Desarrollo de un método colorimétrico en microplaca para determinar la cinética de crecimiento de Staphylococcus aureus

Abstract

Development of a colorimetric method in microplate for determining growth kinetics of Staphylococcus aureus. The information generated by bacterial growth curves is often used as reference information for the evaluation of the antibiotic activity in assays of time-kill assays, but these tests are laborious and time consuming. In this study we report the development of a method for constructing bacterial growth curves in microplates based on reduction of a tetrazolium salt (XTT) by metabolically active bacteria to a colored water-soluble formazan derivate. This compound can be quantified colorimetrically, allowing estimation of viable bacteria easily and faster than the classical method of serial dilution bacterial count plates. The developed method was validated and then used to construct growth curves of six bacterial strains of Staphylococcus aureus. The results obtained indicate that the technique developed is a reliable tool to be used in the study of the kinetics of bacterial growth. Key words: Tetrazolium salt, Staphylococcus aureus, growth kinetic.