Optimizing the Yield of In-and-Out Urinary Catheter Cultures by Applying a "Midstream-Like" Approach in Pediatric Patients

Despite appropriate disinfection, sample contamination during in-and-out urinary catheterization is not uncommon, yielding false-positive and "mixed-culture" interpretations. We implemented a "midstream-like" catheterization technique, and cultured both first- and second-voided urine fractions. Second-fraction cultures exhibited less contaminants and "mixed-culture" interpretations and were better aligned with pyuria, thereby enhancing diagnostic accuracy and minimizing the risk of clinical misdiagnosis and unwarranted antibiotic use.

Diagnostic accuracy of urine biomarkers for urinary tract infection in older women: a case-control study

OBJECTIVES

Urinary tract infection (UTI) is common among older women. However, diagnosis is challenging because of frequent chronic lower urinary tract symptoms, cognitive impairment, and a high prevalence of asymptomatic bacteriuria (ASB). Current urine diagnostics lack specificity, leading to unnecessary treatment and antimicrobial resistance. This study aimed to evaluate the diagnostic accuracy of 12 urine biomarkers for diagnosing UTI in older women.

METHODS

In this case-control study, cases were women ≥65 years with ≥2 new-onset lower urinary tract symptoms, pyuria, and one uropathogen ≥104 CFU/mL. Controls were asymptomatic and classified as ASB (one uropathogen ≥105 CFU/mL), negative culture, or mixed flora. Urine biomarker concentrations were measured through liquid chromatography-mass spectrometry and ELISA. Diagnostic accuracy parameters of individual biomarkers and a biomarker model were derived from receiver operating characteristic curves.

RESULTS

We included 162 community-dwelling and institutionalized older women. Five urine inflammatory biomarkers demonstrated high discriminative ability (area under the curve ≥0.80): interleukin 6, azurocidin, neutrophil gelatinase-associated lipocalin, tissue inhibitor of metalloproteinases 2, and C-X-C motif chemokine 9. Azurocidin exhibited the highest diagnostic accuracy (sensitivity 86% [95% CI 75%-93%] and specificity 89% [95% CI 82%-94%] at 16.7 ng/mmol creatinine). A combined biomarker and pyuria model showed improved diagnostic accuracy in patients with UTI and ASB, compared with pyuria alone.

DISCUSSION

We identified several urine biomarkers that accurately differentiated older women with UTI from asymptomatic women, including ASB. These findings represent a potential advancement towards improved diagnostics for UTI in older women and warrant validation in a diverse population.

Clinical Course of Children 1 to 24 Months Old With Positive Urine Cultures Without Pyuria

OBJECTIVE

To describe the clinical course of children with positive urine cultures without pyuria who were not given antibiotics initially, identify predictors of subsequent antibiotic treatment, and evaluate the association between subsequent treatment and urinary tract infection (UTI) within 30 days.

METHODS

We conducted a multicenter retrospective cohort study of children 1 to 24 months old who had positive urine cultures without pyuria and who were not started on antibiotics upon presentation to 3 health care systems from 2010 to 2021. Outcomes included clinical status at the time urine cultures resulted, escalation of care (emergency department visit or hospitalization) and subsequent antibiotic treatment within 7 days, and subsequent UTI within 30 days of presentation.

RESULTS

Of 202 included children, 61% were female and median age was 9 months. Of 151 patients with clinical status information when cultures resulted, 107 (70.8%, 95% confidence interval [CI] 62.9-77.9%) were improved. Two of 202 children (1.0%, 95% CI 0.2-4.0%) experienced care escalation. Antibiotics were started in 142 (82.2%) children, and treatment was associated with prior UTI (risk ratio [RR] 1.20, 95% CI 1.15-1.26) and lack of improvement (RR 1.22, 95% CI 1.13-1.33). Subsequent UTI was diagnosed in 2 of 164 (1.2%, 95% CI 0.1-4.3%) treated and 0 of 36 (0%, 95% CI 0-9.7%) untreated children.

CONCLUSIONS

Seventy percent of children with positive urine cultures without pyuria improved before starting antibiotics; however, >80% were ultimately treated. Future research should study the impact of diagnostic stewardship interventions and various urine testing strategies to optimize the management of children evaluated for UTI.retain-->.

Urine specific gravity, pyuria, and neutrophil gelatinase-associated lipocalin for identifying urinary tract infection in young children

BACKGROUND

To determine whether urine neutrophil gelatinase-associated lipocalin (uNGAL) might be superior to pyuria for detecting urinary tract infection (UTI) regardless of urine specific gravity (SG) in young children.

METHODS

We conducted a retrospective analysis of children aged < 3 years who were evaluated for UTI with urinalysis, urine culture, and uNGAL measurements during a 5-year period. Sensitivity, specificity, likelihood ratios (LRs), predictive values (PVs), area under the curves (AUCs) of uNGAL cut-off levels, and various microscopic pyuria thresholds for detecting UTI were calculated for dilute (SG < 1.015) and concentrated urine (SG ≥ 1.015).

RESULTS

Of 456 children included, 218 had UTI. The diagnostic value of urine white blood cell (WBC) concentration to define UTI changed with urine SG. For detecting UTI, uNGAL cut-off of 68.4 ng/mL had higher AUC values than pyuria ≥ 5 WBCs/high power field (HPF) for dilute and concentrated urine samples (both P < 0.05). Positive LR and PV and specificity of uNGAL were all greater than those of pyuria ≥ 5 WBCs/HPF regardless of urine SG, although the sensitivity of pyuria ≥ 5 WBCs/HPF was higher than that of uNGAL cut-off for dilute urine (93.8% vs. 83.5%) (P < 0.05). At uNGAL ≥ 68.4 ng/mL and ≥ 5 WBCs/HPF, posttest probabilities of UTI were 68.8% and 57.5% for dilute urine and 73.4% and 57.3% for concentrated urine, respectively.

CONCLUSIONS

Urine SG can affect the diagnostic performance of pyuria for detecting UTI and uNGAL might be helpful for identifying UTI regardless of urine SG in young children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Current Pyuria Cutoffs Promote Inappropriate Urinary Tract Infection Diagnosis in Older Women

BACKGROUND

Pre-existing lower urinary tract symptoms (LUTS), cognitive impairment, and the high prevalence of asymptomatic bacteriuria (ASB) complicate the diagnosis of urinary tract infection (UTI) in older women. The presence of pyuria remains the cornerstone of UTI diagnosis. However, >90% of ASB patients have pyuria, prompting unnecessary treatment. We quantified pyuria by automated microscopy and flowcytometry to determine the diagnostic accuracy for UTI and to derive pyuria thresholds for UTI in older women.

METHODS

Women ≥65 years with ≥2 new-onset LUTS and 1 uropathogen ≥104 colony-forming units (CFU)/mL were included in the UTI group. Controls were asymptomatic and classified as ASB (1 uropathogen ≥105 CFU/mL), negative culture, or mixed flora. Patients with an indwelling catheter or antimicrobial pretreatment were excluded. Leukocyte medians were compared and sensitivity-specificity pairs were derived from a receiver operating characteristic curve.

RESULTS

We included 164 participants. UTI patients had higher median urinary leukocytes compared with control patients (microscopy: 900 vs 26 leukocytes/µL; flowcytometry: 1575 vs 23 leukocytes/µL; P < .001). Area under the curve was 0.93 for both methods. At a cutoff of 264 leukocytes/µL, sensitivity and specificity of microscopy were 88% (positive and negative likelihood ratio: 7.2 and 0.1, respectively). The commonly used cutoff of 10 leukocytes/µL had a poor specificity (36%) and a sensitivity of 100%.

CONCLUSIONS

The degree of pyuria can help to distinguish UTI in older women from ASB and asymptomatic controls with pyuria. Current pyuria cutoffs are too low and promote inappropriate UTI diagnosis in older women. Clinical Trials Registration. International Clinical Trials Registry Platform: NL9477 (https://trialsearch.who.int/Trial2.aspx?TrialID=NL9477).

Optimizing reflex urine cultures: Using a population-specific approach to diagnostic stewardship

BACKGROUND

Clinicians and laboratories routinely use urinalysis (UA) parameters to determine whether antimicrobial treatment and/or urine cultures are needed. Yet the performance of individual UA parameters and common thresholds for action are not well defined and may vary across different patient populations.

METHODS

In this retrospective cohort study, we included all encounters with UAs ordered 24 hours prior to a urine culture between 2015 and 2020 at 3 North Carolina hospitals. We evaluated the performance of relevant UA parameters as potential outcome predictors, including sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV). We also combined 18 different UA criteria and used receiver operating curves to identify the 5 best-performing models for predicting significant bacteriuria (≥100,000 colony-forming units of bacteria/mL).

RESULTS

In 221,933 encounters during the 6-year study period, no single UA parameter had both high sensitivity and high specificity in predicting bacteriuria. Absence of leukocyte esterase and pyuria had a high NPV for significant bacteriuria. Combined UA parameters did not perform better than pyuria alone with regard to NPV. The high NPV ≥0.90 of pyuria was maintained among most patient subgroups except females aged ≥65 years and patients with indwelling catheters.

CONCLUSION

When used as a part of a diagnostic workup, UA parameters should be leveraged for their NPV instead of sensitivity. Because many laboratories and hospitals use reflex urine culture algorithms, their workflow should include clinical decision support and or education to target symptomatic patients and focus on populations where absence of pyuria has high NPV.

Diagnosis of urinary tract infection in infants under 3 months with fever without a source: reliability of urinalysis and urine culture

BACKGROUND

Urinary tract infection (UTI) is infants' most common serious bacterial infection. This study aimed to investigate the reliability of urianalysis (UA) to predict UTI, to specify the colony forming units (CFU)/ml threshold for diagnosis, and to identify variables that help suspect bacteremia in infants under 3 months with UTI.

METHODS

We reviewed clinical records of children under 3 months hospitalized for a fever without source and recorded age, sex, days of fever pre-consultation, temperature and severity at admission, discharge diagnoses, laboratory tests, and treatments. According to the discharge diagnosis, we divided them into UTIs (-) and (+) with or without bacteremia.

RESULTS

A total of 467 infants were admitted: 334 with UTI and 133 without UTI. In UTIs (+), the pyuria had a sensitivity of 95.8% and bacteria (+) 88.3%; specificity was high, especially for nitrites (96.2%) and bacteria (+) (92.5%). Positive predictive value (PPV) for nitrites was 95.9%, for bacteria 96.7%, and oyuria 92.5%. Escherichia coli was present in 83.8% of urine and 87% of blood cultures. UTIs with bacteremia had inflammatory urinalysis, urine culture > 100,000 CFU/ml, and higher percentage of C reactive protein (CRP) > 50 mg (p= 0.002); 94.6% of the urine culture had > 50,000 CFU.

CONCLUSIONS

The pyuria and bacteria (+) in urine obtained by catheterization predict UTI. The cut-off point for diagnosis was ≥ 50,000 CFU/ml. No variables to suspect bacteremia were identified in this study.

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.

Fever, abdominal pain, and adnexal mass

A CT scan pointed to a surgical emergency. But what surgeons found was not the small bowel obstruction they were expecting.

Performance assessment of urine flow cytometry (UFC) to screen urines to reflex to culture in immunocompetent and immunosuppressed hosts

PURPOSE

Urine flow cytometry (UFC) is an automated method to quantify bacterial and white blood cell (WBC) counts. We aimed to determine whether a threshold for these parameters can be set to use UFC as a sensitive screen to predict which urine samples will subsequently grow in culture.

METHODOLOGY

Urines submitted to our microbiology laboratory at a tertiary care centre from 22 July 2015-17 February 2016 underwent UFC (Sysmex UF-1000i) analysis, regular urinalysis and urine culture. Positive urine cultures were defined as growth ≥104 c.f.u. ml-1 of organisms associated with urinary tract infections. The correlation of UFC bacterial and WBC counts with urine culture was assessed using receiver operating characteristics curves. The sensitivity (SN), specificity (SP), negative predictive values (NPVs), positive predictive values (PPVs) and false negative rate (FNR) were calculated at various thresholds in immunocompetent and immunosuppressed patients.

RESULTS

A total of 15 046 urine specimens were submitted, of which 14 908 were analysable in the study. The average time to UFC result from receipt in the laboratory was 0.76 h (+/-1.04). The test performance at a set threshold of UFC bacteria ≥20 or WBC >5 was: SN=96.0 %, SP=39.2 %, PPV=47.0 %, NPV=94.5 % and FNR=4.0 %. This threshold eliminates 26 % of urine cultures. Immunosuppressed hosts had a lower sensitivity of 90.6 % and a higher FNR of 9.4 %.

CONCLUSIONS

UFC is a rapid and sensitive method to screen out urine samples that will subsequently be negative and to reflex urines to culture that will subsequently grow. UFC results are available within 1 h from receipt and enable the elimination of culture when the set threshold is not met.

Pyuria as a screening test for detection of urinary tract infection in patients on long-term hemodialysis

INTRODUCTION. This study was conducted to evaluate the sensitivity and specificity of pyuria detection in centrifuged urine samples of patients on hemodialysis, and its relationship with urinary tract infection. MATERIALS AND METHODS. Clean-catch midstream urine samples of 90 hemodialysis patients (34 women and 56 men) were obtained and divided into two parts for examination of urine sediment and urine culture. Pyuria was defined as the presence of more than 10 leukocytes per high-power field of microscope. RESULTS. Ninety patients with a mean age of 52.8 ± 14.2 and a mean period of dialysis of 3.3 ± 2.3 years were studied. Forty-five participants had pyuria and only 16 (35.5%) of them had a positive urine culture for infection. Pyuria and urinary tract infection were present in 52.9% and 29.4% of the women and 48.2% and 10.7% of the men, respectively. The sensitivity and specificity of pyuria screening for urinary tract infection was 100% and 61.8%, respectively. The positive and negative predictive values were 35.5% and 100%, respectively. CONCLUSIONS. In patients on hemodialysis, because of the low specificity and positive predictive values, samples with positive pyuria should be cultured to confirm urinary tract infections.

Significance of pyuria in the diagnosis of urinary tract infections in neonates

OBJECTIVES

To determine the significance of pyuria as a predictor of culture proven urinary tract infections (UTI) in neonates and to assess the frequency of urinary tract anomalies in neonates with pyuria.

METHODS

Prospective study conducted at the neonatal intensive care unit of a tertiary care hospital; (Liaquat National Hospital Karachi) for a period of 4 months from April 2008 to August 2008. One hundred and ten consecutive infants < or = 28 days of age admitted to the NICU of Liaquat National Hospital for medical reasons were included in the study. Information regarding age, gender, antenatal history, birth weight, clinical examination, laboratory findings and outcome were recorded on a questionnaire. Septic work up was performed and urine samples were collected using urethral catheterization. Patients showing any number of white blood cells on microscopy were included and their urine sent for culture. All patients had Ultrasound done during their hospital stay and those patients with any renal abnormality were further investigated with Micturating cyestoretherogram (MCUG) at 6 weeks.

RESULTS

Out of one hundred and ten patients admitted, thirty five patients showed the presence of pus cells in urine and were included in the study. Of the 35 neonates with pyuria, 71.4% had no growth in urine cultures and 38.2 % neonates with insignificant pyuria (< or = 9 cells in urine) showed a positive culture. The renal ultrasound was normal in 51.4% neonates with pyuria although it was abnormal in 100% of the subjects with higher number of pus cells in urine (> 20 pus cells).

CONCLUSION

Pyuria is not a useful marker for the diagnosis of culture proven UTI in neonates it cannot be used as an indicator of underlying renal abnormality, though it may have some utility in neonates with > 20 /numerous pus cells.

Validity of quantitative unspun urine microscopy, dipstick test leucocyte esterase and nitrite tests in rapidly diagnosing urinary tract infections

OBJECTIVES

Rapid diagnostic tests can screen out negative samples and can save valuable time and money. The study was conducted to assess the usefulness of leukocyte esterase, nitrate reductase and quantitative microscopic unspun urine wet mount examination in rapidly diagnosing urinary tract infections (UTI).

METHODS

Four hundred and fifty samples were tested by semi-quantitative culture on cysteine lactose electrolyte deficient medium, microscopic examination of unspun urine for significant pyuria, dipstick leucocyte esterase test (LET) and nitrite test (NT). Culture was used as gold standard to evaluate the performance of direct microscopy and dipstick tests.

RESULTS

Urine culture examination revealed significant bacteriuria (>10(5) cfu/ml) 98 (21.8%), in urine samples. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and the diagnostic odds ratio (DOR) of the dip-stick LET were 73.5%, 58.5%, 33.0%, 88.8%, and 3.9 respectively; those of the dip-stick NT were 57.1%, 78.7%, 42.7%, 86.8%, and 4.9 respectively; and those for microscopic significant pyuria detection were 68.4%, 60.8%, 32.7%, 87.3%, and 3.4 respectively. Highest sensitivity (95.9%), NPV (97.9%) and DOR (25.7) was obtained on combining microscopy and dip-stick LET and NT (either of them positive). This can potentially cut costs by 79%.

CONCLUSION

Quantitative unspun urine wet mount microscopy and dipstick tests for leucocyte esterase and nitrite test should be added into routine laboratory practices for faster diagnosis of UTI.

Persistent sterile pyuria in children? Don't forget tuberculosis!

Genitourinary tuberculosis (GUTB) is exceptionally uncommon among the local paediatric population. A 10-year-old Chinese girl with no risk factors for tuberculosis presented with recurrent sterile pyuria. Despite extensive renal investigations, no apparent cause could be ascertained for her obstructed left drainage system. The diagnosis was eventually confirmed with urine acid-fast bacilli culture, after a computed tomography scan suggested possible renal tuberculosis. Left nephroureterectomy had to be performed owing to deteriorating left kidney function. This report discusses the importance of considering tuberculosis when assessing a local paediatric patient with an atypical urinary tract infection. Early diagnosis of renal tuberculosis can prevent the sequelae of GUTB, including renal impairment.

Risks of repeated visits for uninvestigated dyspepsia in three community hospitals of Khon Kaen, Thailand

BACKGROUND

Uninvestigated dyspepsia (UD) is common and only 26.4% of these are peptic ulcer disease, while 50% are non-ulcer dyspepsia. A recent study found that nephrolithiasis with urinary tract infection may have the dyspeptic symptoms.

OBJECTIVE

The authors searched for any associations between repeated UD and pyuria, hematuria and other factors.

MATERIAL AND METHOD

A case-control study was performed. It consisted of 489 patients with repeated UD who had visited community hospitals for at least two times per year and 489 controls sampled from the data of the subjects, free of dyspeptic symptoms, from the multi-stage random survey for subjective health complaints in the same province. Multivariate logistic regression models were used for case-control comparisons.

RESULTS

By logistic regression analysis, UD was significantly associated with problems caused by purine-rich foods (PRFs), chronic fatigue, flank paresthesia, hematuria, myofascial pain, and pyuria. The respective adjusted odds ratios and 95% confidence interval (CI) were: 6.67 (4.58, 9.68), 5.06 (3.46, 7.40), 3.98 (2.41, 6.60), 2.97 (2.01, 4.38), 1.91 (1.32, 2.76) and 1.58 (1.01, 2.45). The variables of age (> 48), sex, dysuria, poly-arthralgia, headache and back pain were not significantly associated with UD. The foods that aggravated UD were bamboo shoots, fermented rice noodles, beef alcohol and insects. The rate of pyuria and hematuria was significantly increased with the number of visits within a year [p-value (Chi-square for trend), 0.015 and 0.032].

CONCLUSION

These findings indicate that pyuria, hematuria, and purine-rich foods were associated with repeated hospital visits for dyspepsia.

Clinical study of complicated urinary tract infection using 'The UTI Criteria (Draft Fourth Edition)': measurement methods for pyuria

OBJECTIVE

To evaluate the influences the change of the measurement method of pyuria from conventional centrifuged sediment to microchamber uncentrifuged urine for the results of evaluation of antimicrobial agents in clinical study against complicated urinary tract infections. From the viewpoint of international harmonization of judgement criteria, the recent method for counting white blood cells (WBC) in urine has changed from using uncentrifuged urine to using a microchamber in all countries.

METHODS

Targeted diseases were non-catheterized complicated urinary tract infection, and cefcapene pivoxil hydrochloride or levofloxacin were used as antimicrobial drug. Pyuria was examined using the counting chamber method, a quantitative method using uncentrifuged urine with a microchamber, and the sedimentation method.

RESULTS

Overall clinical efficacy in early evaluation by the two methods in measuring pyuria was evaluated as different in eight patients (7.3%). It was rated excellent in 63 (52.9%), moderate in 32 patients (26.9%) and poor in 24 (20.2%) with an efficacy rate of 79.8% using the counting chamber method, and excellent in 68 (57.1%), moderate in 27 (22.7%) and poor in 24 (20.2%) with an efficacy rate of 79.8% using the conventional sedimentation method

CONCLUSION

No significant difference was seen between the two methods of WBC count in urine.

Can the urine dipstick test reduce the need for microscopy for assessment of systemic lupus erythematosus disease activity?

OBJECTIVE

Urine microscopic examination is an important component of the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). We investigated whether the urine dipstick test can reduce the need for microscopy for the assessment of SLEDAI.

METHODS

We studied 269 urine samples from 259 SLE patients with Albustix and Hemastix reagent strips. The results were compared to concomitant microscopic examination of urinary sediment.

RESULTS

When trace red blood cell was defined as the cutoff, the sensitivity, specificity, and negative predictive value (NPV) of the Hemastix urine test were 0.98, 0.53, and 0.99, respectively, for hematuria; 0.82, 0.47, and 0.90, respectively, for the presence of pyuria; and 0.91, 0.44, and 0.98, respectively, for the presence of casts by microscopic examination. When proteinuria of 1+ was defined as the cutoff, the sensitivity, specificity, and NPV of the Albustix test were 1.00, 0.46, and 0.99, respectively, for urinary casts; and 0.82, 0.49, and 0.90, respectively, for the presence of pyuria. When both Albustix and Hemastix were applied as screening test, urine microscopy could be reduced by 27%; however, 8% of cases with normal Albustix and Hemastix tests had at least one abnormality on urine microscopy examination.

CONCLUSION

In patients with SLE, a combination of Albustix and Hemastix urine tests showed reasonable sensitivity to detect abnormalities in urine sediment. Based on these results, routine urine microscopy can be limited to SLE patients with abnormal Albustix or Hemastix tests. Rarer causes of abnormal renal function in lupus, such as tubulointerstitial nephritis or drug induced interstitial nephritis, would be manifested by pyuria and therefore would not necessarily be detected by changes in the blood and protein detectors on the urine dipstick.

Criteria for urinary tract infection in the elderly: variables that challenge nursing assessment

Urinary tract infections (UTIs) are common in the elderly, yet there is much disagreement in the literature regarding many aspects of this condition. To assist the nurse in developing optimum care strategies, UTI criteria in the elderly are discussed. Using the most recent knowledge to guide clinical assessment and intervention skills, the longterm care facility nurse and nurses who care for the elderly can influence positive outcomes in this challenging population.

Urinary Tract Infections: Does the Smell Really Tell?

Asymptomatic bacteriuria is considered a transient and benign condition in the geriatric population. Before a diagnosis of a urinary tract infection (UTI) can be made, symptoms and significant bacteriuria must be present. One of these symptoms is malodorous urine. Other symptoms of a UTI, typical in the younger population, have been found to be absent or misleading in the older adult population. Though early detection of UTIs improves outcomes, unnecessary laboratory tests are costly and time-consuming, and may encourage inappropriate antibiotic therapy. The purpose of this study was to determine if urine odor is an accurate predictor of a UTI in the older adult incontinent nursing home population. Ninety-seven recently wet incontinence pads of residents in six Midwestern nursing homes were evaluated for odor within 1 hour of voiding. These results were compared to microscopy and culture results of clean-catch urine samples from these individuals. Defining a UTI as either bacteriuria or bacteriuria and pyuria, using urine odor to identify a UTI resulted in error in one third of cases. Results of this study indicate smell of urine in incontinence pads may be an absent or misleading symptom for UTIs in elderly nursing home residents.

Effects of urinary tract inflammation and sample blood contamination on urine albumin and total protein concentrations in canine urine samples

BACKGROUND

Urinary tract inflammation and hemorrhage are believed to be common causes of proteinuria in dogs based on results of studies that measured total urine protein concentration. A method to quantify urine albumin (UAlb) concentration in dogs recently has become available; however, the effect of inflammation on albuminuria is unknown.

OBJECTIVES

The goals of this study were to determine the effects of urinary tract inflammation, as indicated by pyuria and sample blood contamination, on UAlb concentration and on urine protein:creatinine (UPC) ratio in dogs.

METHODS

Urine samples were obtained from dogs with pyuria that were presented to a veterinary teaching hospital or were part of a laboratory colony. To mimic the effects of hematuria, canine whole blood was added to a microscopically normal canine urine sample that had baseline albumin and total protein concentrations below the limits of detection. UAlb concentration was measured using a canine albumin-specific competitive ELISA. UPC ratio was determined using routine methods.

RESULTS

Of 70 samples with pyuria, 67% had negligible UAlb concentrations and 81% had normal UPC ratios. UAlb concentration but not UPC ratio was significantly higher (P < 0.05) in samples with concurrent hematuria or bacteriuria. When whole blood was added to normal urine, UAlb concentration did not exceed 1 mg/dL until the sample became visibly pink; the UPC did not exceed 0.4 at any dilution.

CONCLUSIONS

Many dogs with pyuria do not have albuminuria or proteinuria; however, albuminuria may be more likely in dogs with pyuria and concurrent hematuria or bacteriuria. Hematuria may not cause an increase in UAlb concentration until it becomes macroscopic and even then may not increase the UPC ratio.

Urinary immunocytology for primary bladder B cell lymphoma

Urinary immunocytology is described as a diagnostic tool in a patient with a primary high-grade, large-cell, B cell lymphoma of the bladder. Lymphoma cells were distinguished from abundant leukocytes by immunocytologic staining for CD20. This technique might be useful in the differential diagnosis of patients with chronic bladder inflammation accompanied by pyuria.

Pyuria detection using a dipstick applied to urine in incontinence pads

The purpose of this study was to determine whether pressing a dipstick into a pad within 2 hours of urine saturation detected pyuria as effectively as immersing a dipstick in a urine specimen. Sensitivity, specificity, and positive and negative predictive values indicated that results of the pad method were as effective as those of direct dipstick into clean-catch urine in detecting pyuria. In the elderly, sensitivity of the pad method was 100%, indicating this would be an effective method for initial assessment of pyuria.

A study for the improvement of the cytological urine examination performances in upper tract infection diagnosis

Diagnosis of the location of upper and lower urinary tract infection (UTI) is necessary in defining the therapeutic conduct that has a different period and intensity according to the infection location and in prognosis. Many studies show the lack of clinical criteria peculiarity in revealing the different location of UTI. As a result, the correct location of the level in which UTI develops is the necessity of paraclinical investigations. Urinary sample examination, in which urinary sediment microscopy is essential, is a reliable technique in fast detection and localization of UTI. Finding, in pyuria context, the classic significant bacteriuria (> or = 10(5) CFU/ml) or lower value bacteriuria (< or = 10(4) CFU/ml) confirms the UTI diagnosis. The upper tract infection prognosis increases when leukocyte cylinders, characteristic for pyelonephritis, appear together with intact or degraded leukocytes, single or grouped. We settled an algorithm to examine the urine samples in order to: Concentrate and preserve the structural integrity of leukocytes and cylinders, examining the conventional urinary sediment Precisely identify and differentiate these elements by vital coloration (leukocyte peroxidase coloration and Sternheimer - Malbin coloration) to establish more accurate the UTI level. The vital coloration for leukocyte peroxidase has cytological specificity, confirming the pyuria and the cylinders that contain leukocytes (leukocytary, granular, mixed) and obviously ameliorates the reliability and reproducibility of the urinary sediment cytological exam.

Predicting urine culture results by dipstick testing and phase contrast microscopy

AIMS

Urine is the most frequently received clinical specimen for bacterial culture. To determine whether dipstick or microscopy results reliably predicted the presence or absence of a reportable urinary pathogen we performed dipstick testing and phase contrast microscopy on unspun urine from 500 specimens. We also investigated the relationship between the presence of squamous epithelial cells (SECs) and mixed growth on culture.

METHODS

For each specimen, the presence of leukocyte esterase and urinary nitrite was recorded as well as the quantity of leukocytes (WBC), SECs, and erythrocytes. All cultures had the number and type of each organism recorded. Pyuria was defined as > or =10 WBC/mm(3).

RESULTS

Specimens with <10 SEC/mm(3) had fewer isolates (0.9 isolate per culture) than specimens with > or =10 SEC/mm(3) (two isolates per culture); therefore, SEC contamination was defined as > or =10 SEC/mm(3). Of 500 specimens, 266 (53%) had no growth and 136 (27%) had mixed growth. A total of 288 (58%) specimens had negative dipstick results and completely normal microscopy. Of these, 11 (4%) had a pure growth of a urinary pathogen but the pathogen was present in only three (1%) at > or =10(5) CFU/mL. Of 413 urine specimens without SEC contamination, 323 (78%) had either no detectable growth or pure growth compared with only 41 of 87 (47%) with SEC contamination (P<0.001). Of the 413 urine specimens without SEC contamination, 90 (22%) had > or =2 organisms compared with 46 of 87 (53%) with contamination (P<0.01). Pyuria was present in only 21 of 266 (8%) urine specimens without growth but was present in 60 of 95 (64%) specimens containing a reportable pathogen (P<0.01).

CONCLUSIONS

SEC contamination does not reliably predict cultures with mixed growth, urine specimens with negative dipstick results and microscopy rarely contain a reportable urinary pathogen, and screening algorithms are warranted and justified.

Evaluation of the diagnostic workup in young women referred for recurrent lower urinary tract infections

OBJECTIVES

To evaluate the current practice of the diagnostic workup in The Netherlands and the clinical relevancy of the outcome of various diagnostic procedures in young women referred for recurrent lower urinary tract infections (UTIs).

METHODS

A questionnaire was sent to all urologic departments in The Netherlands (n = 104) inquiring about the diagnostic procedures used for recurrent lower UTIs. Furthermore, we performed a prospective study in 100 consecutive young female patients (18 to 40 years old) referred for evaluation of recurrent lower UTIs. All patients underwent a standardized workup: questionnaire, voiding diary, physical examination, urinalysis and culture, abdominal x-ray with ultrasound or intravenous urography, and cystoscopy.

RESULTS

The response rate to the questionnaires was 92%. The standard procedures were laboratory blood tests in 56%, cystoscopy in 69%, plain abdominal x-ray in 91%, and abdominal ultrasound in 59%. Only 18% of the urologists asked every patient to make a voided urine frequency volume chart. In our group of patients, the radiologic procedures revealed only one relevant abnormality. Cystoscopy confirmed cystitis in 22 patients, but never revealed relevant findings. None of these diagnostic procedures ever contributed to the diagnosis. The 24-hour urine output was less than 1.5 L in 43 patients, which was considered insufficient. The individual self-reports of fluid intake were unreliable.

CONCLUSIONS

Many Dutch urologists perform an extensive routine workup in patients referred for recurrent lower UTIs. The results of our study revealed that the yield of most diagnostic procedures in these patients is low. The focus in evaluating these patients should be directed toward the behavioral aspects. Thus, the routine workup can be restricted to a voiding diary, urinalysis, and urine culture.

Use of urinary gram stain for detection of urinary tract infection in childhood

In this study, urinary culture, urinary Gram stain, and four tests within the urinalysis, leukocyte esterase, nitrite, microscopyfor bacteria, and microscopyforpyuria, were examined in 100 children with symptoms suggesting urinary tract infection. Our purpose was to determine the validity of the urinary Gram stain compared with a combination of pyuria plus Gram stain and overall urinalysis (positiveness of nitrite, leukocyte esterase, microscopy for bacteria, or microscopy for white blood cell). Of 100 children, aged two days to 15 years, 70 (70 percent) had a positive urinary culture: 40 girls (57 percent) and 30 boys (43 percent). Escherichia coli was the most common isolated agent. The sensitivity and specificity of the urinary Gram stain were 80 percent and 83 percent, and that of the combination of pyuria plus Gram stain 42 percent and 90 percent, and that of the overall urinalysis 74 percent and 3.5 percent respectively. Our findings revealed that neither method of urine screen should substitute for a urine culture in the symptomatic patients in childhood.

Rapid urinalysis assays for the diagnosis of urinary tract infection

Urinary tract infection (UTI) in premenopausal women is a frequent complaint in general practice. UTI is usually diagnosed on the basis of clinical symptoms and the use of one or more laboratory tests, the most common being rapid urinalysis reagent assays (urine dip) or midstream urine culture. In order to correlate the leucocyte esterase results of a rapid urinalysis assay with direct urine microscopy for pyuria, undiluted non-centrifuged urine samples from 206 volunteer female healthcare professionals were subjected to analysis using direct urine microscopy using a counting chamber and a rapid urinalysis assay. Of the 206 specimens, 74 were positive for leucocyte esterase using the rapid urinalysis assay, and 39 specimens demonstrated significant pyuria (greater than or equal to 10 leucocytes/microl) on direct microscopy. When the leucocyte esterase results were correlated with the direct urine microscopy results, an assay reading of 15 leucocytes/microl ('trace' on the visual scale) had a sensitivity of 91%, specificity of 79%, positive predictive value of 53% and a negative predictive value of 97%. An assay reading of 25 leucocytes/microl ('+' on the visual scale) or greater had a sensitivity of 63%, specificity of 95%, positive predictive value of 75% and a negative predictive value of 91%. In premenopausal, non-pregnant females, a rapid urinalysis assay result of 25 leucocytes/microl or greater will predict significant pyuria on urine microscopy with reasonable confidence, thereby reducing the need for more costly urine cultures.

Evaluation of the accuracy of leukocyte esterase testing to detect pyuria in young febrile children: prospective study

OBJECTIVE

To study the accuracy and clinical application of the dipstick leukocyte esterase test in the detection of pyuria in young febrile children suspected to have urinary tract infection.

DESIGN

Prospective study.

SETTING

Regional hospital, Hong Kong.

PATIENTS

Urine samples were taken from 215 children younger than 2 years who were suspected to have urinary tract infection (fever without an obvious focus of infection).

MAIN OUTCOME MEASURES

The accuracy of the dipstick leukocyte esterase test in detecting significant pyuria defined as a leukocyte count >or=10 mm(3) (>or=0.01 x 10(9) /L).

RESULTS

Two hundred and fifty-four urine samples collected by bag, midstream clean-catch, suprapubic bladder aspiration, or urethral catheterization were examined. Using urine microscopy results as a reference, the sensitivity and specificity of the leukocyte esterase test in detecting significant pyuria were found to be 72.0% and 85.8%, respectively; the positive and negative predictive values were 55.4% and 92.6%, respectively; and the positive and negative likelihood ratios were 5.1 and 0.3, respectively.

CONCLUSIONS

The dipstick leukocyte esterase test cannot accurately detect pyuria in young febrile children. It is also not appropriate as a screening test to exclude pyuria, reduce the need for the microscopic examination of urine, or indicate when a hospital admission for probable urinary tract infection is needed.

Sterile pyuria: a differential diagnosis

Sterile pyuria is not an uncommon laboratory finding. This article explores the major causes of sterile pyuria, including infectious, systemic, structural and physiologic, and drug-related causes. It also discusses the differential diagnosis of eosinophiluria and the basic workup of sterile pyuria.

The relationship between pyuria and infection in patients with indwelling urinary catheters: a prospective study of 761 patients

BACKGROUND

Pyuria is universally considered as essential for identifying urinary tract infections in noncatheterized patients. The utility of pyuria in the catheterized patient, to identify catheter-associated urinary tract infection (CAUTI), has not been adequately defined.

METHODS

We prospectively studied 761 newly catheterized patients in a university hospital; 82 (10.8%) developed nosocomial CAUTI (> 10(3) colony-forming units per milliliter). While catheterized, each patient was seen daily, a quantitative urine culture was obtained, and the urine white blood cell concentration was measured quantitatively using a hemocytometer.

RESULTS

The mean urine leukocyte count in patients with CAUTI was significantly higher than in patients without infections (71 vs 4 per microliter; P= .006). Pyuria was most strongly associated with CAUTI caused by gram-negative bacilli (white blood cell count, 121 vs 4 per microliter; P = .03); infection with coagulase-negative staphylococci and enterococci (white blood cell count, 39 vs 4 per microliter; P = .25) or yeasts (white blood cell count, 25 vs 4 per microliter; P = .15) produced much less pyuria. Pyuria with a white blood cell count greater than 10 per microliter (>5 per high-power field in a conventional urinalysis) had a specificity of 90% for predicting CAUTI with greater than 10(5) colony-forming units per milliliter but a sensitivity of only 37%.

CONCLUSIONS

In patients with short-term indwelling urinary catheters, pyuria is less strongly correlated with CAUTI than in noncatheterized patients with urinary tract infection. The strongest association is with CAUTI caused by gram-negative bacilli; the association is far weaker for infections caused by gram-positive cocci or yeasts. Most patients with CAUTI are asymptomatic and do not have associated fever. Pyuria should not be used as the sole criterion to obtain a urine culture in a patient with a catheter.

Screening tests for urinary tract infection in children: A meta-analysis

OBJECTIVE

To review systematically and to summarize the existing literature regarding performance of rapid diagnostic tests for urinary tract infection (UTI) in children.

DESIGN

Systematic review and meta-analysis.

METHODS

Published articles reporting the performance of urine dipstick tests (leukocyte esterase [LE] and/or nitrite), Gram stain, or microscopic analysis of spun or unspun urine in the diagnosis of UTI in children </=12 years of age. Articles were identified through a comprehensive MEDLINE search, and those articles meeting a priori inclusion criteria were selected. Eligibility criteria included the use of urine culture as the reference standard, independent comparison of urine culture with the results of one of the screening tests, definition of positive screening test results provided, only pediatric patients included or evaluable separately, and both gold standard and screening test performed on all patients. For each test, heterogeneity of reported sensitivity and specificity of all studies was determined. The subgroups of studies with similar definitions of UTI and age of study subjects were analyzed separately to account for some of the differences in reported results. When significant unexplained heterogeneity among studies precluded simple combining of results, a summary receiver-operator characteristic curve was fitted for each screening test, from which pooled estimates of true-positive rate (TPR; ie, sensitivity) and false-positive rate (FPR; 1-specificity) were calculated.

PRIMARY RESULTS

A total of 1489 titles were identified by the MEDLINE search; 26 articles met all criteria for inclusion. There was significant heterogeneity among studies for nearly all tests for both TPR and FPR, which was explained only partially by the stringency of the definition of UTI or age of subjects studied. Based on the pooled estimates, the presence of any bacteria on Gram stain on an uncentrifuged urine specimen had the best combination of sensitivity (0.93) and FPR (0.05). Urine dipstick tests performed nearly as well, with a sensitivity of 0.88 for the the presence of either LE or nitrite and an FPR of 0.04 for the presence of both LE and nitrite. Pyuria had lower TPR and higher FPR: for presence of >5 white blood cells/high-power field in a centrifuged urine sample, the TPR was 0.67 and the FPR was 0.21, whereas for >10 white blood cells per mm(3) in uncentrifuged urine, the TPR was 0.77 and the FPR was 0.11.

CONCLUSIONS

Both Gram stain and dipstick analysis for nitrite and LE perform similarly in detecting UTI in children and are superior to microscopic analysis for pyuria.

The validity of the uriscreen test for early detection of urinary tract infection in children

OBJECTIVE

To determine the validity of the Uriscreen, a rapid diagnostic test based on the detection of urine catalase for the early detection of urinary tract infection (UTI) in children, compared with standard urinalysis and dipstick tests. STUDY DESIGN. Cross-sectional study.

STUDY POPULATION

Children 1 month to 17 years of age who presented to the emergency department of a pediatric tertiary care center between March and November of 1996 with symptoms suggestive of UTI.

METHODS

Urine specimens obtained from a random sample of 121 patients were evaluated simultaneously for possible UTI by Uriscreen (catalase test), urinalysis (microscopic pyuria), dipstick (leukocyte esterase and nitrite), and quantitative urine culture. All specimens were collected by one of three sterile techniques (midstream void technique, bladder catheterization, or suprapubic aspiration), as appropriate for age, and tested immediately. Using the quantitative urine culture as the gold standard (reference test), the sensitivity, specificity, and positive and negative predictive values of all the screening tests were determined and compared. Age, sex, temperature, presenting symptoms, and method of urine collection were recorded for each participant.

RESULTS

Of the 121 patients, 35 (28.9%) had positive culture results: 30 girls (85.7%) and 5 boys (14.3%). Compared with urinalysis and dipstick tests, Uriscreen had the highest sensitivity (100% vs 88.6% and 97.1%, respectively) and the highest negative predictive value (100% vs 95% and 98.6%, respectively), but the poorest specificity (68.6% vs 88.4% and 82.5%, respectively) and positive predictive value (56.4% vs 75.6% and 69.4%, respectively).

CONCLUSIONS

The clinical use of Uriscreen for the presumptive diagnosis of UTI in children is limited and not significantly superior to urinalysis or the dipstick test. However, because of its 100% sensitivity and negative predictive value and its ease of use, rapidity, and low cost, it is recommended highly for ruling out the diagnosis of UTI. In laboratories, a negative Uriscreen result may prevent the need for performing expensive urine cultures.

[Evaluation of pyuria by means of urinary sediment method--a comparison to the counting chamber method]

We compared the urinary sediment method to counting chamber method in evaluating pyuria, in order to elucidate an issue of urinary sediment method. The KOVA system was used for counting chamber method. Three hundred and ten urine specimens from the patients who visited Fuji City Central Hospital in March, 1995, were employed. The numbers of leukocytes of each specimen was counted by means of urinary sediment method and counting chamber method, and compared. The urinary leukocyte count evaluating by means of these two methods were correlated well. However, the discrepancy of urinary leukocyte counts by means of these two methods were recognized in two specimens. In these two specimens, the leukocyte count was 1 to 4/5HPF by means of urinary sediment method, but more than 50/microliter by means of counting chamber methods. Significant bacteria (10(4) cfu/ml or more), positive esterse reaction, and high pH (8.5) were recognized in both specimens. In addition, one of two these specimens was hypotonic (specific gravity was 1.008). Therefore, it was suggested that leukocytes were sometimes disrupted with centrifugation. These results indicate that counting chamber method is more useful urinary sediment method to detect pyuria.

Indinavir nephropathy in an AIDS patient with renal insufficiency and pyuria

Indinavir has been described to cause crystalluria and nephrolithiasis in a variable number of treated patients. Acute renal failure, often reversible with discontinuation of the medication, induction of a diuresis and correction of urinary obstruction if present, occurs in a smaller percent of patients. One recent report described renal biopsy findings, indinavir crystals within cellular casts in the collecting tubules, in a patient receiving this antiretroviral agent. We report a second case of a patient with mild renal insufficiency and pyuria following indinavir therapy and describe similar renal biopsy findings.

Prevalence of urinary tract infection during outpatient follow-up after renal transplantation

Seven hundred and twenty-seven renal transplant patients are reviewed with respect to the occurrence of urinary tract infection (UTI) after renal transplantation. UTI was defined as the detection of both bacteriuria (10(5) CFU/ml) and pyuria (10 leukocytes/hpf). UTI developed in 11 of the inpatients (20.8%) and in 30 (4.2%) of the outpatients during a one-year period. Among outpatients, 12 had symptomatic infections, comprising seven with acute pyelonephritis and five with acute cystitis. Asymptomatic UTI was detected in 18 patients. In addition, asymptomatic bacteriuria without pyuria was observed in ten (1.4%) patients. UTI was more common in patients with diabetes, and underlying urinary tract complications were present in some patients. Administration of trimethoprim-sulfamethoxazole for about 4 months is suggested to reduce the frequency of UTI in the early period after renal transplantation.

Does pyuria indicate infection in asymptomatic dialysis patients?

It has been suggested that the finding of leukocyturia > 10 WBC/HPF in asymptomatic dialysis patients predicts a positive urine culture and hence indicates urinary tract infection. Seventeen asymptomatic ESRD patients contributed clean catch specimens. Nine patients had ten or more WBC/HPF. One of these grew a possible pathogen in pure culture (23% of specimens excluding those growing multiple organisms). Thus, leukocyturia is not a good marker for positive urine culture and moreover is not demonstrated to indicate infection even when positive cultures follow.

Symptomatic urinary tract infection in women in primary health care. Bacteriological, clinical and diagnostic aspects in relation to host response to infection

OBJECTIVE

To evaluate rapid diagnostic tests for bacteriuria in women with symptoms of urinary tract infection (UTI), and to analyse bacteriological and clinical findings in relation to host response to infection.

DESIGN

Prospective study of symptomatic UTI in women.

SETTING

Primary health care centres.

PATIENTS

819 women with signs and symptoms suggestive of UTI.

MAIN OUTCOME MEASURES

History of UTI and clinical findings were recorded. After randomization but before antibiotic treatment, urine specimens were analysed for pyuria by sediment microscopy and for nitrite using a test strip, and cultures were performed. The systemic inflammatory response was assessed by C-reactive protein (CRP), erythrocyte sedimentation rate, and total white blood cell count.

RESULTS

The combined use of tests for pyuria and nitrite resulted in a high sensitivity (0.93) and efficacy (0.85) when the prevalence of bacteriuria was 0.89. Escherichia coli and Staphylococcus saprophyticus accounted for 93% of the urinary isolates. Significantly more patients infected with S. saprophyticus than E. coli complained of dysuria (p < 0.05), frequency (p < 0.05) or flank pain (p < 0.01). CRP agreed best with the clinical diagnosis of acute pyelonephritis.

CONCLUSIONS

In women with a high probability of bacteriuria, i.e. those with symptoms of lower UTI, examination for pyuria and urinary nitrite offers high diagnostic efficacy. If either or both tests are positive urine cultures can be omitted.

Pyuria among chronically incontinent but otherwise asymptomatic nursing home residents

OBJECTIVE

To determine the prevalence of pyuria and its relationship to bacteriuria in a representative sample of chronically incontinent nursing home residents.

DESIGN

Prospective, descriptive case series.

SETTING

Six nursing homes.

PARTICIPANTS

Two hundred fourteen chronically incontinent, but otherwise asymptomatic, nursing home residents who were enrolled in a clinical intervention trial for urinary incontinence.

MEASURES

Two hundred fourteen urine specimens were collected by a validated clean catch technique. Each specimen underwent dipstick testing for leukocyte esterase, microscopic urinalysis to determine the number of white blood cells per high power field of centrifuged urine, and quantitative urine culture using standard laboratory techniques.

RESULTS

The overall prevalence of pyuria was 45%, as defined by > 10 white blood cells per high field of spun urine, and the overall prevalence of bacteriuria was 43%, as defined by the growth of > 100,000 colony forming units of a urinary pathogen. Fifty-nine percent of the specimens with bacteriuria and 34% of the specimens without bacteriuria had pyuria. Of specimens with pyuria, 56% had bacteriuria, and of specimens without pyuria, 31% had bacteriuria. When any colon change on the leukocyte esterase pad was considered positive, this finding had a sensitivity of 83% and a specificity of 52% for pyuria on microscopic urinalysis.

CONCLUSIONS

Pyuria is common among chronically incontinent nursing home residents, both in the presence and absence of bacteriuria. Clinicians must therefore be cautious in interpreting the presence of pyuria to indicate symptomatic infection in this population. Using pyuria to determine the need for antimicrobial treatment could result in unnecessary expense and morbidity as well as contribute to the development of resistant organisms in nursing homes. Research is needed to define pyuria better, to determine its prevalence and relationship to bacteriuria among nursing home residents with symptoms of acute urinary tract infection, and to elucidate the etiology and significance of sterile pyuria in this population.

Is urine culture necessary to rule out urinary tract infection in young febrile children?

OBJECTIVE

To determine whether the absence of pyuria on the enhanced urinalysis can be used to eliminate the diagnosis of urinary tract infection, avoiding the need for urine culture and sparing large health care expenditures.

DESIGN

Results of an enhanced urinalysis (hemocytometer counts and interpretation of Gram-stained smears) performed on uncentrifuged urine specimens obtained by catheter were correlated with urine cultures in young febrile children at the Children's Hospital of Pittsburgh Emergency Department. In a group of 4253 children (95% febrile) less than 2 years of age, pyuria was defined as > or = 10 white blood cells/mm3, bacteriuria as any bacteria on any of 10 oil immersion fields in a Gram-stained smear and a positive culture as > or = 50,000 colony-forming units/ml. A subgroup of 153 children with their first diagnosed urinary tract infection were enrolled in a separate treatment trial, acute phase reactants (peripheral white blood cell count, erythrocyte sedimentation rate and C-reactive protein) were obtained and 99Tc-dimercaptosuccinic acid renal scans were performed.

RESULTS

The presence of either pyuria or bacteriuria and the presence of both pyuria and bacteriuria have the highest sensitivity (95%) and positive predictive value (85%), respectively, for identifying positive urine cultures. Because a white blood cell count in a hemocytometer is the technically simpler component of the enhanced urinalysis, we chose to analyze the false negative results and achievable cost savings of using pyuria alone as the sole criterion for omitting urine cultures. If in this study urine cultures had been performed only on specimens from children who had pyuria or were managed presumptively with antibiotics, cultures of 2600 (61%) specimens would have been avoided. Twenty-two of 212 patients with positive urine cultures would not have been identified initially. However, based on interpretation of acute phase reactants, initial 99Tc-dimercaptosuccinic acid scan results, response to management and incidence of renal scarring 6 months later, 14 of the 22 patients most likely had asymptomatic bacteriuria and fever from another cause. The remaining 8 patients probably had early urinary tract infection.

CONCLUSIONS

The analysis of urine samples obtained by catheter for the presence of significant pyuria (> or = 10 white blood cells/mm3) can be used to guide decisions regarding the need for urine culture in young febrile children.

Evaluation of dipstrips, direct gram stain and pyuria as screening tests for the detection of bacteriuria

Two hundred and fifty cases of clinically suspected urinary tract infection were analysed for the detection of bacteriuria. Parameters studied included direct Gram staining, pyuria on microscopic examination of uncentrifuged urine and dip strip method for the detection of blood, protein, nitrite and leucocyte esterase. Significant bacteriuria (colony count 10(5) per ml) was found in 112 cases with a positivity ranging from 65 to 83% for the presence of blood, protein, nitrite and leucocyte esterase. Highest positive predictive values were obtained with the presence of nitrite and leucocyte esterase (98%), blood, protein and nitrite (94%) as well as with blood, protein, nitrite and leucocyte esterase (98%). Both pyuria and direct Gram staining were positive in 85% cases. The combined presence of both these parameters gave 100% positive predictive value. Gram staining combined with pyuria was more effective and economical as compared to the dipstrips for the detection of bacteriuria.