Multiplex PCR para identificação de S. aureus, S. intermedius e S. hyicus.

Abstract

Staphylococcus aureus, Staphylococcus hyicus e Staphylococcus intermedius are species of genus Staphylococcus capable of producing enterotoxins, as well as the enzymes termonuclease and coagulase, and are called Staphylococcus Coagulase Positive (SCP). They show very similar biochemical and morphological characteristics, this fact, makes their differentiation and they identification in food by phenotypic techniques very difficult. In this way, the aim of this work was the development of a Multiplex PCR (mPCR), targetting the nuc gene (encoding for thermonuclease) as target, for the identification of S. aureus, S. intermedius, and S. hyicus. Initially, the mPCR was standartizeted using reference strains of S. aureus, S. warneri, S. lugdunensis and Listeria monocytogenes and isolates of S. hyicus and S. intermedius, affer words it was tested with 16 isolates of the three species of SCP. The primers annealing to each of the three species, the conditions for mPCR, the suitability of the Internal Amplification Control (IAC) for the genus Staphylococcus, and the sequences obtained through the amplification by PCR were evaluated. After this, the results were compared with those achieved by biochemical tests for differentiation of SCP. Primers NUC1-NUC2 (for sequences of the S. aureus nuc gene), NUC5-NUC6 (for sequences of the S. intermedius nuc gene), NUC7-NUC8 (for sequences of the S. hyicus nuc gene) and, as IAC, the primers 16S1 16S2 (for sequences of the 16S of rRNA gene) were used. The mPCR proposed enable the identification of S. aureus, S. hyicus e S. intermedius, and the IAC was suitable for the genus. The sequences obtained in PCR showed a high degree of similarity with the sequences of the thermonuclease gene deposited in GenBank. The mPCR showed greater discriminatory power that the biochemical tests for identification the vii S. aureus, S. hyicus e S. intermedius, as well as reduced the time required for the identification of ECP (reduction of 24h) or identification of specie (reduction of 72h).