title: Comparison of microbiological diagnosis of urinary tract infection in young children by routine health service laboratories and a research laboratory: Diagnostic cohort study.
abstract: OBJECTIVE
  To compare the validity of diagnosis of urinary tract infection (UTI) through urine culture between samples processed in routine health service laboratories and those processed in a research laboratory.
  
  
  METHODS
  We conducted a prospective diagnostic cohort study in 4808 acutely ill children aged <5 years attending UK primary health care. UTI, defined as pure/predominant growth ≥105 CFU/mL of a uropathogen (the reference standard), was diagnosed at routine health service laboratories and a central research laboratory by culture of urine samples. We calculated areas under the receiver-operator curve (AUC) for UTI predicted by pre-specified symptoms, signs and dipstick test results (the "index test"), separately according to whether samples were obtained by clean catch or nappy (diaper) pads.
  
  
  RESULTS
  251 (5.2%) and 88 (1.8%) children were classified as UTI positive by health service and research laboratories respectively. Agreement between laboratories was moderate (kappa = 0.36; 95% confidence interval [CI] 0.29, 0.43), and better for clean catch (0.54; 0.45, 0.63) than nappy pad samples (0.20; 0.12, 0.28). In clean catch samples, the AUC was lower for health service laboratories (AUC = 0.75; 95% CI 0.69, 0.80) than the research laboratory (0.86; 0.79, 0.92). Values of AUC were lower in nappy pad samples (0.65 [0.61, 0.70] and 0.79 [0.70, 0.88] for health service and research laboratory positivity, respectively) than clean catch samples.
  
  
  CONCLUSIONS
  The agreement of microbiological diagnosis of UTI comparing routine health service laboratories with a research laboratory was moderate for clean catch samples and poor for nappy pad samples and reliability is lower for nappy pad than for clean catch samples. Positive results from the research laboratory appear more likely to reflect real UTIs than those from routine health service laboratories, many of which (particularly from nappy pad samples) could be due to contamination. Health service laboratories should consider adopting procedures used in the research laboratory for paediatric urine samples. Primary care clinicians should try to obtain clean catch samples, even in very young children.
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Kate
authors.initials: K
authors.lastname: Birnie
authors.affiliation: Centre for Academic Primary Care, NIHR School of Primary Care Research, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Alastair D
authors.initials: AD
authors.lastname: Hay
authors.affiliation: Specialist Antimicrobial Chemotherapy Unit, Public Health Wales Microbiology Cardiff, University Hospital Wales, Cardiff, United Kingdom.
authors.forename: Mandy
authors.initials: M
authors.lastname: Wootton
authors.affiliation: Specialist Antimicrobial Chemotherapy Unit, Public Health Wales Microbiology Cardiff, University Hospital Wales, Cardiff, United Kingdom.
authors.forename: Robin
authors.initials: R
authors.lastname: Howe
authors.affiliation: North Bristol NHS Trust, Bristol, United Kingdom.
authors.forename: Alasdair
authors.initials: A
authors.lastname: MacGowan
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.|Kleijnen Systematic Reviews Ltd, York, United Kingdom.
authors.forename: Penny
authors.initials: P
authors.lastname: Whiting
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Lawton
authors.affiliation: NIHR Biomedical Research Centre at Guy's and St Thomas' NHS Foundation Trust and King's College London, Department of Primary Care and Public Health Sciences, London, United Kingdom.
authors.forename: Brendan
authors.initials: B
authors.lastname: Delaney
authors.affiliation: Centre for Academic Primary Care, NIHR School of Primary Care Research, School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Harriet
authors.initials: H
authors.lastname: Downing
authors.affiliation: Bristol Royal Hospital for Children, University Hospitals Bristol, NHS Foundation Trust, Bristol, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Dudley
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: William
authors.initials: W
authors.lastname: Hollingworth
authors.affiliation: South East Wales Trials Unit (SEWTU), Institute for Translation, Innovation, Methodology and Engagement, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors.forename: Catherine
authors.initials: C
authors.lastname: Lisles
authors.affiliation: Primary Care and Population Sciences Division, University of Southampton, Southampton, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Little
authors.affiliation: Cochrane Institute of Primary Care & Public Health, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors.forename: Kathryn
authors.initials: K
authors.lastname: O'Brien
authors.affiliation: South East Wales Trials Unit (SEWTU), Institute for Translation, Innovation, Methodology and Engagement, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors.forename: Timothy
authors.initials: T
authors.lastname: Pickles
authors.affiliation: Primary Care and Population Sciences Division, University of Southampton, Southampton, United Kingdom.
authors.forename: Kate
authors.initials: K
authors.lastname: Rumsby
authors.affiliation: South East Wales Trials Unit (SEWTU), Institute for Translation, Innovation, Methodology and Engagement, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors.forename: Emma
authors.initials: E
authors.lastname: Thomas-Jones
authors.affiliation: Department of Paediatrics and Child Health, University Hospital of Wales, Cardiff, United Kingdom.
authors.forename: Judith
authors.initials: J
authors.lastname: Van der Voort
authors.affiliation: South East Wales Trials Unit (SEWTU), Institute for Translation, Innovation, Methodology and Engagement, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors.forename: Cherry-Ann
authors.initials: CA
authors.lastname: Waldron
authors.affiliation: Primary Care and Population Sciences Division, University of Southampton, Southampton, United Kingdom.
authors.forename: Kim
authors.initials: K
authors.lastname: Harman
authors.affiliation: South East Wales Trials Unit (SEWTU), Institute for Translation, Innovation, Methodology and Engagement, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors.forename: Kerenza
authors.initials: K
authors.lastname: Hood
authors.affiliation: Cochrane Institute of Primary Care & Public Health, School of Medicine, Cardiff University, Cardiff, United Kingdom.|Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Butler
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Jonathan A C
authors.initials: JA
authors.lastname: Sterne
mesh_terms: D019540:Area Under Curve; D002675:Child, Preschool; D002954:Citrobacter / Q000302:isolation & purification; D015331:Cohort Studies; D003955:Diagnostic Tests, Routine; D004754:Enterobacter / Q000302:isolation & purification; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D006268:Health Facilities; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007709:Klebsiella / Q000302:isolation & purification; D007753:Laboratories; D008297:Male; D016017:Odds Ratio; D011446:Prospective Studies; D012372:ROC Curve; D014552:Urinary Tract Infections / Q000175:diagnosis* / Q000382:microbiology*