PCR detection of staphylococcal enterotoxin genes in Staphylococcus spp. strains isolated from meat and dairy products. Evidence for new variants of seG and seI in S. aureus AB-8802

Abstract

Aims: Evaluation of the occurrence of most known staphylococcal enterotoxin (SE) genes, egc (enterotoxin gene cluster) and TSST1 (toxic shock syndrome toxin 1) gene in both coagulase-positive (CPS) and coagulase-negative (CNS) staphylococcal strains isolated from meat and dairy products. Methods and Results: Specificity and reliability of the PCR detection methods used were ascertained by using nine reference strains of Staphylococcus (S. aureus) harbouring SE genes (seA to seE; seG, seH, seI, seM, seJ, seN and seO) and egc (containing the following sequence of genes: seO, seM, seI, uent1, uent2, seN and seG). Of 109 wild Staphylococcus spp. strains analysed, only 11 S. aureus strains were SE and/or TSST1 PCR-positive. The last 11 strains also appeared to harbour the egc. Restriction endonuclease analysis of part of the egc of both reference and wild strains showed that different variants of the egc exist. Moreover, nucleotide sequences of seG and seI indicate that the egc of the strain AB-8802 is characterized by the presence of variants of these enterotoxins (seGv and seIv). Conclusions: The occurrence of SE genes in CNS and other non-S. aureus species isolated from Napoli-type salami, raw water buffalo milk and natural whey cultures used for mozzarella cheese manufacturing is very rare. Significance and Impact of the Study: During this study it was shown that at least five different egc may exist in S. aureus. A thorough study of egc polymorphism should provide further insight into the phylogenetics of the egc.

Biological Activity of <i>Spartium junceum</i> L. (Fabaceae) Aromatic Water

“…Cells from an overnight growth culture of strains Staphylococcus aureus ATCC 6538 and AB-8802 (enterotoxinogenic strain) [13] were suspended in 0.5 mL of phosphate (KH 2 PO 4 ; Na 2 HPO 4 ) buffer (2 mM, pH 7) and mixed with 6 mL (0.7% w/v) of TSA (Oxoid) (final cell concentration was approximately 10 6 CFU/mL) tempered at 45˚C. Pure SJAW or diluted in ethanol (0.5% v/v) were added to the cell broth mixture yielding final concentrations of: a) SJAW 1% (estimated nerolidol concentration 2 mM); b) SJAW 5% (estimated nerolidol concentration 10 mM); c) SJAW 5% (estimated nerolidol concentration 10 mM) and 5% ethanol.…”

Combined application of origanum vulgare l. essential oil and acetic acid for controlling the growth of staphylococcus aureus in foods

“…These toxins are heat stable, resistant to gut proteases, and stable over a wide range of pH (pH 4-10) (37). Foods that are frequently associated with staphylococcal food poisoning include meat, salads, cream-filled bakery items, sandwich accoutrements, and dairy products (7,18).…”

Detecção de genes do cluster egc em Staphylococcus aureus isolados de alimentos de origem animal

“…Duas cepas, isoladas em embutidos, possuíam apenas o gene seln. Uma hipótese para a presença de cepas de S. aureus com cluster egc incompleto é o alto nível de polimorfismo genético que esse cluster pode apresentar (BLAIOTTA et al, 2004;THOMAS et al, 2006). Um resultado interessante foi que três cepas (uma isolada em embutidos e duas em queijos) não carreavam o gene sei, embora o gene seg tenha sido detectado, haja vista que há controvérsias na literatura em relação à necessidade da coexistência desses genes em uma mesma cepa.…”