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Presence of enterotoxigenic Staphylococcus aureus in artisan fruit salads in the city of San Luis, Argentina.

Estrada CS, Alcaráz LE, Satorres SE, Manfredi E, Velázquez Ldel C - Braz. J. Microbiol. (2014)

Bottom Line: By multiplex PCR, all isolates showed positive results for S. aureus 16S rRNA gene and 63.6% of them were positive for sea gene.The presence of S. aureus might indicate inadequate hygiene conditions during salad elaboration; however, the enterotoxigenicity of the strains isolated in this study, highlights the risk of consumers' intoxication.EDTA could be used to inhibit the growth of S. aureus in artisan fruit salads and extend the shelf life of these products.

View Article: PubMed Central - PubMed

Affiliation: Microbiología General, Universidad Nacional de San Luis, San Luis, Argentina.

ABSTRACT
An increase in the consumption of fruit juices and minimally processed fruits salads has been observed in recent years all over the world. In this work, the microbiological quality of artisan fruit salads was analysed. Faecal coliforms, Salmonella spp, Shigella spp, Yersinia enterocolitica and Escherichia coli O157:H7 were not detected; nevertheless, eleven strains of Staphylococcus aureus were isolated. By multiplex PCR, all isolates showed positive results for S. aureus 16S rRNA gene and 63.6% of them were positive for sea gene. Furthermore, PCR sea positive strains were able to produce the corresponding enterotoxin. Finally, the inactivation of these strains in fruit salads by nisin, lysozyme and EDTA, was studied. EDTA produced a total S. aureus growth inhibition after 60 h of incubation at a concentration of 250 mg/L. The presence of S. aureus might indicate inadequate hygiene conditions during salad elaboration; however, the enterotoxigenicity of the strains isolated in this study, highlights the risk of consumers' intoxication. EDTA could be used to inhibit the growth of S. aureus in artisan fruit salads and extend the shelf life of these products.

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Related in: MedlinePlus

Multiplex PCR for S. aureus enterotoxin genes. A) sea (521 bp), seb (667 bp), sec (284 bp), and 16S ARNr (228 bp). Lines 1–7: isolates corresponded to the seven samples obtained from fruit salads; lines 8–10: sea, seb and sec positive controls respectively; line 11: negative control. B) sed (385 bp), see (171 bp), and 16S ARNr (228 bp). Lines 1–7: isolates corresponding to the seven samples obtained from fruit salads; lines 8 and 9: sed and see positive controls respectively; line 10: negative control. M: 100 bp marker ladder.
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f1-bmj-44-4-1155: Multiplex PCR for S. aureus enterotoxin genes. A) sea (521 bp), seb (667 bp), sec (284 bp), and 16S ARNr (228 bp). Lines 1–7: isolates corresponded to the seven samples obtained from fruit salads; lines 8–10: sea, seb and sec positive controls respectively; line 11: negative control. B) sed (385 bp), see (171 bp), and 16S ARNr (228 bp). Lines 1–7: isolates corresponding to the seven samples obtained from fruit salads; lines 8 and 9: sed and see positive controls respectively; line 10: negative control. M: 100 bp marker ladder.

Mentions: S. aureus was isolated from eleven (7.81%) of the investigated samples, with counts varying between 1.30 and 2.47 log10 cfu/g (mean 1.75 ± 0.49). All the isolates were thermonuclease positive and coagulase 4+. It was observed no organoleptic or physical difference between S. aureus positive and negative fruit salads. All salads were prepared with pieces of oranges, peaches, banana and apples, and had a similar pH. All S. aureus isolates showed positive results when the presence of 16S rRNA gene was studied by multiplex PCR. Furthermore, 7 out of the 11 strains (63.6%) were positive for the sea gene (Figure 1) and for the production of the SEA enterotoxin. None of other investigated genes or toxins were detected. All strains were resistant to penicillin but susceptible to the remaining antimicrobial agents.


Presence of enterotoxigenic Staphylococcus aureus in artisan fruit salads in the city of San Luis, Argentina.

Estrada CS, Alcaráz LE, Satorres SE, Manfredi E, Velázquez Ldel C - Braz. J. Microbiol. (2014)

Multiplex PCR for S. aureus enterotoxin genes. A) sea (521 bp), seb (667 bp), sec (284 bp), and 16S ARNr (228 bp). Lines 1–7: isolates corresponded to the seven samples obtained from fruit salads; lines 8–10: sea, seb and sec positive controls respectively; line 11: negative control. B) sed (385 bp), see (171 bp), and 16S ARNr (228 bp). Lines 1–7: isolates corresponding to the seven samples obtained from fruit salads; lines 8 and 9: sed and see positive controls respectively; line 10: negative control. M: 100 bp marker ladder.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3958181&req=5

f1-bmj-44-4-1155: Multiplex PCR for S. aureus enterotoxin genes. A) sea (521 bp), seb (667 bp), sec (284 bp), and 16S ARNr (228 bp). Lines 1–7: isolates corresponded to the seven samples obtained from fruit salads; lines 8–10: sea, seb and sec positive controls respectively; line 11: negative control. B) sed (385 bp), see (171 bp), and 16S ARNr (228 bp). Lines 1–7: isolates corresponding to the seven samples obtained from fruit salads; lines 8 and 9: sed and see positive controls respectively; line 10: negative control. M: 100 bp marker ladder.
Mentions: S. aureus was isolated from eleven (7.81%) of the investigated samples, with counts varying between 1.30 and 2.47 log10 cfu/g (mean 1.75 ± 0.49). All the isolates were thermonuclease positive and coagulase 4+. It was observed no organoleptic or physical difference between S. aureus positive and negative fruit salads. All salads were prepared with pieces of oranges, peaches, banana and apples, and had a similar pH. All S. aureus isolates showed positive results when the presence of 16S rRNA gene was studied by multiplex PCR. Furthermore, 7 out of the 11 strains (63.6%) were positive for the sea gene (Figure 1) and for the production of the SEA enterotoxin. None of other investigated genes or toxins were detected. All strains were resistant to penicillin but susceptible to the remaining antimicrobial agents.

Bottom Line: By multiplex PCR, all isolates showed positive results for S. aureus 16S rRNA gene and 63.6% of them were positive for sea gene.The presence of S. aureus might indicate inadequate hygiene conditions during salad elaboration; however, the enterotoxigenicity of the strains isolated in this study, highlights the risk of consumers' intoxication.EDTA could be used to inhibit the growth of S. aureus in artisan fruit salads and extend the shelf life of these products.

View Article: PubMed Central - PubMed

Affiliation: Microbiología General, Universidad Nacional de San Luis, San Luis, Argentina.

ABSTRACT
An increase in the consumption of fruit juices and minimally processed fruits salads has been observed in recent years all over the world. In this work, the microbiological quality of artisan fruit salads was analysed. Faecal coliforms, Salmonella spp, Shigella spp, Yersinia enterocolitica and Escherichia coli O157:H7 were not detected; nevertheless, eleven strains of Staphylococcus aureus were isolated. By multiplex PCR, all isolates showed positive results for S. aureus 16S rRNA gene and 63.6% of them were positive for sea gene. Furthermore, PCR sea positive strains were able to produce the corresponding enterotoxin. Finally, the inactivation of these strains in fruit salads by nisin, lysozyme and EDTA, was studied. EDTA produced a total S. aureus growth inhibition after 60 h of incubation at a concentration of 250 mg/L. The presence of S. aureus might indicate inadequate hygiene conditions during salad elaboration; however, the enterotoxigenicity of the strains isolated in this study, highlights the risk of consumers' intoxication. EDTA could be used to inhibit the growth of S. aureus in artisan fruit salads and extend the shelf life of these products.

Show MeSH
Related in: MedlinePlus