Evaluación del citómetro UF-1000i como método de cribado en el diagnóstico de infecciones del tracto urinario / Evaluation of the Sysmex UF-1000i flow cytometer for screening of urinary tract infection

INTRODUCCIÓN: El cultivo de orina supone una enorme carga de trabajo en el Laboratorio de Microbiología y sigue siendo técnica de referencia para el diagnóstico de las infecciones urinarias. Considerando la elevada prevalencia de resultados negativos, la implementación de un método de cribado fiable y rápido podría suponer un ahorro en costes de carga de trabajo y adelantar los resultados negativos. MÉTODO: Evaluamos la utilidad del citómetro de flujo UF-1000i® (bioMérieux, España) para cribado de muestras negativas que se pueden excluir del cultivo. Dividimos las muestras en 2 grupos: grupo 1, hombres y mujeres en edad fértil, que se consideran positivas con un crecimiento ≥ 104 UFC/ml, y grupo 2, consideradas positivas con crecimiento ≥ 105 UFC/ml. RESULTADOS: Enfrentando los datos del cultivo y del cribado en curva ROC, los puntos de mejor sensibilidad y especificidad fueron de 53,1 bacterias/μl para el grupo 1, y de 128,35 bacterias/μl para el grupo 2. En el grupo 1 la sensibilidad fue del 92,2%, la especificidad del 60%, la reducción de cultivos de orina del 46%, con el 2,1% de falsos negativos (42 muestras). En el grupo 2, la sensibilidad fue del 86%, la especificidad del 87,7%, la reducción de cultivos del 57,5%, con el 5,1% de falsos negativos (74 muestras). CONCLUSIÓN: La incorporación del citómetro UF-1000i al cribado de las muestras de orina depende mucho de las características de los pacientes y de la definición de cultivo de orina positivo. En nuestro caso, con el estudio exclusivo de la bacteriuria, los datos de reducción de carga de trabajo y de falsos negativos cuestionan seriamente esta incorporación

INTRODUCTION: The urine culture is a huge workload in the Microbiology Laboratory and remains the gold standard for the diagnosis of urinary tract infections. Considering the high prevalence of negative results, the implementation of a reliable screening method could lead to cost saving in the workload, and speedup reporting of negative results. METHODS: We evaluated the usefulness of the flow cytometer UF-1000i in the screening for negative samples than could be excluded from culture. We divided the samples into two groups, Group 1, males and women of childbearing age who were considered positive with a growth ≥ 104 CFU/ml, and Group 2,considered positive with ≥ 105 CFU/ml growth. RESULTS: On comparing the culture and screening data in the ROC curve, the best sensitivity and specificity points were 53.1 bact/l for Group 1, and 128.3 bact/l for Group 2. In Group 1, the sensitivity was 92.2%and a specificity of 60%, a reduction in urine cultures of 46%, with 2.1% false negative (42 samples). In Group 2, the sensitivity was 86%, with a specificity of 87.7%, a culture reduction of 57.5%, and 5.1% false negatives (74 samples). CONCLUSION: The incorporating of the UF-1000i cytometer to the screening of urine samples depends on the characteristics of the patients and the definition of positive urine culture. In our case, with only studying bacteriuria, the data on the reduction of workload and the false negatives seriously question this incorporation

[Evaluation of the Sysmex UF-1000i flow cytometer for screening of urinary tract infection]. / Evaluación del citómetro UF-1000i como método de cribado en el diagnóstico de infecciones del tracto urinario.

INTRODUCTION: The urine culture is a huge workload in the Microbiology Laboratory and remains the gold standard for the diagnosis of urinary tract infections. Considering the high prevalence of negative results, the implementation of a reliable screening method could lead to cost saving in the workload, and speed up reporting of negative results. METHODS: We evaluated the usefulness of the flow cytometer UF-1000i in the screening for negative samples than could be excluded from culture. We divided the samples into two groups, Group 1, males and women of childbearing age who were considered positive with a growth ≥ 104 CFU/ml, and Group 2, considered positive with ≥ 105 CFU/ml growth. RESULTS: On comparing the culture and screening data in the ROC curve, the best sensitivity and specificity points were 53.1 bact/µl for Group 1, and 128.3 bact/µl for Group 2. In Group 1, the sensitivity was 92.2% and a specificity of 60%, a reduction in urine cultures of 46%, with 2.1% false negative (42 samples). In Group 2, the sensitivity was 86%, with a specificity of 87.7%, a culture reduction of 57.5%, and 5.1% false negatives (74 samples). CONCLUSION: The incorporating of the UF-1000i cytometer to the screening of urine samples depends on the characteristics of the patients and the definition of positive urine culture. In our case, with only studying bacteriuria, the data on the reduction of workload and the false negatives seriously question this incorporation.