Performance of the dipstick screening test as a predictor of negative urine culture / Desempenho da fita de urina como resultado presuntivo para cultura de urina negativa

ABSTRACT Objective To investigate whether the urine dipstick screening test can be used to predict urine culture results. Methods A retrospective study conducted between January and December 2014 based on data from 8,587 patients with a medical order for urine dipstick test, urine sediment analysis and urine culture. Sensitivity, specificity, positive and negative predictive values were determined and ROC curve analysis was performed. Results The percentage of positive cultures was 17.5%. Nitrite had 28% sensitivity and 99% specificity, with positive and negative predictive values of 89% and 87%, respectively. Leukocyte esterase had 79% sensitivity and 84% specificity, with positive and negative predictive values of 51% and 95%, respectively. The combination of positive nitrite or positive leukocyte esterase tests had 85% sensitivity and 84% specificity, with positive and negative predictive values of 53% and 96%, respectively. Positive urinary sediment (more than ten leukocytes per microliter) had 92% sensitivity and 71% specificity, with positive and negative predictive values of 40% and 98%, respectively. The combination of nitrite positive test and positive urinary sediment had 82% sensitivity and 99% specificity, with positive and negative predictive values of 91% and 98%, respectively. The combination of nitrite or leukocyte esterase positive tests and positive urinary sediment had the highest sensitivity (94%) and specificity (84%), with positive and negative predictive values of 58% and 99%, respectively. Based on ROC curve analysis, the best indicator of positive urine culture was the combination of positives leukocyte esterase or nitrite tests and positive urinary sediment, followed by positives leukocyte and nitrite tests, positive urinary sediment alone, positive leukocyte esterase test alone, positive nitrite test alone and finally association of positives nitrite and urinary sediment (AUC: 0.845, 0.844, 0.817, 0.814, 0.635 and 0.626, respectively). Conclusion A negative urine culture can be predicted by negative dipstick test results. Therefore, this test may be a reliable predictor of negative urine culture.

RESUMO Objetivo Verificar se a triagem de urina por fitas reativas é capaz de predizer a cultura de urina. Métodos Estudo retrospectivo realizado entre janeiro e dezembro de 2014 com 8.587 pacientes, com solicitação médica de triagem de urina (fita), sedimento urinário e cultura de urina. Foram analisados sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e curva ROC. Resultados Foram positivas 17,5% das culturas. O nitrito apresentou sensibilidade de 28% e especificidade de 99%. O valor preditivo positivo foi de 89% e o valor preditivo negativo de 87%. Esterase apresentou sensibilidade de 79% e especificidade de 84%. Valor preditivo positivo e valor preditivo negativo foram de 51% e 95%, respectivamente. A combinação de nitrito ou esterase positivos apresentou sensibilidade de 85% e especificidade de 84%. Valor preditivo positivo e valor preditivo negativo foram, respectivamente, 53% e 96%. O sedimento positivo (mais de dez leucócitos por microlitro) apresentou sensibilidade de 92% e especificidade de 71%. O valor preditivo positivo foi 40% e o negativo, 98%. A combinação de nitrito e sedimento urinário positivos apresentou sensibilidade de 82% e especificidade de 99%. Os valores preditivos positivo e negativo foram 91% e 98%, respectivamente. Para o nitrito ou esterase positivos mais os leucócitos positivos, a sensibilidade foi de 94% e a especificidade de 84%. O valor preditivo positivo foi de 58% e o negativo foi de 99%. Com base na curva ROC, o melhor indicador de urocultura positiva foi a associação entre a esterase ou nitrito positivos na fita mais os leucócitos positivos no sedimento, seguido por nitrito e esterase positivos, sedimento urinário positivo isolado, esterase positiva isolada, nitrito positivo isolado e, finalmente, pela associação entre nitrito e sedimento urinário positivos (AUC: 0,845, 0,844, 0,817, 0,814, 0,635 e 0,626, respectivamente). Conclusão Uma urocultura negativa pode ser prevista com resultados negativos na fita. Portanto, este teste pode ser um preditor confiável de urocultura negativa.

Caracterización de lactantes con infección del tracto urinario:2009-2010: Hospital Regional de Antofagasta / Characterization of infants with urinary tract infection: 2009-2010: Regional Hospital of Antofagasta

INTRODUCCION: Las infecciones del tracto urinario (ITU) son una de las enfermedades bacterianas más frecuentes en pediatría. La incidencia de ITU en el paciente pediátrico no se conoce con exactitud. En recién nacidos se estima en 1 por ciento con una mayor proporción de varones, mientras que en lactantes aumenta entre 3 a 5 por ciento con igual proporción en ambos sexos. OBJETIVO: Caracterizar el perfil clínico-epidemiológico de lactantes con diagnóstico de ITU en el servicio de Pediatría del Hospital Regional de Antofagasta. PACIENTES Y METODOS: Estudio descriptivo retrospectivo de corte transversal. Se analizaron fichas clínicas de pacientes de la unidad de lactantes del Servicio de Pediatría del Hospital Regional de Antofagasta con diagnóstico de ITU al egreso del periodo Mayo 2009 - Mayo 2010. La muestra final fue 88 pacientes. Los datos fueron analizados y tabulados en una planilla Excel2007. RESULTADOS: Un 71,5 por ciento fueron sexo femenino. La edad promedio fue de 8,9 meses con rango entre 1 mes y 23 meses. Los síntomas más frecuentes fueron fiebre (97,7 por ciento), vómitos (30,7 por ciento), diarrea (23,1 por ciento), inapetencia (21.6 por ciento) y llanto/irritabilidad (16 por ciento). Las alteraciones de laboratorio fueron PCR elevada (96 por ciento), piuria (94,3 por ciento), leucocitosis (87,5 por ciento) y nitritos positivos (48 por ciento). Sólo fueron consignados el 85,2 por ciento de los urocultivos, de los cuales el patógeno más frecuente fue Escherichia coli en el 84 por ciento. DISCUSION: La ITU en lactantes en nuestro estudio fue más frecuente en el sexo femenino, teniendo como signo preponderante la fiebre. El germen más común fue Escherichia coli, correlacionándose con la literatura. Valoramos la importancia de solicitar urocultivos para la confirmación microbiológica.

INTRODUCTION: Urinary tract infections (UTI) are one of the most frequent bacterial diseases in pediatrics. The incidence of UTI in pediatric patients is not known with accuracy. In newborns is estimated in 1 percent with a larger proportion in males, while in infants increase between 3 to 5 percent with the same proportion for both sex. OBJECTIVE: Characterize clinically and epidemiologically the profile of infants diagnosed with UTI in the Pediatric service of the Regional Hospital of Antofagasta. METHODS AND MATERIALS: A descriptive retrospective cross-sectional study. Medical records of patients diagnosed with UTI by the end of the period of May 2009 - May 2010 from the unit of infants in the Pediatric Service of the Regional Hospital of Antofagasta were analyzed. The final sample was 88 patients. The data was analyzed using an Excel 2007 spreadsheet. RESULTS: 71,5 percent were women. The average age was 8,9 month in a range between 0,5 and 23 month. Most frequent symptoms were fever (97,7 percent), vomit (30,7 percent), diarrhea (23,1 percent), lack of appetite (21,6 percent) and crying/irritability (16 percent). The alterations in laboratory was CRP high (96 percent), pyuria (94,3 percent) and leukocytosis (87,5 percent). Only were record the 85, 2 percent of urine culture of which the most frequent pathogenic agent was Escherichia coli in the 84 percent of the cases. DISCUSSION: The UTI in infants in our study was more frequent in women and its predominant symptom is fever. The most common germ was Escherichia coli which agree the literature. We value the importance of ask for urine culture to microbiological confirmation.

Accuracy of dipstick urinalysis as a screening method for detection of glucose, protein, nitrites and blood

This study determined the reliability of dipstick urinalysis for detection of protein, glucose, blood and nitrites in non-random urine samples from 300 people aged > 50 years attending a health centre for check-up. The gold standards were fasting blood glucose for glucosuria and the sulfosalicylic acid method for urine protein. Microscopic examination of urinary sediment and urine culture were also performed for positive dipstick results for haematuria and nitrites. The sensitivity, specificity and positive and negative predictive values of the dipstick test for detection of protein were 80.0%, 95.0%, 22.2% and 99.6% and for glucose were 100%, 98.5%, 87.0% and 100% respectively. Dipstick urinalysis can be a reliable screening method for diagnosis of urinary tract infection and diabetes mellitus but not for proteinuria

Utility of urinary biomarkers in oral cancer.

OBJECTIVE: Oral cancer is the leading malignancy in India, with tobacco playing a major role in the etiology. The aim of the present study was to quantify nitrate+nitrite (NO2+NO3) in tobacco products as well as to study tobacco exposure related biomarkers in controls, patients with oral precancers (OPC) and oral cancer patients. MATERIALS & METHODS: Healthy individuals (n=90) were grouped into without habit of tobacco (NHT, n=30) and healthy individuals with habit of tobacco (WHT, n=60). Oral cancer patients with a tobacco habit were classified into abstinence (n=62) and non-abstinence (n=64) groups according to status at the study time. Urinary nicotine and cotinine levels were analyzed by modified high-pressure liquid chromatography (HPLC) using a UV detector. Levels of NO2+NO3 in tobacco and urine, and urinary thioether levels were estimated by spectrophotometry. RESULTS: NO2+NO3 levels in different types of tobacco product ranged between 0.13 to 3.39 mg/g. The Odds Ratio (OR) analysis indicated positive associations of both smoking and chewing habits of tobacco with high risk of development of oral cancer. Urinary nicotine, cotinine and NO2+NO3 levels were significantly elevated in WHT, patients with OPC and oral cancer patients as compared with the NHT group. This was also the case for urinary thioether levels. Levels of urinary nicotine and cotinine were also higher in the non-abstinence group with oral cancers. CONCLUSION: The results confirmed that tobacco chewing and smoking habits are prominent risk factors for development of oral cancer in the western part of India (Gujarat). Urinary nicotine, cotinine, NO2+NO3 and thioether levels can be helpful for screening programs for oral cancer.

Urinary NO3 excretion and renal failure in indinavir-treated patients

Treatment with indinavir (IDV), a protease inhibitor, is frequently associated with renal abnormalities. We determined the incidence of renal failure (creatinine clearance <80 mL min-1 1.73 (m²)-1) in HIV patients treated with highly active antiretroviral therapy, including IDV, and investigated the possible mechanisms and risk factors of IDV nephrotoxicity. Thirty-six patients receiving IDV were followed for 3 years. All were assessed for age, body weight, duration of infection, duration of IDV treatment, sulfur-derivative use, total cholesterol, triglycerides, magnesium, sodium, potassium, creatinine, and urinalysis. We also determined renal function in terms of creatinine clearance, urine osmolality and fractional excretion of sodium, potassium, and water. Urinary nitrate (NO3) excretion was measured in 18 IDV-treated patients and compared with that of 8 patients treated with efavirenz, a drug without renal side effects. Sterile leukocyturia occurred in 80.5 percent of the IDV-treated patients. Creatinine clearance <80 mL min-1 1.73 (m²)-1 was observed in 22 patients (61 percent) and was associated with low body weight and the use of sulfur-derivatives. These patients also had lower osmolality, lower urine volume and a higher fractional excretion of water compared to the normal renal function group. Urinary NO3 excretion was significantly lower in IDV-treated patients (809 ± 181 æM NO3-/mg creatinine) than in efavirenz-treated patients (2247 ± 648 æM NO3-/mg creatinine, P < 0.01). The lower NO3 excretion suggests that IDV decreases nitric oxide production.

Participación del óxido nítrico y los metabolitos del ácido araquidónico vía citocromo P450 en la regulación de la presión arterial / Participation of nitric oxide and arachidonic acid metabolites via cytochrome-p450 in the regulation of arterial blood pressure

El óxido nítrico y los metabolitos del ácido araquidónico vía citocromo P450 contribuyen a la regulación de la presión arterial. La modificación en la síntesis de estos autacoides conduce a hipertensión arterial, sin embargo, se desconoce si existe interacción. Por ello, decidimos estudiar el papel modulador del óxido nítrico y los metabolitos del ácido araquidónico vía citocromo P450, y su interacción, sobre la presión arterial y el contenido renal de citocromo P450. Ratas Wistar macho fueron divididas por grupos: 1) Control, 2) L-NAME (100mg/kg/d v.o.), 3) L-NAME + SnCl2 (10mg/kg/d i.p.) y 4) L-NAME + dexametasona (1mg/kg/d s.c.). Se determinó la presión arterial sistólica y la concentración de nitritos por HPLC en orina y sangre. Los valores de presión arterial sistólica fueron: control 97 ± 7 mmHg, L-NAME 151 ± 4.6 mmHg, L-NAME + SnCl2 133 ± 3 mmHg, y L-NAME + dexametasona 152 ± 4.5 mmHg. Los nitritos en orina fueron: 1) 1.832 ± 0.32, 2) 1.031 ± 0.23, 3) 1.616 ± 0.33 y 4) 1.244 ± 0.33 μmol/mL y en sangre: 1) 0.293 ± 0.06, 2) 0.150 ± 0.05, 3) 0.373 ± 0.13 y 4) 0.373 ± 0.07 μmol/mL. El contenido renal de citocromo P450 fue abatido con el tratamiento de L-NAME + SnCl2, y una respuesta semejante se observó con L-NAME + dexametasona. Tanto óxido nítrico como los metabolitos del ácido araquidónico vía CYP participan en la regulación de la presión arterial. Además, el óxido nítrico contribuye regulando parcialmente el contenido renal del citocromo P450.

Nitric oxide and cytochrome P450 arachidonic acid metabolites participate in blood pressure regulation. The synthesis of these autacoids leads to arterial hypertension. However, it is not known whether there is an interaction between them. Therefore, we studied the modulatory effect of nitric oxide and cytochrome P450-arachidonic acid metabolites, their interaction on blood pressure, and the renal content of cytochrome P450. Male Wistar rats were divided: 1) control, 2) L-NAME (100 mg/kg/d p.o.), 3) L-NAME + SnCl2 (10 mg/kg/d i.p.), and 4) L-NAME + dexamethasone (1 mg/kg/d s.c.). We measured blood pressure and collected urine and blood for nitric oxide measurement. NO2 was quantified by HPLC. Blood pressure was: control, 97 ± 7 mmHg; L-NAME, 151 ± 4.6 mmHg; L-NAME + SnCl2, 133 ± 3 mmHg, and L-NAME + dexamethasone 152 ± 4.5 mmHg. Urine nitrite concentration was: 1) 1.832 ± 0.32, 2) 1.031 ± 0.23, 3) 1.616 ± 0.33, and 4) 1.244 ± 0.33 μmol/mL, while the concentration in blood was: 1) 0.293 ± 0.06, 2) 0.150 ± 0.05, 3) 0.373 ± 0.13, and 4) 0.373 ± 0.07 μmol/ mL. L-NAME + SnCl2 decreased cytochrome P450 renal content, and L-NAME + dexamethasone showed a similar response. In conclusion, both, nitric oxide and CYP-arachidonic acid metabolites play a role in the regulation of blood pressure. Nitric oxide also partially regulates renal cytochrome P450 content. (Arch Cardiol Mex 2003; 73:98-104).

Erythropoietin does not affect nitric oxide system in rats with chronic renal failure

We investigated to see whether an altered role of nitric oxide (NO) system is involved in erythropoietin (EPO)-induced hypertension in chronic renal failure (CRF). Male Sprague-Dawley rats were five-sixths nephrectomized to induce CRF. Six weeks after the operation, EPO or vehicle was injected for another 6 weeks. Plasma and urine nitrite/nitrate (NOx) levels were determined. Expression of NO synthase (NOS) proteins in the aortae and kidneys were also determined. In addition, the isometric tension of isolated aorta in response to acetylcholine and nitroprusside was examined. Blood pressure progressively rose in CRF groups, the degree of which was augmented by EPO treatment. Plasma NOx levels did not differ among the groups, while urine NOx levels were lower in CRF groups. Endothelial NOS expression was lower in the kidney and aorta in CRF rats, which was not further affected by EPO-treatment. The inducible NOS expression in the kidney and aorta was not different among the groups. Acetylcholine and sodium nitroprusside caused dose-dependent relaxations of aortic rings, the degree of which was not altered by EPO-treatment. Taken together, EPO-treatment aggravates hypertension in CRF, but altered role of NO system may not be involved.

Decreased nitric oxide synthesis in rats with chronic renal failure

The present study was aimed at investigating whether an altered role of nitric oxide (NO) is involved in chronic renal failure (CRF). Rats were subjected to 5/6 nephrectomy and kept for 6 weeks to induce CRF. On the experimental day, after measurement of arterial pressure under anesthesia, the arterial blood was collected, and thoracic aorta and kidney were rapidly taken. NO metabolites (NOx) were determined in the plasma, urine, aorta and kidney. The expression of NO synthase (NOS) isozymes was determined in the kidney and aorta by Western blot analysis. The expression of NOS mRNA in the glomeruli was also determined by RT-PCR. There were significant increases in arterial pressure and serum creatinine levels in CRF. Urine NOx levels were decreased in CRF, whereas plasma NOx levels were not altered. Aorta and kidney tissue NOx levels were also decreased in CRF. The expression of endothelial constitutive (ec) and inducible (i) isoforms of NOS proteins was decreased in the kidney and aorta in CRF. Accordingly, the expression of ecNOS and iNOS mRNA was decreased in the glomeruli in CRF. In conclusion, NO synthesis is decreased in the kidney and vasculature of CRF rats.

Decreased nitric oxide synthesis in rats with chronic renal failure

The present study was aimed at investigating whether an altered role of nitric oxide (NO) is involved in chronic renal failure (CRF). Rats were subjected to 5/6 nephrectomy and kept for 6 weeks to induce CRF. On the experimental day, after measurement of arterial pressure under anesthesia, the arterial blood was collected, and thoracic aorta and kidney were rapidly taken. NO metabolites (NOx) were determined in the plasma, urine, aorta and kidney. The expression of NO synthase (NOS) isozymes was determined in the kidney and aorta by Western blot analysis. The expression of NOS mRNA in the glomeruli was also determined by RT-PCR. There were significant increases in arterial pressure and serum creatinine levels in CRF. Urine NOx levels were decreased in CRF, whereas plasma NOx levels were not altered. Aorta and kidney tissue NOx levels were also decreased in CRF. The expression of endothelial constitutive (ec) and inducible (i) isoforms of NOS proteins was decreased in the kidney and aorta in CRF. Accordingly, the expression of ecNOS and iNOS mRNA was decreased in the glomeruli in CRF. In conclusion, NO synthesis is decreased in the kidney and vasculature of CRF rats.

An indigenously developed nitrite kit to aid in the diagnosis of urinary tract infection.

OBJECTIVE: To evaluate the utility of an indigenously developed nitrite kit for the rapid diagnosis of urinary tract infection (UTI) METHODS: 1018 urine specimens were collected from all cases where there was clinical suspicion of UTI. Samples were cultured as per standard microbiological protocol. Presence of nitrites was indicated by the development of purple color on addition of color developing solution and compared with the set of graded positive and negative controls also provided in the Kit. RESULTS: The results of the nitrite kit were compared with the semi-quantitative urine culture as the gold standard. The sensitivity, specificity, positive predictive and negative predictive values were 47%, 87%, 31% and 93%, respectively. CONCLUSION: Nitrite kit as a screening test can decrease the work load in the clinical bacteriology laboratory. More importantly in a field set up that is devoid of culture facilities, it can be used to correctly predict the absence of UTI.

Los dos primeros años del programa de evaluación externa de calidad en uroanálisis (PEECU) / The firts two years of an external quality assurance scheme for strip uroanalysis

Objetivo. Analizar los datos de uroanálisis con tira reactiva generados en los primeros dos años de un programa externo de control de calidad. Métodos. Los participantes recibieron 32 controles (4 por 8 envíos) en forma de tabletas para disolver y analizar usando tiras reactivas de uroanálisis. El número de participantes aumentó de < 50 en el 1er. envío a > 200 en el 8o. Midieron de 6 a 10 analitos según el tipo de tira utilizada y enviaron 763 informes. En cada informe se calculó una puntuación por analito (n = 4), por envío (n = 24 a 40) y una global de los 8 envíos (n = 707 a 763), La puntuación de obtuvo comparando el resultado informado con la moda de unos 600 laboratorios de Canadá y EEUU que midieron los mismos 32 controles utilizando exclusivamente tiras Bayer y lecturas instrumentales. La puntuación se extendió de cero ideal a un máximo de 400 puntos malos. Resultados. la mejor puntuación global (3 puntos en 741 informes) fue en nitritos y la peor (58 puntos en 744 informes) en gravedad específica (GE). Los otros ocho analitos tuvieron globales de 11 a 19 puntos (tabla 1). Las puntuaciones más bajas por tipo de métodos (tabla 2) fueron con tiras y aparatos automatizados Bayer (global de 13 puntos) y las lecturas visuales con tiras Bayer (global de 21). Conclusiones. 1. Los resultados nos llevaron a la decisión de suspender el envío de controles a participantes que usan tiras de otras marcas ya que el programa, por estar diseñado por usuarios de tiras Bayer, puede contribuir desorientar a los usuarios de otras tiras. 2. Se confirmó que la lectura instrumental es superior a la visual. 3. Ameritan estudio las causas de la puntuación alta de GE

Método de escrutinio para la detección rápida de bacteriuria / Screening method for rapid detection of bacteriuria

Se evaluó un método rápido de escrutinio urinario, consistente en tinción de Gram, en combinación con las pruebas de esterasa de leucocitos y nitritos para detectar bacteriuria de 748 muestras de orina suministradas pra cultivo. Cuando el crecimiento bacteriano fue >- 105 UFC/ml por el método de referencia, el procedimiento de escrutinio presentó una sensibilidad de 79.8 por ciento, una especificidad de 99.5 por ciento, un valor predictivo positivo de 95.9 por ciento y un valor predictivo negativo de 97.3 por ciento. El método de escrutinio es un método sensible para detectar bacteriuria; así mismo, permite eliminar muestras de orina negativas, haciendo innecesario el cultivo.

The value of positive nitrites in screening asymptomatic bacteriuria amongst Malaysian school children.

It is important to diagnose and treat urinary tract infection in children before renal damage has taken place. Hence a new screening procedure will be of interest. This study was conducted to evaluate the efficacy of urinary nitrite in screening for asymptomatic bacteriuria among school children compared to a more traditional method. Of the 44,816 school children investigated 240 (0.54%) students were judged to have bacteriuria ie 82 (0.19%) in boys and 158 (0.35%) in girls. Escherichia coli was the commonest organism isolated (28.75%). Urine dipstick testing for nitrite was found to have a low sensitivity and positive predictive value. While urinalysis for pyuria was noted to have a sensitivity of 77.9%, a specificity of 95.8% and a negative predictive value of 99.9%.

Evaluation of urinary leukocyte esterase and nitrite tests for diagnosis of bacterial urinary tract infections in the pediatric intensive care unit

This study included 100 infants and children with some urinary tract symptoms who were selected from the pediatric intensive care unit of Al-Hussein University Hospital. The aim of this work is to evaluate the diagnostic performance of the urinary leukocyte esterase and nitrite tests on random urine samples. Also, microscopic urinalysis and urine culture were done to patients with some urinary troubles in the pediatric ICU to provide guidelines for its use. The results showed that the urinary leukocyte esterase test had a sensitivity of 80.36% in detecting leukocyturia [> 10 leukocytes/mm3].The urinary nitrite test had a specifity of 98.01% in detecting bacteriuria. The combination of the urinary leukocyte esterase, nitrite tests and microscopic urinalysis for bacteriuria had a sensitivity of 100%, a specifity of 99.23% and a negative predictive value of 100%. We conclude that, the urinary leukocyte esterase and nitrite tests are rapid screening tests for diagnosis of bacterial urinary tract infections in the pediatric intensive care unit

Utilidad de una tira reactiva y del aspecto macroscópico de la orina para descartar la sospecha clínica de infección del tracto urinario en niños ambulatorios / Assessment of a reagent strip and of the urine macroscopic aspect for discard clinical suspected of urinary tract infection in ambulatory children

A fin de examinar las posibilidades de un método de selección que permita disminuir la demanda urocultivos en los servicios de salud, el resultado de estudio bacteriológico de 900 muestras de orina obtenidas de pacientes ambulatorios con sospecha de infección urinaria fue usado como "estándar de oro" para evaluar la sensibilidad, especificidad y valores predictivos del aspecto macroscópico de la orina, límpido o no límpido, y las reacciones de nitritos, esterasa leucocitaria y proteínas en una tira reactiva, positiva o negativa. El diagnóstico confirmado de infección urinaria fue definido por el hallazgo de urocultivo positivo a un solo germen en recuento ó 10 5 UFC/ml en una muestra de orina con leucocituria ó 10 elementos por mm3, o dos urocultivos con iguales características, obtenidos dentro de un tiempo inferior a cinco días, sin mediar tratamiento. Los cálculos fueron aplicados a las cuatro pruebas de diagnóstico en forma aislada y a las resultantes de las combinaciones entre ellas. La prevalencia de infección urinaria en la muestra fue 35,15 por ciento; la prueba de mayor sensibilidad y valor predictivo negativo corresponde a la combinación de "orina de aspecto no límpido, o nitritos positivos, o esterasa leucocitaria positiva"; la detección de proteínas no contribuyó a mejorar los valores de esta prueba. El motivo de la sospecha clínica de infección urinaria permitió clasificar las muestras en tres grupos: grupo A, niños con algún síntoma atribuible a inflamación de la vía urinaria n: 559; Grupo B, niños con fiebre, sin síntomas urinarios n: 252; y grupo C, pacientes con trastornos nutricionales o gastrointestinales, alteraciones del aspecto de la orina o antecedentes de infección urinaria sin seguimiento posterior n: 169. La prevalencia de enfermedad y le valor predictivo negativo de la prueba "aspecto no límpido o nitritos positivos o esterasa positiva" fueron diferentes en cada una de estas categorías, siendo respectivamente para A: 52,72 por ciento y 92,2; B: 13,49 por ciento y 97,7 por ciento; y C: 8,28 por ciento y 96,5 por ciento. En resumen, la prueba predijo la presencia de infección urinaria en 327 de los 348 casos diagnosticados y descartó el diagnóstico en 95,2 por ciento de los sanos. Los 21 episodios no detectados por la prueba correspondieron mayoritariamente a infecciones bajas poco sintomáticas. En los pacientes con pielonefritis aguda, en cambio, la sensibilidad fue de 97,7 por ciento y el valor predictivo negativo 99,3 por ciento. Esta información permitirá examinar la relación costo/eficacia de este sistema de selección en la atención primaria, según las condiciones de cada servicio de salud

Dipstick uroanálisis: diagnóstico presuntivo de infección urinaria? / Dipstick urinary tests: diagnostic

En el artículo se realiza revisión breve de la metodología paraclínica de laboratorio fundamentada en el uroanálisis: recuento leucocitúrico, recuento bacteriano, tinción gram, estudios de sedimento y pruebas de "Dipstick": Detección de actividad de leucocito esterasa y determinación de nitrito urinaria

Utilidad de dos pruebas para el diagnóstico presuntivo rápido en infección de vías urinarias y embarazo / Usefulness of two tests for the diagnosis, presuntive and quick, in urinary infection and pregnancy

Se estudiaron a 60 pacientes que acudieron al Servicio de Urgencias del INPer, refiriendo sintomatología de IVU. Se les realizó toma de urocultivo y detección de nitritos y estearasa leucocitaria en orina con la tira reactiva Multistix 10 SG (R). Se tomó como grupo testigo a 20 pacientes obstétricas de primera vez, sin sintomatología de IVU bajo la misma metodología. En el grupo de estudio se informaron 34 urocultivos negativos, 9 urocultivos contaminados y 17 urocultivos positivos, con una semsibilidad y especificidad de 94 por ciento para la prueba de nitritos y de 64 por ciento y 100 por ciento, respectivamente, para la prueba de estearasa leucocitaria. En el grupo testigo se observaron dos urocultivos contaminados, 13 negativos y 5 positivos a un microorganismo. La sensibilidad fue de 100 por ciento y la especificidad de 92 por ciento para la prueba de nitritos; y de 40 por ciento y 100 por ciento respectivamente para la estearasa leucocitaria.

Diagnóstico presuntivo de infección de las vías urinarias mediante la identificación de nitritos con tira reactiva / Suspected urinary infection:immediate diagnosis by nitrite reactive strips

El diagnóstico presuntivo de infección de las vías urinarias puede fundamentarse de una manera rápida al pie de la cama del enfermo o en el consultorio, mediante el uso de tiras reactivas que identifican los nitiritos , producto del metabolismo de bacterias que producen los nitratos en nitritos al infectar las vías urinarias, con una certeza de 90 a 100 por ciento corrobarada con el urocultivo. Con esa información es posible iniciar el tratamiento antimicrobiano cuando no se dispone de medios para realizar un urocultivo.