The aim of the present work is to provide information about Enterococcus strains isolated from traditional Turkish cheese samples in Ankara (Turkey), focusing on their prevalence, phenotypic and genotypic characteristics, and antibiotic resistance. A total of 213 probable enterococcal isolates isolated from 215 samples were identified by phenotypic and genotypic methods. As a result of 16S rDNA sequence analysis, 88 of the 213 enterococci strains were identified as Enterococcus faecium and 125 as Enterococcus faecalis. The E. faecalis strains (58.7%) were identified as the dominant species isolated from cheese samples in Turkey. The 213 Enterococcus strains were tested for susceptibility to 12 different antimicrobial agents. The resistance phenotype were as follow: nalidixic acid (100%), kanamycin (98.6%), rifampicin (78.4%), ampicillin (48.8%), ciprofloxacin (45.5%), erythromycin (18.8%), tetracycline (11.7%), penicillin G (5.6%), chloramphenicol (4.2%), gentamycin (3.8%) and streptomycin (1.4%). None of the strains was resistant to vancomycin. E. faecium strains showed more resistant phenotypes than E. faecalis strains as shown by the antibiotic resistance levels. It was also observed that the resistance of E. faecium and E. faecalis strains against the antibiotics was statistically significant (p ˂ 0.05). In total, 100% of E. faecium and 88.8% of E. faecalis strains were resistant to multiple drugs.

Essential oils (EOs) are known for its antimicrobial activity against several pathogenic bacteria. The present work evaluated the antimicrobial activity of 15 different EOs on survival of different strains of different Staphyloccocus aureus strains isolated from traditional cheeses by disc diffusion method. The most antimicrobial activity on the strains was found as oil thyme oil (mean zone diameter 23.203 mm). Clove oil and black seed oil had the highest antimicrobial activity after thyme oil with average zone diameters of 13.698 mm and 11.267 mm respectively. Hypericum perforatum L. oil (mean zone 6.209 mm), ginger oil (mean zone 6.250 mm) and garlic oil (mean zone 6.267 mm) were the lowest antimicrobial activity. New studies about antimicrobial effect of EOs in vivo conditions are recommended.

Listeria monocytogenes is a foodborne pathogen frequently isolated from food that causes different public health problems. In recent years, antibiotic resistance of pathogens has become an important problem affecting human health. For this reason, it is crucial to develop an alternative to antibiotics. Thus, the antibacterial effects of herbal extracts and essential oils are frequently investigated. In this article, the antibacterial activity of extracts obtained from 16 different herbs using ethanol, chloroform, acetone, and distilled water was evaluated against L. monocytogenes strains. The extract showing the highest antibacterial effect against L. monocytogenes was St. John’s Wort extracted in ethanol (31.72 ±0.52 mm). In addition, Myrtus leaf extracted in ethanol (27.2 ±0.52 mm) and St. John’s Wort extracted in acetone (25.6 ±0.52 mm) showed a high antibacterial effect against L. monocytogenes compared to other extracts. In the study, the solvent ethanol in which St. John’s Wort and Myrtus leaf were extracted showed the highest antibacterial activity. In contrast, the solvent that rosemary extract showed the highest antibacterial effect was acetone. However, the most antibacterial herb extracted in distilled water was peppermint (7.03 ±0.52 mm). The extracts of marjoram and yarrow did not show any antibacterial effect in any solvent used in the study. In conclusion, more studies are needed to determine the antibacterial effects of herbal extracts against pathogens in foods and their use.

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