Factores predictivos de infección por el virus de la gripe H1N1 2009 en pacientes con síndrome gripal

espanolpolimerasa en frotis nasofaringeo es uno de los mejores metodos para la deteccion de virus gripales. El objetivo de este estudio es conocer el porcentaje de frotis nasofaringeos positivos durante la pandemia de gripe de 2009 y determinar si existe algun factor predictor de positividad para el virus H1N1 2009. Estudio retrospectivo de todos los pacientes que consultaron en Urgencias por sindrome gripal entre el 15 de julio y el 15 de diciembre de 2009 a los que se realizo un frotis nasofaringeo. Se identificaron aquellos casos en los que el frotis estaba correctamente solicitado. Se dividieron en dos grupos segun la positividad para el virus H1N1 2009. Se realizo un frotis nasofaringeo a 362 pacientes. En 87 casos estaba incorrectamente indicado. De los 275 restantes, fue positivo en 141. Los pacientes con frotis positivo eran mas jovenes (36,1(15) anos vs 42,3(18); p=0,002), tenian menor recuento de leucocitos, neutrofilos y linfocitos, menor valor de proteina C reactiva (5,15(5) vs 10,5(12); p En pacientes con sindrome gripal, el porcentaje de positividades del frotis para detectar H1N1 2009 se situa en el 50%. La edad, los niveles de proteina C reactiva y el recuento linfocitario son factores independientes para predecir el resultado. Englishof the better techniques for viral detection in nasopharyngeal swabs. The objective of this study was to assess the percentage of positive swabs and to determine whether there were differences according to PCR positivity. A retrospective study of 362 patients with flu syndrome attended at the Emergency Department between July 15 and December 15, 2009, in whom PCR of nasopharyngeal swabs for the detection of H1N1 2009 influenza virus was performed. Those cases in which swab testing was adequately requested were identified, and patients were divided into two groups according to positive or negative results for H1N1 2009 influenza virus. Nasopharyngeal swab was inadequately ordered in 87. In the remaining 275 patients, PCR was positive in 141. Patients with positive nasopharyngeal swabs were younger (mean [SD] age 36.1 [15] vs 42.3 [18] years, P = 0.002), had lower white blood cell, neutrophil and lymphocyte counts, lower serum concentrations of C-reactive protein (5.15 [5] vs 10.5 [12] mg/dL, P = 0.036) and lower incidence of radiological infiltrates (20.5% vs 33%, P = 0.036). In the logistic regression analysis, age, serum C-reactive protein levels, and lymphocyte count were independently associated with a positive nasopharyngeal swab. About 50% of patients with flu syndrome had positive nasopharyngeal swabs for H1N1 2009 influenza virus. Age, C-reactive protein, and lymphocyte count were independent predictors of positivity.