Detection of Biofilm and some Enterotoxins of Staphylococcus aureus Isolates in Ice Cream

Abstract

Staphylococcus aureus is the most bacteria that have ability to form a biofilm and secret different types of enterotoxins that cause food poisoning in humans. Biofilms is a community of microorganisms encased in a matrix of extracellular polysaccharide (slime), called polysaccharide intercellular adhesion (PIA). They have related to a diversity of chronic and persistent infections. This study aims to detect the ability of S. aureus isolated from ice cream to form biofilm by Congo red agar (CRA), microliter plate, and PCR and the ability of S. aureus to produce enterotoxins by PCR. 15 S. aureus isolates were grown on CRA and microtiter plate method then subjected for detection of icaA and icaD genes by PCR and for the presence of enterotoxins genes (sea, seb, sec, sed, and see) which are responsible for S. aureus biofilm formation and Staphylococcus food poisoning. 73.3% of the isolates were biofilm producers on Congo red agar, 60% of the isolates were positive for biofilm production using microtiter plate method and by PCR technique, all the isolates 100% had icaD gene and 86.6% had icaA gene. The enterotoxin seb gene was detected in 5 (33.3%) S. aureus isolates, the enterotoxin see gene was detected in 4 (26.6%) S. aureus isolates while sea, seb and sed gens were not detected in any S. aureus isolates. In conclusion all aureus isolates were positive for icaD gene and some of S. aureus isolates were positive for icaA gene which are responsible for biofilm formation and some S. aureus isolates were positive for enterotoxin B and enterotoxin E, which responsible for food intoxication so the ice-cream considered a potential source for food intoxication and persistent infection caused by S. aureus.

Keywords

• biofilm, enterotoxins, food, s. aureus, pcr