Detection of Enterotoxigenic Potential and Determination of Clonal Profile in Staphylococcus aureus and Coagulase-Negative Staphylococci Isolated from Bovine Subclinical Mastitis in Different Brazilian States

Abstract

Epidemiological studies have identified Staphylococcus aureus as the most common agent involved in food poisoning. However, current research highlights the importance of toxigenic coagulase-negative staphylococci (CoNS) isolated from food. The aim of this study was to characterize Staphylococcus spp. isolated from cows with bovine subclinical mastitis regarding the presence of genes responsible for the production of staphylococcal enterotoxins and of the tst-1 gene encoding toxic shock syndrome toxin 1, and to determine the clonal profile of the isolates carrying any of the genes studied. A total of 181 strains isolated in different Brazilian states, including the South, Southeast, and Northeast regions, were analyzed. The sea gene was the most frequent, which was detected in 18.2% of the isolates, followed by seb in 7.7%, sec in 14.9%, sed in 0.5%, see in 8.2%, seg in 1.6%, seh in 25.4%, sei in 6.6%, and ser in 1.6%. The sej, ses, set, and tst-1 genes were not detected in any of the isolates. The typing of the isolates by pulsed-field gel electrophoresis revealed important S. aureus and S. epidermidis clusters in different areas and the presence of enterotoxin genes in lineages isolated from animals that belong to herds located geographically close to each other.

Prevalence and Distribution of Resistance and Enterotoxins/Enterotoxin-likes Genes in Different Clinical Isolates of Coagulase-negative Staphylococcus

“…The tsst gene was identi ed in 25% of CoNS species including 28.6% of S. epidermidis, 21.6% of S. haemolyticus and 20% of S. saprophyticus strains. In contrary with our work, other studies have found tsst gene in any of CoNS species isolated from newborns and cows with bovine mastitis (32,37). But this gene has been detected in 87% of S. aureus isolated from wound and blood cultures and in 15.5% of S. aureus obtained from bovine mastitis milk (38,39).…”

Virulence Factors and Phylogeny of Staphylococcus aureus Associated With Bovine Mastitis in Russia Based on Genome Sequences

“…In previous studies, the occurrence of the seg and sei genes varied. Mello et al (22) detected the seg gene only for 1% of S. aureus and 2% for central nervous system isolates, and sei was detected for 11 and 3% for S. aureus and coagulase-negative isolates, respectively. In contrast, Srinivasan et al (30) detected seg and sei with higher frequencies (60.3% for sei and 24.4% for seg).…”

“…Most often, bovine mastitis is associated with superantigens or enterotoxins produced by S. aureus (19)(20)(21) or coagulasenegative staphylococci (22). Staphylococcal enterotoxin C is the most common cause of bovine mastitis (23)(24)(25).…”

Knowledge gaps and research priorities inStaphylococcus aureusmastitis control

“…Part of these contaminations results from shedding of S. aureus by infected mammary glands. Several studies have found that the majority of S. aureus mastitis isolates carry at least some of the enterotoxin-encoding genes, although with a wide variation in prevalence and enterotoxin profile (Larsen, Aarestrup, & Jensen, 2002;Mello et al, 2016;Ote, Taminiau, Duprez, Dizier, & Mainil, 2011). Foodborne infection risk is low in the countries where pasteurization is applied to most milk products, but there exists a risk with raw milk and products made with raw milk.…”