Identification and characterization of enterococci from bryndza cheese

Area of Science:

• Food microbiology
• Bacterial genetics
• Dairy science

Background:

• Enterococci are common in dairy products, including sheep milk bryndza cheese.
• Understanding the enterococcal species composition and their potential for antibiotic resistance and virulence is crucial for food safety.
• Seasonal variations may influence the microflora in cheese.

Purpose of the Study:

• To identify enterococci in bryndza cheese.
• To compare seasonal differences in enterococcal microflora composition.
• To assess the presence of vancomycin resistance and virulence genes.

Main Methods:

• Isolation and identification of Enterococcus species using phenotypic methods and commercial biochemical sets.
• Confirmation of species identification via PCR with species-specific primers.
• Detection of vancomycin resistance genes (vanA, vanB) and virulence determinants (gelE, agg, cyl genes) using PCR.

Main Results:

• Enterococcus faecium was the dominant species (177 isolates), followed by Enterococcus durans (59) and Enterococcus faecalis (41) among 308 Enterococcus strains.
• Vancomycin resistance genes vanA and vanB were not detected in any isolates.
• The virulence gene gelE was found in 20 E. faecalis isolates, agg in 4 isolates, and cytolysin genes in 7 isolates, though phenotypic expression was limited.
• Enterococcus faecium prevalence was highest in winter cheese samples.

Conclusions:

• Enterococcus faecium is the predominant enterococcal species in bryndza cheese, with higher prevalence during winter.
• No vancomycin resistance (vanA, vanB genes) was found in the analyzed enterococci from bryndza cheese.
• This study provides the first report on enterococcal microflora in bryndza cheese and its associated resistance and virulence determinants.