Performance of a New Rapid Immunoassay Test Kit for Point-of-Care Diagnosis of Significant Bacteriuria

Overcoming challenges in the management of recurrent urinary tract infections

INTRODUCTION

Urinary tract infection (UTI) is a major global health concern. While acute UTIs can usually be effectively treated, recurrent UTIs (rUTIs) impact patients for years, causing significant morbidity and can become refractory to front-line antibiotics.

AREAS COVERED

This review discusses the risk factors associated with rUTI, current rUTI treatment paradigms, prophylactic strategies, and challenges in rUTI diagnostics. We specifically discuss common risk factors for rUTI, including biological sex, age, menopause status, and diabetes mellitus. We also review recently available evidence for commonly used treatments, from oral antibiotic therapy to intravesical antimicrobials, electrofulguration of chronic cystitis, and the last-resort treatment, cystectomy. We discuss the most current literature evaluating prophylactic strategies for rUTI including long-term antibiotic prophylaxis, estrogen hormone therapy, and dietary supplements. Finally, we address the important role of UTI diagnostics in effective rUTI management and review the strengths and limitations of both current and emerging UTI diagnostic platforms as well as their ability to operate at point-of-care.

EXPERT OPINION

We discuss the current challenges faced by clinicians in managing rUTI in women and the steps that should be taken so that clinicians, scientists, and patients can work together to better understand the disease and develop better strategies for its management.

Nanoplasmonic Rapid Antimicrobial-Resistance Point-of-Care Identification Device: RAPIDx

The emergence of antibiotic resistance has become a global health crisis, and everyone must arm themselves with wisdom to effectively combat the "silent tsunami" of infections that are no longer treatable with antibiotics. However, the overuse or inappropriate use of unnecessary antibiotics is still routine for administering them due to the unavailability of rapid, precise, and point-of-care assays. Here, a rapid antimicrobial-resistance point-of-care identification device (RAPIDx) is reported for the accurate and simultaneous identification of bacterial species (genotype) and target enzyme activity (phenotype). First, a contamination-free active target enzyme is extracted via the photothermal lysis of preconcentrated bacteria cells on a nanoplasmonic functional layer on-chip. Second, the rapid, precise identification of pathogens is achieved by the photonic rolling circle amplification of DNA on a chip. Third, the simultaneous identification of bacterial species (genotype) and target enzyme activity (phenotype) is demonstrated within a sample-to-answer 45 min operation via the RAPIDx. It is believed that the RAPIDx will be a valuable method for solving the bottleneck of employing on-chip nanotechnology for antibiotic-resistant bioassay and other infectious diseases.

Inflammatory markers for improved recurrent UTI diagnosis in postmenopausal women

Recurrent urinary tract infection (rUTI) severely impacts postmenopausal women. The lack of rapid and accurate diagnostic tools is a major obstacle in rUTI management as current gold standard methods have >24-h diagnostic windows. Work in animal models and limited human cohorts have identified robust inflammatory responses activated during UTI. Consequently, urinary inflammatory cytokines secreted during UTI may function as diagnostic biomarkers. This study aimed to identify urinary cytokines that could accurately diagnose UTI in a controlled cohort of postmenopausal women. Women passing study exclusion criteria were classified into no UTI and active rUTI groups, and urinary cytokine levels were measured by immunoassay. Pro-inflammatory cytokines IL-8, IL-18, IL-1β, and monocyte chemoattractant protein-1 were significantly elevated in the active rUTI group, and anti-inflammatory cytokines IL-13 and IL-4 were elevated in women without UTI. We evaluated cytokine diagnostic performance and found that an IL-8, prostaglandin E2, and IL-13 multivariable model had the lowest misclassification rate and highest sensitivity. Our data identify urinary IL-8, prostaglandin E2, and IL-13 as candidate biomarkers that may be useful in the development of immunoassay-based UTI diagnostics.

In house-development of a rapid immunochromatographic test for the detection of Escherichia coli in urine samples

Urinary tract infections (UTIs) are a common health concern. Urine culture is the "gold standard" for UTI diagnosis but takes 48h. Rapid methods like dipstick tests are used as point-of-care tests. However, their sensitivity and specificity are variable. In this work, a rapid immunochromatographic test (IT) for detecting Escherichia coli in urine was developed, and its performance was evaluated in urine samples from patients with suspected UTI. The "universal lateral flow assay kit" was employed using an E. coli capture antibody. One hundred and five (105) urine samples were analyzed using the IT, dipstick test, and urine culture. The sensitivity of the IT was 74.5%, specificity 88.9%, positive predictive value (PPV) 86.3%, and negative predictive value (NPV) 78.7%. The combination of the IT with the dipstick test increases sensitivity to 94.1%, specificity to 66.7%, PPV to 72.7%, and NPV to 92.3%. Using the IT for detecting E. coli in urine could be a valuable technique for UTI screening, showing better specificity and diagnostic precision but lower sensitivity than the dipstick test. Based on these results, we propose that the combined use of both screening techniques would allow a rapid and more precise diagnosis of UTI, rationalizing the indication for empirical antibiotics.

Performance of an innovative culture-based digital dipstick for detection of bacteriuria

IMPORTANCE

In this study, we explore the transformative potential of UTI-lizer, an emerging technology not yet commercially available. Our manuscript shows that UTI-lizer is a promising alternative for detecting the five main pathogens that cause urinary tract infections (UTIs). The results also indicate that digital dipsticks have the potential to uniquely provide UTI diagnostic quality on par with that of gold-standard testing, with the added benefits of ease of testing, rapid test handling time, and simple test equipment. This technology can be helpful in quickly ruling out bacterial infections and reducing the unnecessary use of antibiotics, especially in primary care settings or at the point of care. Moreover, the UTI-lizer test can reduce the number of negative urine samples sent to central laboratories, thus easing the burden of UTI diagnostics on the healthcare system. We believe our study, as well as current and upcoming research based on this technology, is highly relevant for clinical microbiologists, microbiology scientists, general practitioners, and urologists.

Direct, Rapid Detection of Pathogens from Urine Samples

The problem of rapidly detecting pathogens directly from clinical samples poses significant analytical challenges. Addressing this issue in relation to urinary tract infections, we propose an effective protocol and related immunomagnetic test kits enabling versatile screening for the presence of pathogenic bacteria in unprocessed urine samples. To achieve this, the components of a typical immunomagnetic separation protocol were optimized towards the sensitive assessment of the aggregates formed out of immunomagnetically tagged target pathogens collected from clinical samples. Specifically, a dedicated immunomagnetic material was developed via the functionalization of standardized, micron-sized magnetic beads with generic antibodies against gram-specific bacterial constituents with mannan binding lectin. As such, we demonstrate efficient procedures for achieving the enhanced, specific, and pathogen-mediated cluster formation of these tailored affinity-coated magnetic beads in complex samples. We further show how cluster analysis, in conjunction with the use of nonspecific, inexpensive fluorescent dye, allows for a straightforward optical assessment of the bacterial load directly from urine samples. The optimized sensing protocol and related kits provide, in less than 60 min, qualitative (positive/negative) information on the bacterial load with 85% specificity and 96% sensitivity, which is appropriate to empower clinical microscopy with a new analytic dimension. The procedure is prone to automation, can be conveniently used in clinical microbiology laboratories and, since it preserves the viability of the captured bacteria, can be interfaced with downstream analyses and antimicrobial susceptibility testing. Moreover, the study emphasizes a suite of practical validation assays that are useful for bringing the tool-box of immunomagnetic materials outside the academic laboratory and into real-life applications.

Point-of-care tests for pediatric urinary tract infections in general practice: a diagnostic accuracy study

BACKGROUND

Early diagnosis of pediatrics urinary tract infections in the outpatient settings is challenging but essential to prevent hospitalization and kidney damage.

OBJECTIVE

We aimed to evaluate the diagnostic test accuracy of a selection of point-of-care tests for pediatric urinary tract infections in general practice.

METHODS

A prospective cross-sectional study in 26 general practices in Flanders, Belgium (clinicaltrials.gov, NCT03835104). Urine was sampled systematically from children between 3 months to 18 years presenting with an acute illness of maximum 10 days. Samples were analyzed at the central laboratory with a routine dipstick test, the Utriplex test, the Uriscreen test and the Rapidbac as index tests, and with urine culture showing more than 105 colony-forming units per milliliter of one pathogen as reference standard. For each test, we calculated sensitivity, specificity, positive and negative likelihood ratios, and predictive values with 95% confidence intervals.

RESULTS

Three-hundred urine samples were available for analysis of which 30 samples were culture positive (10%). Sensitivities and specificities were 32% (95% CI 16%-52%) and 86% (95% CI 82%-90%) for the dipstick test, 21% (95% CI 8%-40%) and 94% (95% CI 91%-97%) for the Utriplex test, 40% (95% CI 16%-68%) and 83% (95% CI 75%-88%) for the Rapidbac test, and 67% (95% CI 38%-88%) with 69% (95% CI 60%-76%) for the Uriscreen test.

CONCLUSION

All 4 point-of-care tests were suboptimal for use in the broad range of children presenting with acute illnesses to general practice. General practitioners need novel methods for obtaining reliable urine samples during the time of the consultation, especially for children not yet toilet-trained.

Paper and thread as media for the frugal detection of urinary tract infections (UTIs)

Urinary tract infections (UTIs) make up a significant proportion of the global burden of disease in vulnerable groups and tend to substantially impair the quality of life of those affected, making timely detection of UTIs a priority for public health. However, economic and societal barriers drastically reduce accessibility of traditional lab-based testing methods for critical patient groups in low-resource areas, negatively affecting their overall healthcare outcomes. As a result, cellulose-based materials such as paper and thread have garnered significant interest among researchers as substrates for so-called frugal analytical devices which leverage the material's portability and adaptability for facile and reproducible diagnoses of UTIs. Although the field may be only in its infancy, strategies aimed at commercial penetration can appreciably increase access to more healthcare options for at-risk people. In this review, we catalogue recent advances in devices that use cellulose-based materials as the primary housing or medium for UTI detection and chart out trends in the field. We also explore different modalities employed for detection, with particular emphasis on their ability to be ported onto discreet casings such as sanitary products.

Establishment of the Risk Prediction Model for Significant Bacteriuria in Adult Patients with Automated Urine Analysis

INTRODUCTION

Urinary tract infections (UTIs) have been proven to be the most encountered bacterial infection in humans. We hope to establish a prediction model for significant bacteriuria by comprehensively analyzing the relevant parameters of age, gender, and urine automatic analysis data.

METHODS

A retrospective study was performed at Tai'an Central Hospital. All samples included in the study were tested for urine culture and urine automatic analysis. Data analysis was conducted with the SPSS.

RESULTS

The binary logistic regression module is used to establish the forecast formula, which gender, age, leukocyte count, bacterial count, leukocyte esterase, and nitrite were included. Receiver operating characteristic (ROC) curves showed that the area under ROC curve (AUC) of the prediction model was 0.878, bigger than the AUCs of the other 6 independent variables. The sensitivity and specificity of prediction model were 61.68 and 95.98%, respectively. The positive and the negative predictive values of the predictive model are 87.13 and 85.02%, respectively.

CONCLUSIONS

The prediction formula obtained in our study can achieve good prediction effect for significant bacteriuria, which can effectively avoid the treatment delay or antibiotic abuse caused by the subjective judgment of doctors.

Finger-powered fluidic actuation and mixing via MultiJet 3D printing

Additive manufacturing, or three-dimensional (3D) printing, has garnered significant interest in recent years towards the fabrication of sub-millimeter scale devices for an ever-widening array of chemical, biological and biomedical applications. Conventional 3D printed fluidic systems, however, still necessitate the use of non-portable, high-powered external off-chip sources of fluidic actuation, such as electro-mechanical pumps and complex pressure-driven controllers, thus limiting their scope towards point-of-need applications. This work proposes entirely 3D printed sources of human-powered fluidic actuation which can be directly incorporated into the design of any 3D printable sub-millifluidic or microfluidic system where electrical power-free operation is desired. Multiple modular, single-fluid finger-powered actuator (FPA) designs were fabricated and experimentally characterized. Furthermore, a new 3D fluidic one-way valve concept employing a dynamic bracing mechanism was developed, demonstrating a high diodicity of ∼1117.4 and significant reduction in back-flow from the state-of-the-art. As a result, fabricated FPA prototypes achieved tailorable experimental fluid flow rates from ∼100 to ∼3000 μL min^-1 without the use of electricity. Moreover, a portable human-powered two-fluid pulsatile fluidic mixer, capable of generating fully-mixed fluids in 10 seconds, is presented, demonstrating the application of FPAs towards on-chip integration into more complex 3D printed fluidic networks.

Successful medical management of perinephric abscess and urosepsis following urethral obstruction in a cat

OBJECTIVE

To describe the clinical presentation and medical management of a cat with perinephric abscessation and urosepsis following urethral obstruction and catheterization.

CASE SUMMARY

A 2-year-old intact male domestic shorthaired cat presented to an emergency and referral center for lethargy, vomiting, and hematuria. Severe azotemia and hyperkalemia were observed on a serum biochemistry panel. The patient was diagnosed with urethral obstruction and was treated with urethral catheterization, calcium gluconate, IV fluid therapy, buprenorphine, and prazosin. The patient's azotemia improved, and the hyperkalemia resolved. Urinary catheterization was discontinued. The patient developed pyrexia, worsening azotemia, hypoalbuminemia, hyperbilirubinemia, and dysuria. Urethral catheterization was repeated. Abdominal radiographs showed left renomegaly, and abdominal ultrasound revealed left perinephric fluid. Ultrasound-guided centesis of the perinephric fluid revealed septic inflammation, and the sample was consistent with urine based upon sample creatinine. Fluid from the perinephric abscess and urine from the bladder both grew Pasturella spp. The patient was treated with perinephric catheterization, saline lavage, and a continuous infusion of cefotaxime for 72 h. The patient's azotemia quickly resolved, and the patient was discharged after 6 days of hospitalization. The patient was reported to have made a full recovery.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first described case of perinephric abscess and urosepsis following urethral obstruction in a cat and its successful medical management. Perinephric abscess not associated with intrarenal abscess has not previously been identified. Additionally, continuous antimicrobial infusion to treat overwhelming infection and the use of the RapidBac Vet immunoassay for point-of-care detection of urinary tract infection has not been described in cats.

Clinical Validation of Innovative Optical-Sensor-Based, Low-Cost, Rapid Diagnostic Test to Reduce Antimicrobial Resistance

The antibiotic susceptibility test determines the most effective antibiotic treatment for bacterial infection. Antimicrobial stewardship is advocated for the rational use of antibiotics to preserve their efficacy in the long term and provide empirical therapy for disease management. Therefore, rapid diagnostic tests can play a pivotal role in efficient and timely treatment. Here, we developed a novel, rapid, affordable, and portable platform for detecting uropathogens and reporting antibiogram to clinicians in just 4 h. This technology replicates the basic tenets of clinical microbiology including bacterial growth in indigenously formulated medium, and measurement of inhibition of bacterial growth in presence of antibiotic/s. Detection is based on chromogenic endpoints using optical sensors and is analyzed by a lab-developed algorithm, which reports antibiotic sensitivity to the antibiotics panel tested. To assess its diagnostic accuracy, a prospective clinical validation study was conducted in two tertiary-care Indian hospitals. Urine samples from 1986 participants were processed by both novel/index test and conventional Kirby Bauer Disc Diffusion method. The sensitivity and specificity of this assay was 92.5% and 82%, respectively (p < 0.0005). This novel technology will promote evidence-based prescription of antibiotics and reduce the burden of increasing resistance by providing rapid and precise diagnosis in shortest possible time.

Validity of microscopy for diagnosing urinary tract infection in general practice - a systematic review

Objective: To investigate the validity of microscopy as a diagnostic tool for urinary tract infection in general practice. Methods: (Design/setting) A systematic review was conducted by searching Medline for clinical studies made in general practice, outpatient clinics or similar settings in which the accuracy/validity of microscopy was evaluated with urine culture as the reference standard. Results: Our search resulted in 108 titles. 28 potentially eligible studies were retrieved for full-text reading. We included eight studies involving 4582 patients in this review. The quality of the studies was moderate to high. Specificity ranged from 27% to 100%, sensitivity from 47% to 97%. The variation between studies did not allow for meta-analysis. Conclusion: We did not find substantial evidence to determine the clinical validity of microscopy performed in general practice on urine samples from patients with symptoms of UTI. Key points Urinary tract infection is common in general practice. Methods for precise diagnosis are needed in order to avoid inappropriate treatment. Currently no evidence-based consensus exists regarding the use of urinary microscopy in general practice. We did not find substantial evidence to determine the overall clinical validity of microscopy performed in general practice on urine samples from patients with symptoms of UTI. Light microscopy with oil immersion had high sensitivity and specificity but is time-consuming. Phase-contrast microscopy is quick and had high specificity but lower sensitivity.

Coherent fluctuation nephelometry as a promising method for diagnosis of bacteriuria

Objectives

Specialized analyzers are used to automate the diagnosis of bacteriuria in laboratory practice. They are based on analysis of microorganisms concentration in urine samples or recording the growth of urine microflora. Coherent fluctuation nephelometry (CFN) has high sensitivity and allows analyzing both parameters simultaneously. The aim of the study is to compare the effectiveness of CFN-based and flow cytometry based analyzers.

Design and methods

Total 117 urine samples from children were studied in parallel using the CFN-analyzer and UF-1000i (Sysmex), the results were confirmed by conventional microbiological methods.

Results

In 21 urine samples (18%), significant bacteriuria was determined (≥10⁴ CFU/ml). The best diagnostic indicators were obtained while testing urine samples using the CFN-analyzer. The most efficient bacteriuria diagnosis is achieved by simultaneous analyses of microorganisms concentration in urine and growth of urine microflora (sensitivity - 95.2%, specificity - 96.9%, positive predictive value - 87%, negative predictive value - 98.9%, diagnostic odds ratio - 81.7, positive likelihood ratio - 30.5, negative likelihood ratio- 0.049, area under curve in ROC-analysis - 0.987). The CFN-analyzer allows the preliminary selection of negative urine samples, which do not require further analysis by conventional microbiological methods, thereby decreasing the number of cultures by 80.3%.

Conclusions

This study suggests that the CFN-analyzer is the effective tool for bacteriuria screening in children.

New and developing diagnostic technologies for urinary tract infections

Timely and accurate identification and determination of the antimicrobial susceptibility of uropathogens is central to the management of UTIs. Urine dipsticks are fast and amenable to point-of-care testing, but do not have adequate diagnostic accuracy or provide microbiological diagnosis. Urine culture with antimicrobial susceptibility testing takes 2-3 days and requires a clinical laboratory. The common use of empirical antibiotics has contributed to the rise of multidrug-resistant organisms, reducing treatment options and increasing costs. In addition to improved antimicrobial stewardship and the development of new antimicrobials, novel diagnostics are needed for timely microbial identification and determination of antimicrobial susceptibilities. New diagnostic platforms, including nucleic acid tests and mass spectrometry, have been approved for clinical use and have improved the speed and accuracy of pathogen identification from primary cultures. Optimization for direct urine testing would reduce the time to diagnosis, yet these technologies do not provide comprehensive information on antimicrobial susceptibility. Emerging technologies including biosensors, microfluidics, and other integrated platforms could improve UTI diagnosis via direct pathogen detection from urine samples, rapid antimicrobial susceptibility testing, and point-of-care testing. Successful development and implementation of these technologies has the potential to usher in an era of precision medicine to improve patient care and public health.

Reverse Fluorescence Enhancement and Colorimetric Bimodal Signal Readout Immunochromatography Test Strip for Ultrasensitive Large-Scale Screening and Postoperative Monitoring

Ultrasensitive and quantitative fast screening of cancer biomarkers by immunochromatography test strip (ICTS) is still challenging in clinic. The gold nanoparticles (NPs) based ICTS with colorimetric readout enables a quick spectrum screening but suffers from nonquantitative performance; although ICTS with fluorescence readout (FICTS) allows quantitative detection, its sensitivity still deserves more efforts and attentions. In this work, by taking advantages of colorimetric ICTS and FICTS, we described a reverse fluorescence enhancement ICTS (rFICTS) with bimodal signal readout for ultrasensitive and quantitative fast screening of carcinoembryonic antigen (CEA). In the presence of target, gold NPs aggregation in T line induced colorimetric readout, allowing on-the-spot spectrum screening in 10 min by naked eye. Meanwhile, the reverse fluorescence enhancement signal enabled more accurately quantitative detection with better sensitivity (5.89 pg/mL for CEA), which is more than 2 orders of magnitude lower than that of the conventional FICTS. The accuracy and stability of the rFICTS were investigated with more than 100 clinical serum samples for large-scale screening. Furthermore, this rFICTS also realized postoperative monitoring by detecting CEA in a patient with colon cancer and comparing with CT imaging diagnosis. These results indicated this rFICTS is particularly suitable for point-of-care (POC) diagnostics in both resource-rich and resource-limited settings.

Urine Culture in Uncomplicated UTI: Interpretation and Significance

Acute uncomplicated urinary tract infection (UTI) is a common clinical problem, accounting for millions of outpatient visits in the USA annually. Although routinely obtaining urine cultures in UTI is not recommended, there are circumstances in which obtaining a pre-therapy culture may be warranted or chosen by clinicians, such as when indicated by the need for careful antimicrobial stewardship. This review focuses on understanding reasons for obtaining a pre-therapy culture, methods of collection, and appropriately interpreting urine culture data.