Epidemiology of bacteriuria during the first year of life

Androgen exposure impairs neutrophil maturation and function within the infected kidney

Urinary tract infections (UTIs) in men are uncommon yet carry an increased risk for severe pyelonephritis and other complications. In models of Escherichia coli UTI, C3H/HeN mice develop high-titer pyelonephritis (most with renal abscesses) in a testosterone-dependent manner, but the mechanisms underlying this phenotype are unknown. Here, using female mouse models, we show that androgen exposure impairs neutrophil maturation in the upper and lower urinary tract, compounded by a reduction of neutrophil function within the infected kidney, enabling persistent high-titer infection and promoting abscess formation. Following intravesical inoculation with uropathogenic E. coli (UPEC), kidneys of androgen-exposed C3H mice showed delayed local pro-inflammatory cytokine responses while robustly recruiting neutrophils. These were enriched for an end-organ-specific population of aged but immature neutrophils (CD49d+, CD101-). Compared to their mature counterparts, these aged immature kidney neutrophils exhibited reduced function in vitro, including impaired degranulation and diminished phagocytic activity, while splenic, bone marrow, and bladder neutrophils did not display these alterations. Furthermore, aged immature neutrophils manifested little phagocytic activity within intratubular UPEC communities in vivo. Experiments with B6 conditional androgen receptor (AR)-deficient mice indicated rescue of the maturation defect when AR was deleted in myeloid cells. We conclude that the recognized enhancement of UTI severity by androgens is attributable, at least in part, to local impairment of neutrophil maturation in the urinary tract (largely via cell-intrinsic AR signaling) and a kidney-specific reduction in neutrophil antimicrobial capacity.IMPORTANCEAlthough urinary tract infections (UTIs) predominantly occur in women, male UTIs carry an increased risk of morbidity and mortality. Pyelonephritis in androgen-exposed mice features robust neutrophil recruitment and abscess formation, while bacterial load remains consistently high. Here, we demonstrate that during UTI, neutrophils infiltrating the urinary tract of androgen-exposed mice exhibit reduced maturation, and those that have infiltrated the kidney have reduced phagocytic and degranulation functions, limiting their ability to effectively control infection. This work helps to elucidate mechanisms by which androgens enhance UTI susceptibility and severity, illuminating why male patients may be predisposed to severe outcomes of pyelonephritis.

Infant Escherichia coli urinary tract infection: is it associated with meningitis?

OBJECTIVES

Determine the prevalence of coexisting bacterial meningitis (BM) and sterile cerebrospinal fluid (CSF) with raised white cell count relative to age ('pleocytosis') in the presence of Escherichia coli urinary tract infection (UTI), with the addition of CSF E. coli PCR analysis.

DESIGN

Single-centre, retrospective cohort study.

SETTING

Tertiary paediatric hospital.

PARTICIPANTS

Children aged 8 days to 2 years, with a pure growth of E. coli from urine and a CSF sample taken within 48 hours of a positive urine culture between 1 January 2014 and 30 April 2019.

MAIN OUTCOME MEASURE

Prevalence of coexisting E. coli BM with UTI, defined as a pure growth E. coli from urine and a CSF culture with pure growth E. coli and/or positive E. coli PCR.

RESULTS

1903 patients had an E. coli UTI, of which 314 (16%) had a CSF sample taken within 48 hours. No cases of coexisting E. coli BM were identified. There were 71 (23%) cases of pleocytosis, 57 (80%) of these had PCR analysis, all of which were E. coli PCR not detected. Patients aged 1-6 months accounted for 72% of all lumbar punctures (LPs).

CONCLUSION

The risk of E. coli UTI and coexisting E. coli BM is low. There is potential to reduce the number of routine LPs in infants with a diagnosis of E. coli UTI with the greatest impact in children up to 6 months of age. CSF E. coli PCR can help further reduce post-test probability of BM in the setting of pleocytosis.

Clinical and Epidemiological Analysis of Children's Urinary Tract Infections in Accordance with Antibiotic Resistance Patterns of Pathogens

The study was conducted to analyze urinary tract infections (UTI) in children by considering epidemiology and antibiotic resistance patterns of pathogens in accordance with inflammatory parameters. The research included 525 patients who demonstrated 627 episodes of UTI. The increasing resistance of bacteria was observed over the years covered by the study (p < 0.001). There was a significant increase of resistance to amoxicillin with clavulanic acid (p = 0.001), gentamicin (p = 0.017) and ceftazidime (p = 0.0005). According to the CART method, we managed to estimate C-reactive protein (CRP), procalcitonin (PCT) and white blood cell (WBC) values, in which antibiotic sensitivity was observed. In children with CRP > 97.91 mg/L, there was a high percentage of sensitive cases to amoxicillin with clavulanic acid (87.5%). Values of WBC above 14.45 K/µL were associated with E. coli more sensitivity to ampicillin. 100% of children with CRP > 0.42 mg/L and PCT ≤ 6.92 ng/mL had confirmed sensitivity to cefuroxime. Concerning sensitivity to gentamicin, the most optimal cut-off point of WBC was >7.80 K/µL, while in the case of nitrofurantoin, it was CRP value > 0.11 mg/L (which was presented in 98.50% of children). These results may guide us with antibiotic therapy and help to inhibit increasing antibiotic resistance.

Androgen-Influenced Polarization of Activin A-Producing Macrophages Accompanies Post-pyelonephritic Renal Scarring

Ascending bacterial pyelonephritis, a form of urinary tract infection (UTI) that can result in hospitalization, sepsis, and other complications, occurs in ~250,000 US patients annually; uropathogenic Escherichia coli (UPEC) cause a large majority of these infections. Although UTIs are primarily a disease of women, acute pyelonephritis in males is associated with increased mortality and morbidity, including renal scarring, and end-stage renal disease. Preclinical models of UTI have only recently allowed investigation of sex and sex-hormone effects on pathogenesis. We previously demonstrated that renal scarring after experimental UPEC pyelonephritis is augmented by androgen exposure; testosterone exposure increases both the severity of pyelonephritis and the degree of renal scarring in both male and female mice. Activin A is an important driver of scarring in non-infectious renal injury, as well as a mediator of macrophage polarization. In this work, we investigated how androgen exposure influences immune cell recruitment to the UPEC-infected kidney and how cell-specific activin A production affects post-pyelonephritic scar formation. Compared with vehicle-treated females, androgenized mice exhibited reduced bacterial clearance from the kidney, despite robust myeloid cell recruitment that continued to increase as infection progressed. Infected kidneys from androgenized mice harbored more alternatively activated (M2) macrophages than vehicle-treated mice, reflecting an earlier shift from a pro-inflammatory (M1) phenotype. Androgen exposure also led to a sharp increase in activin A-producing myeloid cells in the infected kidney, as well as decreased levels of follistatin (which normally antagonizes activin action). As a result, infection in androgenized mice featured prolonged polarization of macrophages toward a pro-fibrotic M2a phenotype, accompanied by an increase in M2a-associated cytokines. These data indicate that androgen enhancement of UTI severity and resulting scar formation is related to augmented local activin A production and corresponding promotion of M2a macrophage polarization.

Urinary tract infections in children

Urinary tract infections (UTIs) in children are among the most common bacterial infections in childhood. They are equally common in boys and girls during the first year of life and become more common in girls after the first year of life. Dividing UTIs into three categories; febrile upper UTI (acute pyelonephritis), lower UTI (cystitis), and asymptomatic bacteriuria, is useful for numerous reasons, mainly because it helps to understand the pathophysiology of the infection. A single episode of febrile UTI is often caused by a virulent Escherichia coli strain, whereas recurrent infections and asymptomatic bacteriuria commonly result from urinary tract malformations or bladder disturbances. Treatment of an upper UTI needs to be broad and last for 10 days, a lower UTI only needs to be treated for 3 days, often with a narrow-spectrum antibiotic, and asymptomatic bacteriuria is best left untreated. Investigations of atypical and recurrent episodes of febrile UTI should focus on urinary tract abnormalities, whereas in cases of cystitis and asymptomatic bacteriuria the focus should be on bladder function.

TGFβ1 orchestrates renal fibrosis following Escherichia coli pyelonephritis

Renal scarring after pyelonephritis is linked to long-term health risks for hypertension and chronic kidney disease. Androgen exposure increases susceptibility to, and severity of, uropathogenic Escherichia coli (UPEC) pyelonephritis and resultant scarring in both male and female mice, while anti-androgen therapy is protective against severe urinary tract infection (UTI) in these models. This work employed androgenized female C57BL/6 mice to elucidate the molecular mechanisms of post-infectious renal fibrosis and to determine how these pathways are altered by the presence of androgens. We found that elevated circulating testosterone levels primed the kidney for fibrosis by increasing local production of TGFβ1 before the initiation of UTI, altering the ratio of transcription factors Smad2 and Smad3 and increasing the presence of mesenchymal stem cell (MSC)-like cells and Gli1 + activated myofibroblasts, the cells primarily responsible for deposition of scar components. Increased production of TGFβ1 and aberrations in Smad2:Smad3 were maintained throughout the course of infection in the presence of androgen, correlating with renal scarring that was not observed in non-androgenized female mice. Pharmacologic inhibition of TGFβ1 signaling blunted myofibroblast activation. We conclude that renal fibrosis after pyelonephritis is exacerbated by the presence of androgens and involves activation of the TGFβ1 signaling cascade, leading to increases in cortical populations of MSC-like cells and the Gli1 + activated myofibroblasts that are responsible for scarring.

Prevalence of Asymptomatic Bacteriuria in Children: A Meta-Analysis

OBJECTIVE

To determine the point prevalence of bacteriuria and bacteriuria without pyuria in asymptomatic children by a systematic review of the literature.

STUDY DESIGN

We searched MEDLINE and EMBASE for English-, French-, German-, Italian-, and Spanish-language articles. We included articles reporting data on bacteriuria in asymptomatic children up to 19 years of age who had urine collected by suprapubic bladder aspiration, bladder catheterization, or by 3 consecutive clean catch samples. Two independent reviewers assessed studies for inclusion and abstracted data.

RESULTS

Fourteen studies (49 806 children) were included. The prevalence of asymptomatic bacteriuria was 0.37% (95% CI, 0.09-0.82) in boys and 0.47% (95% CI, 0.36-0.59) in girls. The corresponding values for asymptomatic bacteriuria without pyuria were 0.18% (95% CI, 0.02-0.51) and 0.38% (95% CI, 0.22-0.58), respectively. The subgroups with the highest prevalence of asymptomatic bacteriuria were uncircumcised males <1 year of age and females >2 years of age. In males, the prevalence of asymptomatic bacteriuria after infancy was 0.08% (95% CI, 0.01-0.37). The median duration of asymptomatic bacteriuria in untreated boys and girls, from the one study reporting this outcome, was 1.5 and 2 months, respectively.

CONCLUSIONS

Some clinicians are concerned that when a preverbal child with asymptomatic bacteriuria develops a nonlocalizing febrile illness and presents for evaluation, they may be mistakenly diagnosed as having a urinary tract infection (UTI). Given that the prevalence of asymptomatic bacteriuria is considerably lower than the prevalence of UTI in most subgroups examined, this will occur extremely rarely. These data suggest that the current definition of UTI should be revisited.

Testing for Urinary Tract Infection in the Influenza/Respiratory Syncytial Virus-Positive Febrile Infant Aged 2 to 12 Months

OBJECTIVE

Infants 12 months or younger with influenza and respiratory syncytial virus (RSV) commonly present to the emergency department (ED) with fever. Previous publications have recommended that these patients have a urinalysis and urine culture performed. We aimed to assess the prevalence of urinary tract infection (UTI) in febrile RSV/influenza positive infants aged 2 to 12 months presenting to the ED. We also examined whether the 2011 American Academy of Pediatrics (AAP) UTI clinical practice guidelines could be used to identify patients at lower risk of UTI.

METHODS

This was a retrospective chart review examining all infants aged 2 to 12 months with a documented fever of higher than 38°C who presented to our ED from 2009 to 2013 and tested positive for influenza and/or RSV.

RESULTS

One thousand seven hundred twenty-four patients were found to meet our inclusion criteria. Of these, 98 were excluded because of known urinary tract anomaly or systemic antibiotic use in the 24 hours preceding evaluation. Of those patients remaining, 10 (0.62%) of 1626 had positive urine cultures (95% confidence interval, 0.3%-1.1%), and 8 (0.49%) of 1626 (95% confidence interval, 0.2%-0.97%) had positive urine cultures with positive urinalyses as defined in the 2011 AAP UTI clinical practice guidelines. All subjects with positive urine cultures as defined by the AAP had risk factors for UTI that placed their risk for UTI above 1%.

CONCLUSIONS

Our population of 2- to 12-month-old febrile infants with positive influenza/RSV testing, who did not have risk factors to make their risk of UTI higher than 1%, may not have required evaluation with urinalysis or urine culture.

Risk of Meningitis in Infants Aged 29 to 90 Days with Urinary Tract Infection: A Systematic Review and Meta-Analysis

OBJECTIVE

To determine the risk of bacterial meningitis in infants aged 29-90 days with evidence of urinary tract infection (UTI).

METHODS

PubMed (MEDLINE), Embase, and the Cochrane Library were systematically searched for studies reporting rates of meningitis in infants aged 29-90 days with abnormal urinalysis or urine culture. Observational studies in infants with evidence of UTI who underwent lumbar puncture (LP) reporting age-specific event rates of bacterial meningitis and sterile cerebrospinal fluid pleocytosis were included. Prevalence estimates for bacterial meningitis in infants with UTI were pooled in a random effects meta-analysis.

RESULTS

Three prospective and 17 retrospective cohort studies were included in the meta-analysis. The pooled prevalence of concomitant bacterial meningitis in infants with UTI was 0.25% (95% CI, 0.09%-0.70%). Rates of sterile pleocytosis ranged from 0% to 29%. Variation in study methods precluded calculation of a pooled estimate for sterile pleocytosis. In most studies, the decision to perform a LP was up to the provider, introducing selection bias into the prevalence estimate.

CONCLUSIONS

The risk of bacterial meningitis in infants aged 29-90 days with evidence of UTI is low. A selective approach to LP in infants identified as low risk for meningitis by other clinical criteria may be indicated.

A Clinical Prediction Rule to Identify Febrile Infants 60 Days and Younger at Low Risk for Serious Bacterial Infections

IMPORTANCE

In young febrile infants, serious bacterial infections (SBIs), including urinary tract infections, bacteremia, and meningitis, may lead to dangerous complications. However, lumbar punctures and hospitalizations involve risks and costs. Clinical prediction rules using biomarkers beyond the white blood cell count (WBC) may accurately identify febrile infants at low risk for SBIs.

OBJECTIVE

To derive and validate a prediction rule to identify febrile infants 60 days and younger at low risk for SBIs.

DESIGN, SETTING, AND PARTICIPANTS

Prospective, observational study between March 2011 and May 2013 at 26 emergency departments. Convenience sample of previously healthy febrile infants 60 days and younger who were evaluated for SBIs. Data were analyzed between April 2014 and April 2018.

EXPOSURES

Clinical and laboratory data (blood and urine) including patient demographics, fever height and duration, clinical appearance, WBC, absolute neutrophil count (ANC), serum procalcitonin, and urinalysis. We derived and validated a prediction rule based on these variables using binary recursive partitioning analysis.

MAIN OUTCOMES AND MEASURES

Serious bacterial infection, defined as urinary tract infection, bacteremia, or bacterial meningitis.

RESULTS

We derived the prediction rule on a random sample of 908 infants and validated it on 913 infants (mean age was 36 days, 765 were girls [42%], 781 were white and non-Hispanic [43%], 366 were black [20%], and 535 were Hispanic [29%]). Serious bacterial infections were present in 170 of 1821 infants (9.3%), including 26 (1.4%) with bacteremia, 151 (8.3%) with urinary tract infections, and 10 (0.5%) with bacterial meningitis; 16 (0.9%) had concurrent SBIs. The prediction rule identified infants at low risk of SBI using a negative urinalysis result, an ANC of 4090/µL or less (to convert to ×109 per liter, multiply by 0.001), and serum procalcitonin of 1.71 ng/mL or less. In the validation cohort, the rule sensitivity was 97.7% (95% CI, 91.3-99.6), specificity was 60.0% (95% CI, 56.6-63.3), negative predictive value was 99.6% (95% CI, 98.4-99.9), and negative likelihood ratio was 0.04 (95% CI, 0.01-0.15). One infant with bacteremia and 2 infants with urinary tract infections were misclassified. No patients with bacterial meningitis were missed by the rule. The rule performance was nearly identical when the outcome was restricted to bacteremia and/or bacterial meningitis, missing the same infant with bacteremia.

CONCLUSIONS AND RELEVANCE

We derived and validated an accurate prediction rule to identify febrile infants 60 days and younger at low risk for SBIs using the urinalysis, ANC, and procalcitonin levels. Once further validated on an independent cohort, clinical application of the rule has the potential to decrease unnecessary lumbar punctures, antibiotic administration, and hospitalizations.

Urinary tract infection in young infants discharged from the emergency room with normal urinalysis

AIM

We describe the clinical, microbiologic, therapeutic, and outcome characteristics of infants under three months of age with a positive urine culture reported after discharge from emergency department with normal urinalysis.

METHODS

We enrolled all infants with a urine culture obtained during an emergency room visit during 2004-2012, discharged without antibiotic therapy and subsequently reported with a positive urine culture.

RESULTS

Three hundred and ninety-three positive urine cultures were reported; 46/393 (11.7%, 42 in patients under two months of age) had positive urine cultures following normal urinalysis at first visit. Fifteen (33%) had positive urine cultures at second visit; 11/15 (73%) infants with second positive urine culture were under one month of age, eight were asymptomatic and seven had mild symptoms at second visit. Pathogens isolated in all 15 infants were identical between first and second visit. All 27 infants re-examined at second visit at the emergency room were hospitalised, completed sepsis work/up and received antibiotic treatment. None developed serious bacterial infections.

CONCLUSION

We propose a new management approach for young infants with normal urinalysis and positive urine culture and suggest restricting the management option including hospitalisation, sepsis work/up and antibiotic treatment at second visit only to infants under one month of age.

Association of Diagnostic Criteria With Urinary Tract Infection Prevalence in Bronchiolitis: A Systematic Review and Meta-analysis

IMPORTANCE

Concomitant urinary tract infection (UTI) is a frequent concern in febrile infants with bronchiolitis, with a prior meta-analysis suggesting a prevalence of 3.3%. However, the definition of UTI in these studies has generally not incorporated urinalysis (UA) results.

OBJECTIVE

To conduct a systematic review and meta-analysis examining the prevalence of UTI in infants with bronchiolitis when positive UA results are incorporated into the UTI definition.

DATA SOURCES

Medline (1946-2017) and Ovid EMBASE (1976-2017) through August 2017 and bibliographies of retrieved articles.

STUDY SELECTION

Studies reporting UTI prevalence in bronchiolitis.

DATA EXTRACTION

Data were extracted in accordance with meta-analysis of observational studies in epidemiology guidelines via independent abstraction by multiple investigators. Random-effects models generated a weighted pooled event rate with corresponding 95% confidence intervals.

MAIN OUTCOMES AND MEASURES

Prevalence of UTI.

RESULTS

We screened 477 unique articles by abstract, with full-text review of 30 studies. Eighteen bronchiolitis studies reported a UTI prevalence and 7 of these reported UA data for inclusion in the meta-analysis. The overall reported prevalence of UTI in bronchiolitis from these 18 studies was 3.1% (95% CI, 1.8%-4.6%). With the addition of positive UA results (defined as the presence of pyuria or nitrites) as a diagnostic criterion, the prevalence of UTI as reported in the 7 studies in bronchiolitis was 0.8% (95% CI, 0.3%-1.4%). Sensitivity analyses yielded similar results, including for infants younger than 90 days. Heterogeneous definitions of UTI and UA criteria introduced uncertainty into prevalence estimates.

CONCLUSIONS AND RELEVANCE

When a positive UA result is added as a diagnostic criterion, the estimated prevalence of concomitant UTI is less than recommended testing thresholds for bronchiolitis.

Pathophysiology, Treatment, and Prevention of Catheter-Associated Urinary Tract Infection

Urinary tract infections (UTIs) are among the most common microbial infections in humans and represent a substantial burden on the health care system. UTIs can be uncomplicated, as when affecting healthy individuals, or complicated, when affecting individuals with compromised urodynamics and/or host defenses, such as those with a urinary catheter. There are clear differences between uncomplicated UTI and catheter-associated UTI (CAUTI) in clinical manifestations, causative organisms, and pathophysiology. Therefore, uncomplicated UTI and CAUTI cannot be approached similarly, or the risk of complications and treatment failure may increase. It is imperative to understand the key aspects of each condition to develop successful treatment options and improve patient outcomes. Here, we will review the epidemiology, pathogen prevalence, differential mechanisms used by uropathogens, and treatment and prevention of uncomplicated UTI and CAUTI.

Androgen exposure potentiates formation of intratubular communities and renal abscesses by Escherichia coli

Females across their lifespan and certain male populations are susceptible to urinary tract infections (UTI). The influence of female vs. male sex on UTI is incompletely understood, in part because preclinical modeling has been performed almost exclusively in female mice. Here, we employed established and new mouse models of UTI with uropathogenic Escherichia coli (UPEC) to investigate androgen influence on UTI pathogenesis. Susceptibility to UPEC UTI in both male and female hosts was potentiated with 5α-dihydrotestosterone, while males with androgen receptor deficiency and androgenized females treated with the androgen receptor antagonist enzalutamide were protected from severe pyelonephritis. In androgenized females and in males, UPEC formed dense intratubular, biofilm-like communities, some of which were sheltered from infiltrating leukocytes by the tubular epithelium and by peritubular fibrosis. Abscesses were nucleated by small intratubular collections of UPEC first visualized at five days postinfection and briskly expanded over the subsequent 24 hours. Male mice deficient in Toll-like receptor 4, which fail to contain UPEC within abscesses, were susceptible to lethal dissemination. Thus, androgen receptor activation imparts susceptibility to severe upper-tract UTI in both female and male murine hosts. Visualization of intratubular UPEC communities illuminates early renal abscess pathogenesis and the role of abscess formation in preventing dissemination of infection. Additionally, our study suggests that androgen modulation may represent a novel therapeutic route to combat recalcitrant or recurrent UTI in a range of patient populations.

The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness

BACKGROUND

It is not clear which young children presenting acutely unwell to primary care should be investigated for urinary tract infection (UTI) and whether or not dipstick testing should be used to inform antibiotic treatment.

OBJECTIVES

To develop algorithms to accurately identify pre-school children in whom urine should be obtained; assess whether or not dipstick urinalysis provides additional diagnostic information; and model algorithm cost-effectiveness.

DESIGN

Multicentre, prospective diagnostic cohort study.

SETTING AND PARTICIPANTS

Children < 5 years old presenting to primary care with an acute illness and/or new urinary symptoms.

METHODS

One hundred and seven clinical characteristics (index tests) were recorded from the child's past medical history, symptoms, physical examination signs and urine dipstick test. Prior to dipstick results clinician opinion of UTI likelihood ('clinical diagnosis') and urine sampling and treatment intentions ('clinical judgement') were recorded. All index tests were measured blind to the reference standard, defined as a pure or predominant uropathogen cultured at ≥ 10(5) colony-forming units (CFU)/ml in a single research laboratory. Urine was collected by clean catch (preferred) or nappy pad. Index tests were sequentially evaluated in two groups, stratified by urine collection method: parent-reported symptoms with clinician-reported signs, and urine dipstick results. Diagnostic accuracy was quantified using area under receiver operating characteristic curve (AUROC) with 95% confidence interval (CI) and bootstrap-validated AUROC, and compared with the 'clinician diagnosis' AUROC. Decision-analytic models were used to identify optimal urine sampling strategy compared with 'clinical judgement'.

RESULTS

A total of 7163 children were recruited, of whom 50% were female and 49% were < 2 years old. Culture results were available for 5017 (70%); 2740 children provided clean-catch samples, 94% of whom were ≥ 2 years old, with 2.2% meeting the UTI definition. Among these, 'clinical diagnosis' correctly identified 46.6% of positive cultures, with 94.7% specificity and an AUROC of 0.77 (95% CI 0.71 to 0.83). Four symptoms, three signs and three dipstick results were independently associated with UTI with an AUROC (95% CI; bootstrap-validated AUROC) of 0.89 (0.85 to 0.95; validated 0.88) for symptoms and signs, increasing to 0.93 (0.90 to 0.97; validated 0.90) with dipstick results. Nappy pad samples were provided from the other 2277 children, of whom 82% were < 2 years old and 1.3% met the UTI definition. 'Clinical diagnosis' correctly identified 13.3% positive cultures, with 98.5% specificity and an AUROC of 0.63 (95% CI 0.53 to 0.72). Four symptoms and two dipstick results were independently associated with UTI, with an AUROC of 0.81 (0.72 to 0.90; validated 0.78) for symptoms, increasing to 0.87 (0.80 to 0.94; validated 0.82) with the dipstick findings. A high specificity threshold for the clean-catch model was more accurate and less costly than, and as effective as, clinical judgement. The additional diagnostic utility of dipstick testing was offset by its costs. The cost-effectiveness of the nappy pad model was not clear-cut.

CONCLUSIONS

Clinicians should prioritise the use of clean-catch sampling as symptoms and signs can cost-effectively improve the identification of UTI in young children where clean catch is possible. Dipstick testing can improve targeting of antibiotic treatment, but at a higher cost than waiting for a laboratory result. Future research is needed to distinguish pathogens from contaminants, assess the impact of the clean-catch algorithm on patient outcomes, and the cost-effectiveness of presumptive versus dipstick versus laboratory-guided antibiotic treatment.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Renal scar formation and kidney function following antibiotic-treated murine pyelonephritis

We present a new preclinical model to study treatment, resolution and sequelae of severe ascending pyelonephritis. Urinary tract infection (UTI), primarily caused by uropathogenic Escherichia coli (UPEC), is a common disease in children. Severe pyelonephritis is the primary cause of acquired renal scarring in childhood, which may eventually lead to hypertension and chronic kidney disease in a small but important fraction of patients. Preclinical modeling of UTI utilizes almost exclusively females, which (in most mouse strains) exhibit inherent resistance to severe ascending kidney infection; consequently, no existing preclinical model has assessed the consequences of recovery from pyelonephritis following antibiotic treatment. We recently published a novel mini-surgical bladder inoculation technique, with which male C3H/HeN mice develop robust ascending pyelonephritis, highly prevalent renal abscesses and evidence of fibrosis. Here, we devised and optimized an antibiotic treatment strategy within this male model to more closely reflect the clinical course of pyelonephritis. A 5-day ceftriaxone regimen initiated at the onset of abscess development achieved resolution of bladder and kidney infection. A minority of treated mice displayed persistent histological abscess at the end of treatment, despite microbiological cure of pyelonephritis; a matching fraction of mice 1 month later exhibited renal scars featuring fibrosis and ongoing inflammatory infiltrates. Successful antibiotic treatment preserved renal function in almost all infected mice, as assessed by biochemical markers 1 and 5 months post-treatment; hydronephrosis was observed as a late effect of treated pyelonephritis. An occasional mouse developed chronic kidney disease, generally reflecting the incidence of this late sequela in humans. In total, this model offers a platform to study the molecular pathogenesis of pyelonephritis, response to antibiotic therapy and emergence of sequelae, including fibrosis and renal scarring. Future studies in this system may inform adjunctive therapies that may reduce the long-term complications of this very common bacterial infection.

Summary: A new model of antibiotic-treated severe pyelonephritis offers a novel platform to study the molecular pathogenesis of pyelonephritis, response to antibiotic therapy, and sequelae, including fibrosis and renal scarring.

Association Between Uropathogen and Pyuria

OBJECTIVE

We sought to determine factors associated with the absence of pyuria in symptomatic children whose urine culture was positive for a known uropathogen.

METHODS

We obtained data on children evaluated at the Children's Hospital of Pittsburgh emergency department between 2007 and 2013 with symptoms of urinary tract infection (UTI) who had paired urinalysis and urine cultures. We excluded children with an unknown or bag urine collection method, major genitourinary anomalies, immunocompromising conditions, or with multiple organisms on culture. We chose a single, randomly-selected urine specimen per child and limited the analysis to those with positive cultures.

RESULTS

There were 46 158 visits during the study period; 1181 children diagnosed with UTI met all inclusion criteria and had a microscopic urinalysis for pyuria. Pyuria (≥5 white blood cells per high-powered field or ≥10 white blood cells per cubic millimeter) was present in 1031 (87%) children and absent in 150 (13%). Children with Enterococcus species, Klebsiella species, and Pseudomonas aeruginosa were significantly less likely to exhibit pyuria than children with Escherichia coli (odds ratio of 0.14, 0.34, and 0.19, respectively). Children with these organisms were also less likely to have a positive leukocyte esterase on dipstick urinalysis. Results were similar when we restricted the analysis to children whose urine samples were collected by bladder catheterization.

CONCLUSIONS

We found that certain uropathogens are less likely to be associated with pyuria in symptomatic children. Identification of biomarkers more accurate than pyuria or leukocyte esterase may help reduce over- and undertreatment of UTIs.

Improving the Diagnosis and Treatment of Urinary Tract Infection in Young Children in Primary Care: Results from the DUTY Prospective Diagnostic Cohort Study

PURPOSE

Up to 50% of urinary tract infections (UTIs) in young children are missed in primary care. Urine culture is essential for diagnosis, but urine collection is often difficult. Our aim was to derive and internally validate a 2-step clinical rule using (1) symptoms and signs to select children for urine collection; and (2) symptoms, signs, and dipstick testing to guide antibiotic treatment.

METHODS

We recruited acutely unwell children aged under 5 years from 233 primary care sites across England and Wales. Index tests were parent-reported symptoms, clinician-reported signs, urine dipstick results, and clinician opinion of UTI likelihood (clinical diagnosis before dipstick and culture). The reference standard was microbiologically confirmed UTI cultured from a clean-catch urine sample. We calculated sensitivity, specificity, and area under the receiver operator characteristic (AUROC) curve of coefficient-based (graded severity) and points-based (dichotomized) symptom/sign logistic regression models, and we then internally validated the AUROC using bootstrapping.

RESULTS

Three thousand thirty-six children provided urine samples, and culture results were available for 2,740 (90%). Of these results, 60 (2.2%) were positive: the clinical diagnosis was 46.6% sensitive, with an AUROC of 0.77. Previous UTI, increasing pain/crying on passing urine, increasingly smelly urine, absence of severe cough, increasing clinician impression of severe illness, abdominal tenderness on examination, and normal findings on ear examination were associated with UTI. The validated coefficient- and points-based model AUROCs were 0.87 and 0.86, respectively, increasing to 0.90 and 0.90, respectively, by adding dipstick nitrites, leukocytes, and blood.

CONCLUSIONS

A clinical rule based on symptoms and signs is superior to clinician diagnosis and performs well for identifying young children for noninvasive urine sampling. Dipstick results add further diagnostic value for empiric antibiotic treatment.

Is screening for urine infection in well infants with prolonged jaundice required? Local review and meta-analysis of existing data

BACKGROUND

The National Institute for Health and Care Excellence (NICE) neonatal jaundice guidance recommends a urine culture for investigation of babies with prolonged jaundice. However, the evidence cited for this guidance is limited. We aimed to review local data and the existing literature to identify evidence to either support or refute this guidance.

METHOD

We retrospectively reviewed 3 years of urine cultures from our outpatient prolonged jaundice clinic. We then conducted literature review with meta-analysis of studies presenting original data on urine tract infection (UTI) rates in jaundiced and prolonged jaundiced babies.

RESULTS

From our local data, none of the 279 patients met our unit clinical criteria for UTI. Literature review revealed considerable differences worldwide in UTI rates in both jaundiced and prolonged jaundiced cases. Using pooled data from our literature review and our local population, the incidence of UTI in prolonged jaundiced babies is 0.21% (95% CI 0.0% to 0.73%) in the UK. This is significantly lower than the figure indicated from the data from elsewhere in the world, 8.21% (95% CI 4.36% to 13.0%).

CONCLUSIONS

The findings both from our local data and the current literature do not support the practice of routine screening for urine infection in well babies with prolonged jaundice. In view of the above, we no longer include urine culture in screening of well infants with prolonged jaundice. We hope that NICE will re-examine the evidence and recommend changes to their guidance on the role of routine screening for urine infection in babies with prolonged jaundice.

Empiric antibiotic treatment for urinary tract infection in preschool children: susceptibilities of urine sample isolates

BACKGROUND

Antibiotic treatment recommendations based on susceptibility data from routinely submitted urine samples may be biased because of variation in sampling, laboratory procedures and inclusion of repeat samples, leading to uncertainty about empirical treatment.

OBJECTIVE

To describe and compare susceptibilities of Escherichia coli cultured from routinely submitted samples, with E. coli causing urinary tract infection (UTI) from a cohort of systematically sampled, acutely unwell children.

METHODS

Susceptibilities of 1458 E. coli isolates submitted during the course of routine primary care for children <5 years (routine care samples), compared to susceptibilities of 79 E. coli isolates causing UTI from 5107 children <5 years presenting to primary care with an acute illness [systematic sampling: the Diagnosis of Urinary Tract infection in Young children (DUTY) cohort].

RESULTS

The percentage of E. coli sensitive to antibiotics cultured from routinely submitted samples were as follows: amoxicillin 45.1% (95% confidence interval: 42.5-47.7%); co-amoxiclav using the lower systemic break point (BP) 86.6% (84.7-88.3%); cephalexin 95.1% (93.9-96.1%); trimethoprim 74.0% (71.7-76.2%) and nitrofurantoin 98.2% (97.4-98.8%). The percentage of E. coli sensitive to antibiotics cultured from systematically sampled DUTY urines considered to be positive for UTI were as follows: amoxicillin 50.6% (39.8-61.4%); co-amoxiclav using the systemic BP 83.5% (73.9-90.1%); co-amoxiclav using the urinary BP 94.9% (87.7-98.4%); cephalexin 98.7% (93.2-99.8%); trimethoprim 70.9% (60.1-80.0%); nitrofurantoin 100% (95.3-100.0%) and ciprofloxacin 96.2% (89.4-98.7%).

CONCLUSION

Escherichia coli susceptibilities from routine and systematically obtained samples were similar. Most UTIs in preschool children remain susceptible to nitrofurantoin, co-amoxiclav and cephalexin.

Low urinary bacterial counts: do they count?

In their article which appears in this issue of Pediatric Nephrology, Dr. S. Swerkersson and co-workers claim that as many as one in every five infants with a true episode of urinary tract infection (UTI) will be missed with the commonly used cut-off level of ≥10(5) colony forming units (CFU)/mL. This controversial finding is supported by the results of seven previous studies including a total of 1587 children. Dr. E.H. Kass, who in the 1950s suggested the presently used cut-off level, knew at the time that it excluded a number of patients with a true infection. Later studies in adult patients also showed that up to 46–49% of women with a likely diagnosis of cystitis had low bacterial counts. These findings can, if true, improve our understanding of cases of unexplained postinfectious renal scarring. Children with low bacterial counts during an acute infectious episode have a significant risk of receiving delayed or even no antimicrobial treatment. The results of scientific studies are also confounded if 20 % of the subjects with a true infection are wrongly included in a control group diagnosed as having no UTI due to low bacterial counts. This problem cannot be easily solved by lowering the cut-off level and generally accepting that any bacterial count signifies a Btrue^ infection as this approach will drastically reduce the specificity of the culture result. Instead, as many as possible urine samples for culture should be collected from babies, infants and small children with a suprapubic bladder puncture, or a catheterised sample. In such samples bacterial counts as low as 103 CFU/mL are generally regarded as significant. In many cases, however, the only possibility is a Bclean catch^ or bag sample. In these situations, the treating physician needs to take all relevant clinical and laboratory parameters into account and if clinically important data support the diagnosis of a UTI not disregard this diagnosis based only on low bacterial counts. C-reactive protein or procalcitonin can, in a febrile child, help the physician differentiate between a febrile bacterial UTI and a viral infection. A positive nitrite test provides, albeit with a low sensitivity, strong support for a UTI diagnosis.

Assessing the Utility of Urine Testing in Febrile Infants Aged 2 to 12 Months With Bronchiolitis

OBJECTIVES

The aims of the study were to investigate whether the prevalence of urinary tract infections (UTIs) in febrile infants aged 2 to 12 months with bronchiolitis is higher than the presumed prevalence of asymptomatic bacteriuria (1%) in similarly aged patients and thus to determine whether UTI testing is necessary for these patients.

METHODS

This was a prospective cohort study in which we enrolled a convenience sample of febrile infants aged 2 to 12 months with a clinical diagnosis of bronchiolitis. All patients were seen in the emergency department at a large children's hospital between November 1, 2011 and April 15, 2012, had reported or documented fever higher than 38°C, and had urine collected for determination of the presence of UTI. After the conclusion of enrollment, a chart review was conducted to assess missed cases.

RESULTS

Positive urine cultures were found in 6/90 (6.7%) patients (confidence interval, 2.5%-13.9%). The positive urine cultures and urinalysis results were found in 4/90 (4.5%) patients (confidence interval, 1.2%-11%).

CONCLUSIONS

In our patient population, a significant proportion of infants aged 2 to 12 months who present with bronchiolitis and fever have a concurrent UTI. Obtaining a urine specimen for UTI testing should be considered in infants aged 2 to 12 months with bronchiolitis and fever. A larger multicenter study is needed to further assess the risk factors for UTIs in this patient population.

When to perform urine cultures in respiratory syncytial virus-positive febrile older infants?

BACKGROUND

Respiratory syncytial virus (RSV) infections are associated with clinically significant rate of urinary tract infections (UTIs) in young infants. Previous research investigating RSV infections and UTIs has been performed mainly in infants younger than 2 to 3 months and has not focused on the risk of UTI in infants 3 to 12 months.

OBJECTIVE

This study aimed to assess the rate of UTIs in febrile RSV-positive older infants admitted as inpatients and identify predictors of UTI in febrile RSV-positive older infants.

METHODS

This is a retrospective comparative study of febrile RSV-positive infants 0 to 12 months of age admitted to the inpatient pediatric unit of Lincoln Medical and Mental Health Center, Bronx, from September through April 2006 to 2012. Infants 3 to 12 months were considered the cases, and infants 0 to 3 months were the comparative group. The rate of UTIs between the 2 groups was compared. Univariate tests and multiple logistic regression were used to identify demographic/clinical factors associated with UTI in febrile RSV-positive older infants.

RESULTS

A total of 414 RSV-positive febrile infants were enrolled including 297 infants 3 to 12 months of age. The rate of UTI in older infants was 6.1% compared with 6.8% in infants younger than 3 months. Positive urinalysis finding was an independent predictor of UTI (P = 0.003) in older infants. All 11 boys with UTI were uncircumcised, and none of the 51 circumcised boys had UTI. Demographic (race, sex, and age) and clinical factors (temperature, white blood cell count, and absolute neutrophil count) were not associated with UTI.

CONCLUSIONS

Febrile older infants who are RSV positive have a clinically significant rate of UTIs. It seems prudent to examine the urine of these older infants. Positive urinalysis finding was a predictive factor of UTI. Circumcised boys are at a decreased risk of UTI, compared with uncircumcised boys.

Factors associated with bacteremia in young infants with urinary tract infection

BACKGROUND

Urinary tract infection (UTI) is the most frequent severe bacterial infection in infants. Up to 31% of infants with UTI have bacteremia.

METHODS

We retrospectively identified all infants aged 0-2 months who were managed in our hospital with UTI during a 1-year period. Those with bacteremia were compared with those without bacteremia, according to the following variables: ethnicity, age, gender, white blood cell and polymorphonuclear counts, C-reactive protein, urinalysis and blood creatinine values as related to age-appropriate norms, imaging and outcome.

RESULTS

We identified 81 infants with 82 episodes of UTI. Most occurred in males (72.8%) and 35 (42.7%) were in infants of non-Jewish origin. In 14/81 (17.3%) of episodes, Escherichia coli was cultured from blood. In multivariate analysis, increased blood creatinine levels (P = 0.004) and non-Jewish origin (P = 0.006) were associated with bacteremia. Time to defervescence was significantly longer in bacteremic versus nonbacteremic children (P = 0.018). Duration of hospitalization was longer in bacteremic infants-10 (7-17) days in bacteremic versus 7 (1-14) days in nonbacteremic children (P < 0.001).

CONCLUSIONS

In infants aged 0-2 months with UTI, increased blood creatinine value at admission was associated with bacteremia. This value provides an additional clue on admission, independent of personal judgment, to help identify infants at higher risk for bacteremia, prolonged hospitalization and possible complications.

Enhanced versus automated urinalysis for screening of urinary tract infections in children in the emergency department

BACKGROUND

Urinary tract infections (UTI) are the most common serious bacterial infection in febrile infants. Urinalysis (UA) is a screening test for preliminary diagnosis of UTI. UA can be performed manually or using automated techniques. We sought to compare manual versus automated UA for urine specimens obtained via catheterization in the pediatric emergency department.

METHODS

In this prospective study, we processed catheterized urine samples from infants with suspected UTI by both the manual method (enhanced UA) and the automated method. We defined a positive enhanced UA as ≥ 10 white blood cells per cubic millimeter and presence of any bacteria per 10 oil immersion fields on a Gram-stained smear. We defined a positive automated UA as ≥ 2 white blood cells per high-powered field and presence of any bacteria using the IRIS iQ200 ELITE. We defined a positive urine culture as growth of ≥ 50,000 colony-forming units per milliliter of a single uropathogen. We analyzed data using SPSS software.

RESULTS

A total of 703 specimens were analyzed. Prevalence of UTI was 7%. For pyuria, the sensitivity and positive predictive value (PPV) of the enhanced UA in predicting positive urine culture were 83.6% and 52.5%, respectively; corresponding values for the automated UA were 79.5% and 37.5%, respectively. For bacteriuria, the sensitivity and PPV of a Gram-stained smear (enhanced UA) were 83.6% and 59.4%, respectively; corresponding values for the automated UA were 73.4%, and 26.2%, respectively. Using criteria of both pyuria and bacteriuria for the enhanced UA resulted in a sensitivity of 77.5% and a PPV of 84.4%; corresponding values for the automated UA were 63.2% and 51.6%, respectively. Combining automated pyuria (≥ 2 white blood cells/high-powered microscopic field) with a Gram-stained smear resulted in a sensitivity of 75.5% and a PPV of 84%.

CONCLUSIONS

Automated UA is comparable with manual UA for detection of pyuria in young children with suspected UTI. Bacteriuria detected by automated UA is less sensitive and specific for UTI when compared with a Gram-stained smear. We recommend using either manual or automated measurement of pyuria in combination with Gram-stained smear as the preferred technique for UA of catheterized specimens obtained from children in an acute care setting.

Prevalence of urinary tract infection in acutely unwell children in general practice: a prospective study with systematic urine sampling

BACKGROUND

Urinary tract infection (UTI) in children may be associated with long-term complications that could be prevented by prompt treatment.

AIM

To determine the prevalence of UTI in acutely ill children ≤ 5 years presenting in general practice and to explore patterns of presenting symptoms and urine sampling strategies.

DESIGN AND SETTING

Prospective observational study with systematic urine sampling, in general practices in Wales, UK.

METHOD

In total, 1003 children were recruited from 13 general practices between March 2008 and July 2010. The prevalence of UTI was determined and multivariable analysis performed to determine the probability of UTI.

RESULT

Out of 597 (60.0%) children who provided urine samples within 2 days, the prevalence of UTI was 5.9% (95% confidence interval [CI] = 4.3% to 8.0%) overall, 7.3% in those < 3 years and 3.2% in 3-5 year olds. Neither a history of fever nor the absence of an alternative source of infection was associated with UTI (P = 0.64; P = 0.69, respectively). The probability of UTI in children aged ≥3 years without increased urinary frequency or dysuria was 2%. The probability of UTI was ≥5% in all other groups. Urine sampling based purely on GP suspicion would have missed 80% of UTIs, while a sampling strategy based on current guidelines would have missed 50%.

CONCLUSION

Approximately 6% of acutely unwell children presenting to UK general practice met the criteria for a laboratory diagnosis of UTI. This higher than previously recognised prior probability of UTI warrants raised awareness of the condition and suggests clinicians should lower their threshold for urine sampling in young children. The absence of fever or presence of an alternative source of infection, as emphasised in current guidelines, may not rule out UTI in young children with adequate certainty.

[Jaundice and urinary tract infection in neonates: simple coincidence or real consequence?]

In neonates, jaundice may be one of the initial symptoms related to urinary tract infection (UTI). The routine testing of the urine in jaundiced neonates is controversial. This study aimed to evaluate the related factors of neonatal infants with the initial presentation of hyperbilirubinemia and the final diagnosis of UTI by evaluating data that help diagnose UTI early in apparently healthy newborns with jaundice.

PATIENTS AND METHODS

We retrospectively investigated the medical records of neonates who had been admitted for management of jaundice (n=26) and compared with neonates with jaundice but without UTI (n=26).

RESULTS

There was a significant difference between the two groups in male gender and maternal conditions (prolonged rupture of membranes, maternal UTI). There was also a significant difference between the two groups in their age at the time jaundice started (4 ± 3 days vs 2 ± 1 days) in the UTI and non-UTI groups, respectively (P>0.05). The cases in the UTI group had significantly lower total bilirubin levels (183 ± 71 mg/l) vs (227 ± 40 mg/l) in the non-UTI group, but a higher indirect bilirubin rate than the non-UTI group (P<0.05). Type B blood group was more common in neonates with UTI (P<0.01). In the cases presented herein, none of the jaundiced infants with UTI presented conjugated hyperbilirubinemia. Therefore, urinary tests for UTI should not be absolutely excluded or neglected in neonates in the early stage with unconjugated hyperbilirubinemia. Performing urinary tests to exclude the possibility of coincidental UTI may be necessary for admitted jaundiced infants younger than if they have a high level of indirect bilirubin, especially in male newborns with group B blood and in the presence of maternal urinary infection.

A review of guidelines for urinary tract infections in children younger than 2 years

CME EDUCATIONAL OBJECTIVES: 1.Review recent guidelines for diagnosis and treatment of urinary tract infections in children younger than 2 years.2.Review recent recommendations for imaging children with urinary tract infection.3.Understand rationale for recent treatment recommendations and prophylaxis of children with urinary tract infection.

Susceptibility to acute pyelonephritis or asymptomatic bacteriuria: host-pathogen interaction in urinary tract infections

Our knowledge of the molecular mechanisms of urinary tract infection (UTI) pathogenesis has advanced greatly in recent years. In this review, we provide a general background of UTI pathogenesis, followed by an update on the mechanisms of UTI susceptibility, with a particular focus on genetic variation affecting innate immunity. The innate immune response of the host is critically important in the antibacterial defence mechanisms of the urinary tract, and bacterial clearance normally proceeds without sequelae. However, slight dysfunctions in these mechanisms may result in acute disease and tissue destruction. The symptoms of acute pyelonephritis are caused by the innate immune response, and inflammation in the urinary tract decreases renal tubular function and may give rise to renal scarring, especially in paediatric patients. In contrast, in children with asymptomatic bacteriuria (ABU), bacteria persist without causing symptoms or pathology. Pathogenic agents trigger a response determined by their virulence factors, mediating adherence to the urinary tract mucosa, signalling through Toll-like receptors (TLRs) and activating the defence mechanisms. In ABU strains, such virulence factors are mostly not expressed. However, the influence of the host on UTI severity cannot be overestimated, and rapid progress is being made in clarifying host susceptibility mechanisms. For example, genetic alterations that reduce TLR4 function are associated with ABU, while polymorphisms reducing IRF3 or CXCR1 expression are associated with acute pyelonephritis and an increased risk for renal scarring. It should be plausible to "individualize" diagnosis and therapy by combining information on bacterial virulence and the host response.

The diagnosis of urinary tract infections in young children (DUTY): protocol for a diagnostic and prospective observational study to derive and validate a clinical algorithm for the diagnosis of UTI in children presenting to primary care with an acute illness

Background

Urinary tract infection (UTI) is common in children, and may cause serious illness and recurrent symptoms. However, obtaining a urine sample from young children in primary care is challenging and not feasible for large numbers. Evidence regarding the predictive value of symptoms, signs and urinalysis for UTI in young children is urgently needed to help primary care clinicians better identify children who should be investigated for UTI. This paper describes the protocol for the Diagnosis of Urinary Tract infection in Young children (DUTY) study. The overall study aim is to derive and validate a cost-effective clinical algorithm for the diagnosis of UTI in children presenting to primary care acutely unwell.

Methods/design

DUTY is a multicentre, diagnostic and prospective observational study aiming to recruit at least 7,000 children aged before their fifth birthday, being assessed in primary care for any acute, non-traumatic, illness of ≤ 28 days duration. Urine samples will be obtained from eligible consented children, and data collected on medical history and presenting symptoms and signs. Urine samples will be dipstick tested in general practice and sent for microbiological analysis. All children with culture positive urines and a random sample of children with urine culture results in other, non-positive categories will be followed up to record symptom duration and healthcare resource use. A diagnostic algorithm will be constructed and validated and an economic evaluation conducted.

The primary outcome will be a validated diagnostic algorithm using a reference standard of a pure/predominant growth of at least >10³, but usually >10⁵ CFU/mL of one, but no more than two uropathogens.

We will use logistic regression to identify the clinical predictors (i.e. demographic, medical history, presenting signs and symptoms and urine dipstick analysis results) most strongly associated with a positive urine culture result. We will then use economic evaluation to compare the cost effectiveness of the candidate prediction rules.

Discussion

This study will provide novel, clinically important information on the diagnostic features of childhood UTI and the cost effectiveness of a validated prediction rule, to help primary care clinicians improve the efficiency of their diagnostic strategy for UTI in young children.

Difficulties in diagnosing urinary tract infections in small children

Urinary tract infections (UTIs) in children appear to be simple and straightforward matters, but there is as yet no consensus on UTIs in this patient group, and it remains one of the most - if not the most - controversial fields in paediatric medicine. Controversy and the lack of consensus can be found in many areas, including the diagnosis and management of UTIs in paediatric patients. Consequently, children with a UTI are investigated and treated quite differently in different parts of the world and also within different parts of the same country. One factor contributing to the current situation is the unexpected difficulty in diagnosing a UTI in children. This difficulty has implications not only for clinical work but also for scientific studies. Substantial over- and under-diagnosing can result from practical difficulties in at least three areas, including problems with collecting urine samples, in interpreting bacterial numbers correctly, and in confusing infantile asymptomatic bacteriuria and a true symptomatic febrile UTI. In this review, these problems will be discussed in detail as well as the implications they have had on clinical practice and research on UTIs.

Pediatric urinary tract infections

Urinary tract infections (UTIs) in children are commonly seen in the emergency department and pose several challenges to establishing the proper diagnosis and determining management. This article reviews pediatric UTI and addresses epidemiology, diagnosis, treatment, and imaging, and their importance to the practicing emergency medicine provider. Accurate and timely diagnosis of pediatric UTI can prevent short-term complications, such as severe pyelonephritis or sepsis, and long-term sequelae including scarring of the kidneys, hypertension, and ultimately chronic renal insufficiency and need for transplant.

Genetics of innate immunity and UTI susceptibility

A functional and well-balanced immune response is required to resist most infections. Slight dysfunctions in innate immunity can turn the 'friendly' host defense into an unpleasant foe and give rise to disease. Beneficial and destructive forces of innate immunity have been discovered in the urinary tract and mechanisms by which they influence the severity of urinary tract infections (UTIs) have been elucidated. By modifying specific aspects of the innate immune response to UTI, genetic variation either exaggerates the severity of acute pyelonephritis to include urosepsis and renal scarring or protects against symptomatic disease by suppressing innate immune signaling, as in asymptomatic bacteriuria (ABU). Different genes are polymorphic in patients prone to acute pyelonephritis or ABU, respectively, and yet discussions of UTI susceptibility in clinical practice still focus mainly on social and behavioral factors or dysfunctional voiding. Is it not time for UTIs to enter the era of molecular medicine? Defining why certain individuals are protected from UTI while others have severe, recurrent infections has long been difficult, but progress is now being made, encouraging new approaches to risk assessment and therapy in this large and important patient group, as well as revealing promising facets of 'good' versus 'bad' inflammation.

Incidence of renal and perinephric abscess in diabetic patients: a population-based national study

This population-based cohort study aimed to investigate the incidence and relative hazard of renal and perinephric abscess (RA) in the diabetic population in Taiwan. More than a half million diabetic patients and sex- and age-matched controls were identified from the 1997 Taiwan National Health Insurance data and were linked to in-patient claims from 1997 to 2007. Person-year approach with Poisson assumption was used to estimate the incidence density (ID) of RA. The hazard ratios (HRs) of hospitalization due to RA in relation to diabetes were analysed using a Cox proportional hazard model. The ID for the diabetic and control subjects was 4·6 and 1·1/10,000 person-years, respectively, in 11 years of follow-up, representing an adjusted HR of 3·81 (95% confidence interval 3·44-4·23). This study confirmed the association of diabetes with RA, and argued that more aggressive urological care should be administered to diabetic patients.

P-fimbriated Escherichia coli in adults with renal scarring and pyelonephritis

The commonest organism in urinary tract infections (UTI) is Escherichia coli. Pyelonephritogenic E.coli strains possess P-fimbriae which firmly attach to uroepithelial cells by recognition of a carbohydrate structure, alpha-D-Galp-(1-4)-beta-D-Galp, which is confined within all glycosphingolipids related to the human P-blood group antigens. Several investigators have studied virulence properties of E.coli and host resistance in relation to UTI. Uroepithelial cells from children and women with recurrent UTI have an increased capacity to bind E.coli. In contrast to previous studies the present one deals with patients with renal scarring, who constitute the major risk group among patients with UTI. P-fimbriae mediated binding to uroepithelial cells was studied and the risk of recurrent UTI in patients with renal scarring was determined. Ninety per cent of the E.coli isolates from female patients with acute non-obstructive pyelonephritis in this study possess P-fimbriae (I). The fecal E.coli colonies obtained from these patients were P-fimbriated in 55% compared to 11% of the fecal E.coli colonies from healthy controls. The P-blood group distribution in 56 female patients with renal scarring and a history of febrile UTI was the same as in a control group of 39 healthy subjects (II). A history of recurrent and/or early infections did not increase the percentage of the P1 blood group phenotype. Forty-nine female patients with renal scarring were prospectively investigated for the incidence of symptomatic UTI in relation to fecal colonization with P-fimbriated E.coli (III). Fifty-three per cent of the patients had altogether 65 episodes of symptomatic UTI during the three-year follow-up (0.036 infections per month). Eight patients (16%) had nine attacks of acute pyelonephritis and 4/5 of the tested E.coli strains from these patients were P-fimbriated. No relationship was demonstrated between the presence of P-fimbriated E.coli in the fecal flora and the development of subsequent acute pyelonephritis. The binding of P-fimbriated E.coli to uroepithelial cells from 19 female patients with renal scarring was studied with the fluorescence-activated cell sorting (FACS) analysis (IV). The uroepithelial cells from the patients with renal scarring exhibited a significantly higher binding capacity (p less than 0.01) than uroepithelial cells from healthy controls. Furthermore, uroepithelial cells from the patients with renal scarring and kidney insufficiency had a higher availability of P-fimbriae receptors on their uroepithelial cells than cells obtained from patients with renal scarring and normal renal function (r = -0.75, p less than 0.001) (V).(ABSTRACT TRUNCATED AT 400 WORDS)

The crying infant: diagnostic testing and frequency of serious underlying disease

OBJECTIVE

To determine the proportion of children evaluated in an emergency department because of crying who have a serious underlying etiology. Secondary outcomes included the individual contributions of history, physical examination, and laboratory investigations in determining a diagnosis.

PATIENTS AND METHODS

We performed a retrospective review of all afebrile patients <1 year of age who presented with a chief complaint of crying, irritability, screaming, colic, or fussiness. All children with a serious underlying illness were identified by using a priori defined criteria. Chart review was conducted to determine if history, physical examination, or investigation data contributed to establishing the child's diagnosis.

RESULTS

Enrollment criteria were met by 237 patients, representing 0.6% of all visits. A total of 12 (5.1%) children had serious underlying etiologies with urinary tract infections being most prevalent (n = 3). Two (16.7%) of the serious diagnoses were only made on revisit. Of the 574 tests performed, 81 (14.1%) were positive. However, only 8 (1.4%) diagnoses were assigned on the basis of a positive investigation. History and/or examination suggested an etiology in 66.3% of cases. Unwell appearance was associated with serious etiologies. In only 2 (0.8%) children did investigations in the absence of a suggestive clinical picture contribute to the diagnosis. Both of these children were <4 months of age and had urinary tract infections. Among children <1 month of age, the positive rate of urine cultures performed was 10%. Ocular fluorescein staining and rectal examination with occult blood testing were performed infrequently, and results were negative in all cases. Successful follow-up was completed with 60% of caregivers, and no missed diagnoses were found.

CONCLUSIONS

History and physical examination remains the cornerstone of the evaluation of the crying infant and should drive investigation selection. Afebrile infants in the first few months of life should undergo urine evaluation. Other investigations should be performed on the basis of clinical findings.

Bilirubin levels predict renal cortical changes in jaundiced neonates with urinary tract infection

BACKGROUND

This study was undertaken to determine the incidence of urinary tract infection (UTI) and the frequency of anatomical abnormalities in newborns with unexplained jaundice and to find out if there is any correlation between bilirubin level and renal damage.

METHODS

We studied 462 full-term neonates for UTI. They were aged 3-25 days, with either high (>10 mg/dL) or prolonged (>10 days) hyperbilirubinemia, with or without manifestations such as fever, vomiting, diarrhea, poor feeding, lethargy, and irritability. Neonates positive for UTI were further investigated with ultrasound, cystourethrography, and acute phase renal scintigraphy with technetium-99m dimercaptosuccinate acid (DMSA).

RESULTS

Thirty neonates (6.5%) were found to have UTI. Twenty-eight of them had indirect hyperbilirubinemia and two had direct hyperbilirubinemia, with total bilirubin levels of 11.8-20.1 mg/dL. None of the neonates was found to have jaundice because of other reasons such as infection. Vesicoureteral reflux was found in 5 neonates and one of them was combined with hydronephrosis. Renal scintigraphy with technetium-99m DMSA showed renal cortex changes in 14 (46.7%) of the 30 neonates with UTI. These 14 neonates also had increased levels of bilirubin in comparison to those with normal findings of DMSA.

CONCLUSIONS

The incidence of UTI in uncomplicated neonatal jaundice is relatively high. Anatomical abnormalities of the urinary tract are not rare in infected children. Increased bilirubin levels are related to pathological findings in renal scintigraphy.

Urinary tract infection in the newborn: clinical and radio imaging studies

The objective of this study was to assess clinical characteristics and results of radio imaging studies and compare community-acquired urinary tract infection (UTI) with nosocomial UTI in 301 neonates with UTI consecutively admitted to 28 neonatal units in Spain over 3 years (community-acquired UTI, n = 250; nosocomial UTI, n = 51). UTI was diagnosed in the presence of symptoms of infection together with any colony growth for a single pathogen from urine obtained by suprapubic aspiration, or >or=10(4) CFU/ml for a single pathogen from urine obtained by urethral catheterization. Abnormal renal ultrasound was present in 37.1% of cases (34% in community-acquired UTI and 54.5% in nosocomial UTI, P < 0.01). The voiding cystourethrography (VCUG) showed vesicoureteral reflux (VUR) in 27% of cases (23.8% in community-acquired UTI and 48.6% in nosocomial UTI, P < 0.01). In patients with abnormal renal ultrasound and VUR, renal scan with dimercaptosuccinic acid (DMSA) performed early after UTI revealed cortical defects in 69.5% of cases. However, in patients with abnormal renal ultrasound and normal VCUG, DMSA also revealed cortical defects in 39% of cases. The absence of VUR in neonates with UTI and abnormal renal ultrasound does not exclude the presence of cortical defects suggestive of pyelonephritis.

Lack of usefulness of an abnormal white blood cell count for predicting a concurrent serious bacterial infection in infants and young children hospitalized with respiratory syncytial virus lower respiratory tract infection

BACKGROUND

There continues to be controversy on the most appropriate way to manage infants and young children with fever and documented RSV lower respiratory tract infection (LRTI). The objective of this study was to determine the usefulness of an abnormal white blood cell (WBC) count for predicting a concurrent serious bacterial infection in patients admitted with RSV LRTI.

METHODS

The medical records were reviewed of patients discharged with RSV LRTI during the 5 RSV seasons from July 1, 2000 through June 30, 2005. Data were collected on age and gender as well as temperature, complete blood count with manual differential and bacterial cultures obtained at admission.

RESULTS

The inclusion criteria was met by 1920 patients. There were 672 febrile patients who had a complete blood count and a bacterial culture. One (5.0%) of 20 patients with a WBC <5000 had a positive culture, 23 (4.7%) of 492 patients with a WBC 5000-14,999 had a positive culture, 5 (4.8%) of 105 patients with a WBC 15,000-19,999 had a positive culture, 2 (5.7%) of 35 patients with a WBC 20,000-24,999 had a positive culture, none of 11 patients with a WBC 25,000-29,999 had a positive culture and 3 (33%) of 9 patients with a WBC >30,000 had a positive culture. Overall, cultures were positive in 34 (5.1%; 95% CI: 3.4-6.8%) of the febrile patients tested and almost all (32; 94%) showed positive urine cultures.

CONCLUSION

The probability of an abnormal WBC count <5000 and 15,000-30,000 being associated with a concurrent serious bacterial infection was very low and no different from that of a normal WBC count in febrile patients admitted with RSV LRTI.

First urinary tract infection in neonates, infants and young children: a comparative study

In an attempt to evaluate first urinary tract infection (UTI) in neonates and infants, we estimated retrospectively in 296 patients (62 neonates and 234 infants) clinical and laboratory findings, occurrence of vesicoureteral reflux (VUR), urinary tract abnormalities and pyelonephritis. First UTI occurred more often in male than female neonates, whereas male and female infants/young children were affected at an equal rate. The pathogens isolated in urine cultures of neonates and infants did not statistically significantly differ (P>0.05); Escherichia coli predominated. Gram-negative bacteria other than E. coli affected boys more often than girls (P=0.0022). Fever was the most frequent symptom. Neonates had lower-grade fever of shorter duration than infants (P<0.05). The incidence of reflux and urinary tract abnormalities did not differ between neonates and infants, male and female neonates and infants (P>0.05). Pyelonephritis affected neonates and infants at an equal rate; it was more prevalent among female patients (P=0.038) and patients with VUR or urinary tract abnormalities other than VUR (P<0.0001). Neonates with reflux were more often affected by Gram-negative bacteria other than E. coli than were neonates without reflux (P=0.0008).