Low bacterial count urinary tract infections in infants and young children

Uropathogens and clinical manifestations of pyuria-negative urinary tract infections in young infants: A single center cross-sectional study

BACKGROUND

Urine leukocyte count under microscopy is one of the most frequently used routine screening tests for urinary tract infection (UTI). Nevertheless, it is observed that pyuria is lacking in 10-25% of children with UTI. This study aims to determine the factors related to pyuria-negative UTI in young infants aged under four months old.

METHOD

This retrospective cross-sectional study was conducted on 157 patients aged under 4 months old with UTI. All subjects had paired urinalysis and urine culture, which were collected via transurethral catheterization. According to the results of their urinalysis, the patients were then classified as UTI cases with pyuria and UTI cases without pyuria. The clinical characteristics and outcomes of both groups were analyzed.

RESULT

Among the 157 UTI patients, the prevalence of pyuria-negative UTI was 44%. Significant risk factors associated with pyuria-negative UTI included non-E.coli pathogens, younger age, shorter duration of fever prior to hospital visit, lower white blood cell (WBC) count upon hospital visit, and absence of microscopic hematuria.

CONCLUSIONS

We found that non-E.coli uropathogens were the strongest factor related to pyuria-negative UTI. The absence of pyuria cannot exclude the diagnosis of UTI in young infants, and it's reasonable to perform both urinalysis and urine culture as a part of the assessment of febrile or ill-looking young infants.

Urinary Tract Infections in Children

Despite the American Academy of Pediatrics guidelines for the evaluation, treatment, and management of urinary tract infections (UTIs), UTI diagnosis and management remains challenging for clinicians. Challenges with acute UTI management stem from vague presenting signs and symptoms, diagnostic uncertainty, limitations in laboratory testing, and selecting appropriate antibiotic therapy in an era with increasing rates of antibiotic-resistant uropathogens. Recurrent UTI management remains difficult due to an incomplete understanding of the factors contributing to UTI, when to assess a child with repeated infections for kidney and urinary tract anomalies, and limited prevention strategies. To help reduce these uncertainties, this review provides a comprehensive overview of UTI epidemiology, risk factors, diagnosis, treatment, and prevention strategies that may help pediatricians overcome the challenges associated with acute and recurrent UTI management.

Urinary tract infections in very premature neonates: the definition dilemma

BACKGROUND AND OBJECTIVES

Data on urinary tract infections (UTIs) in very preterm neonates (VPTNs) are scarce. We aimed to (i) describe the characteristics of UTIs in VPTNs and (ii) compare the diagnostic practices of neonatal clinicians to established pediatric guidelines.

METHODS

All VPTNs (<29 weeks GA) with a suspected UTI at the CHU Sainte-Justine neonatal intensive care unit from January 1, 2014, and December 31, 2019, were included and divided into two definition categories: Possible UTI, and Definite UTI.

RESULTS

Most episodes were Possible UTI (87%). Symptoms of UTIs and pathogens varied based on the definition category. A positive urinalysis was obtained in 25%. Possible UTI episodes grew 2 organisms in 62% of cases and <50,000 CFU/mL in 62% of cases.

CONCLUSION

Characteristics of UTIs in VPTNs vary based on the definition category and case definitions used by clinicians differ from that of established pediatric guidelines.

Epidemiology, risk factors, and applicability of CDC definitions for healthcare-associated bloodstream infections at a level IV neonatal ICU

OBJECTIVES

We studied the epidemiology of primary bloodstream infections (BSIs), secondary BSIs, and central line-associated BSIs (CLABSIs) and applicability of CDC definitions for primary sources of infection causing secondary BSIs in patients in the neonatal ICU.

STUDY DESIGN

We classified healthcare-associated BSIs (HABSIs) as primary BSIs, secondary BSIs, and CLABSIs using CDC surveillance definitions and determined their overall incidence and incidence among different gestational age strata. We assessed the applicability of CDC definitions for infection sources causing secondary BSIs.

RESULTS

From 2010 to 2019, 141 (32.7%), 202 (46.9%), and 88 (20.4%) HABSIs were classified as primary BSIs, secondary BSIs, and CLABSIs, respectively; all declined during the study period (all p < 0.001). Gestational age <28 weeks was associated with increased incidence of all HABSI types. CDC criteria for site-specific primary sources were met in 137/202 (68%) secondary BSIs.

CONCLUSIONS

Primary and secondary BSIs were more common than CLABSIs and should be prioritized for prevention.

Procalcitonin, C-reactive protein, and erythrocyte sedimentation rate for the diagnosis of acute pyelonephritis in children

BACKGROUND

In children with urinary tract infection (UTI), only those with pyelonephritis (and not cystitis) are at risk for developing long-term renal sequelae. If non-invasive biomarkers could accurately differentiate children with cystitis from children with pyelonephritis, treatment and follow-up could potentially be individualized. This is an update of a review first published in 2015.

OBJECTIVES

The objectives of this review were to 1) determine whether procalcitonin (PCT), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) can replace the acute DMSA scan in the diagnostic evaluation of children with UTI; 2) assess the influence of patient and study characteristics on the diagnostic accuracy of these tests, and 3) compare the performance of the three tests to each other.

SEARCH METHODS

We searched MEDLINE, EMBASE, DARE, Web of Science, and BIOSIS Previews through to 17th December 2019 for this review. The reference lists of all included articles and relevant systematic reviews were searched to identify additional studies not found through the electronic search.

SELECTION CRITERIA

We only considered published studies that evaluated the results of an index test (PCT, CRP, ESR) against the results of an acute-phase ⁹⁹Tc-dimercaptosuccinic acid (DMSA) scan (conducted within 30 days of the UTI) in children aged 0 to 18 years with a culture-confirmed episode of UTI. The following cut-off values were used for the primary analysis: 0.5 ng/mL for procalcitonin, 20 mg/L for CRP and 30 mm/hour for ESR.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the selection criteria to all citations and independently abstracted data. We used the bivariate model to calculate pooled random-effects pooled sensitivity and specificity values.

MAIN RESULTS

A total of 36 studies met our inclusion criteria. Twenty-five studies provided data for the primary analysis: 12 studies (1000 children) included data on PCT, 16 studies (1895 children) included data on CRP, and eight studies (1910 children) included data on ESR (some studies had data on more than one test). The summary sensitivity estimates (95% CI) for the PCT, CRP, ESR tests at the aforementioned cut-offs were 0.81 (0.67 to 0.90), 0.93 (0.86 to 0.96), and 0.83 (0.71 to 0.91), respectively. The summary specificity values for PCT, CRP, and ESR tests at these cut-offs were 0.76 (0.66 to 0.84), 0.37 (0.24 to 0.53), and 0.57 (0.41 to 0.72), respectively.

AUTHORS' CONCLUSIONS

The ESR test does not appear to be sufficiently accurate to be helpful in differentiating children with cystitis from children with pyelonephritis. A low CRP value (< 20 mg/L) appears to be somewhat useful in ruling out pyelonephritis (decreasing the probability of pyelonephritis to < 20%), but unexplained heterogeneity in the data prevents us from making recommendations at this time. The procalcitonin test seems better suited for ruling in pyelonephritis, but the limited number of studies and the marked heterogeneity between studies prevents us from reaching definitive conclusions. Thus, at present, we do not find any compelling evidence to recommend the routine use of any of these tests in clinical practice.

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.

Urine neutrophil gelatinase-associated lipocalin and other biomarkers in infants with urinary tract infection and in febrile controls

BACKGROUND

Urine biomarkers are commonly used in the evaluation of acute kidney injury, and are gaining attention as tools for studying urinary tract infections (UTIs). We analyzed neutrophil gelatinase-associated lipocalin (NGAL) and seven other urine biomarkers to evaluate their usefulness in the diagnosis of UTI in infants.

METHODS

Eight urine biomarkers were analyzed in 108 infants with UTI. Controls were 64 febrile children without UTI and 13 healthy children. Logistic regression and construction of receiver operating characteristic (ROC) curves were performed for UTI patients versus febrile controls for all biomarkers.

RESULTS

The best biomarkers to differentiate between UTI and febrile controls were NGAL and interleukin 8 (IL8). Urine NGAL in absolute concentration and adjusted for creatinine had a sensitivity of 93% and 96% and a specificity of 95% and 100% for diagnosing UTI, with a cut-off concentration of 38 ng/mL and 233 ng/mg respectively.

CONCLUSIONS

Urine biomarkers, particularly NGAL, can aid in the diagnosis of UTI among febrile infants. The results suggest that in infants with fever and high NGAL, UTI is most likely, whereas in infants with fever and low NGAL, other causes of fever should be looked for.

Dimercaptosuccinic acid scan or ultrasound in screening for vesicoureteral reflux among children with urinary tract infections

BACKGROUND

There is considerable interest in detecting vesicoureteral reflux (VUR) because its presence, especially when severe, has been linked to an increased risk of urinary tract infections and renal scarring. Voiding cystourethrography (VCUG), also known as micturating cystourethrography, is the gold standard for the diagnosis of VUR, and the grading of its severity. Because VCUG requires bladder catheterisation and exposes children to radiation, there has been a growing interest in other screening strategies that could identify at-risk children without the risks and discomfort associated with VCUG.

OBJECTIVES

The objective of this review is to evaluate the accuracy of two alternative imaging tests - the dimercaptosuccinic acid renal scan (DMSA) and renal-bladder ultrasound (RBUS) - in diagnosing VUR and high-grade VUR (Grade III-V VUR).

SEARCH METHODS

We searched MEDLINE, EMBASE, BIOSIS, and the Cochrane Register of Diagnostic Test Accuracy Studies from 1985 to 31 March 2016. The reference lists of relevant review articles were searched to identify additional studies not found through the electronic search.

SELECTION CRITERIA

We considered published cross-sectional or cohort studies that compared the results of the index tests (DMSA scan or RBUS) with the results of radiographic VCUG in children less than 19 years of age with a culture-confirmed urinary tract infection.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the selection criteria to all citations and independently abstracted data. We used the bivariate model to calculate summary sensitivity and specificity values.

MAIN RESULTS

A total of 42 studies met our inclusion criteria. Twenty studies reported data on the test performance of RBUS in detecting VUR; the summary sensitivity and specificity estimates were 0.44 (95% CI 0.34 to 0.54) and 0.78 (95% CI 0.68 to 0.86), respectively. A total of 11 studies reported data on the test performance of RBUS in detecting high-grade VUR; the summary sensitivity and specificity estimates were 0.59 (95% CI 0.45 to 0.72) and 0.79 (95% CI 0.65 to 0.87), respectively. A total of 19 studies reported data on the test performance of DMSA in detecting VUR; the summary sensitivity and specificity estimates were 0.75 (95% CI 0.67 to 0.81) and 0.48 (95% CI 0.38 to 0.57), respectively. A total of 10 studies reported data on the accuracy of DMSA in detecting high-grade VUR. The summary sensitivity and specificity estimates were 0.93 (95% CI 0.77 to 0.98) and 0.44 (95% CI 0.33 to 0.56), respectively.

AUTHORS' CONCLUSIONS

Neither the renal ultrasound nor the DMSA scan is accurate enough to detect VUR (of all grades). Although a child with a negative DMSA test has an < 1% probability of having high-grade VUR, performing a screening DMSA will result in a large number of children falsely labelled as being at risk for high-grade VUR. Accordingly, the usefulness of the DMSA as a screening test for high-grade VUR should be questioned.

Diagnosis of Urinary Tract Infections in Children

Urinary tract infections (UTIs) are a common occurrence in children. The management and laboratory diagnosis of these infections pose unique challenges that are not encountered in adults. Important factors, such as specimen collection, urinalysis interpretation, culture thresholds, and antimicrobial susceptibility testing, require special consideration in children and will be discussed in detail in the following review.

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.

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.

Evaluation of new American Academy of Pediatrics guideline for febrile urinary tract infection

PURPOSE

To evaluate the practical applications of the diagnosis algorithms recommended by the American Academy of Pediatrics urinary tract infection (UTI) guideline.

METHODS

We retrospectively reviewed the medical records of febrile UTI patients aged between 2 and 24 months. The patients were divided into 3 groups: group I (patients with positive urine culture and urinalysis findings), group II (those with positive urine culture but negative urinalysis findings), and group III (those with negative urine culture but positive urinalysis findings). Clinical, laboratory, and imaging results were analyzed and compared between the groups.

RESULTS

A total of 300 children were enrolled. The serum C-reactive protein level was lower in children in group II than in those in groups I and III (P<0.05). Children in group I showed a higher frequency of hydronephrosis than those in groups II and III (P<0.05). However, the frequencies of acute pyelonephritis (APN), vesicoureteral reflux (VUR), renal scar, and UTI recurrence were not different between the groups. In group I, recurrence of UTI and presence of APN were associated with the incidence of VUR (recurrence vs. no recurrence: 40% vs.11.4%; APN vs. no APN: 23.3% vs. 9.2%; P<0.05). The incidence of VUR and APN was not related to the presence of hydronephrosis.

CONCLUSION

UTI in febrile children cannot be ruled out solely on the basis of positive urinalysis or urine culture findings. Recurrence of UTI and presence of APN may be reasonable indicators of the presence of VUR.

Do English NHS Microbiology laboratories offer adequate services for the diagnosis of UTI in children? Healthcare Quality Improvement Partnership (HQIP) Audit of Standard Operational Procedures

The National Institute of Care Excellence (NICE) 2007 guidance CG54, on urinary tract infection (UTI) in children, states that clinicians should use urgent microscopy and culture as the preferred method for diagnosing UTI in the hospital setting for severe illness in children under 3 years old and from the GP setting in children under 3 years old with intermediate risk of severe illness. NICE also recommends that all 'infants and children with atypical UTI (including non-Escherichia coli infections) should have renal imaging after a first infection'. We surveyed all microbiology laboratories in England with Clinical Pathology Accreditation to determine standard operating procedures (SOPs) for urgent microscopy, culture and reporting of children's urine and to ascertain whether the SOPs facilitate compliance with NICE guidance. We undertook a computer search in six microbiology laboratories in south-west England to determine urine submissions and urine reports in children under 3 years. Seventy-three per cent of laboratories (110/150) participated. Enterobacteriaceae that were not E. coli were reported only as coliforms (rather than non-E. coli coliforms) by 61% (67/110) of laboratories. Eighty-eight per cent of laboratories (97/110) provided urgent microscopy for hospital and 54% for general practice (GP) paediatric urines; 61% of laboratories (confidence interval 52-70%) cultured 1 μl volume of urine, which equates to one colony if the bacterial load is 106 c.f.u. l(-1). Only 22% (24/110) of laboratories reported non-E. coli coliforms and provided urgent microscopy for both hospital and GP childhood urines; only three laboratories also cultured a 5 μl volume of urine. Only one of six laboratories in our submission audit had a significant increase in urine submissions and urines reported from children less than 3 years old between the predicted pre-2007 level in the absence of guidance and the 2008 level following publication of the NICE guidance. Less than a quarter of laboratories were providing a service that would allow clinicians to fully comply with the first line recommendations in the 2007 NICE UTI in children guidance. Laboratory urine submission report figures suggest that the guidance has not led to an increase in diagnosis of UTI in children under 3 years old.

Validity of bag urine culture for predicting urinary tract infections in febrile infants: a paired comparison of urine collection methods

Purpose

Catheter urine (CATH-U) and suprapubic aspiration (SPA) are reliable urine collection methods for confirming urinary tract infections (UTI) in infants. However, noninvasive and easily accessible collecting bag urine (CBU) is widely used, despite its high contamination rate. This study investigated the validity of CBU cultures for diagnosing UTIs, using CATH-U culture results as the gold standard.

Methods

We retrospectively analyzed 210 infants, 2- to 24-month-old, who presented to a tertiary care hospital's pediatrics department between September 2008 and August 2013. We reviewed the results of CBU and CATH-U cultures from the same infants.

Results

CBU results, relative to CATH-U culture results (≥10⁴ colony-forming units [CFU]/mL) were widely variable, ranging from no growth to ≥10⁵ CFU/mL. A CBU cutoff value of ≥10⁵ CFU/mL resulted in false-positive and false-negative rates of 18% and 24%, respectively. The probability of a UTI increased when the CBU bacterial count was ≥10⁵/mL for all infants, both uncircumcised male infants and female infants (likelihood ratios [LRs], 4.16, 4.11, and 4.11, respectively). UTIs could not be excluded for female infants with a CBU bacterial density of 10⁴-10⁵ (LR, 1.40). The LRs for predicting UTIs based on a positive dipstick test and a positive urinalysis were 4.19 and 3.11, respectively.

Conclusion

The validity of obtaining urine sample from a sterile bag remains questionable. Inconclusive culture results from CBU should be confirmed with a more reliable method.

Procalcitonin, C-reactive protein, and erythrocyte sedimentation rate for the diagnosis of acute pyelonephritis in children

BACKGROUND

In children with urinary tract infection (UTI), only those with pyelonephritis (and not cystitis) are at risk for developing long-term renal sequelae. If non-invasive biomarkers could accurately differentiate children with cystitis from children with pyelonephritis, treatment and follow-up could potentially be individualized.

OBJECTIVES

The objectives of this review were to 1) determine whether procalcitonin, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) can replace the acute DMSA scan in the diagnostic evaluation of children with UTI; 2) assess the influence of patient and study characteristics on the diagnostic accuracy of these tests, and 3) compare the performance of the three tests to each other.

SEARCH METHODS

We searched MEDLINE, EMBASE, DARE, Web of Science, and BIOSIS Previews for this review. The reference lists of all included articles and relevant systematic reviews were searched to identify additional studies not found through the electronic search.

SELECTION CRITERIA

We only considered published studies that evaluated the results of an index test (procalcitonin, CRP, ESR) against the results of an acute-phase DMSA scan (conducted within 30 days of the UTI) in children aged 0 to 18 years with a culture-confirmed episode of UTI. The following cutoff values were used for the primary analysis: 0.5 ng/mL for procalcitonin, 20 mg/L for CRP and 30 mm/h for ESR.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the selection criteria to all citations and independently abstracted data. We used the bivariate model to calculate pooled random-effects pooled sensitivity and specificity values.

MAIN RESULTS

A total of 24 studies met our inclusion criteria. Seventeen studies provided data for the primary analysis: six studies (434 children) included data on procalcitonin, 13 studies (1638 children) included data on CRP, and six studies (1737 children) included data on ESR (some studies had data on more than one test). The summary sensitivity estimates (95% CI) for the procalcitonin, CRP, ESR tests at the aforementioned cutoffs were 0.86 (0.72 to 0.93), 0.94 (0.85 to 0.97), and 0.87 (0.77 to 0.93), respectively. The summary specificity values for procalcitonin, CRP, and ESR tests at these cutoffs were 0.74 (0.55 to 0.87), 0.39 (0.23 to 0.58), and 0.48 (0.33 to 0.64), respectively.

AUTHORS' CONCLUSIONS

The ESR test does not appear to be sufficiently accurate to be helpful in differentiating children with cystitis from children with pyelonephritis. A low CRP value (< 20 mg/L) appears to be somewhat useful in ruling out pyelonephritis (decreasing the probability of pyelonephritis to < 20%), but unexplained heterogeneity in the data prevents us from making recommendations at this time. The procalcitonin test seems better suited for ruling in pyelonephritis, but the limited number of studies and the marked heterogeneity between studies prevents us from reaching definitive conclusions. Thus, at present, we do not find any compelling evidence to recommend the routine use of any of these tests in clinical practice.

Association between UTI and urinary tract abnormalities: a case-control study in Erbil City/Iraq

OBJECTIVE

To determine the proportion of ultrasound abnormalities of the urinary system between two groups of children: affected with urinary tract infection (UTI) and unaffected (control). Further, to determine the most common microorganisms causing UTI in those children with urinary tract abnormalities.

METHODS

A case-control study was carried out in Erbil, Iraq between September and December 2012. Ultrasound examinations were carried out on 64 children affected with UTI and on 64 unaffected with UTI (control) in order to detect differences, in the presence of abnormalities, in the urinary tract between the two groups.

RESULTS

A majority (59.4%) of children affected with UTI had ultrasound abnormalities, compared with 26.6% of the control group (P<0.001). Escherichia coli was the most common microorganism in both groups, although the difference was not statistically significant. More than one half (75%) of patients with UTI were female, compared with 25% who were male (P<0.001).

CONCLUSION

More than one half of the children in the present study who presented with UTI were found to have ultrasound abnormalities. E. coli was the most common causative pathogen for children with or without ultrasound abnormalities.

Overactive bladder in women: does low-count bacteriuria matter? A review

Since the description of the overactive bladder (OAB) syndrome, which excludes infection, the precise definition of significant bacteriuria in these women is critical. The traditional definition of 'significant' bacteriuria is >10(5) colony-forming units/ml which was described 50 years ago by a renal physician whose primary interest was the prevention of pyelonephritis. Subsequent studies have shown this to be an insensitive threshold in women with acute lower urinary tract symptoms. Bacterial counts between 10(2) and 10(5) CFU/ml ('low-count bacteriuria') are now considered important in women with acute dysuria and warrant treatment. However, these findings have been slow to translate into routine clinical practice. In addition, the role of low-count bacteriuria in women with OAB symptoms (frequency/urgency/nocturia) without dysuria is poorly studied. One recent study has shown low-count bacteriuria to be more prevalent among women with severe OAB than bacteriuria >10(5) CFU/ml. We present an outline of the history of this issue and summarise current microbiological and clinical concepts.

External quality control results of urine dip-slide devices

Urinary tract infections are frequently diagnosed by using urine dip-slide devices, especially in medical practices and small laboratories. We performed a retrospective analysis of more than 3000 results obtained by several urine dip-slide devices during external quality control surveys. We found that an underestimation of bacterial counts and a difficulty in identifying mixed flora were relatively more frequent in medical practices than in specialized laboratories, and that regular participation in external quality control surveys correlates with better performances.

A comparative study on bacterial cultures of urine samples obtained by clean-void technique versus urethral catheterization

Contamination during urine collection causes difficulty in diagnosing infantile urinary tract infection (UTI). Though considered a gold-standard, suprapubic aspiration is traumatic and not always successful. Catheterization and clean void technique were often preferred but their relative usefulness has not been compared.

OBJECTIVES

To compare the culture results of clean void urine (CVU) and catheter urine (CathU) from children below 2-years old known to have no UTI. We tested whether the false-positive rates of CVU were significantly different from that of CathU.

METHODS

Paired CVU and CathU samples were collected from asymptomatic children admitted for micturiting cystourethrogram, and tested for leucocytes and nitrite, and bacterial culture using standard laboratory methods.

RESULTS

Culture results for 98 children (82 boys, 16 girls; aged 6 +/- 4.3 months) were analysed. Analysis by presence/absence of growths showed good agreement between CVU and CathU for boys (Kappa 0.42) but poor for girls (Kappa 0.18). When analysed by colony counts, agreement was poor with CVU yielding more counts than CathU (Kappa 0.1 for boys and 0.04 for girls). If all mixed growth results were considered as contaminants, the false positive rates for CathU and CVU were similar whether the cut-off was defined as 10(3), 10(4) or 10(5)/mL. If mixed growth was believed to cause UTI, CathU produced less false-positive rates than CVU, though both rates were unacceptably high.

CONCLUSION

In uncircumcized boys, both CVU and CathU were prone to contamination. Though the contaminating bacterial counts were lower in CathU culture, the false-positive rates were high with the lower cut-off CFUs. Contrary to previous recommendations, CathU should be interpreted similar to CVU to avoid false positive diagnosis of UTI.

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).