Molecular Screening of Staphylococcal Enterotoxin B Gene in Clinical Isolates

Abstract

Objective: The role of staphylococcal enterotoxin B (SEB) in food poisoning is well known,however its role in other diseases remains to be explored. The aim of this study is the molecularscreening and characterization of the SEB gene in clinically isolated strains.Materials and Methods: In this experimentally study, 300 Staphylococcus aureus (S.aureus) strains isolated from clinical samples were assayed. The isolated strains wereconfirmed by conventional bacteriological methods. Polymerase chain reaction (PCR)was used to determine the enterotoxin B (ent B) gene. Assessment of toxin productionin all strains that contained the ent B gene was then performed. Finally, using specificantibody against SEB, a Western-blot was applied to confirm detection of enterotoxin Bproduction.Results: Results indicated that only 5% of the 300 clinically isolated S. aureus containedthe ent B gene. All strains which contained the ent B gene produced a proteinous enterotoxinB. The results of sequence determination of the PCR product were compared withthe gene bank database and 98% similarity was achieved. The results of the Western-blotconfirmed that enterotoxin B was produced in strains that contained the ent B gene.Conclusion: The results of this study indicate that 5% of clinically isolated S. aureusstrains produce enterotoxin B. Considering that the enterotoxin B is an important superantigen,it is possible that a delay in diagnosis and lack of early proper treatment can causean incidence of late complications, particularly in staphylococcal chronic infections. Forthis reason, it is suggested that in addition to detecting bacteria, an enterotoxin B detectiontest should be performed to control its toxigenicity.

Keywords

• Screening
• Staphylococcus aureus
• Enterotoxin B
• PCR
• Western-Blot