The impact of Coronavirus disease 2019 (COVID-19) on urinalysis parameters.

BACKGROUND: Creatinine elevation and changes in urinalyse parameters may be seen due to acute kidney injury during COVID-19. In the present study, we aimed to investigate the changes in urinalysis of COVID-19 patients with normal kidney function. METHODS: The data of COVID-19 patients with normal renal functions were retrospectively analyzed. Urinalysis parameters of these patients were recorded. The patients were divided into three groups as mild, moderate and severe with respect to the clinical course of the disease. It was examined whether the urine analysis values in the groups were different from normal reference values and whether these values were different between the groups. In addition, possible relationship between the urinalysis parameters and the clinical severity of the disease was investigated. RESULTS: There are three groups; mild (N.=40), moderate (N.=38) and severe (N.=42). Mean age were significantly higher in the severe group, while gender distribution of the groups was similar (P=0.033, P=0.091) Creatinine values of all patients were normal. There were 6.7% glucose positivity, 13.4% protein positivity, 5.8% urobilinogen positivity and 7.5% ketone positivity in urine dipstick analysis and these changes were all significantly higher than the reference values (P=0.008, P<0.0001, P=0.016, P=0.016). Pyuria and hematuria were detected in 8.3% and 9.2%, respectively. The urinalysis parameters and urine microscopy findings were not affected by the severity of the disease. CONCLUSIONS: Glycosuria, proteinuria, pyuria and hematuria may occur during COVID-19 disease, regardless of comorbidity and renal dysfunction. However, these urine parameters were not correlated with the severity of the disease.

Pyuria and Urine Concentration for Identifying Urinary Tract Infection in Young Children.

OBJECTIVES: Accuracy of pyuria for urinary tract infection (UTI) varies with urine concentration. Our objective of this study was to determine the optimal white blood cell (WBC) cutoff for UTI in young children at different urine concentrations as measured by urine specific gravity. METHODS: Retrospective cross-sectional study of children <24 months of age evaluated in the emergency department for suspected UTI with paired urinalysis and urine culture during a 6-year period. The primary outcome was positive urine culture result as described in the American Academy of Pediatrics clinical practice guideline culture thresholds. Test characteristics for microscopic pyuria cut points and positive leukocyte esterase (LE) were calculated across 3 urine specific gravity groups: low <1.011, moderate 1.011 to 1.020, and high >1.020. RESULTS: Of the total 24 171 patients analyzed, urine culture result was positive in 2003 (8.3%). Urine was obtained by transurethral in-and-out catheterization in 97.9%. Optimal WBC cutoffs per high-power field (HPF) were 3 (positive likelihood ratio [LR+] 10.5; negative likelihood ratio [LR-] 0.12) at low, 6 (LR+ 12; LR- 0.14) at moderate, and 8 (LR+ 11.1; LR- 0.35) at high urine concentrations. Likelihood ratios for small positive LE from low to high urine concentrations (LR+ 25.2, LR- 0.12; LR+ 33.1, LR- 0.15; LR+ 37.6, LR- 0.41) remained excellent. CONCLUSIONS: Optimal pyuria cut point in predicting positive urine culture results changes with urine concentration in young children. Pyuria thresholds of 3 WBCs per HPF at low urine concentrations whereas 8 WBCs per HPF at high urine concentrations have optimal predictive value for UTI. Positive LE is a strong predictor of UTI regardless of urine concentration.

Reevaluating the true diagnostic accuracy of dipstick tests to diagnose urinary tract infection using Bayesian latent class analysis.

OBJECTIVE: Previous studies on diagnostic accuracy of dipstick testing for leukocyte esterase (LE) and nitrite to diagnose urinary tract infection (UTI) had used urine culture, which is an imperfect gold standard. Estimates of diagnostic accuracy obtained using the classical gold standard framework might not reflect the true diagnostic accuracy of dipstick tests. METHODS: We used the dataset from a prospective, observational study conducted in the emergency department of a teaching hospital in southern India. Patients with a clinical suspicion of UTI underwent dipstick testing for LE and nitrite, urine microscopy, and urine culture. Based on the results of urine microscopy and culture, UTI was classified into definite, probable, and possible. Patients with microscopic pyuria and a positive urine culture were adjudicated as definite UTI. Unequivocal imaging evidence of emphysematous pyelonephritis or perinephric collections was also considered definite UTI. We estimated the diagnostic accuracy of LE and nitrite tests using the classical analysis (assuming definite UTI as gold standard) and two different Bayesian latent class models (LCMs; 3-tests in 1-population and 2-tests in 2-populations models). RESULTS: We studied 149 patients. Overall, 64 (43%) patients had definite, 76 (51%) had probable, and 2 (1.3%) had possible UTI; 7 (4.6%) had alternate diagnoses. In classical analysis, LE was more sensitive than nitrite (87.5% versus 70.5%), while nitrite was more specific (24% versus 58%). The 3-tests in 1-population Bayesian LCM indicated a substantially better sensitivity and specificity for LE (98.1% and 47.6%) and nitrite (88.2% and 97.7%). True sensitivity and specificity of urine culture as estimated by the model was 48.7% and 73.0%. Estimates of the 2-tests in 2-populations model were in agreement with the 3-tests in 1-population model. CONCLUSIONS: Bayesian LCMs indicate a clinically important improvement in the true diagnostic accuracy of urine dipstick testing for LE and nitrite. Given this, a negative dipstick LE would rule-out UTI, while a positive dipstick nitrite would rule-in UTI in our study setting. True diagnostic accuracy of urine dipstick testing for UTI in various practice settings needs reevaluation using Bayesian LCMs.

Recuperación de Chlamydia trachomatis y otros patógenos en la orina de varones con piuria estéril atendidos en urgencias / Recovery of Chlamydia trachomatis and other pathogens in urine from men with sterile pyuria attended in an emergency department

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Clinical impact of rapid susceptibility testing on Mueller-Hinton Rapid-SIR directly from urine specimens.

Urinary tract infection diagnosis and management generally involves a 48-h microbiological delay to obtain the antibiotic susceptibility test (AST) results. In the context of multidrug resistance, reducing the time to obtain AST results is an essential factor, allowing for more timely appropriate treatment. We conducted a single-centre prospective study on urinary samples meeting two criteria: significant leukocyturia > 50/mm3 and exclusive presence of Gram-negative bacilli on direct examination. AST were performed by direct inoculation on Mueller-Hinton Rapid-SIR (MHR-SIR) agar. We evaluated the time to antibiotic adaptation by the antimicrobial stewardship team according to rapid AST results. Patients were subsequently excluded from the study if asymptomatic bacteria were confirmed, or in the absence of clinical data. Seventy patients were included. Mean age of patients was 68.8 years (± 21.3). Empirical antibiotic treatment were mainly based on third generation cephalosporins (n = 33), fluoroquinolones (n = 15), beta-lactamin/beta-lactamase inhibitors (n = 7), fosfomycin and nitrofurantoin (n = 5, each). The average time to obtain results was 7.2 h (± 1.6 h). Adaptation of therapy following MHR-SIR was performed for 29 patients (41%) with early switch to oral antibiotics, de-escalation or escalation in respectively 72.3%, 30%, and 11% of cases. Time saving of MHR-SIR compared with the standard technique was 42.6 (± 16.7) h. This study showed that rapid antibiotic susceptibility test results, using MHR-SIR method directly from urine, can be obtained 40 h earlier than conventional AST. The study also demonstrated significant clinical impact on the selection and reduction of the antibiotic therapy spectrum.

Preoperative sterile pyuria as a prognostic biomarker for intravesical recurrence in upper urinary tract urothelial carcinoma.

Purpose: To evaluate if preoperative sterile pyuria can be a prognostic factor for intravesical recurrence (IVR) and overall survival (OS)in patients with upper tract urothelial carcinoma (UTUC) undergoing surgery. Materials and Methods: We retrospectively reviewed the medical records of patients who were diagnosed with UTUC from October 2003 to December 2016 at Korea University Medical Center. Sterile pyuria was defined as urine containing five or more white blood cells per high-power field in the absence of bacteria in urine culture. We used a stepwise multivariable Cox proportional hazards model to assess the independent effects of the prognostic factors for IVR and OS. Results: We investigated a total of 176 patients who were diagnosed with UTUC. Among them, 91 (51.7%) patients had preoperative sterile pyuria. There were no significant differences in the baseline characteristics between the pyuria and non-pyuria groups concerning tumor grade, T stage, tumor multiplicity, and recurrence history. However, there was a significant difference in the IVR between the two groups. In the multivariable analysis, preoperative sterile pyuria, diabetes mellitus, high-grade tumor, and lymphovascular invasion were revealed as independent risk factors for IVR, and only lymphovascular invasion was identified as an independent risk factor for OS. Conclusions: Preoperative sterile pyuria is significantly associated with IVR in patients with UTUC undergoing surgery, but it is not associated with OS. Furthermore, diabetes mellitus, high-grade tumor, and lymphovascular invasion are also independent prognostic factors for these patients.

Squamous epithelial cell presence reduces accuracy of urinalysis for prediction of positive urine cultures.

BACKGROUND: Diagnostic value of urinalysis specimens contaminated with squamous epithelial cells (SEC) from the genital surfaces is assumed to be limited compared to clean-catch samples. However, no studies have quantified the change in predictive value in the presence of SECs for individual urinalysis markers. METHODS: In a retrospective, single center cohort study, we analyzed all urine cultures sent from the ED over a 26-month period with corresponding urinalysis results. Cultures were classified as positive with growth of >104 colony forming units of pathogenic bacteria, negative if no growth, or contaminated for all other results. UA specimens were classified as contaminated or clean based on SEC presence. Accuracy of urinalysis markers for prediction of positive cultures was calculated as an area under the curve (AUC) and was compared between contaminated and clean UA specimens. RESULTS: 6490 paired UA and urine cultures were analyzed, consisting of 3949 clean and 2541 contaminated samples. SEC presence was less common with male gender, older age, and smaller BMI. Urine cultures were 19.2% positive overall, and SECs were more common in contaminated cultures. AUCs for individual markers ranged from 0.557 to 0.796, with pyuria, bacteriuria, and leukocyte esterase having higher AUC in clean samples over contaminated. CONCLUSION: Analysis of AUC for individual urinalysis markers showed reduced diagnostic accuracy in the presence of SECs. SEC presence also reflected much higher rates of contaminated cultures. These results support the reduced reliance on contaminated UA specimens for ruling in UTI in ED patients.

Is sterile pyuria another minor diagnostic criterion in urinary tuberculosis?

INTRODUCTION: Composite reference standard (CRS) is used for diagnosis of urinary tract tuberculosis (UTB). We examined if addition of a new 'component test' as minor criterion in the form of SP could improve the yield. METHODS: We identified patients admitted with a diagnosis of UTB from January 2009 to February 2016 from our patient database. We performed the validation of addition of a new 'component' "sterile pyuria" to the existing basic CRS. RESULTS: SP was seen in 50 patients (65.7%). Forty (52.6%) of these patients had one major criterion positive and 10 (13.1%) were diagnosed based on minor criteria. If SP was added as a minor criterion, an additional 8 (9.2%) patients would have been diagnosed based on minor criteria alone without the need for a histopathology. CONCLUSIONS: SP could improve the diagnostic yield of existing CRS by 8% with a 70% decrease in reliance on histopathology for diagnosis.

Utility of point-of-care Gram stain by physicians for urinary tract infection in children ≤36 months.

Urinary tract infection (UTI) in children requires early diagnosis and treatment to prevent repeated UTI and renal scarring. This study aimed to evaluate the usefulness of the point-of-care Gram stain by physicians for suspected UTI in children at Okinawa Chubu Hospital as a rapid diagnostic test.A single-center, retrospective study was undertaken between January 2011 and December 2015. Patients aged 36 months or younger who were reviewed had suspected UTI in the emergency room or outpatient clinic. Urine culture, urinalysis, and point-of-care Gram stain were performed on a single specimen. Patients with structural or functional urological defects requiring routine catheterization were excluded. We compared the diagnostic performance among the rapid diagnostic tests (i.e., pyuria, point-of-care Gram stain, or both). Kappa statistics were used to evaluate the agreement between the results of point-of-care Gram stain and morphotypes of urine culture with the 95% CI (bias corrected bootstrap interval). We also analyzed which antibiotics were more susceptible to the bacteria of urine culture results, selected by the results of point-of-care Gram stain or empirical treatment based on the Japanese guidelines by McNemar test.Of 1594 patients reviewed in the study, 1546 were eligible according to our inclusion criteria. Using urine culture as the gold standard for UTI, the sensitivity and specificity of pyuria were 73.2% and 95.1%, whereas those of the point-of-care Gram stain were 81.4% and 98.2%, respectively. The concordance rate between the morphotypes of bacteria detected by point-of-care Gram stain and those of urine culture was 0.784 (kappa coefficient) (95% CI 0.736-0.831). Furthermore, the proportion of "susceptible" in the minimum inhibitory concentration of pathogen-targeted treatment based on the point-of-care Gram stain was higher than that of empirical therapy (exact McNemar significance probability: .0001).Our analysis suggests that the point-of-care Gram stain is a useful rapid diagnostic tool for suspected UTI in young children. Pathogen-targeted treatment based on the point-of-care Gram stain would lead to better antibiotic selection compared with empirical therapy.

Commentary on the Current Guidelines for the Diagnosis of Lupus Nephritis Flare.

PURPOSE OF REVIEW: Lupus nephritis flare is a frequent complication in patients with systemic lupus erythematosus. Recognizing disease activity is crucial in lupus nephritis management. Proteinuria magnitude and urine sediment change are major clinical indicators of lupus nephritis activity. This work updates these insights in light of recent findings regarding proteinuria quantification and urine sediment analyses. RECENT FINDINGS: Currently, BILAG and SLEDAI estimate proteinuria magnitude based on the protein/creatinine ratio of "spot" (single void collections) or "intended" 24-h urine collections without specifying the extent to which the collection approaches a 24-h collection. As discussed here, and based on our recently published work, these approaches often incur serious errors that can adversely affect SLE patient management. Also incorporated into this work is a new analysis of the clinical significance of urine sediment hematuria and pyuria changes with regard to recent-onset SLE glomerulonephritis (GN) flare. This analysis is based on a prospective study of urine sediment changes in the Ohio SLE Study, which was an NIH-sponsored prospective observational study of SLE GN patients with SLE flare of recent onset. We propose that BILAG and SLEDAI renal flare criteria can be made more rigorous by incorporating recently published insights into proteinuria quantification using the protein/creatinine ratio of an intended 24-h urine collection that is at least 50% complete based on its creatinine content. Also proposed are new insights into the interpretation of urine sediment hematuria and pyuria based on findings from the Ohio SLE Study.

Management and outcome of obstructive ureteral stones in the emergency department: Emphasis on urine tests and antibiotics usage.

BACKGROUND: Kidney stone related complaints in the Emergency Department (ED) are common. Current guidelines recommend antibiotic therapy for infected obstructive stones and stone removal in a timely fashion, but there is no clear recommendation for prophylactic antibiotic use for bacteriuria or pyuria in the setting of obstructive ureteral stones. OBJECTIVES: The aim of this study is to evaluate the current management of patients with obstructive ureteral stones in a single ED with emphasis on urine tests and antibiotics use. METHODS: The picture archiving and communication system (PACS) was used to filter the list of patients who received a computed tomography (CT) scan of the abdomen and pelvis that positively identified obstructive ureteral stones. Demographics and clinical data were also recorded and analyzed. RESULTS: Of the patients discharged, 278 patients did not receive antibiotics in the ED or a prescription. Of these, 8 patients had positive culture, 4 patients followed up, and one developed and was treated for a urinary-tract infection. One hundred ninety two patients were not given antibiotics in the ED but received an antibiotics prescription, and 4 patients had positive cultures grow. Two followed up and had no infection-related complications. Fourteen patients were discharged without a prescription after receiving a single dose of antibiotics in the ED, with no positive urine cultures and 9 patients following up without complication. CONCLUSION: Antibiotics were given at the discretion of the provider without clear pattern. A high rate of infectious complication did not occur in the followed up patient group.

Cross-over data supporting long-term antibiotic treatment in patients with painful lower urinary tract symptoms, pyuria and negative urinalysis.

PURPOSE: To measure the effects of an unplanned, sudden cessation of treatment in an unselected group of patients with chronic painful LUTS managed with protracted antimicrobial treatment and to report these observational data collected from a cross-over process. MATERIALS AND METHODS: The imposition of a guideline resulted in the immediate cessation of antibiotic treatment in a cohort of patients with chronic painful LUTS and microscopic pyuria. Patients were assessed before treatment withdrawal, whilst off treatment, and following reinstatement. Outcome measures included a validated symptom score, microscopic enumeration of urinary white cells and uroepithelial cells, and routine urine culture. RESULTS: These patients had reported treatment-resistant, painful LUTS for a mean of 6.5 years before treatment at this centre. Treatment was stopped in 221 patients (female = 210; male = 11; mean age = 56 years; SD = 17.81). Sixty-six per cent of women were post-menopausal. After unplanned treatment cessation, 199 patients (90%; female = 188; male = 9) reported deterioration. Eleven patients required hospital care in association with disease recurrence, including acute urinary tract infection (UTI) and urosepsis. Symptom scores increased after cessation and recovered on reinitiating treatment (F = 33; df = 2; p < 0.001). Urinary leucocyte (F = 3.7; df = 2; p = 0.026) and urothelial cells counts mirrored symptomatic changes (F = 6.0; df = 2; p = 0.003). Routine urine culture results did not reflect changes in disease status. CONCLUSION: These data support the hypothesis that treating painful LUTS associated with pyuria with long-term antimicrobial courses, despite negative urine culture, is effective. The microscopy of fresh unspun, unstained urine to count white cells and epithelial cells offers a valid method of monitoring disease. An unplanned cessation of antibiotic therapy produced a resurgence of symptoms and lower urinary tract inflammation in patients with chronic LUTS, supporting an infective aetiology below the level of routine detection.

Recalcitrant chronic bladder pain and recurrent cystitis but negative urinalysis: What should we do?

PURPOSE: Lower urinary tract symptoms (LUTS) may be associated with chronic urinary tract infection (UTI) undetected by routine diagnostic tests. Antimicrobial therapy might confer benefit for these patients. MATERIALS AND METHODS: Over 10 years, we treated patients with chronic LUTS. Pyuria was adopted as the principal biomarker of infection. Urinary leucocyte counts were recorded from microscopy of fresh midstream urine (MSU) samples. Antibiotics were prescribed and the prescription adjusted to achieve a measurable clinical response and a reduction in pyuria. RESULTS: We treated 624 women [mean age = 53.4 years; standard deviation (SD) = 18] with chronic LUTS and pyuria. Mean duration of symptoms prior to presentation was 6.5 years. Only 16% of MSU cultures submitted were positive (≥105 cfu ml-1). Mean treatment length was 383 days [SD = 347; 95% confidence interval (CI) = 337-428]. Treatment was associated with a reduction in total LUTS (F = 98; p = 0.0001), 24-h frequency (F = 75; p = 0.0001), urinary urgency (F = 90; p = 0.0001), lower urinary tract pain (F = 108; p = 0.0001), voiding symptoms (F = 10; p = 0.002), and pyuria (F = 15.4; p = 0.0001). Full-dose first-generation antibiotics for UTI, such as cefalexin, nitrofurantoin, or trimethoprim, were combined with methenamine hippurate. We recorded 475 adverse events (AEs) during 273,762 treatment days. There was only one serious adverse event (SAE). We observed no increase in the proportion of resistant bacterial isolates. CONCLUSION: This large case series demonstrates that patients with chronic LUTS and pyuria experience symptom regression and a reduction in urinary tract inflammation associated with antimicrobial therapy. Disease regression was achieved with a low frequency of AEs. These results provide preliminary data to inform a future randomized controlled trial (RCT).

Lower urinary tract symptoms that predict microscopic pyuria.

INTRODUCTION AND HYPOTHESIS: Urinary dipsticks and culture analyses of a mid-stream urine specimen (MSU) at 105 cfu ml-1 of a known urinary pathogen are considered the gold standard investigations for diagnosing urinary tract infection (UTI). However, the reliability of these tests has been much criticised and they may mislead. It is now widely accepted that pyuria (≥1 WBC µl-1) detected by microscopy of a fresh unspun, unstained specimen of urine is the best biological indicator of UTI available. We aimed to scrutinise the greater potential of symptoms analysis in detecting pyuria and UTI. METHODS: Lower urinary tract symptom (LUTS) descriptions were collected from patients with chronic lower urinary tract symptoms referred to a tertiary referral unit. The symptoms informed a 39-question inventory, grouped into storage, voiding, stress incontinence and pain symptoms. All questions sought a binary yes or no response. A bespoke software package was developed to collect the data. The study was powered to a sample of at least 1,990 patients, with sufficient power to analyse 39 symptoms in a linear model with an effect size of Cohen's f2 = 0.02, type 1 error probability = 0.05; and power (1-ß); 95% where ß is the probability of type 2 error). The inventory was administered to 2,050 female patients between August 2004 and November 2011. The data were collated and the following properties assessed: internal consistency, test-retest reliability, inter-observer reliability, internal responsiveness, external responsiveness, construct validity analysis and a comparison with the International Consultation on Incontinence Modular Questionnaire for female lower urinary tract symptoms (ICIQ-FLUTS). The dependent variable used as a surrogate marker of UTI was microscopic pyuria. An MSU sample was sent for routine culture. RESULTS: The symptoms proved reliable predictors of microscopic pyuria. In particular, voiding symptoms correlated well with microscopic pyuria (χ2 = 88, df = 1, p < 0.001). The symptom inventory has significant psychometric characteristics as below: test-retest reliability: Cronbach's alpha was 0.981; inter-observer reliability, Cronbach's alpha was 0.995, internal responsiveness F = 221, p < 0.001, external responsiveness F = 359, df = 5, p < 0.001. The correlation coefficients for the domains of the ICIQ-FLUTS were around R = 0.5, p < 0.001. CONCLUSION: This symptoms score performed well on the standard, psychometric validation. The score changed in response to treatment and in a direction appropriate to the changes in microscopic pyuria. It correlated with measures of quality of life. It would seem to make a good candidate for monitoring treatment progress in ordinary clinical practice.

Bacteria on Urine Microscopy Is Not Associated with Systemic Infection in Patients with Obstructing Urolithiasis.

INTRODUCTION: Determining whether bacterial presence in urine microscopy represents infection is important as ureteral stent placement is indicated in patients with obstructing urolithiasis and infection. We aim to investigate whether the presence of bacteria on urine microscopy is associated with other markers of infection in patients with obstructing urolithiasis presenting to the emergency room. METHODS: We performed a cross-sectional study of 199 patients with obstructing urolithiasis and divided patients into two groups according to the presence of bacteria on urine microscopy. The primary outcome was serum white blood cell count and secondary outcomes were objective fever, subjective fever, tachycardia, pyuria, and final urine culture. Univariate and multivariate analysis were used to assess whether the presence of bacteria on microscopy was associated with other markers of infection. RESULTS: The study included 72 patients in the bacteriuria group and 127 without bacteriuria. On univariate analysis, the presence of bacteria was not associated with leukocytosis, objective fever, or subjective fever, but it was associated with gender (p < 0.001), pyuria (p < 0.001), positive nitrites (p = 0.001), positive leukocyte esterase (p < 0.001), and squamous epithelial cells (p = 0.002). In a multilinear regression model including the presence of squamous cells, age, and sex, the presence of bacteriuria was not related to serum white blood cell count (coefficient -0.47; 95% confidence interval [CI] -1.1, 0.2; p = 0.17), heart rate (coefficient 0.85; 95% CI -2.5, 4.2; p = 0.62), presence of subjective or objective fever (odds ratio [OR] 1.5; 95% CI 0.8, 3.1; p = 0.18), or the presence of squamous epithelial cells (coefficient -4.4; 95% CI -10, 1.2; p = 0.12). However, the presence of bacteriuria was related to only the degree of pyuria (coefficient 16.4; 95% CI 9.6, 23.3; p < 0.001). CONCLUSIONS: Bacteria on urine microscopy is not associated with other markers of systemic infection and may largely represent a contaminant. Renal colic may be a risk factor for providing a contaminated urine specimen.

Pitfalls of diagnosing urinary tract infection in infants and young children.

BACKGROUND: The aim of this study was to examine the sensitivity and specificity of pyuria-based diagnosis of urinary tract infection (UTI) in urine collected by transurethral catheterization, and the reliability of diagnosis of pyuria in urine collected in a perineal bag. The gold standard for UTI diagnosis is significant colony counts of a single organism in urine obtained in a sterile manner. METHODS: We enrolled 301 patients who underwent medical examination at the present hospital for possible UTI between January 2005 and December 2009. We collected 438 urine samples by transurethral catheterization. We investigated the accuracy of pyuria-based diagnosis of UTI using transurethral catheterization urine specimens, and the reliability of diagnosis of pyuria using bag-collected urine specimens. RESULTS: The false-negative rate of UTI diagnosis based on pyuria in transurethral catheterization urine sediments was 9.0%; there was no significant difference in the false-negative rate of UTI diagnosis between boys and girls. Approximately 28% of pyuria-positive bag-collected urine specimens were pyuria negative on transurethral catheterization; this rate was significantly higher in girls than in boys (56.7% vs. 8.9%, P < 0.0001). CONCLUSIONS: The absence of pyuria in transurethral catheterization urine sediments does not rule out UTI. Pyuria in bag-collected urine specimens frequently consists of urine leukocytes from external genitalia as well as from the urinary tract.

The Importance of Urine Concentration on the Diagnostic Performance of the Urinalysis for Pediatric Urinary Tract Infection.

STUDY OBJECTIVE: The presence of leukocyte esterase by urine dipstick and microscopic pyuria are both indicators of possible urinary tract infection. The effect of urine concentration on the diagnostic performance of the urinalysis for pediatric urinary tract infection has not been studied. Our objective is to determine whether the urinalysis performance for detecting urinary tract infection varies by urine concentration as measured by specific gravity. METHODS: This was a retrospective cross-sectional study of the urine laboratory results of children younger than 13 years who presented to the emergency department during 68 months and had a paired urinalysis and urine culture obtained. Urinary tract infection was defined as pure growth of a uropathogen at standard culture thresholds. Test characteristics were calculated across 4 specific gravity groups (1.000 to 1.010, 1.011 to 1.020, 1.021 to 1.030, and >1.030). RESULTS: In total, 14,971 cases were studied. Median age was 1.5 years (interquartile range 0.4 to 5.5 years) and 60% were female patients. Prevalence of urinary tract infection was 7.7%. For the presence of leukocyte esterase and a range of pyuria cut points, the positive likelihood ratios decreased with increasing specific gravity. From most dilute to most concentrated urine, the positive likelihood ratio decreased from 12.1 (95% confidence interval [CI] 10.7 to 13.7) to 4.2 (95% CI 3.0 to 5.8) and 9.5 (95% CI 8.6 to 10.6) to 5.5 (95% CI 3.3 to 9.1) at a threshold of greater than or equal to 5 WBCs per high-power field and presence of leukocyte esterase, respectively. The negative likelihood ratios increased with increasing specific gravity for leukocyte esterase and microscopic pyuria. CONCLUSION: For the detection of pediatric urinary tract infection, the diagnostic performance of both dipstick leukocyte esterase and microscopic pyuria varies by urine concentration, and therefore the specific gravity should be considered when the urinalysis is interpreted.

Association Between Uropathogen and Pyuria.

OBJECTIVE: We sought to determine factors associated with the absence of pyuria in symptomatic children whose urine culture was positive for a known uropathogen. METHODS: We obtained data on children evaluated at the Children's Hospital of Pittsburgh emergency department between 2007 and 2013 with symptoms of urinary tract infection (UTI) who had paired urinalysis and urine cultures. We excluded children with an unknown or bag urine collection method, major genitourinary anomalies, immunocompromising conditions, or with multiple organisms on culture. We chose a single, randomly-selected urine specimen per child and limited the analysis to those with positive cultures. RESULTS: There were 46 158 visits during the study period; 1181 children diagnosed with UTI met all inclusion criteria and had a microscopic urinalysis for pyuria. Pyuria (≥5 white blood cells per high-powered field or ≥10 white blood cells per cubic millimeter) was present in 1031 (87%) children and absent in 150 (13%). Children with Enterococcus species, Klebsiella species, and Pseudomonas aeruginosa were significantly less likely to exhibit pyuria than children with Escherichia coli (odds ratio of 0.14, 0.34, and 0.19, respectively). Children with these organisms were also less likely to have a positive leukocyte esterase on dipstick urinalysis. Results were similar when we restricted the analysis to children whose urine samples were collected by bladder catheterization. CONCLUSIONS: We found that certain uropathogens are less likely to be associated with pyuria in symptomatic children. Identification of biomarkers more accurate than pyuria or leukocyte esterase may help reduce over- and undertreatment of UTIs.