Using a urine dipstick to identify a positive urine culture in young febrile infants is as effective as in older patients

Urinary tract infections in young infants with a normal urine dipstick

AIM

To assess missed urinary tract infections (UTI) in febrile infants ≤2 months when adhering to recent guidelines suggesting not to send a urine culture with a negative dipstick.

METHODS

A retrospective cohort study of 308 infants ≤2 months with a positive urine culture admitted in 2013-2023, divided into subgroups without exposure to urine dipstick results: 'urosepsis' (UTI with bacteraemia), 'UTI' (positive urine culture, elevated inflammatory markers, no other cause of fever) and 'bacteriuria' (positive urine culture, not meeting the above-mentioned criteria). After retrieving the dipstick results, the 'missed UTI' group (UTI+ negative dipstick) was described.

RESULTS

A negative dipstick was found in 2/20 (10%), 32/127 (25%) and 126/161 (78%) of infants with 'urosepsis', 'UTI' and 'bacteriuria', respectively. In the 'missed UTI' group (n = 34), there were more non-Escherichia coli UTI (68% vs. 9% with positive dipstick, p < 0.001), and lower inflammatory markers (leukocytes 15.5 vs. 17.2 k/μL, p = 0.007, C-reactive protein 21 vs. 58 mg/L, p < 0.001). Three infants had high-grade vesicoureteral reflux (VUR) and renal scarring.

CONCLUSIONS

There is a non-negligible rate of infants ≤2 months with UTI and without pyuria, including those with urosepsis, VUR and renal scarring. We suggest obtaining a urine culture regardless of dipstick results.

Conundrums in the Management of Febrile Infants under Three Months of Age and Future Research

Febrile infants under three months of age pose a diagnostic challenge to clinicians. Unlike in older children, the rates of invasive bacterial infections (IBIs), such as bacteraemia or meningitis, are high. This greater risk of IBI combined with the practical challenges of assessing young infants results in a cautious approach with many febrile infants receiving parenteral antibiotics "just in case". However, there is a range of validated tailored care guidelines that support targeted investigation and management of febrile infants, with a cohort identified as lower risk suitable for fewer invasive procedures and observation without parenteral antibiotics. This manuscript outlines five common conundrums related to the safe application of tailored-care guidelines for the assessment and management of febrile infants under three months of age. It also explores future research which aims to further refine the management of febrile infants.

Multicentre Delphi study of physicians resulted in quality indicators for young infants with fever without source in emergency departments

AIM

Managing febrile infants has evolved without a generally accepted standard of care. We aimed to design quality indicators for managing infants ≤90 days old presenting to emergency departments (EDs) with fever without source.

METHODS

This multicentre Delphi study was carried out by the Febrile Infant Study Group of the Spanish Paediatric Emergency Research Network, from March 2021 to November 2021, and included paediatric emergency physicians from 24 Spanish EDs. A list of care standards was produced, following an extensive literature review and the involvement of all parties. Indicators were essential if they were voted by four panelists and also received a score of ≥4 from at least 95% of the 24 investigators.

RESULTS

We established 20 indicators, including one related to having a protocol, two to triage, nine to diagnostic processes, six to treatment and two to disposition. The following indicators were considered essential: having an ED management protocol, performing urinalysis on every infant, obtaining a blood culture from every infant and administering antibiotics in the ED to any febrile infant who did not appear well.

CONCLUSION

The Delphi method resulted in a comprehensive list of quality indicators for managing febrile young infants in Spanish EDs.

Diagnostic test accuracy of dipstick urinalysis for diagnosing urinary tract infection in febrile infants attending the emergency department

OBJECTIVE

To report the diagnostic test accuracy of dipstick urinalysis for the detection of urinary tract infections (UTIs) in febrile infants aged 90 days or less attending the emergency department (ED).

DESIGN

Retrospective cohort study.

PATIENTS

Febrile infants aged 90 days or less attending between 31 August 2018 and 1 September 2019.

MAIN OUTCOME MEASURES

The sensitivity, specificity and predictive values of dipstick urinalysis in detecting UTIs defined as growth of ≥100 000 cfu/mL of a single organism and the presence of pyuria (>5 white blood cells per high-power field).

SETTING

Eight paediatric EDs in the UK/Ireland.

RESULTS

A total of 275 were included in the final analysis. There were 252 (92%) clean-catch urine samples and 23 (8%) were transurethral bladder catheter samples. The median age was 51 days (IQR 35-68.5, range 1-90), and there were 151/275 male participants (54.9%). In total, 38 (13.8%) participants had a confirmed UTI. The most sensitive individual dipstick test for UTI was the presence of leucocytes. Including 'trace' as positive resulted in a sensitivity of 0.87 (95% CI 0.69 to 0.94) and a specificity of 0.73 (95% CI 0.67 to 0.79). The most specific individual dipstick test for UTI was the presence of nitrites. Including trace as positive resulted in a specificity of 0.91 (95% CI 0.86 to 0.94) and a sensitivity of 0.42 (95% CI 0.26 to 0.59).

CONCLUSION

Point-of-care urinalysis is moderately sensitive and highly specific for diagnosing UTI in febrile infants. The optimum cut-point to for excluding UTI was leucocytes (1+), and the optimum cut-point for confirming UTI was nitrites (trace).

TRIAL REGISTRATION NUMBER

NCT04196192.

A nomogram for predicting the development of serious bacterial infections in febrile term neonates: A single medical center experience in Southern Taiwan

BACKGROUND

Serious bacterial infections (SBIs) could lead to mortality or severe long-term sequelae in neonates and infants aged <3 months. Accordingly, the aim of this study was to develop a quantitative and accurate assessment tool for predicting the risk of SBIs in febrile neonates.

METHODS

This retrospective study enrolled 131 febrile term neonates (aged <30 days) who were hospitalized at Kaohsiung Veterans General Hospital between January 2005 and December 2020. These neonates were classified into SBI and nonbacterial infection (NBI) groups on the basis of microbiological laboratory reports. The clinical characteristics and routine blood tests of both groups at the time of admission were analyzed. Stepwise logistic regression was applied to create and validate the nomogram for SBI prediction.

RESULTS

Among the 131 febrile neonates, 38 and 93 developed SBIs and NBIs, respectively. At the time of admission, ill clinical appearance, serum myelocyte/metamyelocyte presence, C-reactive protein (CRP) > 2.5 mg/dL, and pyuria were associated with an increased risk of SBIs. Accordingly, these four factors were used to develop a nomogram for SBI prediction, which exhibited significantly high performance (area under curve = 0.848, p < 0.001) in predicting SBI risk.

CONCLUSION

We developed a nomogram combining clinical appearance, serum myelocyte/metamyelocyte presence, CRP, and pyuria for predicting SBI risk in febrile neonates. This tool can assist clinicians in making early diagnoses and delivering the appropriate treatment.

Contamination in Urine Samples Collected Using Bladder Stimulation and Clean Catch Versus Urinary Catheterization in Infants Younger Than 90 Days

OBJECTIVES

The objective of this study was to compare the risk of contamination for urine samples collected from patients younger than 90 days using 2 different techniques: bladder stimulation and "clean catch" (CC) and urinary catheterization (CATH).

METHODS

A case-control study was carried out in the pediatric emergency room of a tertiary hospital between January 2016 and September 2017. All urine samples collected from patients younger than 90 days by CC or CATH were included. The incidence of contaminated urine samples was compared for both methods, and the risk of contamination was estimated using univariate and multivariate analyses.

RESULTS

A total of 473 urine samples were collected, 310 via CATH (65.5%) and 163 via CC (34.5%). The median age was 1.4 months (interquartile range, 0.8-2.1 months), and 54.1% were males. Seventeen patients had a history of urinary tract infection (3.6%), and 16 were diagnosed with a congenital urorenal anomaly (3.4%). Sixteen urine samples were found to be contaminated (3.4%): 5 collected via CATH (1.6%) and 11 via CC (6.8%). The univariate analysis revealed a greater risk of contamination in specimens obtained using CC versus CATH (odds ratio, 4.41; 95% confidence interval, 1.51-12.93), and the multivariate analysis confirmed CC collection as an independent risk factor for contamination (odds ratio, 5.61; 95% confidence interval, 1.83-17.19).

CONCLUSIONS

The number of contaminated urine samples in infants younger than 90 days in our pediatric emergency department is low. However, using the CC urine collection technique seems to be an independent risk factor for sample contamination.

Diagnostic value of biomarkers for paediatric urinary tract infections in primary care: systematic review and meta-analysis

Background

Accurate diagnosis of urinary tract infection is essential as children left untreated may suffer permanent renal injury.

Aim

To compare the diagnostic values of biomarkers or clinical prediction rules for urinary tract infections in children presenting to ambulatory care.

Design and setting

Systematic review and meta-analysis of ambulatory care studies.

Methods

Medline, Embase, WOS, CINAHL, Cochrane library, HTA and DARE were searched until 21 May 2021. We included diagnostic studies on urine or blood biomarkers for cystitis or pyelonephritis in children below 18 years of age. We calculated sensitivity, specificity and likelihood ratios. Data were pooled using a bivariate random effects model and a Hierarchical Summary Receiver Operating Characteristic analysis.

Results

Seventy-five moderate to high quality studies were included in this review and 54 articles in the meta-analyses. The area under the receiver-operating-characteristics curve to diagnose cystitis was 0.75 (95%CI 0.62 to 0.83, n = 9) for C-reactive protein, 0.71 (95% CI 0.62 to 0.80, n = 4) for procalcitonin, 0.93 (95% CI 0.91 to 0.96, n = 22) for the dipstick test (nitrite or leukocyte esterase ≥trace), 0.94 (95% CI 0.58 to 0.98, n = 9) for urine white blood cells and 0.98 (95% CI 0.92 to 0.99, n = 12) for Gram-stained bacteria. For pyelonephritis, C-reactive protein < 20 mg/l had LR- of 0.10 (95%CI 0.04–0.30) to 0.22 (95%CI 0.09–0.54) in children with signs suggestive of urinary tract infection.

Conclusions

Clinical prediction rules including the dipstick test biomarkers can support family physicians while awaiting urine culture results. CRP and PCT have low accuracy for cystitis, but might be useful for pyelonephritis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-021-01530-9.

Clinical Features for the Diagnosis of Pediatric Urinary Tract Infections: Systematic Review and Meta-Analysis

PURPOSE

Accurate diagnosis of urinary tract infection in children is essential because children left untreated can experience permanent renal injury. We aimed to assess the diagnostic value of clinical features of pediatric urinary tract infection.

METHODS

We performed a systematic review and meta-analysis of diagnostic test accuracy studies in ambulatory care. We searched the PubMed, Embase, Web of Science, Cumulative Index to Nursing and Allied Health Literature, Cochrane Central Register of Controlled Trials, Health Technology Assessment, and Database of Abstracts of Reviews of Effects databases from inception to January 27, 2020 for studies reporting 2 × 2 diagnostic accuracy data for clinical features compared with urine culture in children aged <18 years. For each clinical feature, we calculated likelihood ratios and posttest probabilities of urinary tract infection. To estimate summary parameters, we conducted a bivariate random effects meta-analysis and hierarchical summary receiver operating characteristic analysis.

RESULTS

A total of 35 studies (N = 78,427 patients) of moderate to high quality were included, providing information on 58 clinical features and 6 prediction rules. Only circumcision (negative likelihood ratio [LR-] 0.24; 95% CI, 0.08-0.72; n = 8), stridor (LR- 0.20; 95% CI, 0.05-0.81; n = 1), and diaper rash (LR- 0.13; 95% CI, 0.02-0.92; n = 1) were useful for ruling out urinary tract infection. Body temperature or fever duration showed limited diagnostic value (area under the receiver operating characteristic curve 0.61; 95% CI, 0.47-0.73; n = 16). The Diagnosis of Urinary Tract Infection in Young Children score, Gorelick Scale score, and UTIcalc (https://uticalc.pitt.edu) might be useful to identify children eligible for urine sampling.

CONCLUSIONS

Few clinical signs and symptoms are useful for diagnosing or ruling out urinary tract infection in children. Clinical prediction rules might be more accurate; however, they should be validated externally. Physicians should not restrict urine sampling to children with unexplained fever or other features suggestive of urinary tract infection.

Prevalence of Bacterial Meningitis Among Febrile Infants Aged 29-60 Days With Positive Urinalysis Results: A Systematic Review and Meta-analysis

IMPORTANCE

Fever in the first months of life remains one of the most common pediatric problems. Urinary tract infections are the most frequent serious bacterial infections in this population. All published guidelines and quality initiatives for febrile young infants recommend lumbar puncture (LP) and cerebrospinal fluid (CSF) testing on the basis of a positive urinalysis result to exclude bacterial meningitis as a cause. For well infants older than 28 days with an abnormal urinalysis result, LP remains controversial.

OBJECTIVE

To assess the prevalence of bacterial meningitis among febrile infants 29 to 60 days of age with a positive urinalysis result to evaluate whether LP is routinely required.

DATA SOURCES

MEDLINE and Embase were searched for articles published from January 1, 2000, to July 25, 2018, with deliberate limitation to recent studies. Before analysis, the search was repeated (October 6, 2019) to ensure that new studies were included.

STUDY SELECTION

Studies that reported on healthy, full-term, well-appearing febrile infants 29 to 60 days of age for whom patient-level data could be ascertained for urinalysis results and meningitis status were included.

DATA EXTRACTION AND SYNTHESIS

Data were extracted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and used the Newcastle-Ottawa Scale to assess bias. Pooled prevalences and odds ratios (ORs) were estimated using random-effect models.

MAIN OUTCOMES AND MEASURES

The primary outcome was the prevalence of culture-proven bacterial meningitis among infants with positive urinalysis results. The secondary outcome was the prevalence of bacterial meningitis, defined by CSF testing or suggestive history at clinical follow-up.

RESULTS

The parent search yielded 3227 records; 48 studies were included (17 distinct data sets of 25 374 infants). The prevalence of culture-proven meningitis was 0.44% (95% CI, 0.25%-0.78%) among 2703 infants with positive urinalysis results compared with 0.50% (95% CI, 0.33%-0.76%) among 10 032 infants with negative urinalysis results (OR, 0.74; 95% CI, 0.39-1.38). The prevalence of bacterial meningitis was 0.25% (95% CI, 0.14%-0.45%) among 4737 infants with meningitis status ascertained by CSF testing or clinical follow-up and 0.28% (95% CI, 0.21%-0.36%) among 20 637 infants with positive and negative urinalysis results (OR, 0.89; 95% CI, 0.48-1.68).

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis, the prevalence of bacterial meningitis in well-appearing febrile infants 29 to 60 days of age with positive urinalysis results ranged from 0.25% to 0.44% and was not higher than that in infants with negative urinalysis results. These results suggest that for these infants, the decision to use LP should not be guided by urinalysis results alone.

External Validation of an Invasive Bacterial Infection Score for Young Febrile Infants

OBJECTIVES

The Aronson rule is a point-based clinical decision rule for the identification of febrile infants ≤60 days of age at low risk of invasive bacterial infection (IBI) in the emergency department. This rule uses variables of temperature, age, urinalysis, and absolute neutrophil count. We sought to externally validate this decision rule.

METHODS

We conducted a secondary analysis of a multicenter prospective cohort of febrile infants ≤60 days old presenting to the emergency department between December 2008 and May 2013. Infants were excluded if they had clinical sepsis or chronic conditions or were missing any laboratory components of the Aronson score. Our outcome was IBI (bacteremia and/or bacterial meningitis). We assessed the accuracy of the Aronson rule by reporting metrics of diagnostic accuracy with 95% confidence intervals (CIs) at different point thresholds.

RESULTS

Of 4130 included patients (780 <21 days of age; 2362 boys), 87 (2.1%) had an IBI, including 65 with isolated bacteremia and 22 with meningitis. Using an Aronson cutoff score of 2 resulted in a sensitivity of 93.1% (95% CI 85.6%-97.4%), specificity of 26.6% (95% CI 25.3%-28.0%), and negative predictive value of 99.4% (95% CI 98.8%-99.8%). Six patients with IBI (3 with bacterial meningitis) were misclassified as low risk when using a threshold of 2.

CONCLUSIONS

The Aronson rule demonstrates metrics of diagnostic accuracy that are comparable to the derivation study. Our findings suggest that the rule may be generalizable for the risk stratification of well-appearing febrile infants.

Catheter-obtained, Enterococcus and Proteus positive urine cultures may represent mostly contamination or asymptomatic bacteriuria in infants <90 days

BACKGROUND

Urinary tract infection (UTI) diagnosis in infants is often made by a positive urine culture result, regardless of urine dipstick findings.

AIM

To assess parameters that may affect positive urine culture results interpretation in infants, including dipstick performance, obtainment method, bacteria type, age and laboratory results.

METHODS

A retrospective, cohort study. Infants <90 days with urine dipstick and culture obtained through subrapubic aspiration (SPA) or catheter, 2015-2016, were included.

RESULTS

Overall, 19% (129/678) of cultures were positive. The dipstick sensitivity was 51% for all cultures; 66%, 47%, 15% and 10% for Escherichia coli (n= 71), Klebsiella (n= 19), Enterococcus (n= 34) and Proteus (n= 10), respectively (p<.001). Sensitivity was higher in SPA vs. catheter for all cultures (67% vs. 43%); E. coli (78% vs. 59%); and Klebsiella (88% vs. 18%). For Enterococcus, dipstick sensitivity was low in both SPA and catheter (0-16%). All Proteus episodes were catheter obtained. Positive culture with negative dipstick and Enterococcus episodes had lower C-reactive protein levels, and higher proportion of mixed infection compared with positive dipstick and E. coli episodes.

CONCLUSIONS

Urine cultures in infants should be obtained by SPA, since catheter-obtained, Enterococcus and Proteus positive cultures may represent contamination or asymptomatic bacteriuria, rather than true UTI.

A positive nitrite test was an independent risk factor for invasive bacterial infections in infants under 90 days of age with fever without source

AIM

This study analysed the association between a positive nitrite dipstick test and an invasive bacterial infection (IBI) in infants younger than 90 days of age with fever without source (FWS).

METHODS

We performed a secondary analysis of data from a prospective multicentre study of infants up to 90 days of age with FWS undergoing care in 19 paediatric EDs between October 2011 and September 2013. Invasive bacterial infection was defined as a positive blood or cerebrospinal fluid culture.

RESULTS

The dipstick urinalysis was positive for nitrite or leucocyte esterase in 766 (22.5%) of the 3401 infants we studied, and 270 (35.2%) had a dipstick test that was just positive for nitrite. Overall, 107 were diagnosed with an IBI (3.1%). The IBI prevalence was 2.2% among patients with a normal urine dipstick, 4.4% if they had positive leucocyte esterase test results, 8.3% where the nitrite test was positive and 10.6% when both tests were positive. After multivariate analysis, a positive nitrite test remained an independent risk factor for IBI (odds ratio 2.7, 95% confidence interval 1.4-4.9).

CONCLUSION

In infants under 90 days of age with FWS, a positive nitrite urine dipstick test was an independent risk factor for IBI.

Updated Italian recommendations for the diagnosis, treatment and follow-up of the first febrile urinary tract infection in young children

AIM

Our aim was to update the recommendations for the diagnosis, treatment and follow-up of the first febrile urinary tract infection in young children, which were endorsed in 2012 by the Italian Society of Pediatric Nephrology.

METHODS

The Italian recommendations were revised on the basis of a review of the literature published from 2012 to October 2018. We also carried out an ad hoc evaluation of the risk factors to identify children with high-grade vesicoureteral reflux or renal scarring, which were published in the previous recommendations. When evidence was not available, the working group held extensive discussions, during various meetings and through email exchanges.

RESULTS

Four major modifications have been introduced. The method for collecting urine for culture and its interpretation has been re-evaluated. We have reformulated the algorithm that guides clinical decisions to proceed with voiding cystourethrography. The suggested antibiotics have been revised, and we have recommended further restrictions of the use of antibiotic prophylaxis.

CONCLUSION

These updated recommendations have now been endorsed by the Italian Society of Pediatric Nephrology and the Italian Society for Pediatric Infectivology. They can also be used to compare other recommendations that are available, as a worldwide consensus in this area is still lacking.

Bacterial meningitis in febrile young infants acutely assessed for presumed urinary tract infection: a systematic review

Urinary tract infections, the most common severe bacterial infections in young infants, may be associated with co-existing meningitis. There is no consensus on when to perform a lumbar puncture in these infants. Our aim was to quantify the frequency of co-existing bacterial meningitis in febrile young infants acutely assessed for presumed urinary tract infections. We systematically reviewed PubMed, EMBASE, and the Cochrane Library for studies including infants ≤ 3 months with suspected/confirmed urinary tract infections, who underwent a lumbar puncture. Two investigators independently reviewed articles for inclusion and extracted relevant data. Our outcomes were culture-confirmed meningitis and identification of low-/high-risk criteria of meningitis. Overall 20/2079 studies, including 4191 infants, met inclusion criteria. A total of 11 infants had bacterial meningitis (frequency between 0 and 2.1% across studies) and were mostly neonates. Of 253 infants meeting the low-risk criteria (well-appearing, age > 21 days, procalcitonin ≤ 0.5 ng/ml, and C reactive protein ≤ 20 mg/L) none developed meningitis, but only 15 underwent lumbar puncture.Conclusion: Co-existing bacterial meningitis in febrile young infants with urinary tract infection is rare. In those meeting low-risk criteria, a lumbar puncture may not be indicated. A case by case assessment should be made in infants not meeting low-risk criteria.Trial registration: CRD42018105339 What is known: • When caring for febrile infants ≤ 3 months with urinary tract infections, clinicians may have uncertainty on whether to perform a lumbar puncture (LP) for possible co-existing meningitis What is new: • An up-to-date systematic review of 20 studies found the frequency of co-existing meningitis in this population to be between 0 and 2.1% • Despite limited data, an LP may not be indicated in infants meeting low-risk criteria (being well-appearing, age > 21 days, procalcitonin ≤ 0.5 ng/ml, C reactive protein ≤ 20 mg/L). Ill-appearance and neonatal age appear to be significant risk factors of co-existing meningitis.

Management of febrile infants aged 1 month and less than 3 months in a French university hospital: Clinical practice evaluation

BACKGROUND

Management of febrile infants is challenging due to the increased risk of serious bacterial infections and it varies among physicians and hospitals. The goals of this study were to describe and compare the management of febrile infants aged 1-2 months in a hospital in 2011 and 2016.

METHODS

We conducted a retrospective study in the Bordeaux Pellegrin University Hospital, France, in 2011 and 2016. All infants aged 1-2 months with diagnosis codes referring to fever were included. Data on infant characteristics, fever episodes, clinical symptoms, and management were collected from medical charts. Univariate analyses and multivariate logistic models were used.

RESULTS

A total of 530 infants were included; 89.2% had blood testing and 81.1% urine testing; 79.6% of the infants were hospitalized, three of them in the pediatric intensive care unit. The median hospitalization duration was 3 days. In the sample investigated, 59.8% of the infants received antibiotic therapy and 128 (24.1%) had bacterial infections with no difference between 2011 and 2016. The main bacterial infection was pyelonephritis (86.7%). Urethral catheterization was implemented in 2016, whereas a urine bag was utilized for 174 out of 177 infants in 2011. The percentage of contaminated urine cultures was higher in 2011 (35.9%) than in 2016 (19.6%, P<0.001). The hospitalization rate was higher in 2016.

CONCLUSIONS

Management of febrile infants changed between 2011 and 2016. The hospitalization rate and antibiotic therapy use remained high regarding the rate of bacterial infection. Use of urethral catheterization decreased the level of contamination.

Using urine nitrite sticks to test for urinary tract infection in children aged < 2 years: a meta-analysis

BACKGROUND

This study aimed to determine whether nitrite sticks are as sensitive at detecting urinary tract infection (UTI) in children <2 years as they are in older children.

METHODS

I reanalysed data on using nitrite sticks to detect UTIs for children aged either < 2 or 2-18 years. For sensitivity, evidence of a UTI was defined as level 1 when a single uropathogen grew ≥ 10⁵ colony forming units/ml (cfu/ml) in two urine samples, level 2 when just one sample was cultured or a threshold of < 10⁵ cfu/ml was used, and level 3 if mixed growths or Staphylococcus albus was considered to be positive. For specificity, children were defined as uninfected if they had 1 sterile urine culture. I also reanalysed our previously published data by age.

RESULTS

The sensitivity was lower for children aged < 2 years (11 studies, 1321 subjects) than for older children (9 studies, 295 subjects), whether the level-1 values or all the studies were analysed (Fisher's exact test, p < 0.0001 for both). The level-1 sensitivities were 0.23 in the infants and 0.81 among older children (odds ratio = 0.07, 95% confidence interval 0.03-0.18). The specificity was very high in infants (10 studies, 1783 cases) and older children (7 studies, 5952 cases), at 0.990 and 0.996.

CONCLUSIONS

Nitrite sticks only have a 23% sensitivity in children aged < 2 years, so cannot reliably rule out UTIs. A positive nitrite stick test is about 99% likely to indicate a UTI in children of any age.

Accuracy of the Urinalysis for Urinary Tract Infections in Febrile Infants 60 Days and Younger

OBJECTIVES

Reports of the test accuracy of the urinalysis for diagnosing urinary tract infections (UTIs) in young febrile infants have been variable. We evaluated the test characteristics of the urinalysis for diagnosing UTIs, with and without associated bacteremia, in young febrile infants.

METHODS

We performed a planned secondary analysis of data from a prospective study of febrile infants ≤60 days old at 26 emergency departments in the Pediatric Emergency Care Applied Research Network. We evaluated the test characteristics of the urinalysis for diagnosing UTIs, with and without associated bacteremia, by using 2 definitions of UTI: growth of ≥50 000 or ≥10 000 colony-forming units (CFUs) per mL of a uropathogen. We defined a positive urinalysis by the presence of any leukocyte esterase, nitrite, or pyuria (>5 white blood cells per high-power field).

RESULTS

Of 4147 infants analyzed, 289 (7.0%) had UTIs with colony counts ≥50 000 CFUs/mL, including 27 (9.3%) with bacteremia. For these UTIs, a positive urinalysis exhibited sensitivities of 0.94 (95% confidence interval [CI]: 0.91-0.97), regardless of bacteremia; 1.00 (95% CI: 0.87-1.00) with bacteremia; and 0.94 (95% CI: 0.90-0.96) without bacteremia. Specificity was 0.91 (95% CI: 0.90-0.91) in all groups. For UTIs with colony counts ≥10 000 CFUs/mL, the sensitivity of the urinalysis was 0.87 (95% CI: 0.83-0.90), and specificity was 0.91 (95% CI: 0.90-0.92).

CONCLUSIONS

The urinalysis is highly sensitive and specific for diagnosing UTIs, especially with ≥50 000 CFUs/mL, in febrile infants ≤60 days old, and particularly for UTIs with associated bacteremia.

Performing a urine dipstick test with a clean-catch urine sample is an accurate screening method for urinary tract infections in young infants

AIM

This study evaluated using urine dipstick tests with the clean-catch method to screen for urinary tract infection (UTI) in febrile infants under 90 days of age.

METHODS

We carried out a comparative diagnostic accuracy study of infants under 90 days old, who were studied for unexplained fever without any source, in the emergency room of a hospital in Madrid from January 2011 to January 2013. We obtained matched samples of urine using two different methods: a clean-catch, standardised stimulation technique and catheterisation collection. The results of the leucocyte esterase test and nitrite test were compared with their urine cultures.

RESULTS

We obtained 60 pairs of matched samples. A combined analysis of leukocyte esterase and, or, nitrites yielded a sensitivity of 86% and a specificity of 80% for the diagnosis of UTIs in clean-catch samples. The sensitivity of leukocyte esterase and, or, nitrites in samples obtained by catheterisation were not statistically different to the clean-catch samples (p = 0.592).

CONCLUSION

Performing urine dipstick tests using urine samples obtained by the clean-catch method was an accurate screening test for diagnosing UTIs in febrile infants of less than 90 days old. This provided a good alternative to bladder catheterisation when screening for UTIs.

Outpatient management of selected young febrile infants without antibiotics

OBJECTIVE

To analyse the outpatient management of selected febrile infants younger than 90 days without systematic lumbar puncture and antibiotics.

METHODS

A prospective registry-based cohort study including all the infants ≤90 days with fever without a source (FWS) who were evaluated in a paediatric emergency department (ED) over a 7-year period (September 2007-August 2014). We analysed the outcome of those infants with low-risk criteria for serious bacterial infection (SBI) managed as outpatients without antibiotics and without undergoing a lumbar puncture. Low-risk criteria: Well appearing, older than 21 days of age, no leucocyturia, absolute neutrophil count ≤10 000, serum C reactive protein ≤20 mg/L, procalcitonin <0.5 ng/mL and no clinical deterioration during the stay in the ED (always <24 hours).

RESULTS

1472 infants with FWS attended the ED. Of these, 676 were classified to be at low risk for SBI without performing a lumbar puncture. After staying <24 hours in the short-stay unit of the ED, 586 (86.6%) were managed as outpatients without antibiotics. Two patients were diagnosed with SBI: one occult bacteraemia and one bacterial gastroenteritis. Both were afebrile when evaluated again and did well. No patient returned to the ED due to clinical deterioration. Fifty-one infants (8.7%) returned to the ED mainly due to persistence of fever or irritability. None was diagnosed with definite SBI or non-bacterial meningitis.

CONCLUSIONS

Outpatient management without antibiotics and systematic lumbar puncture is appropriate for selected febrile infants younger than 3 months of age with close follow-up.

Acute pyelonephritis in children

Acute pyelonephritis is one of the most serious bacterial illnesses during childhood. Escherichia coli is responsible in most cases, however other organisms including Klebsiella, Enterococcus, Enterobacter, Proteus, and Pseudomonas species are being more frequently isolated. In infants, who are at major risk of complications such as sepsis and meningitis, symptoms are ambiguous and fever is not always useful in identifying those at high risk. A diagnosis of acute pyelonephritis is initially made on the basis of urinalysis; dipstick tests for nitrites and/or leukocyte esterase are the most accurate indicators of infection. Collecting a viable urine sample for urine culture using clean voided methods is feasible, even in young children. No gold standard antibiotic treatment exists. In children appearing well, oral therapy and outpatient care is possible. New guidelines suggest less aggressive imaging strategies after a first infection, reducing radiation exposure and costs. The efficacy of antibiotic prophylaxis in preventing recurrence is still a matter of debate and the risk of antibiotic resistance is a warning against its widespread use. Well-performed randomized controlled trials are required in order to better define both the imaging strategies and medical options aimed at preserving long-term renal function.

Urinary nitrite/nitrate ratio measured by isotope-dilution LC-MS/MS as a tool to screen for urinary tract infections

Urinary tract infections (UTIs) are the most common type of nosocomial infection. Traditionally, the presence of white blood cells and microorganisms in the urine provides objective evidence for UTI diagnosis. Here, we describe the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) to measure the nitrite and nitrate levels in urine and investigate the potential of this method for UTI diagnosis. LC-MS/MS analysis was performed in positive electrospray ionization mode. After adding (15)N-labeled internal standards and derivatizing with 2,3-diaminonaphthalene (DAN), the urinary nitrite content was directly analyzed by LC-MS/MS, whereas the urinary nitrate was first reduced to nitrite before derivatization and LC-MS/MS analysis. The derivatization of nitrite and enzymatic reduction of nitrate were optimized. This method was then applied to 241 healthy subjects and 73 UTI patients. Optimization tests revealed that 1 mL of crude urine required at least 6.25 μmol of DAN to completely derivatize nitrite and 2.5 U of nitrate reductase to completely reduce nitrate to nitrite. Urinary analysis showed that the urinary concentration of nitrite and the nitrite/nitrate ratio were higher in UTI patients than in healthy subjects. Compared with the dipstick-based urinary nitrite test and using LC-MS/MS to determine the nitrite concentration (sensitivity: 23-25%), the nitrite/nitrate ratio was significantly more sensitive (95%) and exhibited a satisfactory specificity (91%) in the screening of UTIs. Taken together, the nitrite/nitrate ratio, which reflects the reducing ability of pathogenic bacteria, could be a better method for the diagnosis of UTIs that is not subject to variations in urine specimen quality.