Selective Enterotoxin Production by a Staphylococcus aureus Strain Implicated in a Foodborne Outbreak

Area of Science:

• Foodborne illness investigations
• Microbiology
• Public health

Background:

• Acute gastroenteritis outbreaks can pose significant public health challenges.
• Identifying the causative agent and source is crucial for effective control measures.
• Staphylococcus aureus is a common cause of food poisoning due to enterotoxin production.

Purpose of the Study:

• To investigate the cause of an acute gastroenteritis outbreak at a literary conference.
• To identify the suspect food and the etiological agent.
• To characterize the enterotoxin production of the isolated Staphylococcus aureus strain.

Main Methods:

• Epidemiological investigation including attack rate analysis to identify the suspect food (cheese tortellini).
• Microbiological analysis of food samples for Staphylococcus aureus enumeration.
• Biochemical and molecular characterization of S. aureus isolates, including enterotoxin typing and phage typing.

Main Results:

• Over 34.7% of participants became ill, with attack rate data implicating cheese tortellini.
• Staphylococcus aureus was isolated from the suspect food with high counts.
• The outbreak strain produced both staphylococcal enterotoxin A and C, but only type A was detected in the food due to delayed type C production.

Conclusions:

• The outbreak was caused by Staphylococcus aureus contamination of cheese tortellini.
• Selective enterotoxin production by S. aureus in food can complicate outbreak investigations.
• Understanding differential enterotoxin production kinetics is important for accurate food safety assessments.