What Urinary Colony Count Indicates a Urinary Tract Infection in Children?

Counter-on-chip for bacterial cell quantification, growth, and live-dead estimations

Quantifying bacterial cell numbers is crucial for experimental assessment and reproducibility, but the current technologies have limitations. The commonly used colony forming units (CFU) method causes a time delay in determining the actual numbers. Manual microscope counts are often error-prone for submicron bacteria. Automated systems are costly, require specialized knowledge, and are erroneous when counting smaller bacteria. In this study, we took a different approach by constructing three sequential generations (G1, G2, and G3) of counter-on-chip that accurately and timely count small particles and/or bacterial cells. We employed 2-photon polymerization (2PP) fabrication technology; and optimized the printing and molding process to produce high-quality, reproducible, accurate, and efficient counters. Our straightforward and refined methodology has shown itself to be highly effective in fabricating structures, allowing for the rapid construction of polydimethylsiloxane (PDMS)-based microfluidic devices. The G1 comprises three counting chambers with a depth of 20 µm, which showed accurate counting of 1 µm and 5 µm microbeads. G2 and G3 have eight counting chambers with depths of 20 µm and 5 µm, respectively, and can quickly and precisely count Escherichia coli cells. These systems are reusable, accurate, and easy to use (compared to CFU/ml). The G3 device can give (1) accurate bacterial counts, (2) serve as a growth chamber for bacteria, and (3) allow for live/dead bacterial cell estimates using staining kits or growth assay activities (live imaging, cell tracking, and counting). We made these devices out of necessity; we know no device on the market that encompasses all these features.

Flow cytometric detection of vancomycin-resistant Enterococcus faecium in urine using fluorescently labelled enterocin K1

A urinary tract infection (UTI) occurs when bacteria enter and multiply in the urinary system. The infection is most often caused by enteric bacteria that normally live in the gut, which include Enterococcus faecium. Without antibiotic treatment, UTIs can progress to life-threatening septic shock. Early diagnosis and identification of the pathogen will reduce antibiotic use and improve patient outcomes. In this work, we develop and optimize a cost-effective and rapid (< 40 min) method for detecting E. faecium in urine. The method uses a fluorescently labelled bacteriocin enterocin K1 (FITC-EntK1) that binds specifically to E. faecium and is then detected using a conventional flow cytometer. Using this detection assay, urine containing E. faecium was identified by an increase in the fluorescent signals by 25-73-fold (median fluorescence intensity) compared to control samples containing Escherichia coli or Staphylococcus aureus. The method presented in this work is a proof of concept showing the potential of bacteriocins to act as specific probes for the detection of specific bacteria, such as pathogens, in biological samples.

Evaluation of the diagnostic performance of the urine dipstick test for the detection of urinary tract infections in patients treated in Kenyan hospitals

Introduction

Culture is the gold-standard diagnosis for urinary tract infections (UTIs). However, most hospitals in low-resource countries lack adequately equipped laboratories and relevant expertise to perform culture and, therefore, rely heavily on dipstick tests for UTI diagnosis.

Research gap

In many Kenyan hospitals, routine evaluations are rarely done to assess the accuracy of popular screening tests such as the dipstick test. As such, there is a substantial risk of misdiagnosis emanating from inaccuracy in proxy screening tests. This may result in misuse, under-use or over-use of antimicrobials.

Aim

The present study aimed to assess the accuracy of the urine dipstick test as a proxy for the diagnosis of UTIs in selected Kenyan hospitals.

Methods

A hospital-based cross-sectional method was used. The utility of dipstick in the diagnosis of UTIs was assessed using midstream urine against culture as the gold standard.

Results

The dipstick test predicted 1416 positive UTIs, but only 1027 were confirmed positive by culture, translating to a prevalence of 54.1 %. The sensitivity of the dipstick test was better when leucocytes and nitrite tests were combined (63.1 %) than when the two tests were separate (62.6 and 50.7 %, respectively). Similarly, the two tests combined had a better positive predictive value (87.0 %) than either test alone. The nitrite test had the best specificity (89.8 %) and negative predictive value (97.4 %) than leucocytes esterase (L.E) or both tests combined. In addition, sensitivity in samples from inpatients (69.2 %) was higher than from outpatients (62.7 %). Furthermore, the dipstick test had a better sensitivity and positive predictive value among female (66.0 and 88.6 %) than male patients (44.3 and 73.9 %). Among the various patient age groups, the dipstick test's sensitivity and positive predictive value were exceptionally high in patients ≥75 years old (87.5 and 93.3 %).

Conclusion

Discrepancies in prevalence from the urine dipstick test and culture, the gold standard, indicate dipstick test inadequacy for accurate UTI diagnosis. The finding also demonstrates the need for urine culture for accurate UTI diagnosis. However, considering it is not always possible to perform a culture, especially in low-resource settings, future studies are needed to combine specific UTI symptoms and dipstick results to assess possible increases in the test's sensitivity. There is also a need to develop readily available and affordable algorithms that can detect UTIs where culture is not available.

Liquid NanoBiosensors Enable One-Pot Electrochemical Detection of Bacteria in Complex Matrices

There is a need for point-of-care bacterial sensing and identification technologies that are rapid and simple to operate. Technologies that do not rely on growth cultures, nucleic acid amplification, step-wise reagent addition, and complex sample processing are the key for meeting this need. Herein, multiple materials technologies are integrated for overcoming the obstacles in creating rapid and one-pot bacterial sensing platforms. Liquid-infused nanoelectrodes are developed for reducing nonspecific binding on the transducer surface; bacterium-specific RNA-cleaving DNAzymes are used for bacterial identification; and redox DNA barcodes embedded into DNAzymes are used for binding-induced electrochemical signal transduction. The resultant single-step and one-pot assay demonstrates a limit-of-detection of 10² CFU mL^-1 , with high specificity in identifying Escherichia coli amongst other Gram positive and negative bacteria including Klebsiella pneumoniae, Staphylococcus aureus, and Bacillus subtilis. Additionally, this assay is evaluated for analyzing 31 clinically obtained urine samples, demonstrating a clinical sensitivity of 100% and specify of 100%. When challenging this assay with nine clinical blood cultures, E. coli-positive and E. coli-negative samples can be distinguished with a probability of p < 0.001.

Substantial overlap between symptomatic and asymptomatic genitourinary microbiota states

BACKGROUND

The lack of a definition of urinary microbiome health convolutes diagnosis of urinary tract infections (UTIs), especially when non-traditional uropathogens or paucity of bacteria are recovered from symptomatic patients in routine standard-of-care urine tests. Here, we used shotgun metagenomic sequencing to characterize the microbial composition of asymptomatic volunteers in a set of 30 longitudinally collected urine specimens. Using permutation tests, we established a range of asymptomatic microbiota states, and use these to contextualize the microbiota of 122 urine specimens collected from patients with suspected UTIs diagnostically categorized by standard-of-care urinalysis within that range. Finally, we used a standard-of-care culture protocol to evaluate the efficiency of culture-based recovery of the urinary microbiota.

RESULTS

The majority of genitourinary microbiota in individals suspected to have UTI overlapped with the spectrum of asymptomatic microbiota states. Longitudinal characterization of the genitourinary microbiome in urine specimens collected from asymptomatic volunteers revealed fluctuations of microbial functions and taxonomy over time. White blood cell counts from urinalysis suggested that urine specimens categorized as 'insignificant', 'contaminated', or 'no-growth' by conventional culture methods frequently showed signs of urinary tract inflammation, but this inflammation is not associated with genitourinary microbiota dysbiosis. Comparison of directly sequenced urine specimens with standard-of-care culturing confirmed that culture-based diagnosis biases genitourinary microbiota recovery towards the traditional uropathogens Escherichia coli and Klebsiella pneumoniae.

CONCLUSION

Here, we utilize shotgun metagenomic sequencing to establish a baseline of asymptomatic genitourinary microbiota states. Using this baseline we establish substantial overlap between symptomatic and asymptomatic genitourinary microbiota states. Our results establish that bacterial presence alone does not explain the onset of clinical symptoms. Video Abstract.

Antibiotic resistance patterns of urinary tract pathogens in children from Central Romania

One of the most frequent bacterial infections in children are urinary tract infections (UTIs). In recent years, an increasing incidence of UTIs caused by resistant bacterial strains has been observed, especially with extended-spectrum β-lactamase-producing Enterobacteriaceae that represent about 15% of UTIs. A retrospective study was performed comprising 331 pediatric cases with UTI. Our study aimed to detect the resistance of the uropathogens to common drugs used in UTI treatment. High resistance rates have been recorded for ampicillin, amoxicillin, trimethoprim/sulfamethoxazole (TMP/SMX), cefuroxime, and ciprofloxacin, among E. coli and Klebsiella. The multidrug-resistance (MDR) rate was detected in one-third of the uropathogens, among which more than half were isolated in patients with urinary tract abnormalities. Our study highlighted that nitrofurantoin, ceftriaxone, amikacin and carbapenem may be used for the empirical treatment for febrile or complicated UTI in children. This is the first comprehensive study that evaluates antibiotic resistance in UTIs in children, and their association with urinary tract abnormalities in Romania. As a result of this research, the protocol for initial empiric treatment of infants with febrile or complicated UTI should be modified considering a detailed and ongoing monitoring of local sensitivity of uropathogens to antimicrobial agents.

Diagnosis and management of community-acquired urinary tract infection in infants and children: Clinical guidelines endorsed by the Saudi Pediatric Infectious Diseases Society (SPIDS)

Urinary tract infection (UTI) is the most common bacterial disease in childhood worldwide and may have significant adverse consequences, particularly for young children. In this guideline, we provide the most up-to-date information for the diagnosis and management of community-acquired UTI in infants and children aged over 90 days up to 14 years. The current recommendations given by the American Academy of Pediatrics Practice guidelines, Canadian Pediatric Society guideline, and other international guidelines are considered as well as regional variations in susceptibility patterns and resources. This guideline covers the diagnosis, therapeutic options, and prophylaxis for the management of community-acquired UTI in children guided by our local antimicrobial resistance pattern of the most frequent urinary pathogens. Neonates, infants younger than three months, immunocompromised patients, children recurrent UTIs, or renal abnormalities should be managed individually because these patients may require more extensive investigation and more aggressive therapy and follow up, so it is considered out of the scope of these guidelines. Establishment of children-specific guidelines for the diagnosis and management of community-acquired UTI can reduce morbidity and mortality. We present a clinical statement from the Saudi Pediatric Infectious Diseases Society (SPIDS), which concerns the diagnosis and management of community-acquired UTI in children.

Febrile young infants with abnormal urine dipstick at low risk of invasive bacterial infection

OBJECTIVES

To develop and validate a prediction rule to identify well-appearing febrile infants aged ≤90 days with an abnormal urine dipstick at low risk of invasive bacterial infections (IBIs, bacteraemia or bacterial meningitis).

DESIGN

Ambispective, multicentre study.

SETTING

The derivation set in a single paediatric emergency department (ED) between 2003 and 2017. The validation set in 21 European EDs between December 2017 and November 2019.

PATIENTS

Two sets of well-appearing febrile infants aged ≤90 days with an abnormal urine dipstick (either leucocyte esterase and/or nitrite positive test).

MAIN OUTCOME

Prevalence of IBI in low-risk infants according to the RISeuP score.

RESULTS

We included 662 infants in the derivation set (IBI rate:5.2%). After logistic regression, we developed a score (RISeuP score) including age (≤15 days old), serum procalcitonin (≥0.6 ng/mL) and C reactive protein (≥20 mg/L) as risk factors. The absence of any risk factor had a sensitivity of 96.0% (95% CI 80.5% to 99.3%), a negative predictive value of 99.4% (95% CI 96.4% to 99.9%) and a specificity of 32.9% (95% CI 28.8% to 37.3%) for ruling out an IBI. Applying it in the 449 infants of the validation set (IBI rate 4.9%), sensitivity, negative predictive value and specificity were 100% (95% CI 87.1% to 100%), 100% (95% CI 97.3% to 100%) and 29.7% (95% CI 25.8% to 33.8%), respectively.

CONCLUSION

This prediction rule accurately identified well-appearing febrile infants aged ≤90 days with an abnormal urine dipstick at low risk of IBI. This score can be used to guide initial clinical decision-making in these patients, selecting infants suitable for an outpatient management.

Prevalence and predictors of urinary tract infection in full-term and preterm neonates

Background

Early and prompt diagnosis of urinary tract infection (UTI) in neonates has important therapeutic implications. The aim of this study was to evaluate the prevalence of UTI in neonates admitted to a referral neonatal intensive care unit (NICU) and to identify predictors associated with an increased risk of UTI in NICU population.

Results

The prevalence of culture-proven UTI in the studied neonates was 6.67%. Moreover, UTI was more frequent (70%) among full-term neonates. Additionally, both fever and pyuria were the only clinical and laboratory findings that showed significant association with UTI (p < 0.05). Binary logistic regression revealed that neonates with pyuria in urine analysis were 5.44 times more liable to have UTI, while the presence of fever constitutes a risk of only 0.166 (odds ratios were 5.44 and 0.166, respectively). Additionally, sensitivity, specificity, positive predictive value, and negative predictive value of the regression model were 50.0, 94.5, 20.05, and 98.57%, respectively.

Conclusions

We conclude that UTI is not uncommon in full-term neonates admitted in NICU. Additionally, pyuria was significantly related to positive urine culture and its detection in urine analysis increases the likelihood of UTI by 5.44 times.

Performance of the Modified Boston and Philadelphia Criteria for Invasive Bacterial Infections

BACKGROUND

The ability of the decades-old Boston and Philadelphia criteria to accurately identify infants at low risk for serious bacterial infections has not been recently reevaluated.

METHODS

We assembled a multicenter cohort of infants 29 to 60 days of age who had cerebrospinal fluid (CSF) and blood cultures obtained. We report the performance of the modified Boston criteria (peripheral white blood cell count [WBC] ≥20 000 cells per mm³, CSF WBC ≥10 cells per mm³, and urinalysis with >10 WBC per high-power field or positive urine dip result) and modified Philadelphia criteria (peripheral WBC ≥15 000 cells per mm³, CSF WBC ≥8 cells per mm³, positive CSF Gram-stain result, and urinalysis with >10 WBC per high-power field or positive urine dip result) for the identification of invasive bacterial infections (IBIs). We defined IBI as bacterial meningitis (growth of pathogenic bacteria from CSF culture) or bacteremia (growth from blood culture).

RESULTS

We applied the modified Boston criteria to 8344 infants and the modified Philadelphia criteria to 8131 infants. The modified Boston criteria identified 133 of the 212 infants with IBI (sensitivity 62.7% [95% confidence interval (CI) 55.9% to 69.3%] and specificity 59.2% [95% CI 58.1% to 60.2%]), and the modified Philadelphia criteria identified 157 of the 219 infants with IBI (sensitivity 71.7% [95% CI 65.2% to 77.6%] and specificity 46.1% [95% CI 45.0% to 47.2%]). The modified Boston and Philadelphia criteria misclassified 17 of 53 (32.1%) and 13 of 56 (23.3%) infants with bacterial meningitis, respectively.

CONCLUSIONS

The modified Boston and Philadelphia criteria misclassified a substantial number of infants 29 to 60 days old with IBI, including those with bacterial meningitis.

Diagnosis of Urinary Tract Infection in the Neuropathic Bladder: Changing the Paradigm to Include the Microbiome

Bacteriuria, a non-specific term that refers to the presence of bacteria in the urine, is common in people with neuropathic bladders. However, accurately determining when bacteriuria represents a urinary tract infection (UTI) as opposed to asymptomatic bacteriuria is difficult. There is currently no widely accepted definition of what constitutes a UTI in people with neuropathic bladders. As a result, there is significant variation in care, which likely leads to unnecessary use of antibiotics for bacteriuria. To improve the clinical management of people with neuropathic bladders, it is important to be able to accurately diagnose and treat UTIs. In this article, we review the difficulties associated with accurately diagnosing UTIs and then review proposed definitions. Finally, we discuss the emerging literature of the urinary microbiome and how this may assist in accurately diagnosing UTIs in people with neuropathic bladders.

New Insights in Treatment Options in Pediatric Urinary Tract Infection

Urinary tract infection (UTI) represents one of the most frequent infections with bacterial etiology during childhood. In infants and toddlers with fever without source UTI’ investigation should be carried out, since signs and symptoms are nonspecific. However, obtaining uncontaminated urine samples from these patients can be challenging and time consuming; all current collection methods (clean-catch, plastic collection bag, catheterization, etc) have disadvantages. Criteria for UTI definition are represented by the presence of significant number of a single uropathogen, this number being different depending on the collection method: at least 1000 colony-forming unit (CFU/ml) for catheter samples and at least 100.000 CFU/ml from midstream clean-catch samples or 50.000 CFU/ml and significant pyuria in a symptomatic or febrile child. Accurate diagnosis of UTI is essential to avoid any antibiotic overuse and expensive investigations. UTI caused by resistant bacterial strains has an increasing prevalence in children. In pediatric population, extended spectrum beta-lactamase-producing Enterobacteriaceae (ESBLPE) represent the etiology of around 15% of UTIs. Because of limited therapeutic options the reintroduction of some old antimicrobial agents is necessary, therefore Nitrofurantoin and Fosfomycin, can represent alternatives for oral treatment and prophylaxis of UTIs in children or in case of resistance suspicion to other drug classes. It is important to recognize patients at risk, such as children with recurrent UTIs, kidney abnormalities, like vesicoureteral reflux and previous antibiotherapy, in order to recommend adequate empiric treatment, especially against resistant bacteria.

Urinary tract infections in children: an overview of diagnosis and management

Urinary tract infections (UTIs) are a common and potentially serious bacterial infection of childhood. History and examination findings can be non-specific, so a urine sample is required to diagnose UTI. Sample collection in young precontinent children can be challenging. Bedside dipstick tests are useful for screening, but urine culture is required for diagnostic confirmation. Antibiotic therapy must be guided by local guidelines due to increasing antibiotic resistance. Duration of therapy and indications for imaging remain controversial topics and guidelines lack consensus. This article presents an overview of paediatric UTI diagnosis and management, with highlights of recent advances and evidence updates.