Desarrollo de un método para recuento de Listeria monocytogenes utilizando turbidimetría

Abstract

The present study was performed to develop a method for recounting Listeria monocytogenes using turbidimetry, the proposed method consists in a scale of four equidistant points, prepared with sulfate of sodium and chloride of barium that produce a precipitate of sulfate of barium, which resembles cellular concentration of 10 x 108 UFC/ml to 40 x108 UFC/ml, innovating the scale of turbidity proposed by McFarland in 1907. Using the proposed scale of precipitate of sulfate of barium, an interpolation equation was developed in which readings of the nephelometric turbidity units of microorganisms in culture medium are applied, predicting in a mathematical way the cell concentration in a liquid culture medium. The error rate of this method compared to the plate count method is 0,28 to 3,41 percent. Of the above is possible to use the turbidimeter to predict cell concentration effectively, simplifying microbiological management in investigative procedures, without the need for long preparation time to know the cellular concentration.