the infection rate.

Relationship among vesicoureteral reflux, urinary tract infection and renal damage in children.

PURPOSE: We studied the relationship among vesicoureteral reflux, urinary tract infection and permanent renal damage in children. MATERIALS AND METHODS: We retrospectively analyzed 303 children younger than 2 years with a first time, nonobstructive, culture verified urinary tract infection. The protocol included ultrasonography and voiding cystourethrography within 3 months after urinary tract infection, and (99m)technetium dimercapto-succinic acid scintigraphy after 1 to 2 years. RESULTS: Vesicoureteral reflux was found in 36 of 163 boys (22%) and in 44 of 140 girls (31%). Of the 303 patients 80 (26%) had permanent renal damage according to dimercapto-succinic acid scintigraphy. The rate of abnormality increased significantly with grade of vesicoureteral reflux in boys and girls. The relative risk of renal damage was significantly increased in patients with vesicoureteral reflux grade II and higher. Maximum C-reactive protein concentration, maximum temperature during urinary tract infection, presence of vesicoureteral reflux and febrile recurrences of urinary tract infection were significantly related to permanent renal damage. In stepwise logistic regression vesicoureteral reflux was the only independent variable for boys, while C-reactive protein and vesicoureteral reflux were independent factors for girls. CONCLUSIONS: There was a significant relationship between grade II vesicoureteral reflux and higher and permanent renal damage in boys and girls. However, while the association between renal damage and vesicoureteral reflux was evident in boys, the role of urinary tract infection and renal inflammation seemed to be equally or more important in girls. These findings support the concept that renal damage is associated with vesicoureteral reflux and is often congenital in boys, while in girls it is more related to urinary tract infection with vesicoureteral reflux as a reinforcing factor.

Uncomplicated duplex kidney and DMSA scintigraphy in children with urinary tract infection.

BACKGROUND: Renal duplication is the most common malformation of the urinary tract and is frequently seen among children with urinary tract infection (UTI). OBJECTIVE: To evaluate problems in the interpretation of dimercaptosuccinic acid (DMSA) scintigraphy and to establish the range of relative function in uncomplicated unilateral duplication. MATERIALS AND METHODS: Retrospective analysis of 303 children less than 2 years of age with first time non-obstructive urinary tract infection investigated by both urography and DMSA scintigraphy. At DMSA scintigraphy, renal lesions and/or relative function below 45% was considered abnormal. Urography was used as reference for the diagnosis of duplication. RESULTS: Duplex kidneys were found in 22 of 303 patients (7%). Of the 16 children with unilateral duplication, 10 had bilaterally undamaged kidneys with a range of relative function varying between 51% and 57% in the duplex kidney. In two of the children with unilateral duplication the imaging results were discordant. CONCLUSION: There was risk of underdiagnosis as well as overdiagnosis of renal damage at scintigraphy. Although it is important to be aware of this risk, the rate of misinterpretation was low. A range of 51% to 57% can be used as the limit for normality of the relative function of a unilateral duplex kidney.

Transfer of an ampicillin resistance gene between two Escherichia coli strains in the bowel microbiota of an infant treated with antibiotics.

OBJECTIVES: To investigate the presumed acquisition of ampicillin resistance by an Escherichia coli strain residing in the gut of an infant. METHODS: E. coli strains were quantified in faecal samples obtained at regular intervals from an infant followed from birth to 12 months of age and their resistance profiles were determined. beta-Lactamases were identified by isoelectric focusing and genes by PCR followed by DNA sequencing. Plasmids were characterized by restriction fragment analysis and Southern-blot hybridization, and tested for conjugative transfer. RESULTS: The infant carried two E. coli strains, termed 29A and 29B, simultaneously in the microbiota during the first month of life. All isolates of 29A were resistant to ampicillin, whereas strain 29B, which was initially ampicillin susceptible, acquired resistance following treatment of the infant with ampicillin/amoxicillin because of urinary tract infection. Acquisition of resistance by strain 29B was associated with acquisition of a bla(TEM-1b)-encoding plasmid, pNK29, which was also present in strain 29A. Transfer of plasmid pNK29 could be replicated by conjugation from strain 29A to strain 29B in vitro. Strain 29A also adapted to ampicillin treatment by mutation of the bla(TEM-1b) promoter gene to yield a higher level of resistance. CONCLUSIONS: This is an unequivocal demonstration of gene transfer between two strains co-residing in the human gut, as the donor, recipient and transconjugant strains were isolated. The results suggest the dynamic adaptation by commensal bacteria in response to antibiotic treatment may occur readily.