Enterotoxigenic potential of Staphylococcus spp. isolates recovered from raw milk and artisanal cheese.

Fernanda Danielle Melo,Sandra Maria Ferraz,Ubirajara M Da Costa,Sheila R Wosiacki,Paula Wildemann,Karine Andrezza Dalmina,Ricardo Antonio P Sfaciotte,Leandro Parussolo

doi:10.1590/0001-3765202020180925

Abstract

In this work, we investigated the phenotypic profile of Staphylococcus spp. isolates recovered from raw milk and artisanal cheese, and their enterotoxigenic potential through the detection of classical enterotoxin genes (sea, seb, sec, sed and see). A total of 104 isolates (58 coagulase-positive Staphylococcus - CoPS; and 46 coagulase-negative Staphylococcus- CoNS) were used, of which 33 were retrieved from raw milk and 71 from artisanal cheese produced in the Serrana region of Santa Catarina. Identification of CoPS was conducted via biochemical tests. Detection of the genes sea, seb, sec, sed, and see was carried out by multiplex PCR technique. Among the 58 CoPS analyzed, 64% were identified as S. aureus, 22% as S. scheiferi coagulans, 12% as S. hyicus and as 2% S. intermedius. In the present study was noted that 40% of CoPS isolates retrieved from milk harbored seb gene, while only one from artisanal cheese was positive for gene sea. In this study all CoNS samples investigated were negative for enterotoxins genes. The enterotoxigenic potential of CoPS, is an issue of great importance for public health. For that reason, it is necessary that cheese factories strictly follow the safety processes involved in manufacturing.

Highlights

S. aureus is considered the most important species among Staphylococcus spp. due to its versatile feature to produce several endotoxins, especially the staphylococcal enterotoxins (SE)
A total of 104 Staphylococcus spp. ( 58 CoPS and 46 coagulase-negative staphylococci (CoNS)) isolates retrieved from milk and serrano artisanal cheese samples were used in this study
Of the 20 isolates from raw milk, 8 of them (40%) harbored seb gene, and were characterized as: S. aureus (n=5), Staphylococcus scheiferi coagulans (n=2) and Staphylococcus hyicus (n=1)

Summary

Introduction

S. aureus is considered the most important species among Staphylococcus spp. due to its versatile feature to produce several endotoxins, especially the staphylococcal enterotoxins (SE). Valle et al (1990) described that other coagulase-producing staphylococci exhibited the same characteristic. Pereira et al (2001) demonstrated that some coagulase-negative staphylococci (CoNS) were able to produce toxins under laboratory conditions. Enterotoxins are proteins of low molecular weight, which are resistant to inactivation by stomach proteases and withstand temperatures up to 126.7°C/6.2 min. In some cases they are able to survive in food even after thermal treatment (thermoresistant toxins) (Santana et al 2010). The genes encoding staphylococcal enterotoxins can be present in bacteriophages (sea and sec), plasmids (seb, sed and selj), staphylococcal chromosome (seb, sec, seh, sei, selk, sell, selm, seln, selo, selp and selq) and pathogenicity islands (sec, seb, selk and selq) (Jarraud et al 2001, Zhang et al 1998)

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