Multiplex PCR and RPLA Identification of Staphylococcus aureus enterotoxigenic strains from bulk tank milk

Area of Science:

• Food Safety
• Microbiology
• Veterinary Public Health

Background:

• Enterotoxigenic Staphylococcus aureus (S. aureus) in raw milk presents a significant food safety hazard.
• Accurate identification of S. aureus strains is crucial for risk assessment in milk and dairy products.

Purpose of the Study:

• To determine the prevalence of enterotoxigenic S. aureus in raw milk within the Czech Republic.
• To correlate the presence of staphylococcal enterotoxin genes (ses) with actual toxin production.
• To compare the efficacy of multiplex polymerase chain reaction (PCR) and reversed passive latex agglutination (RPLA) for detecting enterotoxigenic S. aureus.

Main Methods:

• Analysis of 440 bulk tank milk samples from 298 dairy herds.
• Detection of S. aureus using standard microbiological techniques.
• Identification of staphylococcal enterotoxin genes (ses) via multiplex PCR.
• Quantification of staphylococcal enterotoxins (SEs) using RPLA.

Main Results:

• S. aureus was identified in 15.9% of raw milk samples.
• Staphylococcal enterotoxin genes (ses) were found in 55.7% of S. aureus isolates, with sei, seg, and sea being the most common.
• Toxin production was confirmed in 12.9% of isolates, with discrepancies noted between PCR and RPLA, especially for SEA.

Conclusions:

• Multiplex PCR is a valuable tool for detecting staphylococcal enterotoxin genes, aiding in the identification of enterotoxigenic S. aureus strains.
• Discrepancies between gene detection and toxin production highlight the need for comprehensive risk assessment strategies.
• Monitoring enterotoxigenic S. aureus in raw milk is essential for ensuring dairy product safety.