Effect of Leptin Receptor Q223R Polymorphism on Clostridioides difficile Infection-Induced Macrophage Migration Inhibitory Factor Production.

Proinflammatory cytokine levels and host genetic makeup are key determinants of Clostridioides difficile infection (CDI) outcomes. We previously reported that blocking the inflammatory cytokine macrophage migration inhibitory factor (MIF) ameliorates CDI. Here, we determined kinetics of MIF production and its association with a common genetic variant in leptin receptor (LEPR) using blood from patients with CDI. We found highest plasma MIF early after C difficile exposure and in individuals who express mutant/derived LEPR. Our data suggest that early-phase CDI provides a possible window of opportunity in which MIF targeting, potentially in combination with LEPR genotype, could have therapeutic utility.

Clinical utility of multiplex PCR in the detection of pathogens from sterile body fluids.

Rapid identification of pathogens in normally sterile body fluid (NSBF) is essential for appropriate patient management, specifically antimicrobial therapy. Limited sensitivity and increased time to detection of traditional culture prompted us to evaluate additional testing to contribute to the diagnosis of infection. The purpose of this study was to evaluate the GenMark Dx ePlex Blood Culture Identification (BCID) Panels on positive body fluids inoculated into blood culture bottles for the detection of microorganisms. A total of 88 positive body fluids from blood culture bottles were analyzed using a Gram-Positive, Gram-Negative, and/or Fungal pathogen BCID Panel based on the Gram stain result. Each result was compared to routine culture performed from the positive bottle. When using culture as a reference standard, we found the ePlex multiplex panel performed with a positive percent agreement of 96.5% and a negative percent agreement of 99.8%. The use of multiplex PCR may be a useful supplement to routine culture for NSBF in blood culture bottles. IMPORTANCE: The identification of pathogens in normally sterile body fluid (NSBF) is performed using routine culture, the current gold standard. Limitations of this method include sensitivity and increased turnaround times which could potentially delay vital patient care, especially antimicrobial therapy. Adaptations of NSBF in blood culture bottles prompted us to consider the utility of additional methods to bridge the gap in diagnostic challenges for these life-threatening infections. Multiplex molecular panels have been manufactured for use with multiple specimen types including blood, cerebral spinal fluid, stool, and respiratory. Therefore, the purpose of this study was to evaluate the off-label use of ePlex Blood Culture Identification Panels on positive body fluids grown in blood culture bottles for the detection of microorganisms for research purposes.

Ambulatory Long Block: A Model of Precision Education and Assessment for Internal Medicine Residents.

ABSTRACT: High-quality precision education (PE) aims to enhance outcomes for learners and society by incorporating longitudinal data and analytics to shape personalized learning strategies. However, existing educational data collection methods often suffer from fragmentation, leading to gaps in understanding learner and program performance. In this article, the authors present a novel approach to PE at the University of Cincinnati, focusing on the Ambulatory Long Block, a year-long continuous ambulatory group-practice experience. Over the last 17 years, the Ambulatory Long Block has evolved into a sophisticated data collection and analysis system that integrates feedback from various stakeholders, as well as learner self-assessment, electronic health record utilization information, and clinical throughput metrics. The authors detail their approach to data prioritization, collection, analysis, visualization, and feedback, providing a practical example of PE in action. This model has been associated with improvements in both learner performance and patient care outcomes. The authors also highlight the potential for real-time data review through automation and emphasize the importance of collaboration in advancing PE. Generalizable principles include designing learning environments with continuity as a central feature, gathering both quantitative and qualitative performance data from interprofessional assessors, using this information to supplement traditional workplace-based assessments, and pairing it with self-assessments. The authors advocate for criterion referencing over normative comparisons, using user-friendly data visualizations, and employing tailored coaching strategies for individual learners. The Ambulatory Long Block model underscores the potential of PE to drive improvements in medical education and health care outcomes.

Prevalence of SARS-CoV-2 Infection among Children and Adults in 15 US Communities, 2021

During January-August 2021, the Community Prevalence of SARS-CoV-2 Study used time/location sampling to recruit a cross-sectional, population-based cohort to estimate SARS-CoV-2 seroprevalence and nasal swab sample PCR positivity across 15 US communities. Survey-weighted estimates of SARS-CoV-2 infection and vaccine willingness among participants at each site were compared within demographic groups by using linear regression models with inverse variance weighting. Among 22,284 persons >2 months of age and older, median prevalence of infection (prior, active, or both) was 12.9% across sites and similar across age groups. Within each site, average prevalence of infection was 3 percentage points higher for Black than White persons and average vaccine willingness was 10 percentage points lower for Black than White persons and 7 percentage points lower for Black persons than for persons in other racial groups. The higher prevalence of SARS-CoV-2 infection among groups with lower vaccine willingness highlights the disparate effect of COVID-19 and its complications.

Clock-talk: have we forgotten about geographic variation?

Wyeomyia smithii, the pitcher-plant mosquito, has evolved from south to north and from low to high elevations in eastern North America. Along this seasonal gradient, critical photoperiod has increased while apparent involvement of the circadian clock has declined in concert with the evolutionary divergence of populations. Response to classical experiments used to test for a circadian basis of photoperiodism varies as much within and among populations of W. smithii as have been found in the majority of all other insects and mites. The micro-evolutionary processes revealed within and among populations of W. smithii, programmed by a complex underlying genetic architecture, illustrate a gateway to the macro-evolutionary divergence of biological timing among species and higher taxa in general.

Immune and ionic mechanisms mediating the effect of dexamethasone in severe COVID-19.

Introduction: Severe COVID-19 is characterized by cytokine storm, an excessive production of proinflammatory cytokines that contributes to acute lung damage and death. Dexamethasone is routinely used to treat severe COVID-19 and has been shown to reduce patient mortality. However, the mechanisms underlying the beneficial effects of dexamethasone are poorly understood. Methods: We conducted transcriptomic analysis of peripheral blood mononuclear cells (PBMCs) from COVID-19 patients with mild disease, and patients with severe COVID-19 with and without dexamethasone treatment. We then treated healthy donor PBMCs in vitro with dexamethasone and investigated the effects of dexamethasone treatment ion channel abundance (by RT-qPCR and flow cytometry) and function (by electrophysiology, Ca2+ influx measurements and cytokine release) in T cells. Results: We observed that dexamethasone treatment in severe COVID-19 inhibited pro-inflammatory and immune exhaustion pathways, circulating cytotoxic and Th1 cells, interferon (IFN) signaling, genes involved in cytokine storm, and Ca2+ signaling. Ca2+ influx is regulated by Kv1.3 potassium channels, but their role in COVID-19 pathogenesis remains elusive. Kv1.3 mRNA was increased in PBMCs of severe COVID-19 patients, and was significantly reduced in the dexamethasone-treated group. In agreement with these findings, in vitro treatment of healthy donor PBMCs with dexamethasone reduced Kv1.3 abundance in T cells and CD56dimNK cells. Furthermore, functional studies showed that dexamethasone treatment significantly reduced Kv1.3 activity, Ca2+ influx and IFN-g production in T cells. Conclusion: Our findings suggest that dexamethasone attenuates inflammatory cytokine release via Kv1.3 suppression, and this mechanism contributes to dexamethasone-mediated immunosuppression in severe COVID-19.

The low sensitivity of direct smears limit the utility of intraoperative gram stains for predicting culture-positivity in acute surgical settings.

The role of intraoperative Gram stains in acute surgery decision-making is unclear. Our retrospective chart review of microbiology results for specimens submitted by acute surgery attendings showed Gram stain performs with a sensitivity ranging from 18% to 65% compared to culture, depending on organism type, thus limiting its utility.

Induction of a cytokine storm involves suppression of the Osteopontin-dependent TH1 response.

Cytokine release syndromes represent a severe turn in certain disease states, which may be caused by several infections, including those with the virus SARS-CoV-2. This inefficient, even harmful, immune response has been associated with a broad release of chemokines. Although a cellular (type I) immune reaction is efficacious against viral infections, we noted a type I deficit in the cytokine patterns produced by cytokine storms of all reported etiologies. Agents including lipopolysaccharide (LPS, bacterial), anti-CD3 (antibody) and a version of the prominent SARS-CoV-2 viral surface molecule, Spike Glycoprotein, were individually sufficient to induce IL-6 and multiple chemokines in mice. They failed to upregulate the TH1 inducer cytokine Osteopontin, and the pathophysiologic triggers actually suppressed the PMA-induced Osteopontin secretion from monocytic cells. Osteopontin administration partially reversed the chemokine elevation, more effectively so in a mouse strain with TH1 bias. Corroboration was obtained from the inverse correlation in the levels of IL-6 and Osteopontin in plasma samples from acute COVID-19 patients. We hypothesize that the inhibition of Osteopontin by SARS-CoV-2 Spike Glycoprotein or LPS represents an immune evasion mechanism employed by the pathogens of origin. The ensuing dysfunctional inflammatory response promotes a vicious cycle of amplification, resulting in a cytokine storm.

Clinical Utility of the Signal-to-Cutoff Ratio of Reactive HIV Antigen/Antibody Screening Tests in Guiding Emergency Physician Management.

BACKGROUND: The signal-to-cutoff (S/CO) ratio of the HIV antigen/antibody test may help immediately to differentiate true-positive results from false-positive results, which may be particularly useful in time-sensitive circumstances, such as when providing emergency department (ED) care. SETTING: Seven US EDs with HIV screening programs using HIV antigen/antibody assays. METHODS: This cross-sectional study of existing data correlated S/CO ratios with confirmed HIV status. Test characteristics at predetermined S/CO ratios and the S/CO ratio with the best performance by receiver operator characteristic (ROC) curve were calculated. RESULTS: Of 1035 patients with a reactive HIV antigen/antibody test, 232 (22.4%) were confirmed HIV-negative and 803 (77.6%) were confirmed HIV-positive. Of the 803 patients, 713 (88.8%) experienced chronic infections and 90 (11.2%) experienced acute infections. S/CO ratios were greater for HIV-positive (median 539.2) than for HIV-negative patients (median 1.93) (P < 0.001) and lower for acute infection (median 22.8) than for chronic infection (median 605.7) (P < 0.001). All patients with an S/CO ratio < 1.58 (n = 93) were HIV-negative (NPV 100%), and nearly all with an S/CO ≥ 20.7 (n = 760) (optimal level by ROC analysis) were HIV-positive (PPV 98.6%). Of patients with S/CO values between 1.58 and 20.7 (n = 182), 29.7% were HIV-positive. CONCLUSIONS: The S/CO ratio may be used in real time to classify most ED patients as almost certain to be either HIV-positive or HIV-negative long before nucleic acid confirmatory testing is available. When combined with clinical judgment, this could guide preliminary result disclosure and management.

Diagnosing Fracture-Related Infections: Where Are We Now?

Accurate diagnosis of fracture-related infection (FRI) is critical for preventing poor outcomes such as loss of function or amputation. Due to the multiple variables associated with FRI, however, accurate diagnosis is challenging and complicated by a lack of standardized diagnostic criteria. Limitations with the current gold standard for diagnosis, which is routine microbiology culture, further complicate the diagnostic and management process. Efforts to optimize the process rely on a foundation of data derived from prosthetic joint infections (PJI), but differences in PJI and FRI make it clear that unique approaches for these distinct infections are required. A more concerted effort focusing on FRI has dominated more recent investigations and publications leading to a consensus definition by the American Orthopedics (AO) Foundation and the European Bone and Joint Infection Society (EBJIS). This has the potential to better standardize the diagnostic process, which will not only improve patient care but also facilitate more robust and reproducible research related to the diagnosis and management of FRI. The purpose of this minireview is to explore the consensus definition, describe the foundation of data supporting current FRI diagnostic techniques, and identify pathways for optimization of clinical microbiology-based strategies and data.

Take Your Best Shot: Which SARS-CoV-2 Vaccine Should I Get?

Background. Three vaccines against SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) have now received emergency use authorization by the US Food and Drug Administration. Patients may have the opportunity to make a choice about which vaccine they prefer to receive. Vaccine hesitancy is a hurdle to the development of widespread immunity, with many patients struggling to decide whether to get vaccinated at all. Objective. Develop a decision model exploring the question, "Should I get vaccinated with mRNA or adenovirus vector vaccine (AVV) if either is available now?"Design. Markov state transition model with lifetime time horizon. Data Sources. MEDLINE searches, bibliographies from relevant English-language articles. Setting. United States, ambulatory clinical setting. Participants. Previously uninfected, nonimmunized adults in the United States. Interventions. 1) Do Not Vaccinate, 2) Vaccination with mRNA Vaccine, 3) Vaccination with Adenovirus Vector Vaccine. Main Measures. Quality-adjusted life years (QALYs). Key Results. Base case-for a healthy 65-year-old patient, both vaccines yield virtually equivalent results (difference of 0.0028 QALYs). In sensitivity analyses, receiving the AVV is preferred if the short-term morbidity associated with each vaccine dose exceeds 1.8 days. Both vaccines afford an even greater benefit compared with Do Not Vaccinate if the pandemic is in a surge phase with a rising incidence of infection or if the current 7-day incidence is greater than the base case estimate of 105 cases per 100,000. Conclusions. Preferred vaccination strategies change under differing assumptions, but differences in outcomes are negligible. The best advice for patients is to get vaccinated against COVID-19 disease with whatever vaccine is available first. Providing mRNA vaccine to the remaining eligible US population would result in an aggregate gain of 3.92 million QALYs.

Safety, Pharmacokinetics, and Pharmacodynamics of Trazpiroben (TAK-906), a Novel Selective D2 /D3 Receptor Antagonist: A Phase 1 Randomized, Placebo-Controlled Single- and Multiple-Dose Escalation Study in Healthy Participants.

Gastroparesis is a chronic neuromuscular disorder of the upper gastrointestinal tract in which episodic exacerbation can lead to frequent hospitalizations and severe disability. Dopamine D2 /D3 receptor antagonists have been used to treat patients with gastroparesis with some efficacy; however, their chronic use is limited owing to associated central nervous system (CNS) or cardiovascular safety concerns. Trazpiroben (TAK-906) is a dopamine D2 /D3 receptor antagonist under development for the long-term treatment of gastroparesis. Preclinical studies in rat and dog have shown trazpiroben to have minimal brain penetration and low affinity for the human ether-à-go-go-related gene (hERG) potassium channel (IC50 ,  15.6 µM), thereby reducing the risk of the CNS and cardiovascular adverse effects seen with other dopamine D2 /D3 receptor antagonists. This phase 1 trial evaluated the safety, pharmacokinetics, and pharmacodynamics of trazpiroben in healthy participants. Trazpiroben was rapidly absorbed and eliminated (Tmax , ∼1.1 hours; t1/2 , 4-11 hours) after administration of single (5-300 mg) and multiple (50 or 100 mg) doses. Receptor target engagement was confirmed for all doses, as indicated by an increase in serum prolactin levels compared with placebo (mean prolactin Cmax , 134.3 ng/mL after administration of trazpiroben 10 mg vs 16.1 ng/mL with placebo). Therapeutically relevant single and multiple doses of trazpiroben were well tolerated in healthy participants, and no clinically meaningful cardiovascular adverse effects were observed across the whole dose range. These data support the further development of trazpiroben for the treatment of gastroparesis.

Updates in Laboratory Diagnostics for Invasive Fungal Infections.

Appropriate diagnosis of invasive fungal infections (IFIs) is critical due to the high rates of morbidity and mortality, as well as the substantial economic burden, associated with the management of these diseases. The recognition of IFI and differentiation from other infections with similar clinical presentations can be challenging, which can lead to diagnostic error that not only has an impact on individual patient health outcomes but also on antimicrobial drug usage and the growing threat of antimicrobial resistance in bacteria. Therefore, there is a significant need for improved stewardship related to diagnostic testing for and treatment of IFIs. The purpose of this review is to highlight recent advances related to current fungal diagnostics, as well as explore some of the most innovative technology that has emerged with the potential to shift the paradigm of clinical mycology. In general, this review will discuss research related to enhanced fungal culture utilization and identification techniques, expanded applications of fungal antigen testing, and recently developed molecular assays and other novel nonculture fungal diagnostic approaches. Specifically, the application of mass spectrometry, novel glycobiomarker detection, and detection of fungal-specific volatile organic compounds will be reviewed, along with other key updates, to provide the reader with an updated review that extends beyond the basics of IFI laboratory diagnostics. Where appropriate, the reader will be directed to more comprehensive reviews of certain aspects of clinical mycology laboratory testing to provide a broader context for the critical consideration of these updates.

Helicobacter canis bacteraemia and cellulitis in a patient with end-stage renal disease.

Introduction. Invasive infections by Helicobacter canis are uncommon and occur primarily in immunocompromised patients. Here, we describe a case of H. canis bacteraemia and cellulitis in a patient with end-stage renal disease (ESRD). Case presentation. A 49-year-old male with ESRD on haemodialysis presented to an emergency department with cellulitis overlying his left upper extremity arteriovenous fistula for 3 days without constitutional symptoms. Mild leucocytosis and thrombocytopenia was noted on initial laboratory work up. The patient received a dose of vancomycin initially, and then transitioned to oral doxycycline prior to discharge 3 days later. Blood cultures drawn on admission were positive with curved Gram-negative rods at day 5. Routine sub-cultures initially failed to isolate the organism; however, small, tan colonies were observed on sheep blood agar incubated under microaerobic conditions. H. canis was identified by 16S rRNA sequencing. Antimicrobial-susceptibility testing was not performed due to poor growth and lack of interpretive guidelines. The patient was ultimately treated successfully with amoxicillin/clavulanic acid. Conclusion. This case illustrates the importance of recognizing H. canis infections in immunocompromised patients, especially in those with recent pet exposure. In addition, this case highlights the need for improved laboratory diagnostics for H. canis as isolation and identification of this fastidious organism is challenging.

Parents' perceptions of influenza and why they accept or decline the nasal vaccine for their child.

Background Nasal influenza vaccine is offered each year to all children from age two to higher age groups. There is little UK research on whether parents support this vaccination programme. Aim The aim of this study was to explore parents' perceptions of influenza as an illness in children and why they decide to accept or decline nasal influenza vaccine for their child. Method A survey was first distributed to parents via a single primary school. Ten parents were then sampled in semi-structured interviews. From the survey, 91% (n=78) of the parents favoured routine vaccinations but only 47% (n=40) were supportive of nasal influenza vaccination. Findings From the interviews, reasons highlighted for accepting or declining the vaccine concerned the importance of trust, community responsibility, controllability and the perception of risk. Conclusion Parents who typically support vaccination may doubt the necessity of a influenza vaccination for their child. This may reduce uptake and undermine the programme.

A mixed-method study of pain management practice in a UK children's hospital: identification of barriers and developing strategies to maintain effective in-patient paediatric pain management.

AIM: To assess Acute Pain Service and paediatric pain management efficacy in a UK specialist paediatric hospital to inform wider recommendations for future sustainability. BACKGROUND: UK paediatric acute pain services vary. Although comprehensive pain management guidelines exist, consensus on the best model of care is lacking. Worldwide, medical and pharmacological advances and rapid patient turnover have increased the challenges of managing hospitalized children's pain. Simultaneously nurses, who deliver the bulk of pain management, have experienced reduction in skill mix and training opportunities. Specialist Acute Pain Services have evolved to meet these demands; their overall efficacy is unknown. DESIGN: This mixed-methods study explores pain management practice at a UK paediatric hospital to assess current efficacy and future sustainability. METHOD: A 2013 case note review of all Acute Pain Services referrals over 14 days were compared with an interval sample of concurrent non-referred inpatient children; seven semi-structured interviews were conducted with a range of clinical staff. RESULTS: Twenty-two referrals of 15 children were made; 15 comparison children were identified. All 30 children (100%) were appropriately referred/non-referred. Acute Pain Services cases experienced higher pain levels, were more likely to have long term conditions, longer hospital stay and repeat admissions. Three key themes emerged through interview analysis: 'addressing pain', 'changing contexts' 'pain as an "expert" skill'. Increased specialization, reduced clarity between different pain modalities and decreased training opportunities had resulted in potentially unsustainable APS dependence.

Molecular Diagnostic Testing for Aspergillus.

The direct detection of Aspergillus nucleic acid in clinical specimens has the potential to improve the diagnosis of aspergillosis by offering more rapid and sensitive identification of invasive infections than is possible with traditional techniques, such as culture or histopathology. Molecular tests for Aspergillus have been limited historically by lack of standardization and variable sensitivities and specificities. Recent efforts have been directed at addressing these limitations and optimizing assay performance using a variety of specimen types. This review provides a summary of standardization efforts and outlines the complexities of molecular testing for Aspergillus in clinical mycology.

Nappy pad urine samples for investigation and treatment of UTI in young children: the 'DUTY' prospective diagnostic cohort study.

BACKGROUND: The added diagnostic utility of nappy pad urine samples and the proportion that are contaminated is unknown. AIM: To develop a clinical prediction rule for the diagnosis of urinary tract infection (UTI) based on sampling using the nappy pad method. DESIGN AND SETTING: Acutely unwell children <5 years presenting to 233 UK primary care sites. METHOD: Logistic regression to identify independent associations of symptoms, signs, and urine dipstick test results with UTI; diagnostic utility quantified as area under the receiver operator curves (AUROC). Nappy pad rule characteristics, AUROC, and contamination, compared with findings from clean-catch samples. RESULTS: Nappy pad samples were obtained from 3205 children (82% aged <2 years; 48% female), culture results were available for 2277 (71.0%) and 30 (1.3%) had a UTI on culture. Female sex, smelly urine, darker urine, and the absence of nappy rash were independently associated with a UTI, with an internally-validated, coefficient model AUROC of 0.81 (0.87 for clean-catch), which increased to 0.87 (0.90 for clean-catch) with the addition of dipstick results. GPs' 'working diagnosis' had an AUROC 0.63 (95% confidence intervals [CI] = 0.53 to 0.72). A total of 12.2% of nappy pad and 1.8% of clean-catch samples were 'frankly contaminated' (risk ratio 6.66; 95% CI = 4.95 to 8.96; P<0.001). CONCLUSION: Nappy pad urine culture results, with features that can be reported by parents and dipstick tests, can be clinically useful, but are less accurate and more often contaminated compared with clean-catch urine culture.

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.